Current Analytical Chemistry - Volume 20, Issue 4, 2024

Glucose determination, without pain and aches, is essential for biomedical applications. Minimally invasive (MI) and non-invasive (NI) are the approaches that could address these challenges. MI approaches are based on body fluids such as saliva, urine, tears, and interstitial fluid that are exploited to determine glucose levels. NI methods utilize radiation forms to determine glucose concentration without needing body fluids. In this review, MI and NI technologies and their application in glucose measurement, along with current and future devices that use these technologies, are described and discussed. Also, the principles and requirements and operational and analytical performance will be reviewed and discussed.

Aflatoxin B1 is highly toxic, mutagenic, teratogenic, and carcinogenic and is a class I carcinogen. Peanuts, cotton, and corn may be affected by AFB1 during cultivation, which can seriously jeopardize human health. Developing a simple, sensitive, and selective method for detecting AFB1 is imminent. Aptamers are obtained through in vitro screening of ligands by single-stranded oligonucleotides (DNA or RNA) through exponential enrichment (SELEX) technology. As emerging highly selective recognition molecules, they have the advantages of strong affinity, good stability, and strong specificity. Because it does not have the function of signal conversion, it cannot produce physicochemical signals that can be detected in the process of specific binding with target molecules, so it is necessary to convert the process of specific binding of aptamers to target molecules into a process of easily detectable physicochemical signal changes. According to different conversion methods, aptamer biosensors are divided into electrochemical aptamer sensors, fluorescent aptamer sensors, colorimetric aptamer sensors, surface Raman-enhanced aptamer sensors, and so on. Herein, the recent progress and application of aflatoxin B1 detection by nucleic acid aptamer biosensors based on the above signals are reviewed, and the future development prospects and challenges of this kind of biosensor are summarized.

Background: Metformin is a biguanide derivative utilized as a first-line treatment for type 2 diabetes for people over 60 years. However, it faces certain limitations due to its incomplete absorption, resulting in a 50-60% bioavailability. In addition to its blood glucose-lowering effect, the antiproliferative effect of metformin has been demonstrated in vitro. Therefore, it is necessary to consider alternative administration routes that can enhance the bioavailability of metformin, expanding its clinical use beyond its role as an antidiabetic agent. Objective: The aim of the study was to develop a reliable bioanalytical method for the quantitation of metformin in male Sprague-Dawley rat plasma and explore the promising alternative administration route for metformin use. Methods: A robust, high-performance liquid chromatography-tandem mass spectrometry method for the quantification of metformin in rat plasma was developed and validated according to the latest regulatory guidance for bioanalysis. Results: Based on the area under the curves obtained from the rat pharmacokinetic study, subcutaneous injection increased the systemic exposure of metformin by 1.79-fold compared to oral administration in rats. Conclusion: Subcutaneous administration of metformin enhances its bioavailability compared to oral administration, leading to increased antidiabetic effects and potential antitumor activity.

Introduction: In this study, we optimized the extraction process, analyzed the structure and assessed the antioxidant activity of Sanghuangporus baumii polysaccharide (SBP). The present results provide important information for the Sanghuangporus baumii polysaccharides in potential natural antioxidant effects. Background: The extraction and structural analysis of polysaccharides from Sanghuangporus has gained significant attention in the fields of chemistry, medicine, and life sciences. There is great significance in maximizing the extraction of polysaccharides from Sanghuangporus and developing their potential products in a scientific and rational manner. Objective: The study was designed to establish an efficient and practical extraction process for SBP, and then investigated the structure and the antioxidant activity. Methods: The Response Surface Methodology (RSM) based on Box-Behnken design was used to explore the ultrasound-assisted extraction of SBP, and the structure of SBP was studied by ultraviolet spectroscopy, infrared spectroscopy and other instrumental analysis methods. The total antioxidant capacity of SBP was studied by the Ferric Reducing Ability of Plasma (FRAP) method, and the scavenging capacity of ABTS⁺·, DPPH· and OH· was carried out as the index to investigate its antioxidant activity in vitro. Results: The statistical analysis results showed that the optimal conditions for extracting SBP were an ultrasound time of 20.74 min, ultrasound power of 268.40 W and material-liquid ratio of 1:25.71. Under optimal conditions, the experimental yield of SBP was 3.36 ± 0.01%. The RSM optimization process was applied to the experiment of complex enzyme extraction of SBP, and the yield increased to 4.72 ± 0.03%. Structural analysis showed that SBP mainly consisted of glucose, a small amount of mannose and galactose, and the molecular weight distribution was uneven, mainly concentrating in the three parts of 24.5,6.4,2.5 kDa. Moreover, SBP exhibited dose-dependent and strong reducing power and radical scavenging activity. For DPPH·, ABTS⁺· and OH· radical scavenging assays, IC50 values were 1.505 ± 0.050 mg/ml, 0.065 ± 0.036 mg/ml and 0.442 ± 0.007 mg/ml, respectively. Conclusion: In the present study, a β-linked heteroglucan (SBP) was extracted using the optimized process combining enzymes from the fruiting bodies of Sanghuangporus baumii. SBP exhibited effective and dose-dependent antioxidant activities. Our findings were of great value in terms of developing polysaccharides with potential natural antioxidants.

Introduction: In this study, a nanocomposite film was prepared by doping silver nanoparticles onto β-cyclodextrin-chitosan functionalized Reduced Graphene Oxide (RGO), denoted as Ag/ β-CD/CS/G nanocomposite. The average diameter of the Ag NPs was found to be 62±17 nm. Methods: The fabricated composite was applied to monitor trace levels of copper ions in different industrial and environmental water samples. The morphology and microstructure of the fabricated sensor were extensively investigated using different techniques, including XRD, TGA, HR-TEM, FTIR, SEM, XPS, and EDX physicochemical techniques. For the electrochemical monitoring of Cu(II), the Ag/β-CD/CS/G nanocomposite electrode showed remarkable performance in terms of high sensitivity and a low limit of detection that was found to be 0.24 nmol L^-1. Results: The developed sensors showed a linear dynamic range from 10^-3 to 10^-8 mol L^-1 with an R² of 0.99. The impacts of different electrochemical parameters, including medium pH, scanning rate, and interfering ions, were investigated. Conclusion: Furthermore, the fabricated modified electrode showed high efficiency for Cu(II) detection in groundwater samples.