In-situ construction of fluorescent probes for hydrogen peroxide detection in mitochondria and lysosomes with on-demand modular assembling and double turn-on features.

Due to the diverse H2O2 distribution in organelles, fluorescent probes were usually required to be prepared separately, which limited the convenience and practicability. Herein, we reported a flexible strategy to in-situ construct H2O2 fluorescent probes in different organelles. A tetrazine fused probe TP was developed with rapid click reaction capacity and sensitive H2O2 response. When treated with H2O2, the turn-on fluorescence was effectively quenched by the tetrazine part. Only after click reaction with dienophiles, the fluorescence resumed. In application, cells were firstly treated with triphenylphosphorus tagged norbornene (TPP-NB) to label mitochondria, which was followed by the introduction of probe TP to trigger click reaction. The in-situ constructed probe P1 served as a local H2O2 sensor. In a similar way, probe P2 was in-situ constructed in lysosomes via probe TP and morpholine tagged norbornene (MP-NB). With this on-demand modular assembling and double turn-on features, our strategy to construct fluorescent probes presented high flexibility and anti-interference performance, which was expected to inspired more applications in biological studies.

Fabry-Perot Interferometer Based on a Fiber-Tip Fixed-Supported Bridge for Fast Glucose Concentration Measurement.

Blood glucose concentration is important for metabolic homeostasis in humans and animals. Many diabetic patients need to detect blood glucose daily which burdens community hospitals and family healthcare. Optical fiber sensors are widely used in biomedical detection because of their compact structure, fast response, high sensitivity, low cost, and ease of operation. In this work, we constructed a Fabry-Perot (FP) cavity biosensor for the fast detection of glucose concentration in serum. The femtosecond laser micromachining was applied to fabricate the FP cavity by printing the fiber-tip fixed-supported bridge at the end face of the optical fiber. An additional hemisphere was printed at the center of the outer surface of the bridge to avoid multi-beam interference. The results demonstrated that the proposed biosensor had high refractive index (RI) detection sensitivity, roughly 1039 nm/RIU at a wavelength of 1590 nm, and the detection sensitivity for glucose was around 0.185 nm/ (mg/mL) at a wavelength of 1590 nm. Due to its high sensitivity, compact structure, and fast response, the FP cavity biosensor has great potential to be applied in family healthcare for glucose concentration detection of diabetic patients.