[en] Biomass carbon dots synthesized by biological waste conform to the trend of ecological environmental protection and the requirements of green chemistry, which show great application potential in practice. In the study, we used watermelon peels as the raw materials to synthesize a novel blue biomass carbon dots (CDs) by a hydrothermal process with high fluorescence quantum yield of 22.8%. Through bulk polymerization and solgel method, two kinds of core–shell nanospheres were developed as fluorescent probes to recognize and detect ethyl carbamate (EC) rapidly without complex samples pretreatment. The obtained CDs@MIPs integrated the high-performance optical characteristics of CDs with excellent selectivity and adsorption of MIPs, which showed ideal linear relationships in the EC concentration range 1–120 μg L⁻¹ and low LOD of 0.57 μg L⁻¹ and 0.94 μg L⁻¹, respectively. Both CDs@MIPs have a short equilibration time which was around 20 min, and the imprinting factors (IF) are 4.04 and 2.62. The recoveries of the six spiked samples were satisfying, and the RSD precisions were lower than 5.57%. Gas chromatography–mass spectrometry was seen as a parallel analysis to validate the correctness of the results, which indicated the practicability and reliability of the developed method. This proposal strategy of optical sensors provided an effective channel for trace EC recognition, with numerous advantages, involving eco-friendly, low cost, high sensitivity, separation effect, and good selectivity. Graphical abstract:

[en] A supersensitive chiroptical-responsive system of enantioselectively recognizing L- and D-tryptophan (Trp) based on ( +)-diacetyl-L-tartaric anhydride-functionalized 1,3,5-triformylphloroglucinol (DTA-functionalized Tp) was constructed for the first time. With a high fluorescence quantum yield of 15.2% and fluorescence lifetime of 57.6 μs, DTA-functionalized Tp as both fluorescent and chiral recognition nanoprobe was used for the discrimination of L- and D-Trp with excitation/emission maxima at 330/490 nm within 3 min. The linear range of the fluorescence sensing was 0.002–0.15 μg mL⁻¹, and the detection limit achieved 1.4 ng mL⁻¹. Furthermore, a smartphone was employed as a detector and processor to couple with the chiroptical-responsive nanoprobe for establishing a novel and visual integration system for rapid and real-time detection of chiral amino acids with a detection limit of 13 ng mL⁻¹. The spiked recoveries of L-Trp in two commercially available functional beverages ranged from 86.00 to 118.33% in fluorescence and smartphone-based sensing system. Based on the excellent chiroptical-responsive effects, high stability, and biocompatibility, the chiroptical-responsive nanoprobe was successfully applied to visual optosensing and fluorescence imaging in response to L- and D-Trp in HeLa cells. This discrimination methodology with high sensitivity and enantioselectively shows great potential for in-site visually monitoring chiral amino acids in real food samples and tracking physiological processes. Graphical abstract:

[en] A novel and facile method was proposed for preparation of red emissive N-doped carbon dots encapsulated within molecularly imprinted polymers (RNCDs@MIPs) using a one-pot room-temperature reverse microemulsion polymerization. RNCDs used citric acid and urea as carbon and nitrogen sources by one-step solvothermal synthesis with the optimum emission of 620 nm. Unique optical properties of RNCDs coupled with high selective MIPs make the RNCDs@MIPs conjugate capable to adsorb specific targets of pyrraline (PRL), such a binding event was then transduced to quench fluorescence response signal of the RNCDs. RNCDs@MIPs for PRL showed linearity from 0.1 to 40 μg/L, with a detection limit of 65 ng/L. The RNCDs@MIPs exhibited a good reproducibility of 4.67% obtained from four times of rebinding for PRL. The optosensing probe was successfully applied to the detection of PRL in fatty foods with the spiked recovery of 85.93–106.96%. Graphical abstract

[en] An efficient and rapid fluorescent nanoprobe is described for the determination of the aroma compound 4-ethylguaiacol (4-EG). A molecularly imprinted polymer was doped with a covalent organic framework (COF) grafted onto carbon nanodots that was prepared by one-pot reverse microemulsion polymerization. Amino groups at the surface of carbon nanodots coordinate to the COFs to produce a strong bond and this warrants thermal and chemical stability of the probe. Remaining free amino groups interact with the phenolic hydroxyl groups of 4-EG through acid–base pairing interactions. The probe, with excitation/emission maxima at 350/440 nm, responds to 4-EG due to the charge transfer to the carbon nanodots. Under optimized conditions, fluorescence drops linearly as the concentrations of 4-EG increase from 0.025 to 1 μg mL⁻¹, with a detection limit of 17 ng mL⁻¹. The probe was applied to the determination of 4-ethylguaiacol in Chinese Baijiu and wine samples after pretreatment by a single dilution step. The recoveries of spiked samples ranged from 78.4to 110.1%.

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[en] A robust multi-dimensional sensing array based on VBimBF₄B/MAA-anchored quantum dot (QD)-grafted covalent organic frameworks (COFs) [(V-M)/QD-grafted COFs] was established via one-pot strategy. The multi-dimensional sensing array has the outstanding advantages of physicochemical and thermal stability, large specific surface area, and regular pore structures. The assistance of ionic liquid VBimBF₄B enhanced the transduction efficiency, and the synergistic effect of COFs enhanced detection efficiency. The improved multi-dimensional sensing array by COFs and ionic liquid VBimBF₄B served to identify seven insecticides by non-specific interactions via hydrogen bonding, and the differences in the kinetics of the binding to the insecticides resulted in variation of the three-output channel (fluorescence, phosphorescence, and light scattering) signals, thus generating a distinct optical fingerprint. The unique fingerprint patterns of seven kinds of common insecticides at 200 μg L⁻¹ were successfully discriminated using principal component analysis and clustered heat map analysis. The multi-dimensional sensing array showed a response to seven insecticides based on three spectral channels over the range of 0.001–0.4 μg mL⁻¹ with a limit of detection of 1.08–18.68 μg L⁻¹. The spiked recovery of tap water was 79.86–134.22%, with RSD ranging from 0.89–14.9%. This study broadens the applications of sensing arrays technology and provides a promising building block for insecticide determination. Graphical abstract:

[en] Highlights: • Record efficiency was achieved for phthalate ester degradation by strain BJQ0005. • Whole metabolic pathway was proposed using genome sequence and intermediate analysis. • Three hydrolases were identified with one di-ester bond hydrolysis enzyme. • Mechanism affecting enzymatic ester hydrolysis of mono-ester phthalate was proposed. Phthalate ester pollution in the environment and food chain is frequently reported. Microbial treatment is a green and efficient method for solving this problem. The isolation and systematic investigation of microorganisms generally recognized as safe (GRAS) will provide useful resources. A GRAS Bacillus subtilis strain, BJQ0005, was isolated from Baijiu fermentation starter and efficiently degraded phthalate esters (PAEs). The half-lives for di-isobutyl phthalate, di-butyl phthalate and di-(2-ethylhexyl) phthalate were 3.93, 4.28, and 25.49 h, respectively, from the initial amount of 10 mg per 10 mL reaction mixture, which are records using wild-type strains. Genome sequencing and metabolic intermediate analysis generated the whole metabolic pathway. Eighteen enzymes from the α/β hydrolase family were expressed. Enzymes GTW28₀9400 and GTW28₁3725 were capable of single ester bond hydrolysis of PAEs, while GTW28₁7760 hydrolyzed di-ester bonds of PAEs. Using molecular docking, a possible mechanism affecting enzymatic ester bond hydrolysis of mono-butyl phthalate was proposed of GTW28₁7760. The carboxyl group generated by the first hydrolysis step interacted with histidine in the catalytic active center, which negatively affected enzymatic hydrolysis. Isolation and systematic investigation of the PAE degradation characteristics of B. subtilis will promote the green and safe treatment of PAEs in the environment and food industry.