Fabrication of silver nanowires-loaded polydimethylsiloxane film with antimicrobial activities and cell compatibility

Development of PDMS/TiO2/Ag3PO4 antibacterial coating on 316L/PDMS implants: Evaluation of superhydrophobicity, bio-corrosion, mechanical behaviour, surface nanostructure and chemistry

Nanocomposite coatings based on polydimethylsiloxane were developed by adding silver phosphate and titania nanoparticles with a PDMS pre-layer for 316L stainless steel. FTIR spectra and XRD patterns confirmed the synthesis of TiO2 and Ag3PO4 nanoparticles and nanocomposite coating. FESM and AFM images show that with the increase of Ag3PO4 nanoparticles, the roughness of coatings increased (Ra and Rq for adding 7 wt% of Ag3PO4 coating was 29 and 293 nm). The wettability results demonstrated that the presence of 7 wt% Ag3PO4 nanoparticles in the coating has the highest water contact angle (152 °). Nano-scratch results proved that creating a pre-layer of PDMS can increase the scratch resistance of PDMS + TiO2+Ag3PO4 nanocomposite coating (displacement and scratch coefficient were 408 nm and 0.07μΝ-1/2 with the pre-layer). Corrosion current density of 316lSS with PDMS + TiO2+Ag3PO4 coating was 0.00045 μA/cm2, while for 316LSS with pure PDMS coating was 0.00114 μA/cm2 at 37 °C in PBS solution. The Nyquist curves showed the diameter of the semicircle for the nanocomposite coating was larger than pure PDMS coating, which indicates the higher corrosion resistance of the nanocomposite coating (5.98 × 107 Ω). By increasing Ag3PO4 nanoparticles from 1 to 7 wt%, the number of E. coli bacteria in contact with the nanocomposite decreased significantly from 580000 to 31000 CFU/cm2. In the disk diffusion test, the largest inhibition zone was related to the nanocomposite coating with the addition of 7 wt% Ag3PO4 (23 mm). Therefore, the PDMS + TiO2+Ag3PO4 nanocomposite coating has improved properties such as superhydrophobicity, advanced mechanical behavior, bio-corrosion resistance, and antibacterial activity.

Enhanced cardiomyocyte structural and functional anisotropy through synergetic combination of topographical, conductive, and mechanical stimulation

Drug-induced cardiotoxicity, a significant concern in the pharmaceutical industry, often results in the withdrawal of drugs from the market. The main cause of drug-induced cardiotoxicity is the use of immature cardiomyocytes during in vitro drug screening procedures. Over time, several methods such as topographical, conductive, and mechanical stimulation have been proposed to enhance both maturation and contractile properties of these cardiomyocytes. However, the synergistic effects of integrating topographical, conductive, and mechanical stimulation for cardiomyocyte maturation remain underexplored and poorly understood. To address this limitation, herein, we propose a grooved polydimethylsiloxane (PDMS) membrane embedded with silver nanowires (AgNWs-E-PDMS). The proposed AgNWs-E-PDMS membrane enhances the maturation of cardiomyocytes and provides a more accurate evaluation of drug-induced cardiotoxicity. When subjected to 10% tensile stress on the AgNWs-E-PDMS membrane, cardiomyocytes displayed substantial enhancements. Specifically, the contraction force, sarcomere length, and connexin-43 (Cx43) expression are increased by 2.0-, 1.5-, and 2.4-times, respectively, compared to the control state. The practical feasibility of the proposed device as a drug screening platform is demonstrated by assessing the adverse effects of lidocaine on cardiomyocytes. The contraction force and beat rate of lidocaine treated cardiomyocytes cultured on the AgNWs-E-PDMS membrane under mechanical stimulation decreased to 0.9 and 0.64 times their initial values respectively, compared to 0.6 and 0.51 times in the control state. These less pronounced changes in the contraction force and beat rate signify the superior drug response in the cardiomyocytes, a result of their enhanced maturation and growth on the AgNWs-E-PDMS membrane combined with mechanical stimulation.

Silver Nanowire Networks: Ways to Enhance Their Physical Properties and Stability

Silver nanowire (AgNW) networks have been intensively investigated in recent years. Thanks to their attractive physical properties in terms of optical transparency and electrical conductivity, as well as their mechanical performance, AgNW networks are promising transparent electrodes (TE) for several devices, such as solar cells, transparent heaters, touch screens or light-emitting devices. However, morphological instabilities, low adhesion to the substrate, surface roughness and ageing issues may limit their broader use and need to be tackled for a successful performance and long working lifetime. The aim of the present work is to highlight efficient strategies to optimize the physical properties of AgNW networks. In order to situate our work in relation to existing literature, we briefly reported recent studies which investigated physical properties of AgNW networks. First, we investigated the optimization of optical transparency and electrical conductivity by comparing two types of AgNWs with different morphologies, including PVP layer and AgNW dimensions. In addition, their response to thermal treatment was deeply investigated. Then, zinc oxide (ZnO) and tin oxide (SnO2) protective films deposited by Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD) were compared for one type of AgNW. We clearly demonstrated that coating AgNW networks with these thin oxide layers is an efficient approach to enhance the morphological stability of AgNWs when subjected to thermal stress. Finally, we discussed the main future challenges linked with AgNW networks optimization processes.

Silver Nanowire Synthesis and Strategies for Fabricating Transparent Conducting Electrodes

One-dimensional metal nanowires, with novel functionalities like electrical conductivity, optical transparency and high mechanical stiffness, have attracted widespread interest for use in applications such as transparent electrodes in optoelectronic devices and active components in nanoelectronics and nanophotonics. In particular, silver nanowires (AgNWs) have been widely researched owing to the superlative thermal and electrical conductivity of bulk silver. Herein, we present a detailed review of the synthesis of AgNWs and their utilization in fabricating improved transparent conducting electrodes (TCE). We discuss a range of AgNW synthesis protocols, including template assisted and wet chemical techniques, and their ability to control the morphology of the synthesized nanowires. Furthermore, the use of scalable and cost-effective solution deposition methods to fabricate AgNW based TCE, along with the numerous treatments used for enhancing their optoelectronic properties, are also discussed.

Direct Observations of Silver Nanowire-Induced Frustrated Phagocytosis among NR8383 Lung Alveolar Macrophages

The interaction of long nanowires and living cells is directly related to nanowires' nanotoxicity and health impacts. Interactions of silver nanowires (AgNWs) and macrophage cell lines (NR8383) were investigated using laser scanning confocal microscopy and single cell compression (SCC). With high-resolution imaging and mechanics measurement of individual cells, AgNW-induced frustrated phagocytosis was clearly captured in conjunction with structural and property changes of cells. While frustrated phagocytosis is known for long microwires and long carbon nanotubes, this work reports first direct observations of frustrated phagocytosis of AgNWs among living cells in situ. In the case of partial penetration of AgNWs into NR8383 cells, confocal imaging revealed actin participation at the entry sites, whose behavior differs from microwire-induced frustrated phagocytosis. The impacts of frustrated phagocytosis on the cellular membrane and cytoskeleton were also quantified by measuring the mechanical properties using SCC. Taken collectively, this study reveals the structural and property characteristics of nanowire-induced frustrated phagocytosis, which deepens our understanding of nanowire-cell interactions and nanocytotoxicity.

In situ synthesis of silver nanoparticles on periodic supports as highly active and flexible surface-enhanced Raman spectroscopy substrates

With regard to surface-enhanced Raman spectroscopy (SERS), the preparation of substrates with high homogeneity and low cost remains a challenge. In this paper, cheap commercial DVD-R plates were adopted as supports, whose 3D periodic structure was transferred onto the surface of flexible polydimethylsiloxane (PDMS) easily. Then, silver nanoparticles were grown both on DVD and PDMS substrates by the in situ reduction method, and the SERS performances of these two substrates were investigated. The results confirmed that the PDMS-based substrate exhibited better enhancement performance and higher uniformity (RSD=4.16%). In addition, due to the flexibility and transparency of PDMS, it is not restricted by the surface shape of the object when applied in in situ detection. This low-cost, simple method will be widely used in the in situ detection of surfaces of objects of any shape.

Patterned Metal/Polymer Composite Film with Good Mechanical Stability and Repeatability for Flexible Electronic Devices Using Nanoimprint Technology

Mechanical stability and repeatability are significant factors for the application of metal film flexible electronic devices. In this work, patterned metal/polymer composite films with good mechanical stability and repeatability were fabricated through nanoimprint technology. The mechanical properties characteristic of metal/polymer composite films were exhibited by resistance change (ΔR/R₀) after cyclic tension and bending loading. It was found that the ΔR/R₀ and error line of patterned metal/polymer composite film was far lower than the other control groups for repeated experiments, which indicates that patterned metal film has excellent mechanical properties and repeatability. The double cantilever beam method was employed to measure the interfacial adhesion properties of composite films. The average interfacial adhesion of patterned metal/polymer composite films is shown to be over 2.9 and 2.2 times higher than that of metal film deposited on bare polymer and metal nanowire-treated polymer substrates, respectively.

Multifunctional Electronic Textiles Using Silver Nanowire Composites

Textiles represent an appealing platform for continuous wearable applications due to the exceptional combination of compliance, water vapor permeability, and comfortableness for long-term wear. We present mechanically and electrically robust integration of nanocomposites with textiles by laser scribing and heat press lamination. The simple and scalable integration technique enables multifunctional E-textiles without compromising the stretchability, wearability, and washability of textiles. The textile-integrated patterns exhibit small line width (135 μm), low sheet resistance (0.2 Ω/sq), low Young's modulus, good washability, and good electromechanical performance up to 50% strain, which is desirable for wearable and user-friendly electronic textiles. To demonstrate the potential utility, we developed an integrated textile patch comprising four dry electrophysiological electrodes, a capacitive strain sensor, and a wireless heater for electrophysiological monitoring, motion tracking, and thermotherapy, respectively. Beyond the applications demonstrated in this paper, the materials and methods presented here pave the way for various other wearable applications in health care, activity tracking, rehabilitation, sports medicine, and human-machine interactions.

Novel AgNWs-PAN/TPU membrane for point-of-use drinking water electrochemical disinfection

The safety of drinking water remains a major challenge in developing countries and point-of-use (POU) drinking water treatment device plays an important role in decentralised drinking water safety. In this study, a novel material, i.e. a silver nanowires-polyacrylonitrile/thermoplastic polyurethane (AgNWs-PAN/TPU) composite membrane, was fabricated via electrospinning and vacuum filtration deposition. Morphological and structural characterisation showed that the PAN/TPU fibres had uniform diameters and enhanced mechanical properties. When added to these fibres, the AgNWs formed a highly conductive network with good physical stability and low silver ion leaching (<100 ppb). A POU device equipped with a AgNWs-PAN/TPU membrane displayed complete removal of 10⁵ CFU/mL bacteria, which were inactivated by silver ions released from the AgNWs within 6 h. Furthermore, under a voltage of 1.5 V, the bacteria were completely inactivated within 20-25 min. Inactivation efficiency in 5 mM NaCl solution was higher than those in Na₂SO₄ and NaNO₃ solutions. We concluded that a strong electric field was formed at the AgNW tips. Additionally, silver ions and chlorine compounds worked synergistically in the disinfection process. This study provides a scientific basis for research and development of silver nanocomposite membranes, with high mechanical strength and high conductivity, for POU drinking water disinfection.

Fabrication of Low-Cost Flexible Superhydrophobic Antibacterial Surface with Dual-Scale Roughness

In this work, we report a large-area fabrication of a flexible superhydrophobic bactericidal surface decorated with copper hydroxide nanowires. This involves a simple two-step method which involves growth followed by transfer of the nanowires onto the polydimethylsiloxane (PDMS) surface by mechanical peeling. Additional roughness in PDMS is obtained through incomplete wetting of the nanoscale gaps which leads to dual-scale roughness and superhydrophobicity with a contact angle of 169° and hysteresis of less than 2°. The simplicity of the process makes it low-cost and easily scalable. The process allows fabrication of nonplanar 3D surfaces. The surface shows blood repellence and antibacterial activity against Escherichia coli with more than 5 log reductions in bacterial colony. The surface also shows hemocompatible behavior, making it suitable for healthcare applications. The fabricated surface is found to be extremely robust against stretching, twisting, sandpaper abrasion, solid weight impact, and tape peel test. The surface is found to withstand human weight multiple times without losing its hydrophobicity, making it suitable for several practical scenarios in healthcare and household applications.