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In this work, we reported the first use of a novel fluorescent probe for phoxim detection based on yellowish-green emissive carbon quantum dots (CQDs). By facile one-pot hydrothermal treatment of citric acid and p-phenylenediamine, the CQDs with yellowish-green luminescence were synthesized. The sensing mechanism is based on the quenching effect of phoxim on the fluorescence emission of CQDs by inner filter effect (IFE). The CQDs showed a good sensitivity and selectivity to phoxim detection and dual good linear relationships were provided in the concentration ranges of 1–10 μM and 10–98 μM, associated with the limit of detection of 0.09 μM. The proposed assay has been allowed to detect phoxim in real samples with satisfying recoveries ranging from 93 to 105.9%. Furthermore, due to the low cytotoxicity and excellent biocompatibility, the as-prepared CQDs was successfully used for cell imaging, demonstrating the considerable potential applications of such CQDs in biological field. [Display omitted] • A novel sensing platform based on yellowish-green emitting CQDs was developed. • The proposed method exhibited high selectivity and sensitivity towards phoxim. • The new analytical method was feasible for phoxim determination in real samples. • The as-prepared CQDs was successfully used for cell imaging. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is a typical gas signal molecule that plays a vital role in various pathological courses. Despite having the accumulated knowledge on the physiological functions of H 2 S in many diseases, the process in the measurement of its level in mitochondria during oxidative stress is still far away from the expectation. In this regard, it is great significant to design a fluorescent probe for accurately monitoring the dynamics of H 2 S during oxidative stress. In this work, we firstly synthesized an oxidative stress activated fluorescence probe QM-RSH for tracking H 2 S level in mitochondria. It exhibited high selectivity and sensitivity for detecting H 2 S with lower limit of detection (LOD = 44.6 nM) in the presence of H 2 O 2. QM-RSH can be successfully applied to accurately monitor the fluctuation of H 2 S level during oxidative stress without interference from other physiological processes in living cells and zebrafish. Therefore, this multifunctional probe QM-RSH has great potential as an image tool in biological research. It also provides a novel strategy for designing fluorescent probe to investigate biomolecular information and signaling pathways under specific physiological conditions. [Display omitted] •A novel multifunction fluorescent probe QM-RSH was designed and synthesized. • QM-RSH can sequentially detect H 2 O 2 and H 2 S in two signal channels. • QM-RSH exhibited brighter NIR fluorescence and lower detection limit for H 2 O 2 (80.3 nM) and H 2 S (44.6 nM). • QM-RSH can be applied to accurately monitor H 2 S fluctuation during oxidative stress, avoiding interference from other physiological processes. • QM-RSH is used to investigate the main factors of H 2 S up-regulation during oxidative stress. [ABSTRACT FROM AUTHOR]