Contemporary electrochemical sensing and affinity biosensing to assist traces metal ions determination in clinical samples

Abstract

The determination of metals in clinical samples is an important challenge since their levels are relevant to ensure personal exposure to safe environments, as well as to assist in the prevention and treatment of disease. The low concentrations of metal ions in clinical samples and their coexistence with other metals and/or molecules of diverse nature implies the need for sensitive and selective analytical methodologies, which can be provided by conventional techniques. However, most of these techniques do not satisfy other highly demanded requirements such as high sampling frequency, multiplexed ability, and in-field analysis. In this context, the simplicity, speed of response, and compatibility with single or multiplexed point-of-care determinations have led to the successful incursion of electrochemical (bio)sensing into the clinical field for the determination of these analytes. Electrochemical (bio)devices have come on strong by exploiting and combining the unique attributes provided by electrochemical techniques (primarily voltammetry but also giving way to impedimetry in electrochemical affinity biosensing), electrode materials (Hg, Bi, Sb, Au, GCE, CPE, ITO, FTO), and substrates (conventional, screen-printed, flexible, paper, wearable or tattoo-type), suitable modifiers (nanomaterials, polymers, mesoporous films), bioreceptors (aptamers, peptides, biomolecular switches, DNAzymes, and DNA molecules), and nucleic acid amplification strategies (rolling circle and exonucleases-assisted target recycling). Therefore, the purpose of this review is to provide a bird's eye view of the state of the art, discussing the remarkable opportunities and potentialities demonstrated in the last decade by electrochemical sensors and electrochemical affinity biosensors for the analysis of metal ions in challenging clinical samples and forecasting future directions in this exciting field.