One pot green synthesis of Pt, Co and Pt@Co core‐shell nanoparticles using Sechium edule

Abstract BACKGROUND Common approaches for the synthesis of metallic nanostructured materials require the use of fine chemicals and energy‐intensive processes. This work reports a simple eco‐friendly (green) method to engineer the structure of cobalt (Co), platinum (Pt) and PtCo core‐shell nanoparticles using plant‐based analytes present in the extract of Sechium edule , the fruit of a perennial climber plant. RESULTS Ascorbic acid (294 mg kg −1 dry fruit) was found to be the primary analyte and it acted for both metal ion reduction and nanoparticle destabilization forming a conjugate with the carboxylate group. The sharp rise in negative zeta‐potential with the rise in pH from a highly acidic medium resulted from a strong destabilization tendency of Pt and Co nanostructures over a wide pH range. The size and colloidal stability, morphology and crystal structure were confirmed with the support of dynamic light scattering, transmission electron microscopy and X‐ray diffraction. Co nanoprisms (47.3 nm), Pt nanospheres (28.6 nm) and PtCo core‐shell (13.2–26.4 nm) nanoparticles were formed with a polydispersity index of 0.18–0.38. The synergistic effects such as ligand interaction between core and shell and the geometric effect improved the antibacterial activity against Bacillus subtilis and Escherichia coli bacteria in comparison to Pt nanospheres and Co nanoprisms, and these results were comparable with ciprofloxacin and cefprozil as the antibiotic controls. CONCLUSION Plant analytes served as the electron donors for the formation of Pt and Co nanostructures and also stabilized the particles growth to tailor their structures for an improved antibacterial functionality. © 2018 Society of Chemical Industry