Electrochemical detection of 17β-estradiol and bisphenol A using graphene oxide and reduced graphene oxide modified electrodes: A review

Detecting organic emerging contaminants like 17β-estradiol (E2) and bisphenol A (BPA) at low concentrations, around ng/L, using modified electrochemical sensors has posed a significant challenge in recent decades. E2 and BPA, recognized as endocrine disruptors, pose threats to the environment and human health due to their accumulation in ecosystems and biological fluids. Electrochemical detection, a versatile technique applicable to various samples, including foods, water, soil, and human fluids, has been instrumental in addressing this challenge. Graphene oxide (GO), a 2D carbon nanostructure with excellent conductivity and diverse organic functional groups, has emerged as a promising material for modifying electrode surfaces. This study conducts a systematic review and comprehensive analysis of electrode modification using GO to enhance the detection of E2 and BPA. Various approaches involving GO and its reduced forms, including noble metal nanoparticles, metal and metal oxide nanoparticles, metal-organic frameworks, organic groups-functionalized GO, and the use of aptamers or enzymes, have been identified. The study highlights the impact of nanomaterial size, morphology, and distribution on the GO surface, emphasizing their influence on sensor performance. The most frequently reported techniques include differential pulse voltammetry, with glassy carbon being the preferred modified working electrode. The electrocatalytic reaction mechanisms of both contaminants with metal and metal-oxide nanoparticles-GO/r-GO hybrid materials are presented. A key observation is the need for cycle number studies using real samples to establish the material's lifespan, posing a challenge in sensor applications. In conclusion, the study outlines advances and perspectives on the topic, particularly focusing on new types of nanomaterials suggested for electrode modification in future research for sensing.