Carbohydrate polymer-supported metal and metal oxide nanoparticles for constructing electrochemical sensors

Carbohydrate polymers have attracted significant attention due to their favorable characteristics, such as availability, non-toxicity, biocompatibility, and biodegradability, making them promising materials for many medical and industrial applications. Additionally, they can be reinforced with metal and metal oxide nanoparticles (NPs), resulting in the formation of nanocomposites (NCs), which can be incorporated in electrochemical sensors for enhancing their conductivity and catalytic activity. These NPs increase the catalytic activity of electrochemical sensors via redox cycling, while carbohydrate polymers are used to stabilize NPs against self-aggregation and act as matrix for them. The redox cycling process, which depends on NPs as redox mediators, facilitates the oxidation or reduction of the target analytes, leading to an optimized current signal. Carbohydrate polymers are more favorable than synthetic polymers given that they are readily available, cheap, and non-toxic materials. To date, various carbohydrate polymers, such as alginate, cellulose, chitosan, dextran, gums, locust bean gum, latex, mucilage, pectin, and starch, have been used for the preparation of electroactive metal/metal oxide–carbohydrate polymer NCs. Subsequently, these NCs have been employed for the detection of biological analytes, such as drugs, enzymes, hormones, aflatoxins, biomarkers, carbohydrates, and natural oxidants, and water pollutants, such as pesticides, dyes, metal ions, and phenolics. However, there are fewer studies regarding the use of carbohydrate polymers in electrochemical sensors compared with other applications. Overall, metal/metal oxide–carbohydrate polymers are considered promising materials for the detection of many target analytes with enhanced sensitivity, low detection limits, and optimized selectivity.