Bioelectronics meets nanomedicine for cardiovascular implants: PEDOT-based nanocoatings for tissue regeneration.

BACKGROUND: An exciting direction in nanomedicine would be to analyze how living cells respond to conducting polymers. Their application for tissue regeneration may advance the performance of drug eluting stents by addressing the delayed stent re-endothelialization and late stent thrombosis. METHODS: The suitability of poly (3, 4-ethylenedioxythiophene) (PEDOT) thin films for stents to promote cell adhesion and proliferation is tested in correlation with doping and physicochemical properties. PEDOT doped either with poly (styrenesulfonate) (PSS) or tosylate anion (TOS) was used for films' fabrication by spin coating and vapor phase polymerization respectively. PEGylation of PEDOT: TOS for reduced immunogenicity and biofunctionalization of PEDOT: PSS with RGD peptides for induced cell proliferation was further applied. Atomic Force Microscopy and Spectroscopic Ellipsometry were implemented for nanotopographical, structural, optical and conductivity measurements in parallel with wettability and protein adsorption studies. Direct and extract testing of cell viability and proliferation of L929 fibroblasts on PEDOT samples by MTT assay in line with SEM studies follow. RESULTS: All PEDOT thin films are cytocompatible and promote human serum albumin adsorption. PEDOT:TOS films were found superior regarding cell adhesion as compared to controls. Their nanotopography and hydrophilicity are significant factors that influence cytocompatibility. PEGylation of PEDOT:TOS increases their conductivity and hydrophilicity with similar results on cell viability with bare PEDOT:TOS. The biofunctionalized PEDOT:PSS thin films show enhanced cell proliferation. CONCLUSIONS: The application of PEDOT polymers has evolved as a new perspective to advance stents. GENERAL SIGNIFICANCE: In this work, nanomedicine involving nanotools and novel nanomaterials merges with bioelectronics to stimulate tissue regeneration for cardiovascular implants. This article is part of a Special Issue entitled Organic Bioelectronics - Novel Applications in Biomedicine.

Probing biomolecular interaction forces using an anharmonic acoustic technique for selective detection of bacterial spores

Receptor-based detection of pathogens often suffers from non-specific interactions, and as most detection techniques cannot distinguish between affinities of interactions, false positive responses remain a plaguing reality. Here, we report an anharmonic acoustic based method of detection that addresses the inherent weakness of current ligand dependant assays. Spores of Bacillus subtilis (Bacillus anthracis simulant) were immobilized on a thickness-shear mode AT-cut quartz crystal functionalized with anti-spore antibody and the sensor was driven by a pure sinusoidal oscillation at increasing amplitude. Biomolecular interaction forces between the coupled spores and the accelerating surface caused a nonlinear modulation of the acoustic response of the crystal. In particular, the deviation in the third harmonic of the transduced electrical response versus oscillation amplitude of the sensor (signal) was found to be significant. Signals from the specifically-bound spores were clearly distinguishable in shape from those of the physisorbed streptavidin-coated polystyrene microbeads. The analytical model presented here enables estimation of the biomolecular interaction forces from the measured response. Thus, probing biomolecular interaction forces using the described technique can quantitatively detect pathogens and distinguish specific from non-specific interactions, with potential applicability to rapid point-of-care detection. This also serves as a potential tool for rapid force-spectroscopy, affinity-based biomolecular screening and mapping of molecular interaction networks. © 2011 Elsevier B.V.

Dual-mode thin film bulk acoustic wave resonators for parallel sensing of temperature and mass loading

Thin film bulk acoustic wave resonator (FBAR) devices supporting simultaneously multiple resonance modes have been designed for gravimetric sensing. The mechanism for dual-mode generation within a single device has been discussed, and theoretical calculations based on finite element analysis allowed the fabrication of FBARs whose resonance modes have opposite reactions to temperature changes; one of the modes exhibiting a positive frequency shift for a rise of temperature whilst the other mode exhibits a negative shift. Both modes exhibit negative frequency shift for a mass load and hence by monitoring simultaneously both modes it is possible to distinguish whether a change in the resonance frequency is due to a mass load or temperature variation (or a combination of both), avoiding false positive/negative responses in gravimetric sensing without the need of additional reference devices or complex electronics. © 2012 Elsevier B.V.