Aptamers are synthetic bio-receptors of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) origin selected by the systematic evolution of ligands (SELEX) process that bind a broad range of target analytes with high affinity and specificity. So far, electrochemical biosensors have come up as a simple and sensitive method to utilize aptamers as a bio-recognition element. Numerous aptamer based sensors have been developed for clinical diagnostics, food, and environmental monitoring and several other applications are under development. Aptasensors are capable of extending the limits of current analytical techniques in clinical diagnostics, food, and environmental sample analysis. However, the potential applications of aptamer based electrochemical biosensors are unlimited; current applications are observed in the areas of food toxins, clinical biomarkers, and pesticide detection. This review attempts to enumerate the most representative examples of research progress in aptamer based electrochemical biosensing principles that have been developed in recent years. Additionally, this account will discuss various current developments on aptamer-based sensors toward heavy metal detection, for various cardiac biomarkers, antibiotics detection, and also on how the aptamers can be deployed to couple with antibody-based assays as a hybrid sensing platform. Aptamers can be used in various applications, however, this account will focus on the recent advancements made toward food, environmental, and clinical diagnostic application. This review paper compares various electrochemical aptamer based sensor detection strategies that have been applied so far and used as a state of the art. As illustrated in the literature, aptamers have been utilized extensively for environmental, cancer biomarker, biomedical application, and antibiotic detection and thus have been extensively discussed in this article.

The use of titanium dioxide nanotubes in the powder form (TNTP) has been a hot topic for the past few decades in many applications.

The design and development of biosensors, analytical devices used to detect various analytes in different matrices, has emerged. Biosensors indicate a biorecognition element with a physicochemical analyzer or detector, i.e., a transducer. In the present scenario, various types of biosensors have been deployed in healthcare and clinical research, for instance, biosensors for blood glucose monitoring. Pathogenic microbes are contributing mediators of numerous infectious diseases that are becoming extremely serious worldwide. The recent outbreak of COVID-19 is one of the most recent examples of such communal and deadly diseases. In efforts to work towards the efficacious treatment of pathogenic viral contagions, a fast and precise detection method is of the utmost importance in biomedical and healthcare sectors for early diagnostics and timely countermeasures. Among various available sensor systems, optical biosensors offer easy-to-use, fast, portable, handy, multiplexed, direct, real-time, and inexpensive diagnosis with the added advantages of specificity and sensitivity. Many progressive concepts and extremely multidisciplinary approaches, including microelectronics, microelectromechanical systems (MEMSs), nanotechnologies, molecular biology, and biotechnology with chemistry, are used to operate optical biosensors. A portable and handheld optical biosensing device would provide fast and reliable results for the identification and quantitation of pathogenic virus particles in each sample. In the modern day, the integration of intelligent nanomaterials in the developed devices provides much more sensitive and highly advanced sensors that may produce the results in no time and eventually help clinicians and doctors enormously. This review accentuates the existing challenges engaged in converting laboratory research to real-world device applications and optical diagnostics methods for virus infections. The review’s background and progress are expected to be insightful to the researchers in the sensor field and facilitate the design and fabrication of optical sensors for life-threatening viruses with broader applicability to any desired pathogens.

An effective electrochemical sensing platform for the simultaneous determination of benzocaine (BEN) and antipyrine (ANT) based upon titanium dioxide nanoparticle (TiO₂)/graphene oxide nanosheet (GO) bulk modified carbon paste electrodes (TiO₂–GO/CPE) is reported. The TiO₂–GO/CPE electrochemical sensing platform is found to exhibit linear ranges from 1.0 × 10⁻⁶ to 1.0 × 10⁻⁴ M and 1.2 × 10⁻⁸ to 8.0 × 10⁻⁵ M for BEN and ANT, respectively. The TiO₂–GO/CPE sensor is explored towards the analysis of BEN and ANT in oral fluid (saliva) and pharmaceutical products. The synergy between the graphene oxide nanosheets and titanium dioxide nanoparticles results in a dramatic enhancement in the sensitivity of the sensor through a combination of increased surface area and improved electron transfer kinetics compared to other electrode alternatives. The fabricated TiO₂–GO/CPE exhibits high sensitivity and good stability towards the sensing of BEN and ANT and has the potential to be utilised as a clinical assay and QA in pharmaceutical products.

A novel, simple and highly sensitive sensor for the simultaneous determination of isopropamide iodide (ISP) and trifluoperazine hydrochloride (TFP) was developed. A carbon paste electrode was modified with m-cresol purple (MCP) and carboxylated multiwalled carbon nanotubes (MWCNTs). Different techniques were used to characterize the nanostructure and performance of the sensor. Under the optimized experimental conditions, ISP and TFP showed linear responses over the ranges of 5.50 × 10⁻⁶–1.70 × 10⁻⁴ and 5.00 × 10⁻⁷–1.34 × 10⁻³ mol L⁻¹, respectively. The detection limits for ISP and TFP were found to be 9.91 × 10⁻⁷ mol L⁻¹ and 1.10 × 10⁻⁷ mol L⁻¹, respectively. Satisfactory recoveries of analytes from these samples were demonstrated, indicating that the suggested sensor is highly suitable for clinical analysis, quality control and routine determination of ISP and TFP in pharmaceutical formulations and human fluids.

In the present work, we aimed to demonstrate the fabrication of a novel electrochemical sensor for the trace determination of Cu(II) in different food matrices. The new sensor was fabricated using cobalt ferrite nanoparticles (CoFe₂O₄) which were prepared via an eco-friendly green method. The prepared nanoparticles were investigated and characterized using different techniques. The described differential pulse anodic stripping voltammetry (DP-ASV) was optimized and validated. Under the optimal conditions, the sensor showed sensitive response to Cu determination over a wide linear range. The limits of detection and quantification were found to be 0.085 and 0.284 ppb, respectively, which are considered as lower than the reported limits. Furthermore, the developed method was applied for trace quantitation of Cu in water, oil, sugar and tea. This was carried out without interferences from various inorganic and organic species. Satisfactory recoveries of Cu from samples clearly revealed that the proposed sensor can be applied into quality control and routine determination of Cu samples.