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Harmful metal ions and toxic anions produced in industrial processes cause serious damage to the environment and human health. Chemical sensors are used as an efficient and convenient detection method for harmful ions. Electrospun fiber membranes are widely used in the field of solid-state chemical sensors due to high specific surface area, high porosity, and strong adsorption. This paper reviews the solid-state chemical sensors based on electrospinning technology for the detection of harmful heavy metal ions and toxic anions in water over the past decade. These electrospun fiber sensors have different preparation methods, sensing mechanisms, and sensing properties. The preparation method can be completed by physical doping, chemical modification, copolymerization, surface adsorption and self-assembly combined with electrospinning, and the material can also be combined with organic fluorescent molecules, biological matrix materials and precious metal materials. Sensing performance aspects can also be manifested as changes in color and fluorescence. By comparing the literature, we summarize the advantages and disadvantages of electrospinning technology in the field of ion sensing, and discuss the opportunities and challenges of electrospun fiber sensor research. We hope that this review can provide inspiration for the development of electrospun fiber sensors.

By connecting 1,8-naphthalimide and indole sulfonate, a ratio fluorescent probe capable of differential detection of hydrogen sulfite and hypochlorite was synthesized for the first time. It was able to achieve the qualitative detection of HSO3− and ClO− with high sensitivity and selectivity, respectively. It provides a multi-purpose probe and is based on different emission channels without mutual interference. The probe has the advantages of larger Stokes shift (ClO−: 115 nm, HSO3−: 88 nm), longer λem (ClO−: 515 nm, HSO3−: 548 nm) and better water solubility (DMF/PBS = 1:99, v/v). In addition, the probe is a ratio fluorescence probe, which can detect fluorescence intensity with two different emission waves. It provides internal self-calibration, reduces interference from the background and increases detection accuracy. In vitro cytotoxicity and imaging experiments show that the probe can effectively perform the detection of exogenous HSO3− and ClO− in cells. It can also achieve the detection of HSO3− and ClO− in the plasma environment. Because the probe can detect endogenous ClO−, it also has a good prospect for biological application in identifying tumor cells.

Copper is an essential element in living systems and plays an important role in human physiology; therefore, methods to detect the concentration of copper ions in living organisms are important. Herein, we report a highly water-soluble naphthalimide-based fluorescent probe that can be used for the detection of Cu2+. The probe, BNQ, has high selectivity and sensitivity. The fluorescence intensity of the probe at 520 nm was visible to the naked eye under a UV lamp; upon the gradual addition of Cu2+, there was a colour change from green to nearly colourless. Furthermore, the detection limit of BNQ for Cu2+ was 45.5 nM. The detection mechanism was investigated using a Job's plot and density functional theory (DFT) calculations. In addition, owing to great biocompatibility, we were able to successfully use BNQ to detect Cu2+ in living HeLa cells with low toxicity.

A novel highly active fluorescence chemical sensor (TBQN) for HSO3− was synthesized by the Knoevenagel reaction based on triphenylamine–benzothiazole as a new fluorophore. The probe possessed good selectivity toward HSO3− and anti-interference ability with common ions. The fluorescence and UV-vis spectra of the TBQN probe were significantly changed after the addition of HSO3−. At the same time, the probe solution released obvious green fluorescence. Moreover, the limit of detection for HSO3− was calculated to be 3.19 × 10–8 M. The TBQN probe displayed a rapid response to HSO3− and it took about 3 min to complete the recognition. The detection mechanism is the nucleophilic addition reaction between HSO3− and –CC– in the probe molecule. The π-conjugation and ICT (intramolecular charge transfer) transition in the TBQN molecule were destroyed by this addition, which resulted in the change of the fluorescence before and after the addition of HSO3−. Then, the mechanism was verified by theoretical calculations, 1H NMR measurements and mass spectroscopy. In addition, the probe showed low cytotoxicity and could be used for biological imaging in RAW264.7 cells.

A fluorescent hydrazine hydrate probe (DMA) based on 1,4-dihydropyridine derivatives was designed and synthesized. The fluorescence emission peak of this probe is in the near-infrared region (667 nm), which has good selectivity to hydrazine hydrate and low detection limit (11 nM). Importantly, the probe exhibits aggregation-induced emission (AIE) characteristics. In addition, the probe is prepared with a portable test paper to realize the identification of hydrazine hydrate in the solution and the quantitative detection of hydrazine hydrate gas.

We have successfully synthesized NIRF as a near-infrared fluorescence probe for relay recognition of zinc and cyanide ions. The probe possesses well selectivity and anti-interference ability over common ions towards Zn

A novel highly active fluorescence chemical sensor (TBQN) for HSO

Copper is an essential element in living systems and plays an important role in human physiology; therefore, methods to detect the concentration of copper ions in living organisms are important. Herein, we report a highly water-soluble naphthalimide-based fluorescent probe that can be used for the detection of Cu

We have successfully synthesized NIRF as a near-infrared fluorescence probe for relay recognition of zinc and cyanide ions. The probe possesses well selectivity and anti-interference ability over common ions towards Zn2+ and CN-. The results showed that Zn2+ and the probe formed [NIRF-Zn2+] complex after added Zn2+ into the probe NIRF solution, which emited red fluorescence. The probe can be used for quantitative detection of Zn2+ with a detection limit of 4.61 × 10-8 M. It was determined that the binding stoichiometry between the NIRF and Zn2+ was 1:1 according to the job,s curve. Subsequently, CN- was added to the NIRF-Zn2+ solution, CN- combined with Zn2+ to generate [Zn(CN-)x]1-x due to the stronger binding ability between zinc ion and cyanogen, which lead to the red fluorescence disappeared. The quantitative detection of CN- was realized with a detection limit of 7.9 × 10-7 M. In addition, the probe has excellent specificity and selectivity for Zn2+ and CN-. And the probe can be stable in a wide range of pH. Through biological experiments, we found that it can complete cell imaging in macrophages and imaging of living mice, which has application prospects in Bioimaging. In addition, the probe NIRF has good applicability for Zn2+ and CN- detection in actual samples.