Electrochemical sensors based on metal nanoparticles with biocatalytic activity

Abstract

Biosensors have attracted a great deal of attention, as they allow for the translation of the standard laboratory-based methods into small, portable devices. The field of biosensors has been growing, introducing innovations into their design to improve their sensing characteristics and reduce sample volume and user intervention. Enzymes are commonly used for determination purposes providing a high selectivity and sensitivity; however, their poor shelf-life is a limiting factor. Researchers have been studying the possibility of substituting enzymes with other materials with an enzyme-like activity and improved long-term stability and suitability for point-of-care biosensors. Extra attention is paid to metal and metal oxide nanoparticles, which are essential components of numerous enzyme-less catalytic sensors. The bottleneck of utilising metal-containing nanoparticles in sensing devices is achieving high selectivity and sensitivity. This review demonstrates similarities and differences between numerous metal nanoparticle-based sensors described in the literature to pinpoint the crucial factors determining their catalytic performance. Unlike other reviews, sensors are categorised by the type of metal to study their catalytic activity dependency on the environmental conditions. The results are based on studies on nanoparticle properties to narrow the gap between fundamental and applied research. The analysis shows that the catalytic activity of nanozymes is strongly dependent on their intrinsic properties (e.g. composition, size, shape) and external conditions (e.g. pH, type of electrolyte, and its chemical composition). Understanding the mechanisms behind the metal catalytic activity and how it can be improved helps designing a nanozyme-based sensor with the performance matching those of an enzyme-based device. Graphical abstract

Hexagonal cobalt oxide nanosheet-based enzymeless electrochemical uric acid sensor with improved sensitivity

“…[22][23][24][25][26] Cobalt oxide nanostructures are preferred for modifying the working electrode of enzymeless sensors because of their high electrochemical activity and good electrical performance. 27 In this work, we report the successful synthesis of hexagonal cobalt oxide nanosheets by a simple and reproducible hydrothermal method. The as-synthesised nanomaterial was examined using XRD, FESEM, and high-resolution TEM (HR-TEM) techniques to elucidate the morphology and crystallinity.…”

“…22–26 Cobalt oxide nanostructures are preferred for modifying the working electrode of enzymeless sensors because of their high electrochemical activity and good electrical performance. 27…”

Controlled Synthesis of Platinum and Silver Nanoparticles Using Multivalent Ligands

“…In the emerging and attractive world of nanomaterials, nanosized particles of noble metals (platinum, silver, and gold) have attracted much attention in recent years due to their applications in various fields, such as catalysis [1][2][3][4], optics [5][6][7], biological applications [8][9][10][11][12][13], and biosensors [14][15][16][17][18]. Platinum nanoparticles (PtNPs) have shown unique and promising electrocatalytic properties in fuel cells [19][20][21][22]; nonlinear optical properties [23,24] in electronic devices [25,26]; as electrochemical biosensors for the detection of aquatic products [27], glucose [28], and glutamate in food products [29], and for the detection of reactive oxygen species [30,31].…”

Artificial Formate Oxidase Reactivity with Nano-Palladium Embedded in Intrinsically Microporous Polyamine (Pd@Pim-Ea-Tb) Driving the H2o2 – 3,5,3’,5’-Tetramethylbenzidine (Tmb) Colour Reaction

“…Mimicking enzyme processes is of considerable interest for example in electroanalysis [1,2] and in biosensing [3]. Formate oxidase enzyme reactivity is linked to the production of hydrogen peroxide, H 2 O 2 , via formate oxidation [4] (equation 1 and 2).…”