oa Editorial [Hot Topic: Aptamers: Versatile Agents for Biomedical Applications (Guest Editor: Weibo Cai)]

Aptamers, typically selected through systematic evolution of ligands by exponential enrichment (SELEX), have quickly emerged as a versatile class of agents with tremendous potential for a wide range of biomedical applications. Often regarded as “chemical antibodies”, aptamers can fold into well-defined 3D structures and bind to their target molecules with high affinity and specificity. To date, aptamers have been selected against a wide variety of targets such as proteins, phospholipids, sugars, nucleic acids, metal ions, dyes, whole cells, among many others. During the last two decades since aptamers were first selected through SELEX in 1990, an aptamer that binds to human vascular endothelial growth factor (VEGF) has been approved by the United States Food and Drug Administration for clinical use in treating age-related macular degeneration (AMD). A number of aptamers against other molecular targets are currently in clinical investigation. To provide a centralized resource for scientists who are either new to or working in the area of aptamer-based research, I have organized this special issue of Current Medicinal Chemistry. An international ensemble of experts in the field was invited to write a total of twelve review articles, focusing on the selection, modification, and biomedical application of aptamers. In the first review article, Dr. Li and co-workers introduced the identification, modification, and working mechanism of aptamers against cell-surface receptors. Next, Dr. Tan and co-workers reviewed the various methods of SELEX-based selection of aptamers, such as protein- SELEX and cell-SELEX. The major disadvantage of aptamers is that they are typically not stable enough for biomedical applications. Not only are DNA/RNA aptamers susceptible to nuclease degradation, peptide aptamers can also be digested by proteases. In this regard, Dr. Cai and co-workers gave a comprehensive summary of different chemical modifications that have been employed to increase the stability of DNA, RNA, and peptide aptamers. The following two review articles were focused on proteases and protein kinases, respectively. Two world-renowned experts in the field, Dr. Andreasen and Dr. de Franciscis, each gave a superb overview on their specific topic. Next, Dr. Zhang and co-workers provided a summary of the applications of aptamers in nervous system disorders, while Dr. Fang and co-workers focused on aptamers selected against molecular targets that are involved in cardiovascular diseases......