Abstract
An aptamer is a short sequence of synthetic oligonucleotides which bind to their cognate target, specifically while maintaining similar or higher sensitivity compared to an antibody. The in-vitro selection of an aptamer, applying a conjoining approach of chemistry and molecular biology, is referred as Systematic Evolution of Ligands by Exponential enrichment (SELEX). These initial products of SELEX are further modified chemically in an attempt to make them stable in biofluid, avoiding nuclease digestion and renal clearance. While the modification is incorporated, enough care should be taken to maintain its sensitivity and specificity. These modifications and several improvisations have widened the window frame of aptamer applications that are currently not only restricted to in-vitro systems, but have also been used in molecular imaging for disease pathology and treatment. In the food industry, it has been used as sensor for detection of different diseases and fungal infections. In this review, we have discussed a brief history of its journey, along with applications where its role as a therapeutic plus diagnostic (theranostic) tool has been demonstrated. We have also highlighted the potential aptamer-mediated strategies for molecular targeting of COVID-19. Finally, the review focused on its future prospective in immunotherapy, as well as in identification of novel biomarkers in stem cells and also in single cell proteomics (scProteomics) to study intra or inter-tumor heterogeneity at the protein level. Small size, chemical synthesis, low batch variation, cost effectiveness, long shelf life and low immunogenicity provide advantages to the aptamer over the antibody. These physical and chemical properties of aptamers render them as a strong biomedical tool for theranostic purposes over the existing ones. The significance of aptamers in human health was the key finding of this review.
Highlights
The concept of DNA interaction with protein can be dated back to the days of discovery of the DNA foot-printing experiment in 1978, which was primarily used in search of DNA sequences interacting with ligands [1]
It is inevitable that, like antibodies, nucleic acid sequences have a certain degree of affinity to bind with protein, which can be harnessed to replace the antibodies in diagnostics and therapeutics applications
Sugar is modified by changing the bonds, adding a bulky moiety or using an enantiomer: (i) Locked Nucleic acid (LNA) indicates a bond between 20 O and 40 C (Figure 4), which is highly resistant to nuclease degradation
Summary
The concept of DNA interaction with protein can be dated back to the days of discovery of the DNA foot-printing experiment in 1978, which was primarily used in search of DNA sequences interacting with ligands (proteins or small molecules) [1]. The alternate cycles of binding to the ligand and amplification of the bound nucleotide sequences from the initial pool of random sequences resulted in high affinity sequences By this approach, the wild type and the most abundant variant form of the sequences that bound the ligand (e.g., gp43) with highest affinity were obtained. The word ‘aptamer’ is obtained from two different words, i.e., ‘Aptus’ (Latin) and ‘Meros’ (Greek), which denote ‘fit’ and ‘part’, respectively They can be developed against any targets, e.g., small molecules, proteins (ligands, receptors, etc.) or even the cells by combinatorial chemistry with molecular biology tools using traditional SELEX or its variants [6,7,8]. This review helps researchers to develop an idea about the potential role of aptamers as an alternative molecular tool against COVID-19, which may accelerate bench to bedside research
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
