Novel concept on in situ syntheses and investigation of photon energy effect on AgNP size with a custom build device for enhanced antimicrobial efficiency

The objectives of the present study were to examine the influence of visible light photons on photoreduction of the silver nanoparticles (AgNPs), detect optoelectronic feedback, and observe the antimicrobial activity. For this purpose, an optoelectronic device was designed and successfully tested. The finding shows that identical nanocomplexes with silver salt express various responses to the LEDs with different wavelengths by scattering different portions of light. It is the first time to discuss the effect of visible light photons on nano-sized particles in detail based on the quantitative optical/voltage analysis. The photoreduction of the AgNPs is in good agreement with photon energy and the AgNPs occur in nanocomplex in a wavelength versus time-dependent manner. The blue LED having photon energy 7.04 eV reduces the average size of AgNPs down to the range 4–6 nm in 12 min, while AgNPs obtained under influence of green (6.11 eV) and red (5.04 eV) LEDs have average sizes 6–8 nm and 12–14 nm respectively. The successful synthesis of AgNPs was additionally examined using UV–Vis, SEM, XPS, XRD, FTIR, and TEM techniques. AgNPs proved for antimicrobial activity against Escherichia coli 25922, Enterococcus faecalis 29212, Pseudomonas aeruginosa 27853, and Candida albicans 10231 at four different concentrations. The antibacterial test for all selected bacteria showed that AgNPs which have an average size of 4-6 nm synthesized by blue LED revealed the largest inhibition zone around 16–11 mm, while the antifungal test shows that the maximum inhibition zone was exposed by AgNPs which have an average size of 6–8 nm synthesized by red LED.