Fei Wang

Bi-doped LaFeO₃ porous microspheres with competitive gas-sensing performance toward n-butanol were successfully synthesized through a simple glutamic acid-assisted solvothermal method. This approach effectively regulated the oxygen-vacancy concentration in the material. Comprehensive characterization confirmed that Bi³⁺ was successfully incorporated into the LaFeO₃ lattice, promoting partial Fe³⁺/Fe⁴⁺ conversion and generating abundant oxygen vacancies. Based on the optimized La_0.94Bi_0.06FeO₃ sensor, the optimal operating temperature was significantly reduced to 150 ℃. At this temperature, the response to 10 ppm n-butanol reached 21, approximately seven times higher than that of pristine LaFeO₃, with a detection limit as low as 101 ppb. Furthermore, the sensor demonstrated competitive selectivity, long-term stability, and humidity resistance. The improved sensing performance is likely associated with several factors, including oxygen vacancies, surface electronic modulation, and porous structure. This work presents an effective strategy for developing gas sensors based on high-performance perovskites by way of A cation doping. Graphical Abstract

A ratio fluorescence/colorimetry/smartphone triple-mode sensor based on Ru-C₃N₄ was established for precise and rapid detection of melatonin (MT). Specifically, Ru-C₃N₄ with fine luminous characteristic and peroxidase-like activity catalyzes the oxidation of OPD to generate luminescent DAP which in turn suppresses intrinsic fluorescence of Ru-C₃N₄ because of the fluorescence inner filter effect (IFE). MT can inhibit this catalytic process, leading to partial recovery of the fluorescence of Ru-C₃N₄ and the decrease in UV–vis signal of the reaction system, as well as the gradual fading of the yellow color of the reaction solution. Hence, this triple-mode sensor can realize precise, reliable, and high-throughput determination of MT with correlative detection limits of 0.32, 0.46, and 0.67 μM. Moreover, this triple-mode sensor has been applied to MT detection in multiple juice samples with recoveries ranging from 86.00 to 99.68%, which indicates the suitability of the novel idea for the research and development of multimode optical sensors for food analysis. Graphical Abstract

The quantitative determination of conotoxins has great potential in the development of natural marine peptide pharmaceuticals. Considering the time-consuming sample pretreatment and expensive equipment in MS or LC-MS/MS analysis, an electrochemical sensor combined with molecularly imprinted polymer (MIP) is fabricated for the rapid monitoring of conotoxin αB-VxXXIVA to promote its pharmaceutical value and eliminate the risk of human poisoning. Electrochemically reduced graphene oxide–gold composite (rGO-Au) is modified with chitosan (CS) and glutaraldehyde (GA) to immobilize the macromolecular peptide, conotoxin αB-VxXXIVA. Subsequently, acrylamide (AAM) with a cross-linking agent, N,N′-methylene-bisacrylamide (NNMBA), is introduced into the rGO-Au electrode to form MIPs by electro-polymerization. The proposed MIP-based electrochemical sensor, PAM/αB-CTX/CS-GA/rGO-Au/SPE, exhibits satisfactory sensing performance in the detection of αB-VxXXIVA. Based on current change versus logarithm concentration, a wide linear range from 0.1 to 10,000 ng/mL and a low detection limit (LOD) of 0.014 ng/mL for this sensor are obtained. This work provides a promising method in electrochemical determination combined with MIP for the determination of macromolecular peptides.

Biothiols play essential roles in maintaining normal physiological functions, resisting oxidative stress, and protecting cell health. Establishing an effective and reliable sensor array for the accurate quantification and discrimination of diverse biothiols is extremely meaningful. In this work, Ag/Mn₃O₄, Ag₃PO₄, and Ag₃Cit with excellent oxidase-mimetic activity and surface-enhanced Raman scattering (SERS)-enhanced features have been prepared and loaded onto Whatman filter paper (WFP) to build SERS paper chips as three sensing channels, which can induce 3,3',5,5'-tetramethylbenzidine (TMB) oxidation to SERS-active reporters (TMBox) and concurrently generate prominent SERS signals. Nevertheless, the addition of biothiols can suppress conversion from TMB to TMBox, which can cause the reduction of the SERS signal from TMBox. Interestingly, each SERS sensing channel can generate different TMBox signals' variations due to differences in the oxidative inhibition abilities of diverse biothiols and exclusive properties of each paper chip, which can be plotted as specific fingerprint patterns of each biothiol and further translated into intuitive two-dimensional (2D) clustering profiles through linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA) techniques for precise identification of these six biothiols with the minimum concentration of 1 μM. More importantly, this SERS sensor array is exploited for the precise quantification of intracellular glutathione (GSH), and can differentiate between normal and cancer cells based on different intracellular GSH contents and even identify different types of tumor cells, demonstrating its powerful application prospects in disease diagnosis.

A fluorescent multichannel sensor array has been established based on three carbon dots derived from Tibetan medicine waste for rapid quantification and discrimination of six heavy metal ions. Due to the chelation between metal ions and carbon dots (CDs), this fluorescence “turn off” mode sensing array can quantify six metal ions as low as “μM” level. Moreover, the six heavy metal ions display varying quenching effects on these three CDs owing to diverse chelating abilities between each other, producing differential fluorescent signals for three sensing channels, which can be plotted as specific fingerprints and converted into intuitive identification profiles via principal component analysis (PCA) and hierarchical cluster analysis (HCA) technologies to accurately distinguish Cu²⁺, Fe³⁺, Mn²⁺, Ag⁺, Ce⁴⁺, and Ni²⁺ with the minimum differentiated concentration of 5 μM. Valuably, this sensing array unveils good sensitivity, exceptional selectivity, ideal stability, and excellent anti-interference ability for both mixed standards and actual samples. Our contribution provides a novel approach for simultaneous determination of multiple heavy metal ions in environmental samples, and it will inspire the development of other advanced optical sensing array for simultaneous quantification and discrimination of multiple targets. Graphical abstract