ACS Measurement Science Au最新文献

Neuroendocrine tumors (NETs), often misdiagnosed and mistreated, require early detection for precise therapeutic interventions. This study presents a newly developed competitive electrochemical immunosensor for sensitive and selective detection of chromogranin A (CgA), a key biomarker for diagnosing and monitoring NETs. The sensor, featuring a sandwiched structure with versatile and multifunctional graphene oxide (GO), utilizes polyethylenimine-capped gold nanoparticles (PEI-AuNPs) to enhance the electroreactivity and biocompatibility of a screen-printed electrode (SPE). The immunosensor operates by immobilizing standard CgA antigens on the PEI-AuNPs/GO-modified SPE surface and employing GO nanotags loaded with anti-CgA antibodies (Ab) and ferrocene monocarboxylic acid (Fc) redox probes to capture target CgA. As the CgA concentration increases, the current response of the immunosensor decreases due to a reduction in the amount of Fc/Ab/GO tags on the electrode surface. This reduction occurs because the nanotags bind to the free CgA in the sample rather than the CgA immobilized on the electrode. The immunosensor demonstrates a good linearity (0.10-50 ng mL^-1), a low detection limit of 90 pg mL^-1, and high accuracy in detecting CgA levels in human serum samples. With its high specificity, long-term stability, and excellent reproducibility, our cost-effective and user-friendly platform holds promise for clinical screening and point-of-care diagnosis of NETs. Further optimization of the immunosensor's design and exploration of its use for additional biomarkers could enhance NETs' diagnosis and provide advancements in managing other related health conditions.

Repeated freezing and thawing (F-T) of meat, a common practice in home kitchens, markets, and transportation, reduces meat quality due to wide temperature fluctuations. This study presents the electrochemical analysis of oxidation in beef longissimus lumborum muscle sarcoplasm under repeated F-T cycles, which differs from prior reports that focused on other related meat aspects, such as discoloration, adulteration, freshness, and antibiotic detection. Moreover, comparing the complexity of meat extract analysis using certain spectral methods, such as Raman, NMR, FTIR, and expensive mass spectrometry, electrochemical methods offer simplicity, speed, and cost-effectiveness. Increased current responses at specific peaks (0.82 ± 0.01 V and -0.25 ± 0.01 V vs Ag/AgCl) correlated strongly (r = 0.99, p < 0.01) with elevated metmyoglobin content, which is responsible for the discoloration or brown color of meat, validated by spectrophotometry. Frozen sarcoplasm (day 3) exhibited significantly higher currents and metmyoglobin levels (p < 0.01) compared to fresh sarcoplasm (day 0), indicating biochemical changes during F-T cycles. Electrocatalytically accessed redox signals of purified beef myoglobin confirmed the contributions from the rapid oxidation of myoglobin, as well as other meat sarcoplasmic proteins. This research introduces a portable, cost-effective electrochemical tool for point-of-need monitoring of meat oxidation under various practical, experimental, and environmental conditions. Future research could focus on obtaining insights into biochemical changes in longissimus lumborum sarcoplasm during frozen storage and developing strategies to mitigate the effects of F-T cycles on meat quality.