Analysis & sensing最新文献

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.

This study highlights the electrochemical drug (ECD) sensor with a glassy carbon electrode modified with ruthenium(II) complex (RBNH), which showed a stronger response to the detection of tetracycline (TC) antibiotic residue in real samples like chicken eggs and cow milk compared to other substrate materials. Glassy carbon electrodes are covalently functionalized with ruthenium(II) complex containing the redox active 2, 2 bipyridine, and a hydrazone ligand (BNH) via., drop casting method. This results in the electrocatalytic behavior of the modified electrode (GCE/RBNH) on the oxidation of TC. Further, the modified electrode′s sustainability was tested with various antibiotics, including different concentrations of tetracycline, and scan rates by different techniques like cyclic voltammetry (CV), linear sweep voltammetry (LSV). Then a GCE/RBNH was used to create a linear calibration curve for TC concentrations ranging from 10 to 100 μmol L⁻¹ (R²=0.99), with a limit of detection and quantification 0.0675 μmol L⁻¹ and 0.224 μmol L⁻¹. The current approach, which possesses an effortless electrode modification step and offers the lowest detection limit and a comparatively wider linear dynamic range, performed better for determining TC in chicken eggs and milk samples than recently reported voltammetric methods.

Ammonia (NH₃) is a widely used etchant gas in the plasma-enhanced chemical vapor deposition (PECVD) synthesis of carbon nanofibers (CNFs). In addition to being an effective etchant, NH₃ also serves as a dopant by providing N heteroatoms. However, this secondary role has not been comprehensively investigated. Moreover, the influence of N-doping on the electroanalytical performance of CNFs has not been thoroughly assessed. In this work, we have prepared CNFs of two varieties by altering the ratio of etchant and feedstock gases (NH₃ and C₂H₂, respectively), resulting in N-doped CNFs with different doping levels. Differences were also observed in the morphology and electrochemical characteristics of the CNFs. While inner sphere redox (ISR) characteristics were not significantly affected, a significant shift between the peak potentials of ascorbic acid (AA) and dopamine (DA) was detected in the higher doped CNFs, resulting in enhanced selectivity towards DA. Our results demonstrate a simple yet effective method for enhancing the electroanalytical properties of CNFs.

This work reports two simplified paper-based approaches for immunosensing of carcinoembryonic antigen (CEA) in serum. On-paper enzyme-linked immunosorbent assay (p-ELISA) (using enzymatic generation of a colored product) and metal-linked immunosorbent assay (p-MeLISA) (using gold nanoparticles (AuNPs) as labels) were implemented using low-cost diagnostic bio-conjugated paper mini disks as platforms for the fast colorimetric immunosensing of CEA in human serum. The colour intensity was captured with a commercial scanner and analyzed using an open-source software. Different parameters of the preparation of the bioconjugated disks and of the immunoassays were studied and, under the selected conditions, LODs of 0.4 ng mL⁻¹ with p-ELISA and 0.1 ng mL⁻¹ with p-MeLISA were achieved while recoveries of CEA in serum samples were in the range from 88 to 112 % with coefficient of variation of <12 %. The assay time was 90 s for p-ELISA and 85 s for p-MeLISA. The immunoassays exhibited satisfactory selectivity in the presence of other cancer biomarkers and good stability under storage. Thanks to simple and rapid fabrication and modification, simple analysis protocol, affordability (<0.05 € per device), equipment-free quantification, low sample and reagents requirments, stability and satisfactory analytical characteristics, these approaches are fit-for-purpose for assay of CEA in serum at the point-of care in resource-limited settings.