Aptamer-Based Biosensors for the Colorimetric Detection of Blood Biomarkers: Paving the Way to Clinical Laboratory Testing

Abstract

Clinical diagnostics for human diseases rely largely on enzyme immunoassays for the detection of blood biomarkers. Nevertheless, antibody-based test systems have a number of shortcomings that have stimulated a search for alternative diagnostic assays. Oligonucleotide aptamers are now considered as promising molecular recognizing elements for biosensors (aptasensors) due to their high affinity and specificity of target binding. At the moment, a huge variety of aptasensors have been engineered for the detection of various analytes, especially disease biomarkers. However, despite their great potential and excellent characteristics in model systems, only a few of these aptamer-based assays have been translated into practice as diagnostic kits. Here, we will review the current progress in the engineering of aptamer-based colorimetric assays as the most suitable format for clinical lab diagnostics. In particular, we will focus on aptasensors for the detection of blood biomarkers of cardiovascular, malignant, and neurodegenerative diseases along with common inflammation biomarkers. We will also analyze the main obstacles that have to be overcome before aptamer test systems can become tantamount to ELISA for clinical diagnosis purposes.

A colorimetric immunoassay for the detection of human vascular endothelial growth factor 165 (VEGF165) based on anti-VEGF-iron oxide nanoparticle conjugation

“…They frequently employ aptamer/antibody combinations, offering high specificity and selectivity. Furthermore, the repeatability, stability, and affordability of the test system can be improved by using antibodies and/or aptamers [ 75 ]. In our case, the results show that the prepared LpAB-FeNP/anti-VEGF has many advantages over the others, including a better LOD and a broader linear detection range.…”

Biosensing Platforms for Cardiac Biomarker Detection

“…Nucleic acids, in the form of aptamers, are short DNA or RNA fragments with unique spatial structures that enable them to bind to specific molecular targets. Aptamers possess advantages such as thermal stability, extended shelf life, and lenient storage and handling requirements due to their chemical structure . Antibodies are complex proteins composed of two identical light chains and two identical heavy chains.…”

“…Aptamers possess advantages such as thermal stability, extended shelf life, and lenient storage and handling requirements due to their chemical structure. 81 Antibodies are complex proteins composed of two identical light chains and two identical heavy chains. They are employed as bioreceptors in biosensors and their functional outcome is determined by the quality and quantity of antibodies.…”

Application of different biosensors for biomarkers analysis

“…As shown in Fig. 3, the aptamer can be used to design a new colorimetric biosensor for the VEGF detection [7]. When it was used to bind with the target substance, the aptamer can form an active G-quadruplex structure.…”