Abstract
An electrochemical immunosensor employs antibodies as capture and detection means to produce electrical charges for the quantitative analysis of target molecules. This sensor type can be utilized as a miniaturized device for the detection of point-of-care testing (POCT). Achieving high-performance analysis regarding sensitivity has been one of the key issues with developing this type of biosensor system. Many modern nanotechnology efforts allowed for the development of innovative electrochemical biosensors with high sensitivity by employing various nanomaterials that facilitate the electron transfer and carrying capacity of signal tracers in combination with surface modification and bioconjugation techniques. In this review, we introduce novel nanomaterials (e.g., carbon nanotube, graphene, indium tin oxide, nanowire and metallic nanoparticles) in order to construct a high-performance electrode. Also, we describe how to increase the number of signal tracers by employing nanomaterials as carriers and making the polymeric enzyme complex associated with redox cycling for signal amplification. The pros and cons of each method are considered throughout this review. We expect that these reviewed strategies for signal enhancement will be applied to the next versions of lateral-flow paper chromatography and microfluidic immunosensor, which are considered the most practical POCT biosensor platforms.
Highlights
In 1962, Clark and Lyons introduced a glucose sensor that utilized a specific enzyme
The hydroxyl surface of Indium tin oxide (ITO) can be modified with various chemicals to create functional layers terminated with amines, carboxylic acids, or thiols—often called the self-assembled monolayer (SAM)—for the immobilization of the capture antibody
The ITO-based substrate was chosen as a working electrode due to its high electrical conductivity, low detection limit (30 fg/mL) and wide dynamic range (14.25–712.5 fg/mL) of RACK1 in samples. Conducting polymer such as a polyaminobenzoic acid (PABA) can provide carboxyl groups on the ITO substrate and enable surface modification with active ester, which is highly reactive to the amine groups presented around an antibody molecule [36]
Summary
In 1962, Clark and Lyons introduced a glucose sensor that utilized a specific enzyme (i.e., glucose oxidase). There are many commercially-available immunochemistry analysis tools manufactured by the renowned diagnostic companies such as Roche, Abbott and Siemens These models claim the highly sensitive measurement of target molecules (e.g., protein) up to 1–100 pg/mL in samples. Developing an ideal POC immunosensor to comply with the sample rigor and detection limit still present a challenge To this end, signal amplification strategies have gained increased attention for the high-performance analysis of the electrochemical immunoassay used for clinical diagnosis and environmental monitoring [6,7,8,9,10,11]. A large portion of these strategies have both paper-based and microfluidic-based immunosensor system applications, which are practical biosensor platforms for on-site biomolecule measurement
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
