Fluorescent nanosensors that enable non-invasive, real-time molecular diagnostics in complex biological environments remain a key challenge in bioimaging and biosensing. Here, we present a unified strategy for the design of enzyme–conjugated single-walled carbon nanotube (SWCNT) nanosensors that combine the high selectivity of natural molecular recognition with the tissue-transparent, non-photobleaching near-infrared fluorescence of SWCNTs. Specifically, we develop and compare two distinct enzyme–SWCNT architectures: (1) a non-covalent glucose nanosensor prepared by direct sonication with glucose oxidase, where fluorescence modulation is driven by glucose–enzyme binding independent of catalysis [1], and (2) a covalently constructed hydrogen peroxide (H₂O₂) sensor using horseradish peroxidase, enabled by defect-free azide chemistry that preserves both enzymatic activity and SWCNT emission [2].
These nanosensors demonstrate rapid, reversible, and highly selective responses toward their target analytes, with a ΔF/F₀ of up to 40% within seconds, and maintain functionality in complex media including blood plasma and brain tissue slices. Mechanistically, we show that catalytic activity is not a prerequisite for fluorescence modulation, and that enzyme–SWCNT conjugation can be tailored for affinity-based or reaction-based sensing modalities. Together, these findings establish a versatile platform for engineering non-invasive, tissue-compatible nanosensors and open the door to generalizable strategies for diagnostic applications across a broad range of biomolecular analytes.
References
[1] Nishitani et al., Angew. Chem. Int. Ed. 2024, 63, e202311476.
[2] Ledesma, Nishitani et al., Adv. Funct. Mater. 2024, 2316028.
