Biosynthesis of Silver Nanoparticles Functionalized with Histidine and Phenylalanine Amino Acids for Potential Antioxidant and Antibacterial Activities

Due to biochemicallyactive secondary metabolites that assist inthe reduction, stabilization, and capping of nanoparticles, plant-mediatednanoparticle synthesis is becoming more and more popular. This isbecause it allows for ecologically friendly, feasible, sustainable,and cost-effective green synthesis techniques. This study describesthe biosynthesis of silver nanoparticles (AgNPs) functionalized withhistidine and phenylalanine using the Lippia abyssinica (locally called koseret) plant leaf extract. The functionalizationwith amino acids was meant to enhance the biological activities ofthe AgNPs. The synthesized nanoparticles were characterized usingUV-Visible absorption (UV-Vis), powder X-ray diffraction(pXRD), scanning electron microscopy (SEM), energy-dispersive X-ray(EDX) spectroscopy, transmission electron microscopy (TEM), and Fouriertransform infrared (FTIR) spectroscopy. The surface plasmonic resonance(SPR) peak at about 433 nm confirmed the biosynthesis of the AgNPs.FTIR spectra also revealed that the phytochemicals in the plant extractwere responsible for the capping of the biogenically synthesized AgNPs.On the other hand, the TEM micrograph revealed that the morphologyof AgNP-His had diameters ranging from 5 to 14 nm. The antibacterialactivities of the synthesized nanoparticles against Gram-positiveand Gram-negative bacteria showed a growth inhibition of 8.67 & PLUSMN;1.25 and 11.00 & PLUSMN; 0.82 mm against Escherichia coli and Staphylococcus aureus, respectively,at a concentration of 62.5 & mu;g/mL AgNP-His. Moreover, the nanoparticlehas an antioxidant activity potential of 63.76 & PLUSMN; 1.25% at 250 & mu;g/mL. The results showed that the green-synthesized AgNPs possesspromising antioxidant and antibacterial activities with the potentialfor biological applications.