Comparison of Antimicrobial, Antioxidant and Anticancer Activities of ZnO Nanoparticles Prepared by Lemon Juice and Citric Acid Fueled Solution Combustion Synthesis

In the present work, combustion synthesis of ZnO nanoparticles using lemon juice and citric acid as fuels has been carried out. A comparative analysis of the obtained powders has been conducted to understand the strategic advantages of using lemon juice over citric acid as the combustion fuel for the synthesis of ZnO nanopartilcles. The X-ray diffractograms of both the samples revealed the presence of wurtzite hexagonal structure with the standard JCPDS pattern of zincite [36-1451] with varying crystallite sizes. Surface morphology of the samples was studied by scanning electron microscopy. Particle shapes and sizes were determined by transmission electron microscopy. Although wurtzite hexagonal structures were seen in both the synthesis methods, their morphology and sizes differed significantly with samples prepared by lemon juice presenting smaller size. The band gap energy value determined by Wood-Tauc method was found to be ~ 3.2 eV for both the samples. DPPH assay revealed the antioxidant activity of the samples at varied concentrations. Further, antimicrobial studies were greater for those prepared by lemon juice. Furthermore, trypan blue and MTT assay evaluation of nanoparticles against PC-3, HCT116, A549, and MDA-MB-231 cancer cell lines indicated enhanced anticancer activity of ZnO nanoparticles prepared by lemon juice. It was found that the sample prepared using lemon juice exhibited IC 50 values of 78.80 μg/mL, 28.75 μg/mL, and 10.7 μg/mL, whereas the sample prepared using citric acid as fuel exhibited IC 50 values of 103.6 μg/mL, 41.52 μg/mL, and 20.06 μg/mL, towards PC-3, HCT 116, and MDA-MB-231 respectively.