Aptamer: “smart bomb” facilitates delivery of drugs to the cancer cells

Aptamers are single-stranded synthetic DNA- or RNA-based oligonucleotides that fold into various shapes to bind to a specific target. They may serve as both drugs and drug-carriers. 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. They are obtained using iterative method, called (Systematic Evolution of Ligands by Exponential Enrichment) SELEX and cell-based SELEX (cell-SELEX).? They have been used in biosensing, drug delivery, disease diagnosis and therapy (especially for cancer treatment). In this review, we have summarized aptamers, its types, limitations, advantages, in clinical studies and recent applications of DNA and RNA aptamers in cancer theranostics. Furthermore, with the development of nanoscience and nanotechnology, the conjugation of aptamers with functional nanomaterials paved an exciting way for the fabrication of theranostic agents for cancers, which might be a powerful tool for cancer treatment. Due to their excellent specificity and high affinity to targets, aptamers have attracted great attention in various fields in which selective recognition units are required.