Simultaneous Determination of Isoproterenol, Acetaminophen and Folic Acid Using a Novel Nanostructure-Based Electrochemical Sensor

Online regeneration of a piezoelectric and impedimetric immunosensor for the detection of C-reactive protein on the oriented antibody gold surface

Cardiovascular diseases (CVDs) refer to diseases that affect the heart and blood vessels. CVDs are considered silent killers, which are fatal (death occurs abruptly) particularly when their diagnosis is delayed. Among the biomarkers related to cardiovascular diseases, C-reactive protein (CRP) is expressed or found in high concentrations during a cardiac event. Therefore, CRP is an excellent biomarker to diagnose cardiac events, and therefore quantitative monitoring of CRP is necessary. Herein, we report the fabrication of an immunosensor for the detection and monitoring of CRP. The anti-CRP monoclonal antibody (anti-CRP-mAb), which is specific to the CRP antigen, was immobilized on the surface of gold pre-modified with 4-mercaptophenyl boronic acid (MPBA) to act as a capture antibody. The self-assembled monolayer (SAM) of 4-mercaptophenyl boronic acid (4-MPBA), Au-MPBA, was used for the oriented immobilization of anti-CRP-mAb for piezoelectric (mass-sensitive) and piezoelectric (impedance) measurements. Controlling the orientation of anti-CRP-mAb was crucial to eliminate false positive and negative results during sample analysis. The quartz-crystal microbalance with dissipation (QCM-D) measurements enabled us to follow the covalent immobilization of anti-CRP-mAb on AuCQC-MPBA in real-time. QCM-D was further used to follow the affinity reactions between anti-CRP-mAb and CRP and further with the anti-CRP polyclonal antibody (anti-CRP-pAb). The changes in frequency (Δf, Hz) were related to the changes in the mass (Δm, ng cm^-2) of CRP up to a concentration of 0.10 μg mL^-1, which is equivalent to 0.10 mg L^-1. CRP was detected using the direct affinity immunoassay (anti-CRP-mAb < CRP) and also a sandwich immunoassay using anti-CRP-pAb for signal enhancement. The developed piezoelectric CRP detection protocol was translated to a gold disc electrode for electrochemical impedance spectroscopy (EIS) measurements. The limit of detection (LOD) using both methods was at the μg mL^-1 or mg L^-1 level. Furthermore, the developed electrode could be regenerated using acidic buffer (0.10 M HCl). The detected signal could be reproduced to within 5% relative standard deviation (% RSD) in buffer and serum samples, showing excellent selectivity and specificity toward CRP.

Nano optical and electrochemical sensors and biosensors for detection of narrow therapeutic index drugs

For the first time, a comprehensive review is presented on the quantitative determination of narrow therapeutic index drugs (NTIDs) by nano optical and electrochemical sensors and biosensors. NTIDs have a narrow index between their effective doses and those at which they produce adverse toxic effects. Therefore, accurate determination of these drugs is very important for clinicians to provide a clear judgment about drug therapy for patients. Routine analytical techniques have limitations such as being expensive, laborious, and time-consuming, and need a skilled user and therefore  the nano/(bio)sensing technology leads to high interest.

A distinguished cancer-screening package containing a DNA sensor and an aptasensor for early and certain detection of acute lymphoblastic leukemia

A disposable package of biosensors was developed along with the corresponding guidelines for early detection of the acute lymphoblastic leukemia cancer. This proposed cancer-screening package included a DNA sensor and an aptasensor as two main types of biosensors. The biosensors were used simultaneously. This combination of sensors can detect not only the presence of mutant genes but also the biomarkers of cancer. At current work, the combination of sensors were used to detect the presence of BCR-ABL1 as a mutant gene and CEA as a biomarkers of cancer, such a capability makes the package liable for early and certain detection of acute lymphoblastic leukemia. To construct both the DNA sensor and the aptasensor, a nanocomposite consisting of electrosynthesis carbon quantum dots and biosynthesized gold nanoparticles was applied. The construction of these biosensors was characterized using four different electrochemical methods including DPV (Differential Pulse Voltammetry), EIS (Electrochemical Impedance Spectroscopy), CV (Cyclic Voltammetry) and chronoamperometry. The peak current of a catechol solution that was used as an electroactive probe on the biosensor was linearly related to the logarithm of the concentrations of the target DNA and the target antigen in the range of 10 pM to 100 μM and 1 pg mL^-1 to 0.001 g mL^-1 with the detection limits of 1.5 pM and 0.26 pg mL^-1 respectively, which are quite good results.

Electroanalytical Performance of a Carbon Paste Electrode Modified by Coffee Husks for the Quantification of Acetaminophen in Quality Control of Commercialized Pharmaceutical Tablets

Electrochemical determination of acetaminophen (APAP) was successfully performed using a carbon paste electrode (CPE) modified with coffee husks (CH-CPE). Scanning electron microscopy (SEM) and SEM-energy dispersive X-ray spectroscopy (SEM-EDX) were, respectively, used for the morphological and elemental characterization of coffee husks prior to their utilization. The electrochemical oxidation of APAP was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV). SWV technique appeared to be more sensitive since the oxidation current of APAP was twofold higher with the CH-CPE sensor than with the bare CPE, in relation to the increase in the organophilic character of the electrode surface. Furthermore, on CH-CPE, the current response of APAP varied linearly with its concentration in the range of 6.6 μM to 0.5 mM, leading to a detection limit of 0.66 μM (S/N=3). Finally, the proposed CH-CPE sensor was successfully used to determine the amount of APAP in commercialized tablets (Doliprane® 500 and Doliprane 1000), with a recovery rate ranging from 98% to 103%. This novel sensor opens the way for the development of low-cost and reliable devices for the electroanalysis of pharmaceutical formulations in developing countries.

Preparation, characterization and analytical application of an electrochemical laccase biosensor towards low level determination of isoprenaline in human serum samples

A novel electrochemical biosensor has been developed based on the immobilization of multiwalled carbon nanotubes (MWCNT) followed by sol–gel entrapment of laccase (Lac) enzyme on to the GCE.