Microwave-Assisted Synthesis of Chromium Oxide Nanoparticles for Fluorescence Biosensing of Mercury Ions and Molecular Logic Computing

Cumbersome and inefficient synthesis of chromium-based nanomaterials with unique physicochemical properties and bioactivity limits their wide and practical applications. Simple, fast, and green synthesis of chromium-based nanomaterials will help promote the discovery of their properties and expansion of their application fields. Herein, we proposed rapid, inexpensive, and large-scale methods for the synthesis of chromium oxide nanoparticles (Cr2O3 NPs) by simply microwave-heating Cr3+ ions and citrate for several minutes. The citrate-coated Cr2O3 NPs with a universal fluorescence quenching ability as the sensing platform can combine with biomolecules (DNA) for application in fluorescence biosensing of mercury ions and complex molecular logic computing. The Hg2+ assay had wide linear ranges (0.21–2 and 4.2–50.5 μM), a low detection limit (5.78 nM), and good recovery rates in actual water samples. In addition, the interaction of matter and energy (fluorescence) in the Cr2O3 NPs-based sensing system can be used to perform molecular logic gate operations from simple (YES, NOT, AND, and OR gates) to complex circuits. This research can provide an idea for rapid and large-scale preparation of chromium-based nanomaterials and offer an opportunity for the extensive and in-depth exploration of properties (such as unique optical or enzyme-mimetic) and multipurpose applications (sensing, catalysis, logic computing, and encryption) of chromium-based nanomaterials.