Wettability Modification of Nanomaterials by Low-Energy Electron Flux

Composite Drug Delivery System Based on Amorphous Calcium Phosphate-Chitosan: An Efficient Antimicrobial Platform for Extended Release of Tetracycline

One major warning emerging during the first worldwide combat against healthcare-associated infections concerns the key role of the surface in the storage and transfer of the virus. Our study is based on the laser coating of surfaces with an inorganic/organic composite mixture of amorphous calcium phosphate–chitosan–tetracycline that is able to fight against infectious agents, but also capable of preserving its activity for a prolonged time, up to several days. The extended release in simulated fluids of the composite mixture containing the drug (tetracycline) was demonstrated by mass loss and UV–VIS investigations. The drug release profile from our composite coatings proceeds via two stages: an initial burst release (during the first hours), followed by a slower evolution active for the next 72 h, and probably more. Optimized coatings strongly inhibit the growth of tested bacteria (Enterococcus faecalis and Escherichia coli), while the drug incorporation has no impact on the in vitro composite’s cytotoxicity, the coatings proving an excellent biocompatibility sustaining the normal development of MG63 bone-like cells. One may, therefore, consider that the proposed coatings’ composition can open the prospective of a new generation of antimicrobial coatings for implants, but also for nosocomial and other large area contamination prevention.

Supported and Suspended 2D Material-Based FET Biosensors

Field Effect Transistor (FET)-based electrochemical biosensor is gaining a lot of interest due to its malleability with modern fabrication technology and the ease at which it can be integrated with modern digital electronics. To increase the sensitivity and response time of the FET-based biosensor, many semiconducting materials have been categorized, including 2 dimensional (2D) nanomaterials. These 2D materials are easy to fabricate, increase sensitivity due to the atomic layer, and are flexible for a range of biomolecule detection. Due to the atomic layer of 2D materials each device requires a supporting substrate to fabricate a biosensor. However, uneven morphology of supporting substrate leads to unreliable output from every device due to scattering effect. This review summarizes advances in 2D material-based electrochemical biosensors both in supporting and suspended configurations by using different atomic monolayer, and presents the challenges involved in supporting substrate-based 2D biosensors. In addition, we also point out the advantages of nanomaterials over bulk materials in the biosensor domain.

Enhancement of Thermal Diffusivity in Phase-Separated Bismaleimide/Poly(ether imide) Composite Films Containing Needle-Shaped ZnO Particles

Phase-separated polymer blend composite films exhibiting high thermal diffusivity were prepared by blending a soluble polyimide (BPADA-MPD) and a bismaleimide (BMI) with needle-shaped zinc oxide (n-ZnO) particles followed by high-temperature curing at 250 °C. Images recorded with a field-emission scanning electron microscope (FE-SEM) equipped with wavelength-dispersive spectroscopy (WDS) demonstrated that the spontaneously separated phases in the composite films were aligned along the out-of-plane direction, and the n-ZnO particles were selectively incorporated into the BMI phase. The out-of-plane thermal diffusivity of the composite films was significantly higher than those of the previously reported composite films at lower filler contents. Based on wide-angle X-ray diffraction (WAXD) patterns and image analysis, the enhanced thermal diffusivity was attributed to the confinement of the anisotropically shaped particles and their nearly isotropic orientation in one phase of the composite films.

Transfer-printing of active layers to achieve high quality interfaces in sequentially deposited multilayer inverted polymer solar cells fabricated in air

Polymer solar cells (PSCs) are greatly influenced by both the vertical concentration gradient in the active layer and the quality of the various interfaces. To achieve vertical concentration gradients in inverted PSCs, a sequential deposition approach is necessary. However, a direct approach to sequential deposition by spin-coating results in partial dissolution of the underlying layers which decreases the control over the process and results in not well-defined interfaces. Here, we demonstrate that by using a transfer-printing process based on polydimethylsiloxane (PDMS) stamps we can obtain increased control over the thickness of the various layers while at the same time increasing the quality of the interfaces and the overall concentration gradient within the active layer of PSCs prepared in air. To optimize the process and understand the influence of various interlayers, our approach is based on surface free energy, spreading parameters and work of adhesion calculations. The key parameter presented here is the insertion of high quality hole transporting and electron transporting layers, respectively above and underneath the active layer of the inverted structure PSC which not only facilitates the transfer process but also induces the adequate vertical concentration gradient in the device to facilitate charge extraction. The resulting non-encapsulated devices (active layer prepared in air) demonstrate over 40% increase in power conversion efficiency with respect to the reference spin-coated inverted PSCs.

Maskless, High-Precision, Persistent, and Extreme Wetting-Contrast Patterning in an Environmental Scanning Electron Microscope

A maskless and programmable direct electron beam writing method is reported for making high-precision superhydrophilic-superhydrophobic wetting patterns with 152° contact angle contrast using an environmental scanning electron microscope (ESEM). The smallest linewidth achieved is below 1 μm. The reported effects of the electron beam induced local plasma may also influence a variety of microscopic wetting studies in ESEM.

Thickness Influence on In Vitro Biocompatibility of Titanium Nitride Thin Films Synthesized by Pulsed Laser Deposition

We report a study on the biocompatibility vs. thickness in the case of titanium nitride (TiN) films synthesized on 410 medical grade stainless steel substrates by pulsed laser deposition. The films were grown in a nitrogen atmosphere, and their in vitro cytotoxicity was assessed according to ISO 10993-5 [1]. Extensive physical-chemical analyses have been carried out on the deposited structures with various thicknesses in order to explain the differences in biological behavior: profilometry, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction and surface energy measurements. XPS revealed the presence of titanium oxynitride beside TiN in amounts that vary with the film thickness. The cytocompatibility of films seems to be influenced by their TiN surface content. The thinner films seem to be more suitable for medical applications, due to the combined high values of bonding strength and superior cytocompatibility.

Hydrophobic plasma polymer coated silica particles for petroleum hydrocarbon removal

In recent years, functionalized hydrophobic materials have attracted considerable interest as oil removal agents. This investigation has applied plasma polymerization as a novel method to develop hydrophobic and oleophilic particles for water purification. 1,7-Octadiene was plasma polymerized onto silica particles using a radio frequency inductively coupled reactor fitted with a rotating chamber. Plasma polymerized 1,7-octadiene (ppOD) films were deposited using plasma power of 40 W and monomer flow rate of 2 sccm, while polymerization time was varied from 5 to 60 min. The surface chemistry of ppOD coated particles was investigated via X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy, while Washburn capillary rise measurements were applied to evaluate the hydrophobicity and oleophilicity of the particles. The effectiveness of ppOD coated particles for the removal of hydrophobic matter from water was demonstrated by adsorption of motor oil, kerosene, and crude oil. Petroleum hydrocarbon removal was examined by varying removal time and particle mass. The morphology of oil-loaded ppOD coated particles was examined via environmental scanning electron microscopy observations. Increasing the polymerization time increased the concentration of hydrocarbon functionalities on the surface, thus also increasing the hydrophobicity and oil removal efficiency (ORE). The ppOD coated particles have shown to have excellent ORE. These particles were capable of removing 99.0-99.5% of high viscosity motor oil in 10 min, while more than 99.5% of low viscosity crude oil and kerosene was adsorbed in less than 30 s. Plasma polymerization has shown to be a promising approach to produce a new class of materials for a fast, facile, and efficient oil removal.

Addition of silver nanoparticles reduces the wettability of methacrylate and silorane-based composites

Incorporation of silver nanoparticles into composite resins is recommended for their reported antibacterial properties, but this incorporation can affect the wettability of such materials. Therefore, this study evaluated the effect of nano-silver addition to silorane-based and methacrylate-based composites on their contact angle. Nano-silver particles were added to Z250 (methacrylate-based) and P90 (silorane-based) composites at 0.5% and 1% by weight. The control group had no additions. SEM-EDX analysis was performed to confirm the homogeneity of the nano-silver distribution. Seventy-two composite discs were prepared and standardized to the identical surface roughness values, and then distributed randomly into 6 groups containing 12 samples each (N = 12). Two random samples from each group were observed by atomic force microscopy. Distilled water contact angle measurements were performed for the wettability measurement. Two-way ANOVA, followed by the Tukey-HSD test, with a significance level of 5%, were used for data analysis. It was observed that wettability was significantly different between the composites (p = 0.0001), and that the addition of nano-silver caused a significant reduction in the contact angle (p = 0.0001). Wettability varied depending on the concentration of the nano silver (p = 0.008). Silorane-based composites have a higher contact angle than methacrylate-based composites. Within the limitations of this study, it can be concluded that the addition of 0.5% nano-silver particles to the composites caused a decrease in the contact angle of water.

Silica nanoparticles treated by cold atmospheric-pressure plasmas improve the dielectric performance of organic-inorganic nanocomposites

We report on the application of cold atmospheric-pressure plasmas to modify silica nanoparticles to enhance their compatibility with polymer matrices. Thermally nonequilibrium atmospheric-pressure plasma is generated by a high-voltage radio frequency power source operated in the capacitively coupled mode with helium as the working gas. Compared to the pure polymer and the polymer nanocomposites with untreated SiO(2), the plasma-treated SiO(2)-polymer nanocomposites show higher dielectric breakdown strength and extended endurance under a constant electrical stress. These improvements are attributed to the stronger interactions between the SiO(2) nanoparticles and the surrounding polymer matrix after the plasma treatment. Our method is generic and can be used in the production of high-performance organic-inorganic functional nanocomposites.