Electrochemically Prepared Unzipped Single Walled Carbon Nanotubes-MnO2 Nanostructure Composites for Hydrogen Peroxide and Glucose Sensing

Designing Nanocomposite-Based Electrochemical Biosensors for Diabetes Mellitus Detection: A Review

This review will unveil the development of a new generation of electrochemical sensors utilizing a transition-metal-oxide-based nanocomposite with varying morphology. There has been considerable discussion on the role of transition metal oxide-based nanocomposite, including iron, nickel, copper, cobalt, zinc, platinum, manganese, conducting polymers, and their composites, in electrochemical and biosensing applications. Utilizing these materials to detect glucose and hydrogen peroxide selectively and sensitively with the correct chemical functionalization is possible. These transition metals and their oxide nanoparticles offer a potential method for electrode modification in sensors. Nanotechnology has made it feasible to develop nanostructured materials for glucose and H2O2 biosensor applications. Highly sensitive and selective biosensors with a low detection limit can detect biomolecules at nanomolar to picomolar (10-9 to 10-12 molar) concentrations to assess physiological and metabolic parameters. By mixing carbon-based materials (graphene oxide) with inorganic nanoparticles, nanocomposite biosensor devices with increased sensitivity can be made using semiconducting nanoparticles, quantum dots, organic polymers, and biomolecules.

Release of free-state ions from fulvic acid-heavy metal complexes via VUV/H2O2 photolysis: Photodegradation of fulvic acids and recovery of Cd2+ and Pb2+ stripping voltammetry currents

Fulvic acid (FA), a ubiquitous organic matter in the environment, can enhance the mobility and bioavailability of Cd²⁺ and Pb²⁺ through competitive complexation to form FA-heavy metal ions (FA-HMIs) complexes with excellent solubility. Because FA-HMIs are electrochemically inactive, square wave anodic stripping voltammetry (SWASV) cannot accurately detect the content of bioavailable Cd²⁺ and Pb²⁺ in soils and sediments. This study ostensibly aimed to efficiently recover SWASV signals of Cd²⁺ and Pb²⁺ in FA-HMIs by disrupting FA-HMIs complexes using the combined vacuum ultraviolet and H₂O₂ (VUV/H₂O₂) process. Essentially, this study explored the photodegradation behavior and photolysis by-products of FA and their effects on the conversion of FA-HMIs complexes to free-state Cd²⁺ and Pb²⁺ using multiple characterization techniques, as well as revealed the complexation mechanism of FA with Cd²⁺ and Pb²⁺. Results showed that reactive groups such as carboxyl and hydroxyl endowed FA with the ability to complex Cd²⁺ and Pb²⁺. After FA-HMIs underwent VUV/H₂O₂ photolysis for 9 min at 125 mg/L of H₂O₂, FA was decomposed into small molecular organics while removing its functional groups, which released the free-state Cd²⁺ and Pb²⁺ and recovered their SWSAV signals. However, prolonged photolytic mineralization of FA to inorganic anions formed precipitates with Cd²⁺ and Pb²⁺, thereby decreasing their SWSAV signals. Moreover, the VUV/H₂O₂ photolysis significantly improved the SWASV detection accuracy toward the Cd²⁺ and Pb²⁺ in real soil and sediment samples, verifying its practicality.

Emerging Biosensors for Oral Cancer Detection and Diagnosis—A Review Unravelling Their Role in Past and Present Advancements in the Field of Early Diagnosis

Oral cancer is a serious concern to people all over the world because of its high mortality rate and metastatic spread to other areas of the body. Despite recent advancements in biomedical research, OC detection at an early stage remains a challenge and is complex and inaccurate with conventional diagnostics procedures. It is critical to study innovative approaches that can enable a faster, easier, non-invasive, and more precise diagnosis of OC in order to increase the survival rate of patients. In this paper, we conducted a review on how biosensors might be an excellent tool for detecting OC. This review covers the strategies that use different biosensors to target various types of biomarkers and focuses on biosensors that function at the molecular level viz. DNA biosensors, RNA biosensors, and protein biosensors. In addition, we reviewed non-invasive electrochemical methods, optical methods, and nano biosensors to analyze the OC biomarkers present in body fluids such as saliva and serum. As a result, this review sheds light on the development of ground-breaking biosensors for the early detection and diagnosis of OC.

Applications of Pristine and Functionalized Carbon Nanotubes, Graphene, and Graphene Nanoribbons in Biomedicine

This review is dedicated to a comprehensive description of the latest achievements in the chemical functionalization routes and applications of carbon nanomaterials (CNMs), such as carbon nanotubes, graphene, and graphene nanoribbons. The review starts from the description of noncovalent and covalent exohedral modification approaches, as well as an endohedral functionalization method. After that, the methods to improve the functionalities of CNMs are highlighted. These methods include the functionalization for improving the hydrophilicity, biocompatibility, blood circulation time and tumor accumulation, and the cellular uptake and selectivity. The main part of this review includes the description of the applications of functionalized CNMs in bioimaging, drug delivery, and biosensors. Then, the toxicity studies of CNMs are highlighted. Finally, the further directions of the development of the field are presented.

Low temperature NO2 gas sensing with ZnO nanostructured by laser interference lithography

ZnO conductometric gas sensors have been widely studied due to their good sensitivity, cost-efficiency, long stability and simple fabrication. This work is focused on NO₂ sensing, which is a toxic and irritating gas. The developed sensor consists of interdigitated electrodes covered by a ZnO sensing layer. ZnO has been grown by means of the aerosol assisted chemical vapor deposition technique and then nanostructured by laser interference lithography with a UV laser. The SEM and XRD results show vertically oriented growth of ZnO grains and a 2D periodic nanopatterning of the material with a period of 800 nm. Nanostructuring lowers the base resistance of the developed sensors and modifies the sensor response to NO₂. Maximum sensitivity is obtained at 175 °C achieving a change of 600% in sensor resistance for 4 ppm NO₂versus a 400% change for the non-nanostructured material. However, the most relevant results have been obtained at temperatures below 125 °C. While the non-nanostructured material does not respond to NO₂ at such low temperatures, nanostructured ZnO allows NO₂ sensing even at room temperature. The room temperature sensing capability possibly derives from the increase of both the surface defects and the surface-to-volume ratio. The long stability and the gas sensing under humid conditions have also been tested, showing improvements of sensitivity for the nanostructured sensors.

ZnO gas sensing improvement due to laser interference nanostructuration.

A Review: Electrochemical Biosensors for Oral Cancer

Oral cancer poses a serious threat worldwide owing to its soaring case-fatality rate and its metastatic characteristics of spreading to the other parts of the body. Despite the recent breakthroughs in biomedical sciences, the detection of oral cancer at an early stage is still challenging. Conventional diagnosis in clinics and optical techniques to detect oral cancer in the initial stages are quite complicated as well as not completely accurate. To enhance the survival rate of oral cancer patients, it is important to investigate the novel methodologies that can provide faster, simpler, non-invasive, and yet ultraprecise detection of the onset of oral cancer. In this review, we demonstrate the promising aspects of an electrochemical biosensor as an ideal tool for oral cancer detection. We discuss the cutting-edge methodologies utilizing various electrochemical biosensors targeting the different kinds of biomarkers. In particular, we emphasize on electrochemical biosensors working at the molecular levels, which can be classified into mainly three types: DNA biosensors, RNA biosensors and protein biosensors according to the types of the analytes. Furthermore, we focus on the significant electrochemical methods including cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) to analyze the oral cancer biomarkers (such as IL-6, IL-8, CYFRA 21-1, CD 59 and CIP2A) present in body fluids including saliva and serum, using non-invasive manner. Hence, this review provides essential insights into the development of pioneering electrochemical biosensors for the detection of oral cancer at an early stage.