Identification and Engineering of Aptamers for Theranostic Application in Human Health and Disorders

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.

A terminal functionalization strategy reveals unusual binding abilities of anti-thrombin anticoagulant aptamers

“… 1 , 2 , 3 Several aptamers are currently in different stages of clinical trials, and the search for new aptamer-based drugs, drug carriers, and even diagnostic tools is rapidly expanding. 4 , 5 In this context, recent strategies aim to broaden the aptamer applications by introducing in the backbone hydrophobic groups that compensate the low hydrophobicity of nucleic acids, thus expanding the variety of interactions between aptamers and target molecules. 6 …”

Cas-based bacterial detection: recent advances and perspectives

“…94 At the same time, paper-based materials are suitable for use by untrained operators and have a shelf life of at least one year, and these advantages have driven the commercialization of LFA. 95 TB-QUICK is a detection platform for MTB 96 that targets the IS6110 gene (Fig. 3f ).…”

Inhibition of α-Synuclein Seeding-Dependent Aggregation by ssDNA Aptamers Specific to C-Terminally Truncated α-Synuclein Fibrils

“…To circumvent these limitations, nucleic acid-based aptamers hold a great potential to be used as a promising approach for immunotherapy. 31 Aptamers are single-stranded oligonucleotides isolated from random nucleic acid sequences (20−80 bp) through an in vitro screening assay named systematic evolution of ligand by exponential enrichment (SELEX). Aptamers can bind to a wide range of targets ranging from simple inorganic molecules to large protein complexes and cells with high affinity and specificity.…”

“…Antibodies cannot easily access the intracellular compartments, cannot cross the blood–brain barrier, and also have higher immunogenicity. To circumvent these limitations, nucleic acid-based aptamers hold a great potential to be used as a promising approach for immunotherapy …”

“…Aptamers are single-stranded oligonucleotides isolated from random nucleic acid sequences (20–80 bp) through an in vitro screening assay named systematic evolution of ligand by exponential enrichment (SELEX). Aptamers can bind to a wide range of targets ranging from simple inorganic molecules to large protein complexes and cells with high affinity and specificity. , Compared to antibodies, aptamers offer many advantages including their nonimmunogenic and nontoxic nature and their high thermal stability and can maintain their structural integrity over repeated cycles of denaturation and renaturation. Moreover, their generation, synthesis, and modification are cheaper than those of a conventional antibody .…”