Analysis & sensing最新文献

In this study, sulfur-nitrogen-codoped carbon nanodots (N,S-doped CNDs) are synthesized both in their soluble pristine form and incorporated into aminosilica particles. These materials, are utilized for the fluorometric detection of Hg(II) and Cr(VI). Both the soluble N,S-doped CNDs and the aminosilica/N,S-doped CNDs exhibit two distinct emission spectral bands when the excitation wavelength is varied. The fluorescence of soluble N,S-doped CNDs at λ_ex/λ_em = 390 nm/470 nm is quenched in the presence of both Hg(II) and Cr(VI); however, only Hg(II) quenches the fluorescence at λ_ex/λ_em = 450 nm/553 nm. In contrast, only Cr(VI) quenches the fluorescence of aminosilica/N,S-doped CNDs at λ_ex/λ_em = 380 nm/463 nm, while the fluorescence at λ_ex/λ_em = 440 nm/538 nm remains unaffected. By exploiting the fluorescence quenching behavior of free and aminosilica-embedded N,S-doped CNDs, fluorescence-based probes are developed to selectively detect Hg(II) and Cr(VI). The limits of detection, defined as the concentrations corresponding to a signal-to-noise ratio of 3, are determined to be 0.04 and 0.06 μM for Hg(II) and Cr(VI), respectively. Further investigations reveal distinct quenching mechanisms for each system: the fluorescence quenching effect on N,S-doped CNDs by Hg(II) is attributed to a static mechanism, and the quenching of aminosilica/N,S-doped CNDs by Cr(VI) is ascribed to the inner filter effect.

An imidazolium salt (E)-3-(hydroxy-4-(((2-hydroxyphenyl) imino) methyl) benzyl)-1-methyl-1 H-imidazol-3-ium chloride (HBIm) is synthesized and evaluated for its fluorescence behavior toward metal ions. The probe detected Al³⁺ and As³⁺ ions when excited at 326 nm in an aqueous medium. The nonfluorescent HBIm exhibited a “turn-on” fluorescence response upon being treated with Al³⁺ (λ_em = 510 nm) and As³⁺ (λ_em = 499 nm) ions due to the chelation-enhanced fluorescence effect. The detection limits for Al³⁺ and As³⁺ are low and are found to be 0.38 and 2.37 nM, respectively. Furthermore, the binding constants for these ions are significantly high, 1.59 × 10⁵ M⁻¹ for Al³⁺ and 3.54 × 10⁴ M⁻¹ for As³⁺. The binding mechanism between HBIm and Al³⁺ and As³⁺ ions is supported by various techniques, including ESI-MS, Job's plot, ¹H NMR, X-ray photoelectron spectroscopy, SEM-EDS, and density functional theory studies. The reversibility experiments are conducted using EDTA ions to develop the corresponding logic gates. HBIm has the potential to detect Al³⁺ and As³⁺ ions in real samples, such as plant cells, tissues, and water samples.

Industrial wastewater release of dyes poses serious environmental and health risks when introduced into natural water systems. Herein, a cyclodextrin-based polymer sensor (Ech-CDP) is developed for real-time, visible detection of harmful methylene blue (MB) and methyl orange (MO) dyes in distilled and contaminated natural water samples. The sensor works through a competitive host-guest mechanism between sodium dodecyl sulphate (SDS) and Ech-CDP, altering liquid crystal alignment. Initially, SDS induces homeotropic ordering, which shifts to a tilted state upon binding with Ech-CDP. The presence of MB or MO displaces SDS, reverting the alignment and causing a visible bright-to-dark transition under polarizers. The sensor exhibits high selectivity, with detection limits of 0.03 mM for MB and 0.05 mM for MO in aqueous solutions, and 0.08 mM for MB and 0.26 mM for MO in real water samples, remains effective for 3 days, and is unaffected by pH variations between 4.8 and 9.1. Additionally, the sensor demonstrates an on–off switching capability, suggesting potential applications for molecular logic gates and advancing environmental monitoring techniques in dye-polluted waters.

In Brazil, grocery stores and local markets commonly sell handmade cigarettes crafted from cornhusk and treated tobacco. Once a regional tradition, these artisanal cigarettes are now the second most consumed type in the country. Tobacco products contain nicotine (NIC), a highly addictive substance linked to cardiovascular diseases. This study presents an electrochemical synthesis method for a reduced graphene oxide/silver–copper–hexacyanoferrate (rGO/AgCuHCF) composite, optimized for sensitive NIC detection. The optimized material is prepared using a 3:1 Ag:Cu ratio in an initial cyclic voltammetry step, followed by treatment with a pH = 7.0 ferricyanide solution, achieving a sensitivity of 13.0 nA L mol⁻¹ via a 2² factorial design experiment. Microscopic analysis reveals uniformly distributed PBA particles over the wrinkled carbon support, while spectroscopic and diffraction techniques confirm distinct bimetallic PB analogue structural features from monometallic variants. Batch injection analysis-assisted amperometry with the rGO/AgCuHCF-modified electrode exhibits a linear current response for NIC between 5.0 and 2000.0 μmol L⁻¹, achieving a superior sensitivity of 32.9 nA L mol⁻¹ and a low detection limit of 0.9 μmol L⁻¹. This sensor demonstrates viability and reliability for NIC detection in industrial and artisanal cigarettes tobacco samples.

Fluorescent functional materials, particularly luminescent metal–organic frameworks (LMOFs), have been central to material science research over the past decade. Herein, we report a Co-MOF [Co(phen)(5-aipa)]_∞ (phen: 1,10-phenanthroline, 5-aipa: 5-aminoisophthalic acid), synthesized solvothermally, for luminescence-based, recyclable, “turn-on” detection of “tumor biomarker” glutathione (GSH), and industrial pollutant formaldehyde (FA). Sophisticated characterizations, including XRD, XPS, TGA, FESEM, FT-IR, and Hirshfeld analysis, demonstrate high phase purity, thermal stability, robustness, presence of π–π stacking, and weak H-bonding in the framework. The MOF shows low detection limits for GSH (60.37 nM) and FA (9.77 μM) with fast response times (25 s for GSH, <2 min for FA). Biomarker GSH was detected in complex biological samples, including fetal bovine serum, vegetable, and human urine, with recovery rates between 81% and 89%. A smartphone-assisted GSH-sensing platform was proposed via RGB color variations of several sensor-analyte adducts. A 5-input, 4-output molecular logic gate was also demonstrated based on the sensor's spectroscopic response to varying GSH concentrations. FA detection was extended to fish, meat, and wastewater samples, with recoveries of 91–107%. DFT calculations revealed that analyte interactions restricted photo-induced electron transfer in the MOF, enhancing fluorescence phenomenon. These findings open new possibilities for MOF-based sensor technologies.

Xinomavro wine is one of the most renowned Greek varieties, primarily produced in Northern Greece. The Amynteo and Naoussa regions are included in the protected designation of origin (PDO) zones where differences in terroir are evident. These differences occur due to several factors, such as soil conditions of the cultivated vineyards, temperature, altitude, and climatic variations. Herein, 22 Xinomavro wines from Amynteo and Naoussa, produced with an identical vinification procedure are analyzed using ultra high performance liquid chromatography–trapped ion mobility spectrometry–quadrupole time of flight–mass spectrometry (UHPLC–TIMS–QTOF–MS) with reverse phase chromatography and negative ionization mode. The aim is to evaluate the impact of the geographical origin on their phenolic profile. Both target and non-target screening workflows are employed, leading to the identification and quantification of 26 phenolic compounds and the determination of 25 geographical origin biomarkers. Compounds like catechin and hydroxytyrosol are more abundant in samples from Naoussa while Amynteo is characterized by increased concentration of resveratrol and polydatin. All samples are correctly classified based on their geographical origin, achieving satisfactory, Q² = 0.915 and R² = 0.923, prediction ability results, developing a partial least-squares discriminant analysis model.

Electrical noses that mimic the human olfactory system have been developed to detect odors or flavors. Unfortunately, little research on sensing reactions to various odors like a human nose can be found in the literature. Herein, an electronic nose is proposed using a multi-thin film transistor (TFT) sensor array with various polymer selectors and multi-output signal processing to detect various odorants with high selectivity. Through the combination of multi-output produced by eight polymer variables based on indium gallium zinc oxide (IGZO) TFTs, a specific radar pattern and its selectivity are generated for the eight different odor substances. Eight multi-output signal processing reduced the correlation coefficient of similarity from 77.9% to 45% relative to the case of four multi-output processing. Because the polymers have different functional groups, polymers showed specific reactions to various odorants, like the human's system, and multi-output analysis could distinguish various odors, even if polymers did not show single selectivity to a specific odor. And the sensitivity improved when compared to two-terminal structures by using TFTs based on IGZO. The advantage is that it can classify multiple odors with good selectivity and sensitivity. This sensor and signal processing concept can be applied to E-nose systems capable of odor monitoring.

Toll-like receptor 2 (TLR2) is involved in infectious diseases, inflammatory processes and carcinogenesis. Soluble TLR2 (sTLR2) can be released into circulation stream acting as an endogenous negative regulator of TLR2 signaling, essential for the prevention of chronic inflammation and tissue destruction. In this context, we propose pioneering electrochemical biotechnology for the determination of sTLR2 in plasma of colorectal cancer (CRC) patients. The method involves the use of magnetic particles as micro-supports for the implementation of a sandwich immunoassay using a pair of specific antibodies and horseradish peroxidase as enzymatic tracer to carry out the amperometric transduction on screen-printed carbon electrodes in the presence of H₂O₂ and hydroquinone. The proposed immunoplatform shows attractive operational and analytical characteristics, reaching a low limit of detection of 241 pg mL⁻¹ for TLR2 standards in buffered solutions, and showing an excellent reproducibility (RSD 1.4 %), and a wide dynamic range (804 to 25000 pg mL⁻¹). It has been applied to the analysis of a cohort of 21 plasma samples from healthy individuals and CRC patients at different stages of the disease, demonstrating precise quantitative determinations, in just 45 min and requiring minimal sample amount and pre-treatments. The results demonstrate the promising utility of TRL2 plasma levels for minimally invasive monitoring of CRC progression.

2D MXenes offer exceptional advancements in biosensing owing to their tunable optical properties with large surface area of interaction and hydrophilicity. This revolutionizes the biosensing of analytes using advanced sensing modes such as surface enhanced Raman scattering (SERS), surface plasmon resonance (SPR), and colorimetry with high selectivity and sensitivity in biomedical application. More in the Review by Durgalakshmi Dhinasekaran and co-workers.

Herein we report synthesis, photophysical properties and amine sensing applications of a carbazole-dicyanovinyl based sensor (2). Sensor molecule 2 shows solid state fluorescence (φ=~41 %), mechanochromic fluorescence and aggregation induced emission. Presence of donor and acceptor groups in 2 resulted in strong absorption bands in the visible region of electromagnetic spectrum which is exploited for colorimetric sensing of primary amines. Amine sensing mechanism of 2 is established using ¹H NMR titration studies. Test kit developed using probe 2 showed prominent color change in presence of biogenic amines generated from decomposed meat product.