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Latent fingerprints (LFPs) at the crime scene are served as important clues to locate the trajectory of criminal behavior and portray the characteristics of the suspect. Therefore, visualizing LFPs is of considerable significance. In this work, the europium metal-organic framework (Eu-MOF) sensor was successfully constructed for sensitive detection of gallic acid (3,4,5-trihydroxybenzoic acid, GA) and visualization of the sweat LFPs. The boric-acid-modified Eu-MOF was prepared by using the simple one-pot solvothermal method using Eu as the metal ion center and 3,5-dicarboxybenzeneboronic acid (BBDC) as the organic ligand. The sensor showed desirable photoluminescent performance through the chelating of BBDC with Eu3+. The sensor exhibited the satisfactory linear relationship to GA in the range of 1 nM to 20 nM with a low detection limit of 0.34 nM under the optimized conditions. The prepared sensor with ideal selectivity to GA was successfully applied for visualizing LFPs on porous substrates with the high contrast and superior stability. Given the good performance of the sensor, all fingerprint images obtained from 1 200 samples presented clear friction ridges and met the identification criteria. Notably, the sensor had less impact on the subsequent deoxyribonucleic acid (DNA) detection, displaying a promising perspective for applications in extracting physical evidence of site investigation. [ABSTRACT FROM AUTHOR]

In this work, easily accessible carbon dots (N, B-CDs) were synthesized via a one-step microwave method. In the powder state, N, B-CDs exhibited bright blue fluorescence and stable green phosphorescence with a lifetime of 539 ms, visible to the naked eye for 9 s. Due to their excellent phosphorescent properties, N, B-CDs have been successfully applied in information encryption. Graphic security and information encryption schemes were designed using N, B-CDs and rhodamine 6G. N, B-CDs contained many hydroxyl and amino groups on the surface, which can be utilized to detect specific ions and compounds. N, B-CDs have been successfully applied to detect Sn2+ and gallic acid (GA). Theoretical calculations and mechanistic studies suggested that the sensing of Sn2+ was attributed to the photoinduced electron transfer between Sn2+ and N, B-CDs, and the limit of detection (LOD) was determined as 3.5 μM with the 3s/k rule. In addition, N, B-CDs and GA form cross-links, as determined by Fourier transform infrared spectral analysis, with an LOD of 0.35 μM with the 3s/k rule. [ABSTRACT FROM AUTHOR]

We performed a comparative study using aqueous extracts of dandelion flowers and blueberry fruits to synthesize gold‐ (Au) and silver‐ (Ag) nanostructures (NSs). The blueberry extracts gave nanowire and spherical AuNSs upon changing the ratio of the extracts to Au3+precursor while altering the ratio for the dandelion extracts resulted in formation of only anisotropic AuNSs. Similar results were obtained during the AgNSs, where the dandelion extracts resulted in formation of quasi‐spherical AgNSs at the tested ratio (extract/AgNO3 ratio) while altering the ratio for the blueberry extracts resulted in nanorod and nanoplates formation. We argued that this could be from dominancy of a lone compound or a group of compounds and tested this claim by introducing chrysin and amino acid mixtures to the blueberry extracts. Altering the added chrysin amount triggered nanoplate and spherical AuNSs formation while alteration in amino acid mixture content did not change the morphology, and spherical AuNSs were obtained. The antibacterial studies revealed the AgNSs are toxic to Pseudomonas aeruginosa with 8 μg/mL MBC (minimum bactericidal concentration) and 3 μg/mL values for the blueberry and dandelion extracts synthesized AgNSs while penicillin/streptomycin sulfate mixture carrying Dandelion‐AuNSs gave 12‐times lower MBC value in comparison to free penicillin/streptomycin sulfate mixture. [ABSTRACT FROM AUTHOR]

In this study, an Fe–N–C/AuNP nanohybrid was combined with a glassy carbon electrode (GCE) to construct a novel electrochemical sensor for rapid detection of gallic acid (GA). The synthesized materials and corresponding sensors were characterized using various physical and electrochemical techniques. Density functional theory (DFT) calculations showed that Fe–N–C nanocomposites can provide an electronic transmission channel for GA detection, while AuNPs with excellent electrical conductivity can significantly accelerate the electron transfer rate between the prepared materials and the target analyte. The Fe–N–C/AuNP nanohybrid provided the advantages of rapid electron transfer, more active sites, excellent catalytic activity, and high conductivity. Under optimal conditions, the Fe–N–C/AuNP/GCE sensor exhibited excellent performance to detect GA with a linear response range of 5–500 μM and a detection limit of 1.284 μM (S/N = 3), which illustrated its wide detection range, high sensitivity, and low detection limit. Furthermore, the constructed sensor was also effectively used to detect GA in honey, black tea and green tea samples with satisfactory recoveries (97.22–102.28%). Overall, unique modified electrode materials were investigated in this study for fabricating electrochemical sensors. [ABSTRACT FROM AUTHOR]

In this work, the determination of gallic acid was performed using surface‐renewable carbon paste electrodes fabricated with multi‐walled carbon nanotubes (MWCNT) and a mixture of N‐octylpyridinium hexafluorophosphate (OPyPF6) ionic liquid with mineral oil (MO) as binder. This system shows remarkable amperometric sensor characteristics and promotes a better electronic transfer. An electroanalytical study of gallic acid shows a linear range from 4.98±0.25 to 74.1±2.2 μmol L−1, with R2=0.9958 and an experiment a limit of detection of 2.70±0.08 μmol L−1 (S/N=3), and a sensitivity of 0.029 μA μmol−1 L. [ABSTRACT FROM AUTHOR]