Facile green synthesis, analysis, in vitro antidiabetic and antimicrobial activity of ZnO macropores

Rapid increase in population and development in industry causes many problems such as microbial contaminations and chronic diseases such as diabetes. Materials synthesized at nanoscale are novel antidiabetic and antimicrobial agents. ZnO nanoparticles with macropores characteristics are synthesized by green methods. Turmeric, clove buds and green tea extracts are used as additives. X-ray diffraction results confirmed the hexagonal wurtzite structure of ZnO nanoparticles and crystallinity was quit high in case of green tea extract. Sample synthesized with clove shows relatively higher crystallite size (10.64) which is pertaining to variation in Zn²⁺ and OH^- ions. The nanoparticles are more or less spherical in nature, macropores and clustered together revealed by SEM images. Macroporosity of the sample was further confirmed by nitrogen adsorption-desorption isotherm. The deep absorption band at 605 cm^-1 in FTIR spectra attributed the wurtzite-type ZnO. The major dominating sharp peak was detected at 437 cm^-1 in Raman spectra which is a feature of the wurtzite hexagonal phase ZnO. UV-Vis spectra showed red shift from wavelength 362 to 375 nm with different plant extracts. Impedance analysis showed a high dielectric constant and low tangent loss in case of green tea extract. ZnO synthesized using green tea exhibited ~ 95% α-glucosidase inhibition activity and 91% α-amylase inhibition activity. Antibacterial results revealed that synthesized ZnO nanoparticles showed activity against Bacillus subtilis and E. coli with inhibition zone 35 mm and 29 mm, respectively.