Synthesis of Ag-Doped Tetrahedral Amorphous Carbon Coatings and Their Antibiofilm Efficacy for Medical Implant Application.

Tetrahedral amorphous carbon (taC) is a hydrogen-free carbon with extensive properties such as hardness, optical transparency, and chemical inertness. taC coatings have attracted much attention in recent times, as have coatings doped with a noble metal. A known antimicrobial metal agent, silver (Ag), has been used as a dopant in taC, with different Ag concentrations on the Ti64 coupons using a hybrid filtered cathodic vacuum arc (FCVA) and magnetron sputtering system. The physiochemical properties of the coated surface were investigated using spectroscopic and electron microscopy techniques. A doping effect of Ag-taC on biofilm formation was investigated and found to have a significant effect on the bacterial-biofilm-forming bacteria Staphylococcus aureus and Pseudomonas aeruginosa depending on the concentration of Ag. Further, the effect of coated and uncoated Ag-taC films on a pathogenic bacterium was examined using SEM. The result revealed that the Ag-taC coatings inhibited the biofilm formation of S. aureus. Therefore, this study demonstrated the possible use of Ag-taC coatings against biofilm-related complications on medical devices and infections from pathogenic bacteria.

Synthesis of antibacterial hydroxypropyl methylcellulose and silver nanoparticle biocomposites via solution plasma using silver electrodes.

The biocomposites of hydroxypropyl methylcellulose (HPMC)/silver nanoparticles (AgNPs) were synthesized using the solution plasma process (SPP). HPMC/AgNPs were synthesized in 1-5 % HPMC solutions using silver electrodes. UV-Vis spectroscopy showed a peak near 400 nm and the peak increased as the concentration of HPMC and discharge time increased. FTIR analysis indicated no change in the chemical structure of the HPMC based biocomposites. Spherical shaped AgNPs with size ranges about 2-18 nm and well dispersed in the porous HPMC matrices with fringed edges were observed by TEM and SEM/EDS analyses. The synthesized biocomposites were found to be thermo-stable by TGA analysis. The inhibition zones of bacterial growth formed by the HPMC/AgNPs biocomposites were in the range of 8-14.3 mm; minimal inhibition concentrations, in the range of 10-15 µg·mL-1 for Gram-negative bacteria; 25-30 µg·mL-1 for Gram-positive bacteria. The biocomposites were non-toxic to the HEK293 cells up to 125 µg·mL-1. The results indicated that the synthesis of antibacterial agents in the HPMC matrix using silver electrodes via SPP would be an efficient and safe way for the development of biopolymer based antimicrobials and wound healing biomaterials.