Four-in-One: Advanced Copper Nanocomposites for Multianalyte Assays and Multicoding Logic Gates

The usage of non-noble-metal nanomaterials for nanoprobes or functional modules is still a big challenge because of their poor stability, functionality, and surface plasmon resonance property. In this work, copper ion, mercaptosuccinic acid, and nanocrystalline cellulose are combined for facile one-step synthesis and self-assembly of ultrasmall copper nanoparticles to produce supercolloidal particles (NCC@MSA-Cu SPs). Cu SPs show advanced multifunctionality for fast point-of-care tests (POCTs) of four metal ions (Hg2+, Pb2+, Ag+, and Zr4+). These selective recognitions integrate four different chemical reaction mechanisms (ion etching, core-shell deposition, templated synthesis, and precipitation) to produce four distinct readout signals. The multisignal mode-guided multianalyte sensing strategy can effectively avoid interference that affects single signal mode-based sensing. Benefiting from the creative multi-input and multireadout abilities, the visual multicoding logic gates of OR, NOR, AND, and INHIBIT are built based on optical responses of Cu SPs.