Alprazolam Detection Using an Electrochemical Nanobiosensor Based on AuNUs/Fe-Ni@rGO Nanocomposite

Despite all the psychological advantages of alprazolam, its long list of toxic properties and interactions has caused concern and highlighted the need for a reliable sensing method. In this study, we developed a simple, highly sensitive electrochemical nanobiosensor to determine the desirable dose of alprazolam, averting the undesirable consequences of overdose. Gold nanourchins (AuNUs) and iron-nickel reduced graphene oxide (Fe-Ni@rGO) were immobilized on a glassy carbon electrode, which was treated beforehand. The electrode surface was characterized using cyclic voltammetry, Fourier transform infrared spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and differential pulse voltammetry. The fabricated sensor showed two linear ranges (4 to 500 µg L−1 and 1 to 50 mg L−1), low limit of detection (1 µg L−1), high sensitivity, good repeatability, and good recovery. Increased –OH and carboxyl (-COOH) groups on the electrode surface, resulting in improved the adsorption of alprazolam and thus lower limit of detection. This nanobiosensor could detect alprazolam powder dissolved in diluted blood serum; we also studied other benzodiazepine drugs (clonazepam, oxazepam, and diazepam) with this nanobiosensor, and results were sensible, with a significant difference.</jats:p

Sensitive nanobiosensor for miR-155 detection using a novel nanocomposite of carbon nanofiber, metal-organic framework, and two quantum dots

The unique micro-RNA signatures of different tumours distinguish cancer from normal tissue. MicroRNA-155 (miR-155) is one of the biomarkers approved for breast cancer diagnosis. Due to this compound's very low concentration level in the early stages of cancer in the human body, it is challenging to quantify this miRNA in serum/plasma using conventional methods. To accurately and specifically identify this biomarker, an electrochemical nanobiosensor is proposed in the present work that is constructed based on microRNA complementary strand hybridization, and the final signal was measured using hematoxylin as a label. To achieve these goals, a novel nanocomposite of carbon nanofiber, nickel-metal-organic frameworks (Ni-MOF@GO), Ag-doped graphene (GQD-Ag), and CdS quantum dots (CdSQDs) was used to immobilize single-stranded RNA probes. Various electrochemical methods, such as cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy, were used to investigate the step by step of fabrication of the proposed nanobiosensor. The analytical results of applying the fabricated nanobiosensor for miR-155 determination showed a low detection limit of 0.1 fM with a dynamic range of 0.3 fM-500 pM under the optimal experimental conditions in PBS buffer. The nanobiosensor was also specific to the target miRNA sequence compared to one-, three-base mismatches, miR-21 (as the non-complementary target), and their combination. In addition, the nanobiosensor demonstrated a notable performance in evaluating real samples by not showing any noticeable interference. Hence, this platform is believed to be promising for future applications in diagnosing and screening breast cancer