Aptamers as Both Drugs and Drug-Carriers

Abstract

Aptamers are short nucleic acid oligos. They may serve as both drugs and drug-carriers. Their use as diagnostic tools is also evident. They can be generated using various experimental, theoretical, and computational techniques. The systematic evolution of ligands by exponential enrichment which uses iterative screening of nucleic acid libraries is a popular experimental technique. Theory inspired methodology entropy-based seed-and-grow strategy that designs aptamer templates to bind specifically to targets is another one. Aptamers are predicted to be highly useful in producing general drugs and theranostic drugs occasionally for certain diseases like cancer, Alzheimer's disease, and so on. They bind to various targets like lipids, nucleic acids, proteins, small organic compounds, and even entire organisms. Aptamers may also serve as drug-carriers or nanoparticles helping drugs to get released in specific target regions. Due to better target specific physical binding properties aptamers cause less off-target toxicity effects. Therefore, search for aptamer based drugs, drug-carriers, and even diagnostic tools is expanding fast. The biophysical properties in relation to the target specific binding phenomena of aptamers, energetics behind the aptamer transport of drugs, and the consequent biological implications will be discussed. This review will open up avenues leading to novel drug discovery and drug delivery.

AS1411 aptamer-modified theranostic liposomes co-encapsulating manganese oxide nano-contrast agent and paclitaxel for MRI and therapy of cancer

“…As reported in the literature, the IC50 of AS1411 aptamer was at around 2 mM concentration range, and a 7 day exposure of AS1411 aptamer at 10 mM dose could induce more than 60% killing of three leukemia and two of three lymphoma cell lines. 50,51 Zhang's group also reported similar results that AS1411 aptamer within 0 to 400 nM displayed no obvious cytotoxicity on human ovarian cancer cell lines (SKOV3 and OVCAR3) and human normal liver cell line (L02). 52 Liposome-PEG-MnO nanocomplex displayed a longer blood circulation half-life of 333.35 min, which was 5.6 times that of PEG-MnO NPs (59.76 min), 27 favoring their effective accumulation in the tumor tissue to enhance MRI sensitivity (Fig.…”

Chemical Modifications of Nucleic Acid Aptamers for Therapeutic Purposes

“…In addition, nucleic acid aptamers have minimal immunogenicity, high chemical synthesis production, low cost and high chemical stability, drawing extensive attention of researchers to the development of aptamer therapeutics [5].…”

Cell-targeting aptamers act as intracellular delivery vehicles

“…This is due to the fact that no animals are involved in the generation of aptamers and the availability of the abovementioned modifications that increase the half-lives of aptamers under physiological conditions. A list of aptamers currently undergoing various phases of trials for the development of future drugs can be found in Table 1 (Que-Gewirth and Sullenger 2007; Esposito et al 2011;Ashrafuzzaman 2014). An aptamer-based drug called BMacugen^(Pegaptanib, by Pfizer and Eyetech) has been accepted by the FDA to treat age-related macular degeneration for the elderly, although clinical studies were initially begun with a different aptamer (ARC 183) that was generated to target thrombin and was tested on canine cardiopulmonary bypass models.…”