http://mbal.adv.br/templates/vuvupal/localizar-celular-robado-iusacell.html Good surface location and release properties were obtained via two-step functionalisation with APTES and IPTES silane anchoring moieties, which play a key role in delivering antimicrobial properties. Cell viability assays on planktonic and sessile bacteria and SEM characterisation of bacterial attachment were carried out for three model microorganisms associated to medical device biofilms, E.
We demonstrated that our surface modification approach led to effective antibacterial coatings based on surface-located interactions that allow the creation of stacking nucleation points of the biocide at the interface. This approach could be translated to existing medical devices and be used to prevent surface colonisation by bacterial pathogens. Resume : This study makes evident the possibility of the Bi-doped hydroxyapatite nanocrystals to be deposited on the titanium implant surface by a solution-derived process according to an established biomimetic methodology.
Titanium implants were then coated with a Bi-doped hydroxyapatite layer under biomimetic conditions by using a supersaturated calcification solution SCS modified by adding a bismuth salt.
Biointerface Characterization by Advanced IR Spectroscopy. Book • Edited by: C.M. Pradier and Y.J. Chabal. Browse book content. About the book. Purchase Biointerface Characterization by Advanced IR Spectroscopy - 1st Edition. Print Book & E-Book. ISBN ,
The obtained results confirmed that the nanohydroxyapatite coatings on titanium surface were produced and bismuth ions incorporated into hydroxyapatite lattice. The Bi-doped hydroxyapatite coatings exhibit radiopacity, enhancing thus their applications in dental and orthopedic fields. These coatings show antimicrobial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Resume : Hydrogels and porous scaffolds are two major categories of biomaterials used in tissue engineering.
These two materials exhibit different, but complementary properties. Hydrogels are easy to fabricate and injectable in clinic but they are soft and lack of mechanical integrate for cell attachment and directed cell growth. On the other hand, porous scaffolds can be fabricated by electrospinning with aligned 3D fibrous structure that promotes cell migration and directional growth.
However, the scaffold needs surgically implanted into human body. To take the merits of each material, one can make injectable nano-composite hydrogels with mechanical integrate for clinic use. So far, most nano-composite hydrogels used in tissue engineering are composed of peptide self-assembly nano-particles which are crosslinked by divalence ions.
By ionic crosslinking, the nano-composite hydrogels are soft enough for injection and nano-particles become 2D sheet to adhere cells at the same time. To be able to self-assemble into nano-particles, these peptides have to have specific amino-acid sequence, which is high-cost, time-consuming and low yield in synthesis.
Thus, we develop a new kind injectable nano-composite hydrogel basis on polypeptide and cellulose nano-fiber CNF. The polypeptide is synthesized using conventional ring opening polymerization of r-benzyl-L-glutamate N-carboxy anhydride. This modification make the polypeptide become water-soluble. The nanocomposite is made by blending modified polypeptide with CNF. The modified side chain is capable to interact with CNF to form hydrogen bond that results in hydrogel. Furthermore, the material has 3D structure with directional frame work that has potential application in the required directional growth of neural tissue engineering.
Resume : Antimicrobial peptides AMPs are promising alternatives to antibiotics for the treatment of drug-resistant and biofilm-associated infections, which are a serious global health threat. Adhesion tests to assess the substrate-nanocoating interface were also performed. The biocompatibility of the obtained nanocoatings was investigated using in vitro models.
This approach may be employed to enhance the anti-biofilm properties of implants, medical devices, and other surfaces. Resume : The current research endeavors in the biomedical field are focused on innovative biointerface materials design that can replace the classical silica-based bioactive glass SBG systems, possessing a significant thermal expansion coefficient CTE mismatch with respect to Ti-based alloys, and simultaneously endow with superior biological functionalities e. For biological evaluation, antibacterial against Staphylococcus aureus and Escherichia coli strains tests, and human mesenchymal stem cells cytocompatibility assays were also carried out.
The results showed that the coupled incorporation of zinc and strontium ions into the parent glass composition has a synergetic benefit. In particular, the? Our work opens new perspectives in the crucial development of future mechanically adherent implant-type SBG coatings. Resume : In living tissues, cells are supported by a 3D extracellular matrix ECM that controls and supports cellular functions.
A plethora of nanomaterials have been engineered to mimic the properties of fibers present in natural ECMs. Moreover, nanomaterials can be combined to synthetic scaffolds to add wireless, localized cellular cueing properties. Among potential scaffold materials, cellulose nanocrystals CNC are attractive owing to cellulose availability, excellent mechanical properties and functionalization possibilities .
In this work, we construct 2D matrices based on CNC and in-situ grown gold nanoparticles AuNPs allowing for light-driven, photothermal and electrical cell stimulation. The effect of deposition parameters on scaffold properties is studied with atomic force microscopy and spectrophotometry. CNC patterning and coverage are controlled with micro-contact printing. As previously observed for other biological fibers , AuNPs selectively grow from CNC, their morphology being controlled from spherical to wire shape by varying growth conditions. Satisfactory cellular viability and positive preliminary cell actuation results show excellent prospects for localised cellular stimulation in both 2 and 3D using hybrid CNC scaffolds.
Nanoscale , 6, Resume : Gold nanoparticles AuNP are ideal theranostic platforms, due to their unique optoelectronic and biological properties . Hyaluronic acid HA -derived conjugates and nanoparticles that specifically binds the CD44 receptor, overexpressed in many cancer cells, have been reported for targeted delivery of therapeutics and imaging agents . The HA biological activity, which depends on the molecular weight, is strongly affected in vivo by enzyme degradation as well as in extreme reaction conditions such as the high temperature.
The fluorescein-labelled HAF derivative was used as well. Confocal cell imaging and viability tests performed on CD44 overexpressing PC3 line and non-expressing SHSY5H line cells demonstrated selective targeting and dose-dependent cytotoxicity. Di Pietro et al. Bhattacharya et al. Lowry et al. Resume : The effects of grain-boundary on the osteoconductivity of hydroxyapatite were newly investigated.
The hydroxyapatite disks, which had small specimen S and large specimen L grain sizes, were prepared through microwave sintering at oC for 6 min and min, respectively. The average grain size of specimen S was about 15 times smaller than that of specimen L. Their surface roughnesses were the same after polishing.
The surface energy of specimen S, obtained from contact angle measurements, was about 1. The adsorbed amounts of total serum proteins, fibronectin, vitronectin, and osteogenic growth peptide, substances related to osteogenic capacity, were all about two times higher on specimen S than on specimen L. The attachment and proliferation activities of pre-osteoblastic cells evaluated by MTS assay were also enhanced on specimen S as compared to specimen L. The differentiation capacity measured by alkaline phosphatase and Alizarin Red S activities were also upregulated for the cells cultured on specimen S as compared to those on specimen L.
The osteoconductivity of specimen S was superior to that of specimen L four weeks after implantation in calvarial defects of New Zealand white rabbits. Taken together, it can be concluded that the hydroxyapatite with a small grain size, which had high numbers of grain-boundaries per unit area, had a strong osteogenic capacity compared with the hydroxyapatite with a large grain size due to its high surface energy, which enriched the adsorption of serum proteins.
Resume : Bioadhesive polymeric hydrogels capable of firm adhesion to various biological tissues have acquired considerable attention due to their significance in medicine and dentistry. Thus far many types of bioadhesive hydrogels have been investigated using different polymers such as polyacrylates, poly ethylene glycol s, and the derivatives of polysaccharides and proteins, while less attention has been paid to polyamphoteric properties of crosslinked polymer networks. Tissue adhesion of hydrated gels was evaluated in vitro using the excised porcine intestine as a substrate, and the data were compared with that measured for the pure poly acrylic acid PAAc hydrogel that is a bioadhesive system most-extensively studied ever.
In this study, we will demonstrate that incorporation of a small fraction of the cationic monomer, DMAPAA, to a PAAc hydrogel produces the polyamphoteric hydrogel that exhibits firm adhesion toward mucosa. The adhesion enhancement by cation incorporation will be discussed in terms of the network structure of the polyamphoteric hydrogels and its nanoscale dynamics leading to firm interactions between polymer segments and mucosal components.
Although these cells are considered to be a promising source for stem cell-based regenerative therapy for CNS disorders, a novel technology is still required to efficiently produce a pure population of NPCs in large quantity. For this challenge, we made an attempt to molecularly design the surface of culture substrates, taking advantage of an ability of epidermal growth factor EGF that can specifically interact with NPCs to promote these cells to proliferate. In this study, EGF was immobilized onto the surface of glass-based substrate.
On the other hand, NPC-containing neurospheres were obtained by culturing mouse induced pluripotent stem iPS cells in suspension in the presence of soluble EGF and basic fibroblast growth factor. The neurospheres were dissociated into single cells and seeded to the EGF-immobilized substrates.
It was observed that neurosphere-forming cells seeded and cultured on the EGF-immobilized surface formed a 2-dimensional cellular network that is characteristic of NPCs. The number of cells increased approximately 9 folds after 3-day culture on the substrate, demonstrating that the substrate enable us to efficiently expand NPCs derived from iPS cells. Resume : The effectiveness of cancer therapy relies on delivering therapeutic agent specifically and recognizing of target site precisely.
These two factors play a vital role in optimizing the treatment outcome while minimizing side effects. In this study, we demonstrate that iron-doped hydroxyapatite nanocrystals with mesoporous structure MPmHAp are successfully prepared through one-pot synthesis process. The size of MPmHAp is nm in length and nm in width with short rod-like morphology. These MPmHAp not only demonstrate mesoporous structure, high surface to volume ratio for efficient drug loading capacity, but also have good cell biocompatibility.
Also, they possess superparamagnetic property and show controlled drug release profile through magnetic triggering. MPmHAp nanocrystals can further generate heat under applied alternative magnetic field. Resume : Hydrogels are water-swollen polymer networks that have found a range of applications from drug delivery to regenerative medicine.
Historically, their design has consisted mainly of static systems and those that undergo simple degradation. However, advances in polymer synthesis and processing have led to a new generation of dynamic systems that are capable of responding to artificial triggers and biological signals with spatial precision. These systems will open up new possibilities for hydrogels as model biological structures and in tissue regeneration. In this presentation, we will report the evolution of hydrogel design towards dynamic behavior and particularly emphasize recent developments in hydrogel design that offer the ability to precisely control trigger-responsive properties.
Resume : Repairing cartilage defects remains challenging due to its sophisticated properties and limited regeneration capacity. To address this, we developed an injectable thermosensitive hydrogel based on chitosan, which can be administered to the site of injury non-invasively. This hydrogel is able to provide long-term release of two drugs with different therapeutic effects including kartogenin KGN , a small molecule which promotes chondrogenesis and diclofenac sodium DS which is commonly used as an anti-inflammatory drug.
To achieve such properties, chitosan was chemically modified with maleimide, and for further enhancement of the hydrogel? In addition, KGN was encapsulated in the starch microspheres by a droplet microfluidic chip for chondrogenic differentiation of human adipose mesenchymal stem cells hAMSCs which were further incorporated in the hydrogel.
Also, further incorporation of the microspheres within the hydrogel, increased chondrogenic differentiation of hAMSCs significantly. We believe that this innovative hydrogel shows promising capability to be used for cartilage tissue engineering applications. Resume : Bone tissue engineering aims regeneration of defected biological bones by combining cells, scaffolds, and growth factors. However, growth rate of bone tissue components are slower than adjacent soft tissues. Therefore, defected bone tissues are required a barrier membrane and a guiding scaffold for intact restoration of a target tissue.
Here, we prepared patient-customizable guided bone regeneration GBR membrane-guided tissue regeneration GTR scaffold hybrid constructs for precise bone tissue restoration without dimensional collapse. Silk fibroin nanofiber membranes were prepared by electrospinning method. Initial attachment and proliferation of preosteoblasts on a PGA scaffold was analyzed by seeding efficiency and MTT assay.
In vivo animal study was performed using rabbit calvarial defect model for 8 weeks. Regenerated tissues were visualized by Masson Trichrome staining. Regenerated bone volume was calculated by micro-computed tomography. The silk fibroin-PGA hybrid scaffold group showed significant regeneration of bone tissue compared to control groups. They have effectively shown fascinating results in diseases such as cancer, infectious or neurodegenerative disorder.
They have indeed received a great attention since their development as a liver contrasting agent 20 years ago1. Furthermore, their nanoparticulate properties represented by the nanosized dimension and shape allow different biodistribution and opportunities beyond the conventional imaging of chemical agents. Coating those biocompatible NPs by a smart polymer shell that can ensure not only a better stability of the nanomaterials in the body but also enhance their biodistribution and new functionalities which make them ideal candidates for medicinal applications2.
The second family consists in the same nanoparticles were the folic acid was grafted at the chain end to target Fr-? From the results obtained, it can be concluded that our new nanomaterials can be considered for further use as multi-modal cancer therapy tools. Resume : Although cancer stem cells CSC are thought to be responsible for tumor recurrence and resistance to chemotherapy, CSC-related research and drug development have been hampered by the limited supply of diverse, patient-derived CSC.
Here, we present a functional polymer thin film PTF platform that promotes conversion of cancer cells to highly tumorigenic three-dimensional 3D spheroids without the use of biochemical or genetic manipulations. Culturing various human cancer cells on the specific PTF, poly 2,4,6,8-tetravinyl-2,4,6,8-tetramethyl cyclotetrasiloxane pV4D4 , gave rise to numerous multicellular tumor spheroids within 24 hours with high efficiency and reproducibility.
Cancer cells in the resulting spheroids showed a significant increase in the expression of CSC-associated genes and acquired increased drug resistance compared with two-dimensional monolayer-cultured controls. These spheroids also exhibited enhanced xenograft tumor-forming ability and metastatic capacity in nude mice. By enabling the generation of tumorigenic spheroids from diverse cancer cells, the surface platform described here harbors the potential to contribute to CSC-related basic research and drug development.
The present study analyzes long term in vitro degradation profile of simple and composite films in dynamic flux of simulated body fluid. The obtained biological results proved that the thin films stimulate and support tissue growth. Static water contact angles measurement indicated that hydrophilicity of the composite films containing more PEG has improved considerably.
It has been shown that the degradation of PCL-PEG blends increase with a decreasing crystallinity of the PEG, and can be controlled by adjusting the component ratio of the blends. It was found that the degradability of the polycaprolactone was improved by introducing a PEG component into it. The degradation of PCL -PEG copolymer increase with a decreasing crystallinity of the copolymer, and can be controlled by adjusting the component ratio of the copolymer.
Ezymatic biofuel cells EBFCs , which convert chemical energy of the oxidation of carbohydrates, such as glucose, in combination with oxygen reduction, under mild condition, come to attract considerable attention as power sources for wearable devices or self-powered sensor-node systems. A combination of electron transfer technology and porous carbon material would be helpful in achieving a much higher and stable current output, thus contributing to a practical advance in the sustainable energy field.
To realize high current density per geometric surface area, the concentration of buffer solution should be increased to prevent the local pH change during the electro-enzymatic reaction and also to minimize the ohmic solution resistance in the cell. I will show the effect of characteristics and concentration of electrolyte on the electroenzymatic reaction.
We report here the characterization and bioelectrocatalysis of? We depart from the traditional use of immobilized redox molecules and polymers and instead explore the use of solubilized redox nanoparticles and enzymes in solution for mediated bioelectrocatalysis. This approach can offer possibilities such as refueling, higher biocatalyst concentrations compared to immobilisation methods, size exclusion principles to avoid cross-reactions, and dynamic reactivity based on diffusion and rotation.
We will provide spectroscopic and electrochemical data which reveals the controlled self-assembly of nanoparticles with host-guest functionality that can integrate insoluble redox species in aqueous buffer solutions . The use of different nanoparticles with bilirubin oxidase and FAD-dependant glucose dehydrogenase enzymes will be demonstrated and compared with classical systems for oxygen reduction and glucose oxidation, respectively.
Finally, the new SEFC-carbon nanotube buckypaper biodevice and its use for long-term quasi-continuous power generation will be demonstrated [3,5]. It is feasible that SEFCs, in combination with a boost converter, could be exploited as a new generation of green power sources for low-power electronics such as lab-on-a-chip sensing and data transmission devices. Resume : Electrical interactions between bacteria and the environment are delicate and essential . For instance, by means of electron transfer, bacteria complete respiration on the cell membrane to supply energy for cell growth, proliferation, and maintenance and disturbing electron transfer in bacteria can raise the production of reactive oxygen species ROS to hinder growth.
In this study , an external electrical current is applied to capacitive titania nanotubes doped with carbon TNT-C to evaluate the effects on bacteria killing and the underlying mechanism is investigated. When TNT-C is charged, post-charging antibacterial effects proportional to the capacitance are observed. This capacitance-based antibacterial system works well with both direct and alternating current DC, AC and the higher discharging capacity in the positive DC DC group leads to better antibacterial performance.
Extracellular electron transfer observed during early contact contributes to the surface-dependent post-charging antibacterial process. Physiologically, the electrical interaction deforms the bacteria morphology and elevates the intracellular reactive oxygen species level without impairing the growth of osteoblasts. This is the first systematic study on the post-charging antibacterial properties of biomaterials with tunable capacitance.
Our finding spurs the design of light-independent antibacterial materials and provides insights into the use of electricity to modify biomaterials to complement other bacteria killing measures such as light irradiation. References  G. Wang, H. Feng, et al. Wang, W. Jin, et al. Biomaterials, vol.
Nature Communications, vol. We have demonstrated that these nanofiber mats deposited on five-patterned indium tin oxide finger electrodes are excellent candidates for use as functional bioelectronic interfaces for the isolation, detection, sequential collection, and enrichment of rare CTCs through electrical activation of each single electrode. This combination behaved as an ideal model system displaying a high cell-capture yield for antibody-positive cells while resisting the adhesion of antibody-negative cells.
This 3D PEDOT-based bioelectronic device approach appears to be an economical route for the large-scale preparation and detection of systems for enhancing the downstream characterization of rare CTCs. Resume : The interaction of biomolecules with solid surfaces? The diversity of carbon allotropes gives access to a large variety of structural and textural properties, while the complexity of biomolecules e.
In this presentation, I will discuss few examples of biomolecule-carbon interfaces for the design of functional materials. In a first example, I will present the preparation of aqueous colloidal suspensions obtained via the co-dispersion of multi-walled carbon nanotubes MWCNTs and polysaccharides, e. Such dispersions were successfully employed to stabilize oil-in-water smart interfaces and elaborate hierarchical composite structures, e.
In a second example, I will introduce the importance of biomolecule-carbon interfaces in enzymatic catalysis and electrocatalysis, via pore confinement and surface modification. In our group, a particular attention has been given to formate dehydrogenases FDHs , which require the loosely bound cofactor nicotinamide adenine dinucleotide NAD. We recently developed carbon-based flow through enzymatic reactors for the production of formate from carbon dioxide and a novel method to covalently immobilize NAD onto carbonaceous materials.
Resume : Despite research and clinical efforts of the last decades, there is no cure for spinal cord injury to date. Remarkable drawbacks of this type of lesions include dramatic changes in the quality of life and life expectancy of patients, affected by a disruption of neural connections through the spinal cord. Aiming to provide more effective therapeutic alternatives, neuroscience, nanotechnology, and materials science are working together on the development of novel biocompatible implants capable of improving the functionality of the damaged neural tissue at the lesion.
In the ByAxon Project, we have developed a new generation of 2D nanoelectrodes consisted of vertically arranged metal nanowires NWs made of Ni and Au and grown by template-assisted electrodeposition over a flexible gold base. The behavior of neural progenitor cells isolated from rat embryos has been studied in culture on these substrates with focus on cell adhesion, viability, morphology, and differentiation. Neural cells properly adhere and spread, closely interacting with the metallic NWs. After 2 weeks, these cells are able to form dense neural networks with high viability and mainly composed of neurons.
These results encourage further research in the use of these materials as stimulating nanoelectrodes for the development of a local bypass directly working at the spinal cord. This project is funded by the European Union? Resume : The concept to artificially reconstitute an electroactive biofilm is a recent strategy used in order to optimize extracellular electron transfer EET reactions and mimic natural biofilms . Those artificial biofilms would greatly benefit to electrochemical bacterial devices such as microbial fuel cell or sustain biosensors.
They would also benefit to microbial electrosynthesis or electrocatalysis. Recent studies have reported the application of microbial electrochemical systems in biochemical production of ethanol or hydrogen and to the bioremediation of sulphate or nitrogen species in aqueous environment. In this work, we studied the direct electron transfer reactions occurring in a biocomposite resulting from the self-assembly of microbes with carbon nanomaterials and proteins.
Both bacteria and yeast cells have been evaluated. For example, with Shewanella oneidensis MR1, the onset potential observed for fumarate electroreduction was found very close to 0. In this communication, we will describe and discuss this new way to promote direct electron transfer reactions in electroactive artificial biofilms. Pinck et al. Resume : A major challenge for bioelectronics lies in the monitoring of electrical activities of neurons at the single cell level, both with high resolution of measure and applied simultaneously to multiple locations.
One breakthrough is the development of a new class of devices that take advantage of miniaturization in electronics, thereby refining the investigation resolution. Here, we present a bio-platform with 3D passive nanoprobes based on nanostructures with very high surface-to-volume ratio.
The device is created using a large-scale fabrication process based on conventional silicon processing. The electrodes are composed of several nanowires, where the design size, pitch … has been optimized to favour the engulfment of the cell. We demonstrate that the surface engineering of the probes at nanoscale leads to drastic reduction in the electrode impedance.
This key factor is able to enhance the signal resolution fold when compared to conventional MEA planar technology. We could register spontaneous activity of primary rat neurons with record amplitudes, not only for action potentials ten of mV , but also smaller signals Pre- and Post-Synaptic Potentials PSPs usually invisible with planar MEAs.
Resume : Science is facing the challenge of directly interact with neural tissues to perform electrical stimulation of the neural activity in zones that have been compromised. Spinal cord stimulators, cortical electrodes or retina implants, are some of the devices inspired by this technology. These electrode-based devices nowadays present size, morphology and rigidity issues that unleashes an immunologic response that inactivates them. We are developing new biocompatible flexible electrodes with nanostructured surface.
They are composed by a flexible Au thin sheet with one of its surfaces covered by a network of metallic vertical NWs. The aspect-ratio of the NWs ensures high contact with neural tissue and their size in the nanoscale minimises the damage. We obtain our structures depositing metals using template assisted electrodeposition. We can vary the diameter, length and material Au, Ni, Fe The positive results of the biocompatibility studies support the potential and viability of our electrodes as functional electrical stimulating devices.
Resume : Among the single-molecule detection methods proposed so far, only a few are exploitable for real clinical sensing. Large-area organic-bioelectronics is emerging as a cross-disciplinary research field for the development of a platform capable of selective, label-free and fast biomarker detection at the physical limit in real biofluids. A mass-manufacturable platform with such characteristics holds the potential to bring precision medicine into the everyday medical practice, revolutionizing our current approach to clinical analysis.
This lecture aims at critically prioritize the main technologies for single-molecule detection. Scrutinized figures-of-merit include, besides limit-of-detection and selectivity, feasibility of operation in real-fluids, time-to-results and cost-effectiveness. Electrolyte-Gated Field-Effect-Transistors EG-FETs  with a bio-functionalized large-area sensing gate, appear as very promising, also over organic-electrochemical-transistor. The material science and the devices operational aspects underpinning EG-FETs unprecedented sensing performance, including the role of the cooperative hydrogen-bonding network and the gate-channel strong capacitive coupling, are discussed.
References 1. Macchia, E. Single molecule detection with a millimetre-sized transistor. Nature Communications 9, Nature highlights - Selections form the scientific literature. Nature , Label-free and selective single-molecule bioelectronic sensing with a millimeter-wide self-assembled monolayer of anti-immunoglobulins. Chemistry of Materials in press 4. Analytical and Bioanalytical Chemistry in press Resume : This talk will provide an overview of the PIs' efforts to understand the dynamics of biomineralization via in-situ transmission electron microscopy.
First we demonstrate how to utilize graphene sheets to build a liquid-cell nanoreactor that fits the chamber of high-resolution TEM. Graphene is impermeable to liquids such as aqueous solutions and therefore can be used to seal liquid solutions from leaking to the high vacuum of TEM environment. In addition, the excellent electrical conductivity of graphene and its ability to scavenge the radicals produced by the interaction of electron beam and liquid solutions provide an excellent platform to perform imaging of biological or hydrated specimens.
We then demonstrate our success to observe the biomineralization of hydroxyapatite HA crystals. Our results show that HA crystals follow classical and non-classical nucleation theories to from within a supersaturated solution. The solution initially goes through ion-rich and ion-poor liquid-liquid phase separation. We also studied the effect of molecular modifiers on the effect of calcium oxalate crystals that are the primary constituent of kidney stones.
We show that the addition of citrate can affect the crystallization pathway of these minerals. Interestingly, the citrate molecules affect the pre-nucleation stage of CaOx crystals making them thermodynamically stable. In addition, the addition of citrate reduces the stability of calcium oxalate monohydrates. In addition, we will showcase some examples of biomineralization of iron oxide core in ferritin proteins and demonstrate the ability to monitor the biomineralization of these crystals using graphene liquid cells in TEM.
We will show that the ratio of L and H subunits in the ferritin protein shells can affect the nucleation and growth of iron oxide cores. We also will present our latest results on the biomineralization of magnetosomes in magnetotactic bacteria grown in iron-rich media using in situ GLC-TEM studies. We observed that such bacteria can remain alive and intact during TEM imaging and follows the classical nucleation theory for the biomineralization of magnetosomes. Resume : Nanohydroxyapatite nanoHA are key materials for bone tissue healing, and their functional behavior is ruled in large extent by nature and structure of sites exposed at their surfaces.
Relevant challenges are well beyond the recognition of crystallographic facets limiting nanoparticles: for nanoHA the most abundant terminations are just of one type, namely , but the atomic structure they expose can be of three types: stoichiometric, Ca-rich and P-rich . These important features are often elusive by direct microscopy imaging, in particular the assessment of their relative amount.
Astala and M. Stott, Phys. B 78  B. Kasemo, Surf. The control on the distribution of ceramic nanoparticles such hydroxyapatite HA and Lactoferrin LF could significantly influence the cellular response at nano-composites interfaces, as well as the final application towards implants application. Therefore, this work is focused on embedding HA spherical nanoparticles and lactoferrin LF within synthetic biodegradable copolymers Poly ethylene glycol - block-poly?
The controlled incorporation of HA and LF within the synthetic copolymeric substrates was performed by matrix assisted pulsed laser evaporation MAPLE method using a modular target system. The biofunctionality of the coatings has been tested using the correlated characteristics of the coatings with macrophages and MC3T3- E1 murine osteoblasts response in vitro. Resume : Nanostructured thin films are extensively studied in orthopedics, to overcome the limitations of medical devices and respond to several clinical needs, such as infection and scarce osseointegration.
Here, nanostructured antibacterial and biomimetic films are deposited by Ionized Jet Deposition IJD , by ablation of silver and deproteinized bone apatite targets, respectively. Coating are mainly proposed for metallic implants, but, because IJD deposition can be carried out without heating the substrate, proof-of-concept of deposition onto heat-sensitive porous substrates polymeric electrospun patches is shown.
All films exhibit a nanostructured morphology and sub-micrometric thickness, and are composed of nanosized globular aggregates. The morphology and dimensions of the aggregates, as well as the deposition rate, strongly depend on the characteristics of the target. Both silver and bone apatite coatings exhibit a composition closely mimicking that of the deposition target and a high adhesion to the substrate. When deposited on electrospun polymers, the films grow around the fibers, without significantly altering their shape and the porosity of the patch or causing significant damage to the substrate.
Our aim was to obtain the controlled release of the therapeutically active substance, under the action of a magnetic and electric fields for use of these coatings for biomedical applications. It follows that the deposited thin films exhibit a convenient nanostructured surface for bone implants and the unaltered transfer of the initial biomaterials was obtained. The corrosion resistant structures exhibited a significant antibacterial activity against Escherichia coli, Staphylococcus aureus and Candida Albicans strains meanwhile biocompatibility assay MTT, imunostaining and cellular morphology demonstrated that the obtained implants are not cytotoxic for bone cells.
These results encourage further assessment of this type of biomaterials for their application in controlled drug release at implantation sites by electrical impulse stimulation. The resulting large bone defects lead to scarred, mangled facial appearance and the loss of mastication and speaking function, requiring aesthetic and functional reconstruction as basis for physical and physiologic rehabilitation. The analysis performed considered the assessment of the impact of 3D printing material on the activation of the genotoxic stress pathway in an in vitro model using human osteoblasts and osteoblast-like cancer cells - SaOS The method of analysis considered micronucleus test and evaluation of the expression of selected genes involved in the genotoxic stress pathway.
Resume : Functionalization of nanocrystals is essential for their practical application to living systems, but synthesis on nanocrystal surfaces is limited by incompatibilities with certain key reagents. The copper-catalyzed azide-alkyne cycloaddition CuAAC is among the most useful methods for ligating biomolecules to surfaces, but has been largely useless for semiconductor quantum dots QDs because Cu ions quickly and irreversibly quench QD fluorescence.
To discover non-quenching synthetic conditions for Cu-catalyzed click reactions on QD surfaces,1 we developed a combinatorial fluorescence assay to screen over reaction conditions to maximize cycloaddition efficiency while minimizing QD quenching. Based on insight from the combinatorial screen and mechanistic studies of Cu coordination and quenching, we find that superstoichiometric concentrations of Cu can promote full coupling if accompanied by ligands that selectively compete the Cu from the QD surface but allow it to remain catalytically active.
We also report novel covalent protein labeling ligands i. This specific and improved protein labeling allows live-cell imaging of kinesin motors and dual-color QD labeling of kinesin heads and to track single protein stepping movement in live cells. Mann, A. Powers, D. Tilley, J. Sack and B. ACS Nano 12, 2. Wichner, V. Powers, M. Segal, M. Mir, J. Bandaria, M. DeWitt, X. Darzacq, A. Yildiz and B. ACS Nano 11, ? Resume : Introduction: Diabetes is a critical medical challenge affecting all of the world. The insulin injection according to the glucose level is a key issue for the treatment of type 1 and advanced type 2 diabetes.
In this study, based on gold nanoclusters GNCs and MEMS microneedle patches, we aim to develop a smart insulin releasing system responding to the surrounding glucose levels. Method: We used GNCs as a novel carrier due to their high loading capacity of drugs 1. We decorated the GNCs with phenylboronic acid molecules, which serve as key switch factor for glucose-responsive insulin release. Moreover, using MEMS technology, we developed a microneedle patch containing the above GNCs for skin penetration and responsive drug release in vivo.
Results: We are able to develop glucose-responsive insulin releasing GNCs, with strong sensitivity to glucose concentrations. Moreover, MEMS microneedle patches enabled the painless puncture of skins and the in vivo drug release. In both in vitro glucose solution and in type 1 diabetic mice in vivo, our system effectively released insulin according to the glucose concentrations, and can regulate the blood glucose in normoglycemic range for up to 3 days. Conclusion: This painless and responsive system can help the diagnosis and treatment of diabetes. Keywords: gold nanoclusters; microneedle patch; glucose control; drug delivery.
Yifeng Lei, et al. Nature Communications. Resume : Metal nanoparticle clusters are regarded as metamaterials, and dispersions of nanoparticle clusters are regarded as metafluids. Surface-enhanced Raman scattering SERS from molecules adsorbed on the nanoparticle clusters is one of a notable property of metafluids. SERS is expected to permit the realization of single-molecule detection in chemical and biological samples, especially cells and tissues.
However, the most of SERS measurements have been done on substrates, local information of cells and tissues have been hard to obtain. In order to measure the local information of cells, using SERS active particles is one of the answers. Furthermore, transporting the SERS particles to the desired position is crucial for obtaining high resolution. In this report, gold nanoparticle clusters based on polymer core? The enhancement factor of the SERS signal was determined by the size of composited gold nanoparticles.
Furthermore, the migration direction of the gold nanoparticle cluster composite particles in aqueous media was successfully controlled by the application of an external magnetic field. This technique provides a novel way to analyze in situ distribution of biomolecules in cells and tissues. Resume : The fabrication of flexible photonic materials with accessible and cost effective techniques has proven to be a difficult task in materials sciences, usually resorting to lithography techniques, opals and colloidal aggregates, greatly limiting the uses and sizes of these structures.
New methods and structures for the production of Bragg refractors can be developed by taking examples available in the natural world, in which living organisms take advantage of the natural trade-off between employed resources and functionality to obtained efficient photonic structures that aid in several organic processes. This approach is made possible by the combination of a simple polymer infiltration technique, called melt infiltration, in periodically modulated aluminum oxide templates, producing a 3 dimensional polyethylene nanonetworks with a wide range of tuneable photonic responses.
The reported method allows the production of such structures in wide areas, resorting to cheap materials like industrial grade polymers and aluminum alloys. The merging of an easy and scalable method with a 3 dimensional network-like structure offers new opportunities in areas as photonics, sensing, energy and clothing. Optical Mater. Resume : In their native environment cells are constantly exposed to biochemical and biophysical signals that guide and regulate complex biological phenomena.
Many of these signals impact on the adhesion properties of cells, which define morphology, cytoskeleton arrangements and cell mechanics. Adhesion signals are far from being static, but change in time and space according to specific programmes. Non-correct display of signals may result in catastrophic events. Yet, our understanding on the effects of the dynamics of signal presentation on cell functions and fates is limited.
Here we present our recent developments in the engineering of light-responsive platforms to enable the dynamic presentation of patterns of adhesion signals whose features can be controlled in space and time. Irradiation of azobenzene based substrates can alter surface topography in the time frame of few tens of seconds, allowing formation of submicron features, a scale that interferes with focal adhesion formation.
We show the potency of these substrates in stimulating individual cells with topographic patterns over varying lengths and timescales, and how dynamic patterns alter cytoskeleton arrangements and cell mechanics. Development of platforms for dynamic signal display would provide valuable insights into cell-biophysical signal interactions and into mechanotransduction phenomena, paving the way to novel systems that mimic physiologic or pathologic extracellular environments for in vitro cell stimulation.
Resume : The detailed understanding of interfaces in biological systems is essential to achieve controllable bioresponses. Here, we characterized two types of biointerfaces in human cortical bone tissues with osteoporosis using high-resolution microscopy and spectroscopy techniques and proposed novel strategies for improving their biomechanical response. First, the boundary between osteonal and interstitial bone materials known as the cement line CL was investigated.
It was found that CLs are hypermineralized tougher interfaces with varying mineralization levels depending on the osteon age, indicating distinct biomineralization dynamics in CLs and osteons attributed to their different organic compositions. According to finite element modelling, having CLs with higher toughness deflect microcracks, thus preventing extensive bone fracture. Second, the interfacial interaction between osteocyte cells and surrounding bone tissue was studied.
Highly mineralized plugs explained by a unique biomineralization mechanism following osteocytes death were found. These occlusions can locally alter cellular communication and bone homeostasis, thus decreasing bone fracture resistance. Future medication has to focus on preserving osteocytes, also because they can inhibit mineralization resulting in an empty pericellular space crucial for the fluid flow between cells.
Based on these results, smart bioinspired implant materials can be developed to ensure bone stability in elderly individuals. Resume : Stem cell culture is of paramount importance in tissue engineering and regenerative medicine. Neural stem cells or mesenchymal stem cells therapies have the potential to treat neurodegenerative diseases, either by replenishing the cell pool or through the secretion of paracrine factors.
In order to successful apply these therapies, we need to develop appropriate scaffolds that, by mimicking the extracellular matrix to culture cells in vitro and control their fate, offers the prospects to turn these in vitro studies into efficient medical processes. In addition to the thin film-based scaffolds, the use of polymeric fibers, prepared by electrospinning, based on various polymers, including blends with conjugated polymers, is also being explored. In this communication we report on our progress in the search for polymer based films and fibers scaffolds, including the use of conductive polymers as these offer the possibility to use electrical stimuli, and their ability to sustain viable cell culture.
Pires, Q. Ferreira, C. Rodrigues, J. Morgado, F. Resume : Cells sense their environment by transducing mechanical stimuli into biochemical signals. Commonly used tools to study cell mechanosensing provide limited spatial and force resolution. Here, a novel nanowire? Nanowires are functionalized with ligands for cell immunoreceptors, and they are used to explore the mechanosensitivity of natural killer NK cells. In particular, it is found that NK cells apply centripetal forces to nanowires, and that the nanowires stimulate cell contraction. Based on the nanowire deformation, it is calculated that cells apply forces of down to 10 pN, which is the smallest value demonstrated so far by microstructured platforms for cell spreading.
Furthermore, the roles of: i nanowire topography and ii activating ligands in the cell immune function are studied and it is found that only their combination produces enhanced population of activated NK cells. Thus, a mechanosensing mechanism of NK cells is proposed, by which they integrate biochemical and mechanical stimuli into a decision?
This work reveals unprecedented mechanical aspects of NK cell immune function and introduces an innovative nanomaterial for studying cellular mechanics with unparalleled spatial and mechanical resolution. Resume : Controlled extracellular chemical and topographical cues can generate physicochemical changes that influence the proliferation and differentiation of neural cells; external electrical stimulation ES via conductive bioelectrodes can promote neural differentiation by increasing neurite outgrowth.
Therefore, combining this unique PEDOT:PSS blend solution with various fabrication processes appears to be a facile approach toward bioelectronic interface coatings displaying tunable surface properties for manipulating the cellular behavior of neurons during ES. Initial adhesion is followed by emergence of surface-programmed bacterial properties and biofilm growth. A distinction between nanostructured surfaces can be made based on periodic- or random-occurrence of features, although often nanostructured surfaces are microstructured due to merging of their nanofeatures.
Characterization of such surfaces is not trivial due to the myriad of different nanoscaled morphologies. Both superhydrophobic and hydrophilic, nanostructured surfaces generally yield low bacterial adhesion. On smooth surfaces, bacteria deform when adhering, causing membrane surface tension changes and responses yielding emergent properties. Adhesion to nanostructured surfaces, causes multiple cell wall deformation sites when adhering in valleys, while for hill-top adhesion, highly localized cell wall deformation occurs.
Accordingly, adhesion to nanostructured surfaces yields emergent responses ranging from pressure-induced EPS production to cell wall rupture and death. Other promising features are increased antibiotic housing, thermal effects and photo-induced ROS production, but the latter two promises are based on properties of suspended nanoparticles and may not hold in nanostructured coatings or materials.
To bring nanostructured coatings and materials to application, experiments are needed that go beyond the current limit of the laboratory bench. Resume : In nature bacteria generally exist as biofilms. Biofilms are a dynamic and structurally complex community of microorganisms embedded in a self-produced matrix of extracellular polymeric substances EPS. One possible approach to eradicate unwanted biofilms is to use smart responsive technologies that are activated by an environmental cue. Due to bacterial metabolism, cells embedded in the biofilm create a localized acidic microenvironment which is unaffected by the external pH.
Therefore, pH monitoring is a promising approach for understanding the complexities of biofilms with potential applications in diagnostics; however, pH measurement is not a trivial task in a 3D and highly heterogeneous system such as a biofilm. A nanoscale pH-responsive sensor would enable in-situ analysis of pH gradient inside biofilms, without altering its natural structure.
The fluorescence intensity IF drops drastically when the pH is decreased from 8 to 3. The former coincides with the broad band in the red related to AuNps aggregation ca. The latter does not undergo any local electronic effect, but the s—d interband transition as explained before. The fact that the vibration amplitude linearly increases with N s for both SFG and DFG is also consistent with the previous observation of an exaltation factor for the detection of molecules adsorbed on AuNps.
Indeed, we had previously estimated this factor to be around 20 to explain the differences observed with a flat gold surface covered by a full monolayer of thiophenol [ 4 ]. However, this latter result implied that the vibrational amplitude increased linearly with N s , which is confirmed in the present work. As a consequence, our results show that no coupling of nonlinear optical spectroscopy with the optical properties of aggregated AuNps occurs.
Finally, we illustrated that the effective medium models of MG and BM were not sufficient to precisely take into account the LSPR coupling with the adsorbed molecules. Neglecting the molecular contribution was not possible to properly quantify the coupling between plasmonics and nonlinear optical vibrational spectroscopy. To go further quantitatively and describe the role of the local fields, the next steps should include a continuous tuning of the incident visible laser beam on several samples of different AuNps densities.
In this perspective, the fine tuning of the LSPR with the visible, SFG or DFG beams would allow to increase the molecular sensitivity required in plasmonic plateforms used as biosensors where the precise targeting of specific chemical bonds between molecular probes and targets is of crucial importance to characterize the biomolecular recognition process at play in those systems.
The authors also acknowledge C. Six and A. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author s and the source are credited. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author s and the source are credited.
Skip to main content Skip to sections. Advertisement Hide. Download PDF. Optical spectroscopy of functionalized gold nanoparticles assemblies as a function of the surface coverage. Authors Authors and affiliations C. Humbert O. Pluchery E. Lacaze A. Tadjeddine B. Open Access. First Online: 24 November Introduction The manufacturing of well-designed nanosensors is a key step to improve their sensitivity threshold in the probe-target scheme encountered in molecular recognition, especially when expecting the detection of materials traces to the single molecule level. Nanosensors are based on a molecular recognition process evidenced by monitoring the SPR shift.
For an efficient use of these sensors, a perfect knowledge of the chemistry of the process at play is mandatory, but plasmonics alone does not enlighten which molecular bonds are involved in the recognition of the target molecule by the probe molecule. To reach that goal, vibrational optical techniques are preferred such as infrared and Raman spectroscopic tools. Therefore, the main advantage of this technique for nanotechnological devices characterization lies in its interface intrinsic molecular sensitivity at the sub-monolayer level and its potential coupling to the SPR resonance as recently demonstrated by considering samples based on solid substrate as platforms for nanosensors, an amplification factor of the molecular SFG signal was put in evidence for functionalized AuNps films with respect to a flat gold reference surface.
AuNps were deposited either on silicon in external reflection configuration [ 4 ] or on glass substrates in total internal reflection configuration [ 5 ] to compare the sensitivity and molecular ordering of functionalized AuNp films as a function of the surface coverage on glass [ 6 ], to unravel the orientation of grafted molecules on AuNps and AgNps [ 7 ] and to extract and deduce the nature of the vibration modes thanks to the SPR amplification on functionalized AuNp films in the fingerprint spectral range of aromatic molecules with density functional theory DFT calculations [ 8 ].
In a general way, SFG has also proven its efficiency in biomolecular recognition on glass substrate [ 9 ], in DNA-based biosensors on Pt single crystal [ 10 ] and in enlightening DNA hybridization on glass [ 11 ] and -facetted gold films [ 12 ]. Open image in new window. The geometrical configuration depicted in Fig. In these conditions, to switch from SFG to DFG configuration, only one mirror is tilted in the lateral direction to send either SFG or DFG photons in the same direction for their detection after spatial and spectral filtering through a monochromator.
To compensate for eventual misalignment of the SFG detection direction, the baseline of the SFG spectra is recovered by a linear fit of the experimental data.
In order to compare quantitatively the SFG data with respect to the DFG data, an experimental scaling factor set to 1. It is easily explained by considering Fig. Table 2 Evolution of the interface Fresnel factors F and thiophenol molecular amplitude a. AFM measurements We show the representative and typical AFM pictures of our four samples differing by the AuNps surface coverage monitored by the dipping time in the colloidal solution in Fig.
As shown on Fig. From these measurements, in addition to the AuNps height i. Moreover, by performing profile measurement in the lateral direction, it is possible to evaluate the average distance between the centres of two AuNps. In these conditions, it is expected that the optical properties will be drastically modified as checked by UV-visible measurements. This demonstrates that thiophenol exclusively interacts with gold.
Moreover, the IR peak is fairly broad which does not allow identifying clearly all these features. It should be noted that the correct assignment of this vibration mode requires being careful because it is a rich spectral range influenced by the molecular adsorption on gold atoms [ 18 ]. Whatever the precise nature of the vibration mode, it should have a sufficient infrared activity to be detected in FTIR.
The interested reader will find in the Electronic Supplementary Information some discussion based on literature and DFT calculations on this peculiar point. This vibrational feature corresponds to the stretching vibration mode of the CH groups of the aromatic core of the thiophenol [ 4 ] that we already mentioned in the FTIR measurements. For both nonlinear configurations, we observe that the vibration mode intensity increases with the immersion time in the AuNps solution, which is evidently related to the increasing N s as deduced from AFM measurements.
We present the corresponding UV-vis reflectance curves of the four samples in Fig. The optical features are strongly modified with the immersion time in the colloidal solution. However, on silicon in the reflection geometry, the results seem to be very different and counter-intuitive. Very often, the appearance of shoulder at ca. Moreover, these negative features are unusual. All these peculiarities can be explained when studying more closely the analytical expression of the reflectance in the case of AuNps deposited on silicon. The electric field reflected from a surface can be calculated analytically with the Fresnel Formula.
This model satisfactorily captures the plasmon resonance of AuNps in term of plasmon position and intensity. The analysis of the formula is essential to understand the main features that give the shape to the spectra of Fig. To illustrate the influence of the sample reflectivity, we report the evolution of a zzz in Fig. In this manner, it is possible to compare and discuss the accuracy or discrepancy between the molecular amplitudes within the framework of the effective medium models developed above.
Talanta —42 CrossRef Google Scholar. Nanotechnology , 1—7 CrossRef Google Scholar. Walter SR, Geiger FM DNA on stage: showcasing oligonucleotides at surfaces and interfaces with second harmonic and vibrational sum frequency generation. Tourillon G, Dreesen L, Volcke C, Sartenaer Y, Thiry PA, Peremans A Close-packed array of gold nanoparticles and sum frequency generation spectroscopy in total internal reflection: a platform for studying biomolecules and biosensors.
Roke S, Gonella G Nonlinear light scattering and spectroscopy of particles and droplets in liquids. Aspnes DE, Theeten JB Investigation of effective-medium models of microscopic surface roughness by spectroscopic ellipsometry. Humbert 1 Email author O. Pluchery 2 E. Lacaze 2 A.