Supramolecular Macrocycle–Quantum Dot Interfaces for Molecular Sensing and Bioimaging

Abstract Quantum dots (QDs) provide bright optical, electrochemiluminescent, and electrochemical readouts for molecular sensing and bioimaging, but by themselves they do not provide selectivity, matrix tolerance, or a reliable mechanistic assignment. Supramolecular macrocycles can address these limitations by adding cavity-defined binding, guest exchange, analyte preconcentration, redox activity, interfacial organization, or biological targeting. This review critically evaluates porphyrin-, phthalocyanine-, calixarene-, pillararene-, and cyclodextrin–QD interfaces. Particular attention is paid to how the intact macrocycle and the QD jointly create function, how FRET, PET, inner-filter effects, static or dynamic quenching, aggregation, host–guest displacement, ECL, and electrochemical pathways can be distinguished, and whether analytical claims survive real-matrix or cellular validation. Quantitative sensing performance is compared where reported, and macrocycle recognition is positioned against antibody-, aptamer-, and molecularly imprinted polymer-functionalized QDs. Bioimaging examples are retained only when a spectrally resolved QD signal supports localization, carrier tracking, release monitoring, or image-guided therapy. On this basis, this study proposes application-specific choices grounded in cavity–target matching, interfacial stability, mechanism-specific controls, and evidence that the hybrid adds value beyond either component alone.