Preparation of Yellow Fluorescent N,O-CDs and its Application in Detection of ClO. J Fluoresc 2021;31:659-666. [PMID: 33534115 DOI: 10.1007/s10895-021-02686-4]

Hydrothermal synthesis of modified lignin-based carbon dots derived from biomass waste for fluorescence determination of valsartan

Recently, carbon dots (CDs) have been extensively investigated as potential tools for numerous applications. Modified lignin-based CDs have been synthesized and used in the field of drug detection. They were found to be highly selective and sensitive to valsartan (VAL). Using a simple hydrothermal method, phosphorus and chlorine co-doped CDs were synthesized using lignin extracted from date seeds. The fluorescence properties of the synthesized CDs are influenced by several factors, which were investigated in detail. The optimal synthesis conditions were 1.50 g of lignin, 18 mL of 2 M NaOH, 1 mM H3PO4, 3 mM HCl and the mixture was heated at 220 °C for 16 hours. The synthesized lignin-based CDs have excellent FL properties and are well soluble in water with reasonable stability. Characterization of the prepared CDs revealed that they have various functional groups with a graphene oxide-like structure. The developed CDs show a good quantum yield of 37.7%. The FL of the CDs is quenched by VAL at λ em 313 nm after λ ex at 275 nm by a combination of static and dynamic quenching mechanisms. The response of VAL was linear in the range of 4.0-100.0 μg mL-1. The detection and quantification limits of VAL were 1.23 and 3.71 μg mL-1, respectively. The nanoprobe was successfully used to analyze VAL in drug samples and provided satisfactory results.

Comparing the abundance of HClO in cancer/normal cells and visualizing in vivo using a mitochondria-targeted ultra-fast fluorescent probe

Organisms are operating and evolving with a highly sophisticated and intelligent defense mechanism to resist bacterial and viral infections. This process involves a variety of reactive oxygen species (ROS), and they coordinate with each other to support different physiological activities. Due to its strong oxidizing properties, hypochlorous acid (HClO), a part of ROS, is a powerful antimicrobial agent in living organisms and exerts a crucial role in the immune system. However, the excessive production of HClO can cause cell damage and even cell death. Herein, we combined benzene-conjugated benzopyrylium as the fluorophore and dimethylthiocarbamoyl chloride as the recognition site to rationally design a probe (BBD). The fluorescence of the probe was quenched based on an effective PET molecular mechanism. Surprisingly, BBD exhibited a turn-on red fluorescence signal for HClO with ultra-fast response (5 s) and high selectivity. Moreover, BBD located mitochondria well and it was found that the abundance of HClO is higher in HeLa cells compared to that in normal cells. Finally, BBD was successfully applied to the visualization of HClO in zebrafish and nude mice.