In this paper, a novel, accurate, sensitive and rapid ratiometric fluorescent sensor was fabricated using a copper nanoclusters@infinite coordination polymer (ICP), specifically, terbium ion-guanosine 5’-disodium (Cu NCs@Tb-GMP) nanocomposites as the ratiometric fluorescent probe, to detect alkaline phosphatase (ALP) in water. The fluorescence probe was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The experimental results showed that, compared with Tb-GMP fluorescent sensors, Cu ratiometric fluorescent sensors based on NCs encapsulated in Tb-GMP had fewer experimental errors and fewer false-positive signals and were more conducive to the sensitive and accurate detection of ALP. In addition, the developed fluorescent probe had good fluorescence intensity, selectivity, repeatability and stability. Under optimized conditions, the ratiometric fluorescent sensor detected ALP in the range of 0.002–2 U mL⁻¹ (R² = 0.9950) with a limit of detection of 0.002 U mL⁻¹, and the recovery of ALP from water samples was less than 108.2%. These satisfying results proved that the ratiometric fluorescent probe has good application prospects and provides a new method for the detection of ALP in real water samples.

As an efficient and easily available pesticide, imidacloprid (IM) has been widely used in agriculture to kill pests. However, threats to the ecological environment are becoming increasingly prominent, caused by abuse and pesticide residues. This paper reports a sensitive electrochemiluminescence (ECL) sensor based on upconverting nanoparticle functional zeolite imidazolate framework (UCNPs@ZIF-8) nanocomposites combined with molecularly imprinted polymers (MIPs) to successfully achieve the quantitative detection of IM. The composites exhibited a certain multi-faceted prismatic structure and the effective binding of UCNPs was demonstrated by characterization technology. In addition, a sensor with MIPs/UCNPs@ZIF-8/GCE as the working electrode exhibited outstanding ECL performance, including a strong and stable signal and excellent selectivity under optimal conditions. This sensor showed a good linear response to IM over a wide concentration range (0.1 ng L⁻¹–1 mg L⁻¹), with a limit of detection as low as 0.01 ng L⁻¹. More significantly, it was successfully applied to the determination of IM concentration levels in food, which provides broad application prospects for the construction of pesticide ECL sensors.

The excessive concentration of heavy-metal mercury ions (Hg²⁺) in the environment seriously affects the ecological environment and even threatens human health. Therefore, it is necessary to develop rapid and low-cost determination methods to achieve trace detection of Hg²⁺. In this paper, an Electrochemiluminescence (ECL) sensing platform using a functionalized rare-earth material (cerium oxide, CeO₂) as the luminescent unit and an aptamer as a capture unit was designed and constructed. Using the specific asymmetric matching between Hg²⁺ and thymine (T) base pairs in the deoxyribonucleic acid (DNA) single strand, the “T−Hg−T” structure was formed to change the ECL signal, leading to a direct and sensitive response to Hg²⁺. The results show a good linear relationship between the concentration and the response signal within the range of 10 pM–100 µM for Hg²⁺, with a detection limit as low as 0.35 pM. In addition, the ECL probe exhibits a stable ECL performance and excellent specificity for identifying target Hg²⁺. It was then successfully used for spiked recovery tests of actual samples in the environment. The analytical method solves the problem of poor Hg²⁺ recognition specificity, provides a new idea for the efficient and low-cost detection of heavy-metal pollutant Hg²⁺ in the environment, and broadens the prospects for the development and application of rare-earth materials.

In this paper, the electrochemiluminescence (ECL) of sulfur quantum dots (SQDs) in a potassium persulfate cathodic co-reactant was studied. Based on the selective quenching of the ECL emission from the SQDs by β-nicotinamide adenine dinucleotide (NADH), an ultrasensitive ECL biosensor with NADH as an important parameter was established for the highly sensitive and selective detection of total bacterial count (TBC). A linear response between the ECL intensity and the NADH concentration in the range of 1 pM to 10 μM was obtained, thus achieving a detection limit of 1 pM. As the content of NADH in cells is positively correlated with the TBC, a sensor has been successfully applied to detect the TBC in actual water samples with a good recovery rate of 10³–10⁷ CFU mL⁻¹. This study provides a green and feasible method for TBC detection in the environment.