Adaptable, turn-on maturation (ATOM) fluorescent biosensors for multiplexed detection in cells

Destabilized near-infrared fluorescent nanobodies enable background-free targeting of GFP-based biosensors for imaging and manipulation

Near-infrared (NIR) probes are highly sought after as fluorescent tags for multicolor cellular and in vivo imaging. Here we develop small NIR fluorescent nanobodies, termed NIR-FbLAG16 and NIR-FbLAG30, enabling background-free visualization of various GFP-derived probes and biosensors. We also design a red-shifted variant, NIR-Fb(718), to simultaneously target several antigens within the NIR spectral range. Leveraging the antigen-stabilizing property of the developed NIR-Fbs, we then create two modular systems for precise control of gene expression in GFP-labeled cells. Applying the NIR-Fbs in vivo, we target cells expressing GFP and the calcium biosensor GCaMP6 in the somatosensory cortex of transgenic mice. Simultaneously tracking calcium activity and the reference signal from NIR-FbLAGs bound to GCaMP6 enables ratiometric deep-brain in vivo imaging. Altogether, NIR-FbLAGs present a promising approach for imaging and manipulating various processes in live cells and behaving animals expressing GFP-based probes.

Metal Halide Perovskite Nanocrystals-Intermediated Hydrogel for Boosting the Biosensing Performance

Metal-halide perovskites have become attractive nanomaterials for advanced biosensors, yet the structural design remains challenging due to the trade-off between environmental stability and sensing sensitivity. Herein, a trinity strategy is proposed to address this issue by integrating Mn (II) substitution with CsPb2Cl5 inert shell and NH2-PEG-COOH coating for designing Mn2+-doped CsPbCl3/CsPb2Cl5 core/shell hetero perovskite nanocrystals (PMCP PNCs). The trinity strategy isolates the emissive Mn2+-doped CsPbCl3 core from water and the Mn2+ d-d transition generates photoluminescence with a long lifetime, endowing the NH2-PEG-COOH capped Mn2+-doped CsPbCl3/CsPb2Cl5 PNCs with robust water stability and oxygen-sensitive property. Given the structural integration, photoluminescent hydrogel biosensors are designed by embedding the PMCP PNCs into the hydrogel system to deliver on-site pesticide information on food products. Impressively, benefiting from the dual enzyme triggered-responsive property of PMCP PNCs, the hydrogel biosensor is endowed with ultra-high sensitivity toward chlorpyrifos pesticide at the nanogram per milliliter level. Such a robust PMCP PNCs-based hydrogel sensor can provide accurate pesticide information while guiding the construction of photoluminescent biosensors for upcoming on-site applications.