Novel Synthesis and Biophysical Characterization of Zinc Oxide Nanoparticles Using Virgin Coconut Oil

One of the primary concerns in the field of green synthesis of nanoparticles (NPs) utilizing plant materials is the scarcity of high purity, challenges in achieving large-scale production, and limited global accessibility. Hygienic preparation and safe storage of plant extracts are also considerable challenges in this field. So, an investigation was started to overcome these limitations. Virgin coconut oil (VCO) in its purest form is available commercially all over the world. Also, it has high medicinal value with excellent biomedical applications. Very limited work has been reported on oils as bio reducers and stabilizers. In those reports, they used a few chemicals as mediators in the processes of synthesis and cleaning. So, to the best of our knowledge, for the first time, zinc oxide (ZnO) NPs were synthesized using VCO as a reducing and capping agent with zero chemical mediators. A comprehensive investigation of the structural, microstructural, and optical properties was reported. X-ray diffraction confirms the formation of VCO-ZnO NPs with an average crystallite size of 32.81 nm in a hexagonal structure. UV characteristics confirm quantum confinement through a well-defined SPR near 223 nm with fwhm of 67 nm and a direct band gap at 3.96 eV. FTIR reveals the capping of VCO through carboxylic functional groups, particularly the -COO- group of coconut oil at 1770 cm^-1 with a shift of about 30 cm^-1 compared to plain VCO. TEM confirms the polycrystalline nature with nearly spherical and 10-22 nm particle size. The zeta potential of -15.4 ± 5.0 mV signifies the stability and antiagglomeration properties. FESEM with EDS results confirms morphological excellence, the purity level of synthesized NPs (99.5%), and the prominent scalability of NPs (84.38% yield). Finally, as-synthesized VCO-ZnO NPs showed very good antioxidant (IC₅₀ 78.991, 51.464, and 4.677 μg/mL in DPPH, ABTS, and FRAP assays, respectively), anti-inflammatory (IC₅₀ 22.42 μg/mL in protein denaturation), antimicrobial (MIC 0.156 mg/mL for <i>Pseudomonas</i> and 0.316 mg/mL for <i>S. aureus</i>), and antidiabetic properties (IC₅₀ 88.45 and 147.67 μg/mL for α-amylase and α-glucosidase assays, respectively).