Precise size-control and functionalization of gold nanoparticles synthesized by plasma-liquid interactions: using carboxylic, amino, and thiol ligands.

Using gold nanoparticles (GNPs) in high-standard applications requires GNPs to be fabricated with high-quality size and surface properties. Plasma-liquid interactions (PLIs) have the unique ability to synthesize GNPs without using any reducing agents, and the GNP surface is free of stabilizing agents. It is an extreme advantage that ensures success for the subsequent functionalization processes for GNPs. However, fabricating GNPs via PLIs at the desired size has still been a challenge. Here, we present a simple approach to achieving the precise size-control of GNPs synthesized by PLIs. By adding suitable ligands to the precursor solution, the ligands wrap GNPs which interrupts and slows down the rapid growth of GNPs under PLIs. This way, the size of the GNPs can be precisely controlled by adjusting the ligand concentration. Our results showed that the size of the GNPs in the range of 10-60 nm can be fitted to reciprocal functions of the ligand concentration. The potency of the size-control depends on the type of ligands in the order of thiol > amine > carboxylate. The size-control has been well investigated with four common ligands: l-cysteine, glucosamine, salicylic acid, and terephthalic acid. XPS, FTIR, and zeta potential techniques confirmed the presence of these ligands on GNPs. The results indicated that functionalized ligands could be utilized to control the size and functionalize the GNP surface. Hence our approach could simultaneously achieve two goals: precise size-control and functionalization of GNPs without the ligand-exchange step.

Optimization and characterization of electrospun polycaprolactone coated with gelatin-silver nanoparticles for wound healing application.

Bacterial infection and damage caused by dressing removal are two concerning problems which prolong the healing process in treatment of skin injuries. In this study, plasma treated electrospun polycaprolactone (PCL) scaffold was coated with silver nanoparticles (AgNPs) embedded in gelatin (Gel) by multi-immersion technique to optimize its antibacterial performance and reduce wound-scaffold adhesion. Water interaction test was used to examine the hydrophilization of PCL electrospun fibers after plasma treatment. Scanning Electron Microscopy (SEM) and weight calculation were employed to investigate the morphology and absorptive ability of the GelAg multi-coated PCL membrane (EsPCLGelAg). Antibacterial property of the membrane was evaluated using agar diffusion method against gram positive and gram negative bacteria. Mice model was also used to examine the efficiency of the membrane in healing process and its ability to prevent damage of newly formed tissue when peeling off. SEM results showed that the thickness of GelAg layer on EsPCL membrane increases correspondingly to the number of coating times. In vitro and in vivo data also demonstrated that the greater number of GelAg coating times, the more significant the antibacterial property of the membrane while not sticking to the wound site. These results suggest that multi-coating technique can be applied to optimize the antibacterial property of EsPCLGelAg scaffold and prevent removal-induced damage for wound dressing applications.