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. ). S. Dzyadevych is also working as a deputy director of the same institute since 2019. They received PhD degrees in biotechnology. They are developing electrochemical enzyme-based biosensors for medical, research, and industrial applications. The biosensors are based on amperometric, ISFET, and conductometric transducers and immobilized enzymes.a AgNPssilver nanoparticles; AuNPsgold nanoparticles; CNTscarbon nanotubes; NADHreduced nicotinamide adenine dinucleotide; PdNPs palladium nanoparticles; PtNPsplatinum nanoparticles; QDsquantum dots.This journal is Fig. 1 Ways of embedding NMs in the enzyme-based biosensors. (a) Enzyme immobilization on the NM-modified electrode. (b) Schematic of the biosensor based on phosphotriesterase (PTE) immobilized via glutaraldehyde on the graphene surface with platinum nanoparticles. Reprinted with permission from . 25 (c) Enzyme/NM co-immobilization on the electrode. (d) Schematic of the biosensor based on glucose oxidase encapsulated in a chitosan-kappa-carrageenan bionanocomposite. Reprinted from Material Science and Engineering: C, 95, I. Rassas, M. Braiek, A. Bonhomme, F. Bessueille, G. Rafin, H. Majdoub, and N. Jaffrezic-Renault, Voltammetric glucose biosensor based on glucose oxidase encapsulation in a chitosan-kappa-carrageenan polyelectrolyte complex, 152-159, Copyright (2018), with permission from Elsevier. 26 4562 | Nanoscale Adv., 2019, 1, 4560-4577 This journal is Fig. 5 Schematics of the hydrogen peroxide biosensor based on oligoaniline-cross-linked HRP/CNT composite and cyclic voltammograms of the bio...

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Complex graphene electrode fabrication protocols including conventional chemical vapor deposition and graphene transfer techniques as well as more recent solution‐phase printing and postprint annealing methods have hindered the wide‐scale implementation of electrochemical devices including solid‐state ion‐selective electrodes (ISEs). Herein, a facile graphene ISE fabrication technique that utilizes laser induced graphene (LIG), formed by converting polyimide into graphene by a CO2 laser and functionalization with ammonium ion (NH4+) and potassium ion (K+) ion‐selective membranes, is demonstrated. The electrochemical LIG ISEs exhibit a wide sensing range (0.1 × 10−3–150 × 10−3 m for NH4+ and 0.3 × 10−3–150 × 10−3 m for K+) with high stability (minimal drop in signal after 3 months of storage) across a wide pH range (3.5–9.0). The LIG ISEs are also able to monitor the concentrations of NH4+ and K+ in urine samples (29–51% and 17–61% increase for the younger and older patient; respectively, after dehydration induction), which correlate well with conventional hydration status measurements. Hence, these results demonstrate a facile method to perform in‐field ion sensing and are the first steps in creating a protocol for quantifying hydration levels through urine testing in human subjects.

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The majority of biosensors for adenosine-5'-triphosphate (ATP) determination are based on cascades of enzymatic reactions; therefore, they are sensitive to glucose or glycerol (depending on the enzymatic system) as well as to ATP. The presence of unknown concentrations of these substances in the sample greatly complicates the determination of ATP. To overcome this disadvantage of known biosensors, we developed a biosensor system consisting of two biosensors: the first one is based on glucose oxidase and is intended for measuring glucose concentration, and the second one is based on glucose oxidase and hexokinase and is sensitive toward both glucose and ATP. Using glucose concentration measured by the first biosensor, we can analyze the total response to glucose and ATP obtained by the second biosensor. Platinum disc electrodes were used as amperometric transducers. The polyphenilenediamine membrane was deposited onto the surface of platinum electrodes to avoid the response to electroactive substances. The effect of glucose concentration on biosensor determination of ATP was studied. The reproducibility of biosensor responses to glucose and ATP during a day was tested (relative standard deviation, RSD, of responses to glucose was 3-6% and to ATP was 8-12%) as well as storage stability of the biosensors (no decrease of glucose responses and 43% drop of ATP responses during 50 days). The measurements of ATP and glucose in pharmaceutical vials (including mixtures of ATP and glucose) were carried out. It was shown that the developed biosensor system can be used for simultaneous analysis of glucose and ATP concentrations in water solutions.