Carbon nanotube-coated silicone as a flexible and electrically conductive biomedical material

An Overview of Antimicrobial Properties of Carbon Nanotubes-Based Nanocomposites

The development of carbon-based nanomaterials has extensively facilitated new discoveries in various fields. Carbon nanotube-based nanocomposites (CNT-based nanocomposites) have lately recognized as promising biomaterials for a wide range of biomedical applications due to their unique electronic, mechanical, and biological properties. Nanocomposite materials such as silver nanoparticles (AgNPs), polymers, biomolecules, enzymes, and peptides have been reported in many studies, possess a broad range of antibacterial activity when incorporated with carbon nanotubes (CNTs). It is crucial to understand the mechanism which governs the antimicrobial activity of these CNT-based nanocomposite materials, including the decoupling individual and synergistic effects on the cells. In this review, the interaction behavior between microorganisms and different types of CNT-based nanocomposites is summarized to understand the respective antimicrobial performance in different conditions. Besides, the current development stage of CNT-based nanocomposite materials, the technical challenges faced, and the exceptional prospect of implementing potential antimicrobial CNT-based nanocomposite materials are also discussed.

Carbon Nanotube/Poly(dimethylsiloxane) Composite Materials to Reduce Bacterial Adhesion

Different studies have shown that the incorporation of carbon nanotubes (CNTs) into poly(dimethylsiloxane) (PDMS) enables the production of composite materials with enhanced properties, which can find important applications in the biomedical field. In the present work, CNT/PDMS composite materials have been prepared to evaluate the effects of pristine and chemically functionalized CNT incorporation into PDMS on the composite's thermal, electrical, and surface properties on bacterial adhesion in dynamic conditions. Initial bacterial adhesion was studied using a parallel-plate flow chamber assay performed in conditions prevailing in urinary tract devices (catheters and stents) using Escherichia coli as a model organism and PDMS as a control due to its relevance in these applications. The results indicated that the introduction of the CNTs in the PDMS matrix yielded, in general, less bacterial adhesion than the PDMS alone and that the reduction could be dependent on the surface chemistry of CNTs, with less adhesion obtained on the composites with pristine rather than functionalized CNTs. It was also shown CNT pre-treatment and incorporation by different methods affected the electrical properties of the composites when compared to PDMS. Composites enabling a 60% reduction in cell adhesion were obtained by CNT treatment by ball-milling, whereas an increase in electrical conductivity of seven orders of magnitude was obtained after solvent-mediated incorporation. The results suggest even at low CNT loading values (1%), these treatments may be beneficial for the production of CNT composites with application in biomedical devices for the urinary tract and for other applications where electrical conductance is required.

Highly Flexible and Patternable Multiwalled-Carbon Nanotube/Nitrocellulose Hybrid Conducting Paper Electrodes as Heating Platforms for Effective Ignition of Nanoenergetic Materials

In this study, a highly flexible, patternable multiwalled-carbon nanotube (MWCNT) paper electrode was specially designed and fabricated. The addition of a nitrocellulose (NC) polymer binder at less than the critical amount (≤2 wt %) was found to be effective for maintaining both the flexibility and electrical conductance of the resulting MWCNT paper electrode. The fabricated MWCNT paper electrode was then employed as a heating platform to ignite Al/CuO nanoparticle-based nanoenergetic materials (nEMs). The nEM layer was drop-cast on the surface of the MWCNT paper electrode with specially patterned shapes using a plotter, and its ignition was evaluated by applying various voltages through the MWCNT paper electrode. To increase the adhesion between the nEM layer and MWCNT paper electrode and to decrease the sparking sensitivity of the nEM layer, it was essential to incorporate NC in the nEM matrix. However, the combustion and explosion properties of nEM layers deteriorated with the addition of NC, enabling the estimation of the optimum amount of NC to be incorporated. The fabricated igniter can be employed in various thermal engineering applications, such as in the ignition of explosives and propellants, and in pyrotechnics. To demonstrate this, a compact, flexible, and patternable igniter composed of the NC/nEM layer (NC/nEM = 2:8 wt %) on an MWCNT paper electrode was used to successfully ignite solid propellants for launching a small rocket.

Modulation of dielectric and viscoelastic features of silicone rubber (SR) by nano-hydroxylapatite (n-HA) embedding

We report the modulation of dielectric and dynamic mechanical features of silicone rubber (SR), the extensively employed biocompatible elastomer, by embedding it with nano-hydroxylapatite (n-HA) particles.

From 2D to 3D: novel nanostructured scaffolds to investigate signalling in reconstructed neuronal networks

To recreate in vitro 3D neuronal circuits will ultimately increase the relevance of results from cultured to whole-brain networks and will promote enabling technologies for neuro-engineering applications. Here we fabricate novel elastomeric scaffolds able to instruct 3D growth of living primary neurons. Such systems allow investigating the emerging activity, in terms of calcium signals, of small clusters of neurons as a function of the interplay between the 2D or 3D architectures and network dynamics. We report the ability of 3D geometry to improve functional organization and synchronization in small neuronal assemblies. We propose a mathematical modelling of network dynamics that supports such a result. Entrapping carbon nanotubes in the scaffolds remarkably boosted synaptic activity, thus allowing for the first time to exploit nanomaterial/cell interfacing in 3D growth support. Our 3D system represents a simple and reliable construct, able to improve the complexity of current tissue culture models.