Metal Oxide Microrings with Femtoliter Capacity for Raman Microspectroscopy

A simple strategy, based on ultrafast heating of polystyrene microspheres infiltrated with a zinc acetate solution, is employed here for preparing ZnO microcontainers with femtoliter capacity. Their potential exploitation in micro-Raman assays for basic studies in bio- and nanotechnology is tested in different proof-of-concept experiments concerning the in situ analysis of L-glutathione crystals and gold-yeast cytochrome c bioconjugates. The ZnO microcontainers are also used as scaffolds for atomic layer deposition of TiO2 overlayers with a fine-tuning of thickness and morphology. The resulting ZnO/TiO2 heterostructures are tested in different photocatalytic experiments involving degradation and laser-induced conversion of methylene blue.