Molecular architectonics of semiconducting polymer dots for next-generation NIR-II fluorescence bioimaging

Abstract

Next-generation semiconducting polymer dots (Pdots) engineered through molecular architectonics are redefining NIR-II fluorescence bioimaging and precision theranostics. By integrating donor-acceptor engineering, π-conjugated backbone rigidification, and side-chain modulation, molecular architectonics enables precise bandgap tuning, exciton delocalization, and enhanced photochemical stability. Architectonic control across molecular, supramolecular, and interfacial levels yields Pdots with superior quantum yields, ultradeep tissue penetration, and negligible autofluorescence. This review elucidates the structure-function paradigms governing NIR-II emission and examines frontier strategies for photostability enhancement, including nanoscale confinement within hybrid matrices, intersystem energy dissipation modulation, and conformational locking. At the biointerface, rational surface architectonics, via dynamic ligand exchange, stealth polymer cloaking, and adaptive functionalization, prolongs circulation, minimizes opsonization, and facilitates targeted delivery. Integrating NIR-II fluorescence with photothermal, photodynamic, and image-guided drug delivery modalities, Pdots emerge as molecularly architected cores for multimodal theranostic systems synergized with photoacoustic and magnetic resonance imaging. Despite rapid progress, biodegradability, long-term biosafety, and regulatory compatibility remain major challenges. Emerging architectonic solutions, bioresponsive degradation and hybridization with clinically approved carriers, are bridging molecular design and clinical translation, positioning NIR-II Pdots as key enablers of next-generation intelligent nanomedicine.