An outlook on electrochemical approaches for molecular diagnostics assays and discussions on the limitations of miniaturized technologies for point-of-care devices

The detection of specific biomarkers for health monitoring, i.e., molecular diagnostics, can be classified as early or emergency diagnostics. Emergency diagnostics is related to those diseases which is necessary a rapid patient intervention, such as stroke and cardiac attack, in addition to the detection of infectious diseases to monitor and control outbreaks and epidemics, and early diagnosis requires the highly sensitive quantification of the biomarkers related to, specially, degenerative and cancer diseases for a successful treatment. Herein, the challenges of designing improved point-of-care (PoC) molecular diagnostic devices were reviewed, and the limitations of standard technologies were discussed. Despite their high sensitivities, precisions, and reliabilities, standard technologies are still limited by their requirements for expensive reagents and equipment, as well as laborious and time-consuming sample pretreatments, elaborate protocols, and qualified personnel, which highly impact their applications in loco and affordability. PoC assays exhibiting high selectivity and portability have been demonstrated feasibility in biosensing technologies. To explore the biosensor application regarding the limitations of achieving the commercialization of these technologies, the strategies for developing label-based and label-free biosensors will be discussed as they relate to the types of bioreceptor and the signal transduction methods. Electrochemical biosensors will especially be focused on because of their advantages, such as scalability, miniaturization, and sensitivity (with some electrochemical biosensing setups not requiring complex steps, such as sample pretreatment, to complete the diagnostics, thus availing reliable PoC analysis). Further, the challenges of developing reliable commercial PoC devices will be discussed.