Magnetic Nanofiber Layers as a Functional Surface for Biomolecule Immobilization and One-Use ‘Sensing in-a-Drop’ Applications

Single-drop electrochemical immunosensor with 3D-printed magnetic attachment for onsite smartphone detection of amoxicillin in raw milk

Amoxicillin is a beta-lactam group of antibiotics used against bacterial infections. The growth of the antibiotic market and abuse of amoxicillin led to its accumulation in nature, especially in foods. Thus, rapid amoxicillin tests are needed to protect human health and increase food safety. In this study, a single drop, mobile electrochemical amoxicillin immunosensor was developed for the first time. The immunosensor platform is based on amoxicillin antibodies conjugated magnetic nanoparticles. A 3-Dimensional (3D) cell capable of accumulating amoxicillin molecules, which interact with antibody-conjugated magnetic nanoparticles on the electrode surface was designed and 3D-printed. A small potentiostat connected to an Android mobile phone was used to detect amoxicillin in a single-drop raw milk sample in a 3D-printed cell. Results demonstrated linearity between 0.5 and 100 µM with an LOD of 0.44 µM. Due to its rapid and portable application, the designed immunosensor shows good potential in on-site amoxicillin detection from milk samples.

Novel Approaches to Enzyme-Based Electrochemical Nanobiosensors

Electrochemistry is a genuinely interdisciplinary science that may be used in various physical, chemical, and biological domains. Moreover, using biosensors to quantify biological or biochemical processes is critical in medical, biological, and biotechnological applications. Nowadays, there are several electrochemical biosensors for various healthcare applications, such as for the determination of glucose, lactate, catecholamines, nucleic acid, uric acid, and so on. Enzyme-based analytical techniques rely on detecting the co-substrate or, more precisely, the products of a catalyzed reaction. The glucose oxidase enzyme is generally used in enzyme-based biosensors to measure glucose in tears, blood, etc. Moreover, among all nanomaterials, carbon-based nanomaterials have generally been utilized thanks to the unique properties of carbon. The sensitivity can be up to pM levels using enzyme-based nanobiosensor, and these sensors are very selective, as all enzymes are specific for their substrates. Furthermore, enzyme-based biosensors frequently have fast reaction times, allowing for real-time monitoring and analyses. These biosensors, however, have several drawbacks. Changes in temperature, pH, and other environmental factors can influence the stability and activity of the enzymes, affecting the reliability and repeatability of the readings. Additionally, the cost of the enzymes and their immobilization onto appropriate transducer surfaces might be prohibitively expensive, impeding the large-scale commercialization and widespread use of biosensors. This review discusses the design, detection, and immobilization techniques for enzyme-based electrochemical nanobiosensors, and recent applications in enzyme-based electrochemical studies are evaluated and tabulated.