Synthesis of Co₃O₄ Cotton-Like Nanostructures for Cholesterol Biosensor

Emerging Trends in Non-Enzymatic Cholesterol Biosensors: Challenges and Advancements

The development of a highly sensitive and selective non-enzymatic electrochemical biosensor for precise and accurate determination of multiple disease biomarkers has always been challenging and demanding. The synthesis of novel materials has provided opportunities to fabricate dependable biosensors. In this perspective, we have presented and discussed recent challenges and technological advancements in the development of non-enzymatic cholesterol electrochemical biosensors and recent research trends in the utilization of functional nanomaterials. This review gives an insight into the electrochemically active nanomaterials having potential applications in cholesterol biosensing, including metal/metal oxide, mesoporous metal sulfide, conductive polymers, and carbon materials. Moreover, we have discussed the current strategies for the design of electrode material and key challenges for the construction of an efficient cholesterol biosensor. In addition, we have also described the current issues related to sensitivity and selectivity in cholesterol biosensing.

Synthesis, Characterization and Applications of Spinel Cobaltite Nanomaterials

Recently, spinel structures (AB₂O₄) Nanoparticles (NPs) having binary and ternary mixtures of metal oxides have been established as promising redox catalysts. Due to the presence of two mixed valence metal cations, transport of electrons takes place easily between multiple transition-metal cations with relatively low energy of activation. Among these, spinel cobaltite (MCo₂O₄) is very attractive due to its low cost, non-toxicity, higher stability, higher electronic conductivity and electrochemical property. To date, MCo₂O₄ has been used in the fabrication of supercapacitors, electrodes for oxygen evolution reaction, and electrochemical sensors for glucose. A variety of MMCo₂O₄materials have been synthesized, characterized, and utilized in the fabrication of super capacitors, electrodes for oxygen evolution reaction, and electrochemical sensors for glucose. The progress in the field of the spinel MCo₂O₄ materials opens the door to novel and efficient applications in the nanoscience and nanotechnology, and elctrochemistry.

A label-free aptasensor FET based on Au nanoparticle decorated Co3O4 nanorods and a SWCNT layer for detection of cardiac troponin T protein

Acute myocardial infarction (AMI) is a serious health problem that must be identified in its early stages. Considerable progress has been made in understanding the condition of AMI through ascertaining the role of biomarkers, such as myoglobin, cardiac troponin proteins (T and I), creatine kinase-MB, and fatty acid-binding protein (FABP). A field-effect transistor (FET) is an effective platform; however, innovations are required in all layers of the FET for it to become robust and highly sensitive. For the first time, we made use of the synergistic combination of noble metal nanoparticles (AuNPs) with Co₃O₄ for the detection of cardiac troponin T (cTnT) in a FET platform. We determined the morphology of Au-decorated Co₃O₄ NRs and their electronic properties by characterizing the channel layer using electron microscopies and transient measurements. Subsequently, we performed the detection of cardiac troponin T by immobilizing its complementary biotinylated DNA aptamer on the channel surface using a drop-casting method. To understand the changes in drain current caused by this interaction, we probed our SWCNT-Co₃O₄ NR transistor with limited gate and drain bias (≤1 V), achieving a sensitivity of 0.5 μA μg^-1 mL^-1 for the Au-decorated NRs. A 250% increase in the sensitivity and a limit of detection (LOD) of 0.1 μg mL^-1 were achieved by using this device. Finally, selectivity studies proved that this synergistic combination works well in the FET configuration for the successful detection of cTnT.

Cobalt Oxide Porous Nanocubes-Based Electrochemical Immunobiosensing of Hepatitis B Virus DNA in Blood Serum and Urine Samples

In this work, we report a new biosensing platform for hepatitis B virus (HBV) DNA genosensing using cobalt oxide (Co₃O₄) nanostructures. The tunable morphologies of Co₃O₄ nanostructures such as porous nanocubes (PNCs), nanooctahedra (NOHs), and nanosticks (NSKs) are synthesized, and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) patterns, nitrogen adsorption/desorption isotherms (BET), and electrochemical impedance spectral (EIS) methods. The HBV probe DNA (ssDNA) is immobilized on the Co₃O₄ nanostructures through coordinate bond formation between nucleic acid of ssDNA and Co metal, which results in highly stable nanostructured biosensing platform. To the best of our knowledge, first time the target cDNA of HBV is detected using ssDNA/Co₃O₄PNCs/GCE electrode by EIS method with a limit of detection (LOD) of 0.38 pM (signal-to-noise ratio (S/N) = 3). Moreover, the ssDNA/Co₃O₄PNCs/GCE has shown excellent specificity to HBV target cDNA, compared with noncomplementary DNA, and 1- and 3-mismatch DNAs. Finally, we explore ssDNA/Co₃O₄PNCs/GCE as potential electrode to test HBV DNA in blood serum and urine samples for practical applications.

Highly active 3-dimensional cobalt oxide nanostructures on the flexible carbon substrates for enzymeless glucose sensing

3-Dimensional cobalt oxide nanostructures on the flexible carbon substrates for enzymeless glucose sensing.