Influence of different nanozeolite particles on the sensitivity of a glucose biosensor

Impedimetric Microcystin-LR Aptasensor Prepared with Sulfonated Poly(2,5-dimethoxyaniline)–Silver Nanocomposite

This paper presents a novel impedimetric aptasensor for cyanobacterial microcystin-LR (L, l-leucine; R, l-arginine) (MC-LR) containing a 5′ thiolated 60-mer DNA aptamer (i.e., 5′-SH-(CH2)6GGCGCCAAACAGGACCACCATGACAATTACCCATACCACCTCATTATGCCCCATCT CCGC-3′). A nanocomposite electrode platform comprising biocompatible poly(2,5-dimethoxyaniline) (PDMA)-poly(vinylsulfonate) (PVS) and silver nanoparticle (Ag0) on a glassy carbon electrode (GCE), i.e., (GCE/PDMA–PVS–Ag0) was used in the biosensor development. Small-angle X-ray scattering (SAXS) spectroscopic analysis revealed that the PDMA–PVS–Ag0 nanocomposites were polydispersed and contained embedded Ag0. Electrochemical impedance spectroscopy (EIS) responses of the aptasensor gave a dynamic linear range (DLR) and limit of detection (LOD) values of 0.01–0.1 ng L−1 MC-LR and 0.003 ng L−1 MC-LR, respectively. The cross-reactivity studies, which was validated with enzyme-linked immunosorbent assay (ELISA), showed that the aptasensor possesses excellent selectivity for MC-LR.

In situ deposition of MOF-74(Cu) nanosheet arrays onto carbon cloth to fabricate a sensitive and selective electrocatalytic biosensor and its application for the determination of glucose in human serum

A new electrocatalytic biosensor (MOF-74(Cu) NS-CC) based on the in situ deposition of MOF-74(Cu) nanosheet on carbon cloth via a bottom-up synthetic approach in a glass tube was developed. The electrocatalytic activity of the deposited MOF-74(Cu) NS was demonstrated in the oxidation of glucose to gluconate under alkaline conditions. The results revealed that the proposed method of in situ formation of MOF-74(Cu) NS onto a carbon cloth surface in a multi-layer solution is capable to generate a stable MOF-74(Cu) NS-CC electrode with excellent sensing performance. When the as-synthesized MOF-74(Cu) NS-CC was applied directly as the working electrode for glucose sensing, it showed much higher conductivity and redox activity than MOF-74(Cu) NS-GCE. With the potential applied at 0.55 V (vs. Ag/AgCl), this new electrocatalytic biosensor exhibits an excellent linear relationship between current density and concentration of glucose. Moreover, a wide linear range of detection (1.0 to 1000 μM) was observed. The limit of detection was found to be 0.41 μM (S/N = 3). The response sensitivity is 3.35 mA mM^-1 cm^-2 when the concentration of glucose is in the range 1-100 μM and 3.81 mA mM^-1 cm^-2 for the 100-1000 μM concentration range. This study provides a low-cost, easy to prepare, and reproducible methodology for the synthesis of highly redox-active nanomaterials based on the in situ formation of two-dimensional MOF-74(Cu) NS for the development of new electrocatalytic biosensors. Graphical abstract.

Advances in nanomaterial application in enzyme-based electrochemical biosensors: a review

Electrochemical enzyme-based biosensors are one of the largest and commercially successful groups of biosensors. Integration of nanomaterials in the biosensors results in significant improvement of biosensor sensitivity, limit of detection, stability, response rate and other analytical characteristics. Thus, new functional nanomaterials are key components of numerous biosensors. However, due to the great variety of available nanomaterials, they should be carefully selected according to the desired effects. The present review covers the recent applications of various types of nanomaterials in electrochemical enzyme-based biosensors for the detection of small biomolecules, environmental pollutants, food contaminants, and clinical biomarkers. Benefits and limitations of using nanomaterials for analytical purposes are discussed. Furthermore, we highlight specific properties of different nanomaterials, which are relevant to electrochemical biosensors. The review is structured according to the types of nanomaterials. We describe the application of inorganic nanomaterials, such as gold nanoparticles (AuNPs), platinum nanoparticles (PtNPs), silver nanoparticles (AgNPs), and palladium nanoparticles (PdNPs), zeolites, inorganic quantum dots, and organic nanomaterials, such as single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon and graphene quantum dots, graphene, fullerenes, and calixarenes. Usage of composite nanomaterials is also presented.

Creatinine Deiminase Adsorption onto Silicalite-Modified pH-FET for Creation of New Creatinine-Sensitive Biosensor

In the work, silicalite particles were used for the surface modification of pH-sensitive field-effect transistors (pH-FETs) with the purpose of developing new creatinine-sensitive biosensor. Creatinine deiminase (CD) adsorbed on the surface of silicalite-coated pH-FET served as a bioselective membrane. The biosensor based on CD immobilized in glutaraldehyde vapor (GA) was taken as control. The creatinine-sensitive biosensor obtained by adsorption on silicalite was shown to have better analytical characteristics (two- to threefold increased sensitivity to creatinine, three- to fourfold lesser response and recovery times, a decrease of the detection limit of creatinine determination to 5 μM, etc.).Additionally, the biosensor based on CD adsorbed on silicalite (Sil/CD) was characterized by high signal reproducibility (relative standard deviation (RSD) for creatinine measurement = 2.6 %) and stability during storage (over 13 months). It was experimentally confirmed that the proposed biosensor was not sensitive either to high concentrations of sodium chloride or to the macromolecular protein fractions and can be used for direct quantitative analysis of creatinine in the blood serum.It was concluded that the method of CD adsorption on silicalite is well-suited for the creation of creatinine-sensitive biosensor with improved working characteristics.

Application of silicalite-modified electrode for the development of sucrose biosensor with improved characteristics

The application of silicalite for improvement of working characteristics of conductometric enzyme biosensors for determination of sucrose was studied in this research. Biosensors based on different types of silicalite-modified electrodes were studied and compared according to their analytical characteristics. Polyethylenimine/glutaraldehyde/silicalite-modified biosensors showed higher sensitivity compared with others type of biosensors. Moreover, the polyethylenimine/glutaraldehyde/silicalite sucrose biosensors were characterized by high selectivity and signal reproducibility (relative standard deviation (RSD) = 2.78% for glucose measurements and RSD = 3.2% for sucrose measurements). Proposed biosensors were used for determination of sucrose in different samples of beverages. The obtained results had good correlation with results obtained by HPLC. Thus, polyethylenimine/glutaraldehyde/silicalite-modified biosensors have shown perspective characteristics for the development of effective conductometric enzyme biosensors.