Design of an electrochemical aptasensor in the presence of an array of gold nanostructure and a GO-MWCNTs nanocomposite: application in diagnosis of Alzheimer's disease.

Alzheimer's disease (AD) is considered one of the main progressive chronic diseases in elderly individuals. Early diagnosis using related biomarkers, specifically beta-amyloid peptide (Aß), allows finding expected treatment routes. Here, we developed an electrochemical aptasensing platform for AD by employing a glassy carbon electrode (GCE) modified with a layer of jagged gold (JG) nanostructure (diameter: 60-185 nm) and graphene oxide-carboxylic acid functionalized multiwalled carbon nanotubes (GO-c-MWCNTs) nanocomposite. These surface modifications acted as the signal amplifier and provided an optimum nano-interface substrate for immobilizing aptamer strands. The measurements of Aß were performed via differential pulse voltammetry (DPV), and the aptasensor detected the analyte in a linear range from 0.1 pg mL-1 to 1 ng mL-1, with an estimated limit of detection (LOD) of about 0.088 pg mL-1 (S/N = 3). The aptasensor showed sufficient stability (11 days), reversibility (three times), and reproducibility (five times re-fabrication with relative standard deviation (RSD): 1.27). The potential interfering agents showed negligible impact on the sensing performance. Finally, the application of the aptasensor was evaluated in the presence of 10 serum samples, and the recovery values were from 93 to 110.1%.

Electrochemical Nanomaterial-based Sensors/Biosensors for Drug Monitoring.

Determining the amount of medication used is essential for correctly managing treatment systems. The unauthorized use of drugs and the importance of determining the absorbed and required dose of drugs in target organs are essential factors that justify the design of new drug monitoring systems. Electrochemical sensors and biosensors based on nanomaterials have been developed for drug monitoring in the past few years. The use of nanomaterials to optimize the analyte detection process and facilitate electron transfer in electrochemical processes has enhanced intermolecular interactions and increased diagnostic sensitivity. Considering this review, in the first part, the evaluation of cancer drugs is examined, which can be used to determine the exact dose of the drug required in different stages of cancer. Accurate monitoring of cancer drugs can increase patient life expectancy, reduce side effects, and increase economic savings. In the next section, sensors and biosensors designed for antibiotics are examined. Accurate measurement of antibiotics for determining the effectiveness of the dose in controlling infections and preventing antibiotic resistance is possible with the help of these drug diagnostic platforms. In the next part, the diagnosis of different hormones is considered. Abnormal amounts (low/high) of hormones cause multiple physiological complications and various disabilities. Therefore, accurate determination of hormone levels can effectively treat hormonal changes. In the last section, other drugs, including drugs and analgesics for which the use of electrochemical diagnostic platforms can significantly help drug distribution and social health systems, are also discussed.

Screening of Passiflora L. mineral content using principal component analysis and Kohonen self-organizing maps.

A method using digestion with diluted nitric acid and inductively coupled plasma optical emission spectrometry was applied to determine metal ions in the peel, pulp, and seed of Passiflora edulis f. flavicarpa and Passiflora cincinnata cultivated in the Bahia state, Brazil. Plasma parameters (radio frequency power and argon flow rates) were optimized. The quantification limits (µg g-1) were: Ca (43.0); Co (1.3); Cu (10.0); Fe (10.0); K (20.0); Mg (26.6); Mn (0.33); Na (56.6) and Zn (10.0). The accuracy of the method was evaluated by the analysis of certified reference materials (NIST 1567a Wheat Flour and NIST 1577b Bovine Liver). Recovery studies were carried out and values found were between 89 and 120%. PCA and Kohonen self-organizing maps showed the formation of groups, corresponding to the fruit parts. Thus, passion fruit has great importance and biological potential, due to its high content of K and low Na.