aptamerbased

Aptamer-based approaches use aptamers as recognition elements in diagnostics, therapeutics, and research tools. Aptamers are short, single-stranded DNA or RNA oligonucleotides that fold into three-dimensional structures to bind targets with high affinity and specificity. They are identified through SELEX, a process of iterative selection and amplification from a large randomized library, typically followed by truncation and chemical modifications to improve affinity, specificity, and nuclease resistance.

Compared with antibodies, aptamers can be synthesized chemically in large quantities with high reproducibility, modified to enhance stability (for example, 2'-fluoro, 2'-O-methyl, pegylation), and easily labeled for detection or conjugation. They can target a wide range of molecules, including small molecules, proteins, nucleic acids, cells, and whole organisms.

Applications include aptamer-based diagnostics and biosensors (aptasensors) that translate binding events into optical, electrochemical, or mass-sensitive signals; therapeutic aptamers that inhibit or modulate target activity; and targeted drug delivery and imaging agents when combined with nanomaterials or carriers. Notable approved aptamer drugs include pegaptanib (Macugen) for age-related macular degeneration. Other aptamers in clinical development target coagulation factors, cancer-associated proteins, or inflammatory mediators.

Challenges for aptamer-based technologies include in vivo stability, rapid renal clearance of small aptamers, potential off-target binding, and immunogenicity of modified backbones or conjugates. Delivery remains a major hurdle for therapeutic aptamers, and regulatory pathways can be complex due to the nucleic acid nature of the agents. Nevertheless, ongoing advances in chemical modification, selection techniques, and nanotechnology continue to expand aptamer-based applications in medicine and biotechnology.