Systematic evolution of ligand by exponential enrichment (SELEX) is an efficient method used to isolate high-affinity single stranded oligonucleotides from a large random sequence pool. These SELEX-derived oligonucleotides named aptamer, can be selected against a broad spectrum of target molecules including proteins, cells, microorganisms and chemical compounds. Like antibodies, aptamers have a great potential in interacting with and binding to their targets through structural recognition and are therefore called “chemical antibodies”. However, aptamers offer advantages over antibodies including smaller size, better tissue penetration, higher thermal stability, lower immunogenicity, easier production, lower cost of synthesis and facilitated conjugation or modification with different functional moieties. Thus, aptamers represent an attractive substitution for protein antibodies in the fields of biomarker discovery, diagnosis, imaging and targeted therapy. Enormous interest in aptamer technology triggered the development of SELEX that has underwent numerous modifications since its introduction in 1990. This review will discuss the recent advances in SELEX methods and their advantages and limitations. Aptamer applications are also briefly outlined in this review.

通过指数富集（SELEX）进行配体的系统进化是一种用于从大型随机序列库中分离高亲和力单链寡核苷酸的有效方法。这些SELEX衍生的寡核苷酸称为适体，可以针对包括蛋白质，细胞，微生物和化学化合物在内的多种目标分子进行选择。像抗体一样，适体在通过结构识别与靶标相互作用和结合方面具有巨大潜力，因此被称为“化学抗体”。然而，适体提供了优于抗体的优势，包括更小的尺寸，更好的组织渗透，更高的热稳定性，更低的免疫原性，更容易生产，更低的合成成本以及促进了与不同功能部分的缀合或修饰。因此，适体代表了在生物标志物发现，诊断，成像和靶向治疗领域中蛋白质抗体的诱人替代品。对适体技术的极大兴趣引发了SELEX的发展，自1990年引入以来，SELEX经历了许多修改。本文将讨论SELEX方法的最新进展及其优点和局限性。适体的应用程序也简要概述在这篇评论中。