Molecular rivet-enhanced in situ polymerized nonconventional luminescent hydrogels for rapid and sensitive biosensing

Nonconventional luminescent hydrogels, which integrate optical reporting functions with a biomimetic three-dimensional matrix, exhibit significant potential in chemical sensing due to their excellent biocompatibility, photostability, and ease of synthesis. Despite these advantages, their practical application as high-performance analytical platforms faces two critical challenges: first, their inherently low fluorescence quantum yield (QY) in aqueous environments severely limits detection sensitivity for trace analysis; second, the slow mass transfer of analytes within traditional pre-prepared solid hydrogel networks results in sluggish response kinetics, substantially hindering real-time sensing applications.

Herein, we report a synergistic strategy to simultaneously address these challenges. We first implemented a copolymerization strategy employing N,N'-methylenebisacrylamide (BIS) as a "molecular rivet" to construct a rigid network, which achieves conformational locking of the polymer chains and significantly enhances the fluorescence quantum yield of the hydrogel. On this basis, we established a novel sensing method, in situ polymerization luminescence (ISPL), which effectively overcomes the mass transfer barrier and enables a rapid response by completing the sensing and signal reporting in a homogeneous solution. This platform demonstrates excellent versatility and has been successfully used for the signal-off detection of Fe³⁺ and the signal-on enzyme-linked analysis of glucose. The results from its application in clinical serum samples are highly consistent with those of clinical reference methods, indicating its accuracy.

This work presents a synergistic strategy that combines molecular-rivet-based material design with an ISPL sensing methodology that effectively reduces mass-transfer limitations. The molecular rivet approach significantly enhances fluorescence quantum yield by restricting intramolecular motion. The ISPL technique eliminates mass transfer limitations through rapid analyte-triggered polymerization. The resulting platform achieves versatile sensing modes with high clinical accuracy, offering an effective pathway for developing point-of-care diagnostic technologies that demand both rapid detection and ultra-high sensitivity.