Quantum Dot-Amphiphilic Polymer Composite Colloids for Nitric Oxide Sensing

Nitric oxide (NO) regulates diverse physiological pathways, functioning as an immune mediator, vascular regulator, and neurotransmitter. Sensitive and selective NO readout is important for biomedical research and diagnostics. We report two types of QD-amphiphilic polyethylenimine (amPEI) composite probes that showcase ratiometric detection of NO. The composites coencapsulate large numbers of fluorescent quantum dots (QDs) together with distinct cohosted NO-responsive molecules: the fluorescent dye 1,2-diaminoanthraquinone or the colorimetric ferric tetra-amido macrocyclic ligand [Fe(TAML)] complex. The flexible amPEI scaffold provides hydrophobic pockets that promote efficient gas permeation and probe–analyte interactions. Both types of composite probes exhibit a fast response and high sensitivity, showcasing submicromolar limits of detection. This multicomponent ratiometric design underscores the robustness and reliability for NO sensing, potentially in complex environments.