Mediator-free total cholesterol estimation using a bi-enzyme functionalized nanostructured gold electrode

Abstract

We report the fabrication of a bi-enzyme functionalized nanostructured Au electrode for the mediator-free determination of total cholesterol. A one-step electrochemical route for the synthesis, functionalization and deposition of Au nanostructures via the electroreduction of gold chloride onto indium tin oxide (ITO) coated glass plates has been proposed. The covalent biofunctionalization of the optimized Au electrode was done with cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) to investigate the kinetic parameters and the sensing characteristics. The ChEt-ChOx/Glu-NanoAu/ITO bioelectrode has a surface-controlled electrode reaction with an electron transfer coefficient and a charge transfer rate constant of 0.68 and 7.09 s À1 , respectively. Under the optimal conditions, the bioelectrode undergoes a direct electron transfer reaction and exhibits a high sensitivity of 0.53 mA mM À1 cm À2 and a low detection limit of 1.57 mM for cholesterol ester without the use of any redox mediator. In addition, the kinetic analysis reveals that the bioelectrode exhibits a surface concentration of 8.82 Â 10 À12 mol cm À2.The sensor has also been validated with clinical samples. The proposed biosensor shows good sensitivity, stability and selectivity towards total cholesterol and may thus find implications in the fabrication of biosensing devices.

Flexible Label-Free Platinum and Bio-PET-Based Immunosensor for the Detection of SARS-CoV-2

“…Therefore, the electrode surfaces before and after the modifications showed a hydrophilic character, presenting a contact angle of 80 ± 1 • and 66 ± 1 • , respectively. The decrease in the contact angle can be explained by the presence of cysteamine, which shows a more hydrophilic behavior in the water measurements [49], proving its presence on the electrode surface, which is interesting for the success of the immobilization of biomolecules in later stages.…”

Development of a Sensitive Electrochemical Enzymatic Reaction-Based Cholesterol Biosensor Using Nano-Sized Carbon Interdigitated Electrodes Decorated with Gold Nanoparticles

“…Recently, some research studies on electrochemical cholesterol biosensors have focused on the direct electron transfer between ChOx and electrode surfaces at a lower potential to avoid the interference from the co-existing species [ 12 ]. However, some problems, including the poor compatibility of the support matrix with the enzyme [ 24 , 25 ], deep embedment of redox active site in the protein, and leaching of the enzyme from the electrode surface, may restrict the analytical efficiency of the developed biosensor [ 14 ].…”

Dual Functional Full-Color Carbon Dot-Based Organelle Biosensor Array for Visualization of Lipid Droplet Subgroups with Varying Lipid Composition in Living Cells

“…The interior of LDs is neutral lipids, which are mainly composed of triacylglycerol (TAG) and cholesterol ester (CE), accounting for more than 85% of total lipids. , LDs of mammalian cells, especially adipocytes and hepatocytes, are the main storage sites for energy, where the main lipid component is TAG, while CE is more abundant in the steroidal cells of the adrenal cortex, testis, and ovary, which are mainly responsible for the synthesis of hormone substrates . Therefore, we hypothesize that by combining LD localization information and internal lipid (TAG and CE) level measurements, it would be possible to decode in situ the association of LD subgroups and functions in living cells. ,, However, both TAG and CE are long-chain low-polarity lipids that are difficult to detect with high selectivity and accuracy by nonenzymatic methods. , Semiselective sensing methods combining multidimensional sensor arrays and clustering algorithms have been widely used for subgroup analysis of biomolecules and organisms, such as amino acids, bacteria, and cells . Therefore, we speculate that the development of multiple LD-targeted TAG/CE semiselective fluorescent probes can enable in situ differential lighting of LDs to obtain fingerprint response patterns based on lipid composition, and combine LD localization information for in situ visualization of LD diversity.…”

“…1,4,5 However, both TAG and CE are long-chain low-polarity lipids that are difficult to detect with high selectivity and accuracy by nonenzymatic methods. 20,21 Semiselective sensing methods combining multidimensional sensor arrays and clustering algorithms have been widely used for subgroup analysis of biomolecules and organisms, 22 such as amino acids, 23 bacteria, 24 and cells. 25 Therefore, we speculate that the development of multiple LDtargeted TAG/CE semiselective fluorescent probes can enable in situ differential lighting of LDs to obtain fingerprint response patterns based on lipid composition, and combine LD localization information for in situ visualization of LD diversity.…”