Analysis & sensing最新文献

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.

The accurate and selective detection of vitamins are very much needed in the food, and pharmaceutical industries and health care. In this study, a new sustainable disposable electrochemical platform was fabricated with nano silver/Cu₂O composite (nAg/Cu₂O) for sensing ascorbic acid (vitamin C). The modified electrode exhibited reduced resistance to charge transfer and improved electro active area. The analyte displayed excellent electrochemical activity on the surface of nAg/Cu₂O modified paper electrode and showed a concentration-dependent response between 0.05 to 500 μM with a detection limit (S/N=3), 0.04 μM. Furthermore, the anti-interference studies revealed that the nAg/Cu₂O nanocomposites have high selectivity towards ascorbic acid. Notably, the sensor based on nAg/Cu₂O showed exceptional stability and reproducibility, with a relative standard deviation for peak currents measuring approximately 7 % or less while testing for a week of time. The real-world application and analytical performance was realized by identifying ascorbic acid in commercial vitamin C tablets with satisfactory results.

Breath biomarker detection represents a transformative frontier in non-invasive diagnostics, offering rapid, real-time insights into health conditions ranging from metabolic disorders to cancer. Metal oxide nanostructures (MONs) have emerged as key materials in this research because of their large surface area, adjustable electrical characteristics, and sensitivity to gaseous biomarkers at trace quantities. This paper examines current advances in chemiresistive MON-based sensors, focusing on the importance of structural optimization, hybrid material systems, and functionalization strategies in improving performance. Exploring the study of complicated datasets, the prediction of biomarker signatures, and dynamic aims in tuning the quality of the sensors. Functionalization strategies also play a vital role in enhancing the performance of MON-based sensors. By modifying the surface chemistry of chemiresistive metal oxides, researchers can tailor the sensors to preferentially adsorb certain gaseous biomarkers while minimizing interference from other compounds present in breath. Future opportunities include the development of multimodal sensors, simplified and portable devices, and durable, reusable platforms capable of long-term operation in real-world environments. With the confluence of nanotechnology and data-driven analytics, MON-based breath sensors have the potential to transform customized healthcare by providing worldwide early detection, illness monitoring, and preventative medication.

As interest in monitoring the nutritional and antioxidant levels in fruits and vegetables grows, the need for efficient, non-invasive detection methods increases. In this work, a novel coated microneedle colorimetric sensing platform is designed to rapidly and sensitively detect total phenolic compounds (TPC) in fruits and vegetables, which is the key indicator of their nutritional and antioxidant properties. The platform utilizes a swollen microneedle structure to efficiently collect juice samples, enhancing detection efficiency through colorimetric analysis and eliminating the complexity of traditional methods. The microneedles are fabricated from a composite material consisting of 10,12-pentacosadiynoic acid (PCDA) and methacrylated gelatin (GelMA), with a secondary layer containing α-cyclodextrin to selectively bind polyphenols, thereby inducing a visible color change for the specific detection of TPC. The colorimetric response is directly correlated with the concentration of TPC, facilitating on-site analysis. Using phenol as a model molecule, the detection range of the system for phenol is 10–60 mM, with an LOD of 0.5 mM. Furthermore, a mobile application enables portable detection and analysis, reducing detection time from several hours to just 30 min. This technology offers a promising approach for the rapid, reliable monitoring of phenolic content in fresh produce, with potential applications in food quality control, nutritional analysis, and agricultural monitoring.

Metal-organic frameworks (MOFs) offer an impeccable platform for glucose sensing, contributing in both enzymatic- and non-enzymatic-based electrochemical detection. Comprising metal ions and organic ligands, MOFs with their exceptional properties including tunable porosity, high surface area, diverse structural configuration, strong adsorptive capacity, electrocatalytic behavior, and abundant active sites pave way for improving healthcare diagnostics. More in the Review by R. Ajay Rakkesh and co-workers.