Synthesis and characterization of poly(methyl methacrylate)/silver/porphyrin nanoparticles and its antibacterial studies on escherichia coli and staphylococcus a ureus

Abstract

Preventing the bacterial colonization of different surfaces specially in the biomedical field with a technique that avoids the emergence of resistant bacteria is the key to limiting the spread of infections. The advancement of an antimicrobial coating material with photoactivated properties can be helpful in obviating the misuse or overuse of antibacterial substances and, therefore, prevents the development of superbugs. As a potential light-activated antibacterial material that employs two different antibacterial strategies, poly(methyl methacrylate) (PMMA) nanoparticles were impregnated with silver nanoparticles and cationic 5,10,15,20-tetrakis(Amethylpyridinium- 4-yl)porphyrin (TMPyP) via a novel one-pot miniemulsion technique. At first, silver nanoparticles were prepared via chemical and physical methods. The resultant colloids were compared based on the particle size and yield of the reaction. Chemical reduction of silver was carried out using aniline and sodium borohydride (NaBH4) as different reducing agents. The effect of various parameters was optimized such as the order of mixing the reactants, presence of a stabilizer and time on stability, as well as size and concentration of the silver nanoparticles which were studied by UV-Vis. As a comparison, the physical technique was performed with ablation of a silver plate in distilled water with Q-switched Nd:YAG laser. The effect of ablation time and presence of a stabilizer on the production and stability of silver nanoparticles were optimized by using UV-Vis. Afterwards, the silver nanoparticles prepared via NaBH4 reduction method were incorporated into PMMA via a novel miniemulsion method. The obtained products were then studied using UV-Vis DR, FTIR, 1H NMR, FESEM, and TEM to investigate and optimize the polymerization, size of the particles and presence of silver in the samples. In the next phase, cationic porphyrin of TMPyP was synthesized from tetra pyridinyl porphyrin (TPyP) which was initially prepared via Alder-Longo condensation method. The obtained porphyrins were then characterized with UV-Vis, 1H NMR, and FTIR. Consequently, PMMA/TMPyP and PMMA/TMPyP/silver nanoparticles were synthesized via our established miniemulsion method and were studied using UV-Vis DR and TEM to investigate the presence of porphyrin and silver in the samples. The antibacterial activities for all samples were evaluated by Kirby-Bauer test in dark against Gramnegative E. coli and Gram-positive S. aureus. Samples containing porphyrin were further tested under illumination to study the photoactivation of porphyrin. Silver nanoparticles studies showed that the silver nanoparticles prepared via reduction with NaBH4 produced the highest yield with the size ranged between 7-25 nm and hence it was used in the production of polymer nanoparticles. Moreover, it was observed that in the physical technique, the production of silver nanoparticles increased by the time of ablation however, due to blockage of laser beam by silver nanoparticles the production was limited. The results of miniemulsion synthesis showed the successful production of PMMA/silver, PMMA/TMPyP, and PMMA/TMPyP/silver nanoparticles with high yields. The antibacterial test revealed that the use of two different antibacterial strategies improved the antibacterial properties of the polymer nanoparticles.