Poly(β-L-malic acid) (PMLA) is a natural polyester produced by numerous microorganisms. Regarding its biosynthetic machinery, a nonribosomal peptide synthetase (NRPS) is proposed to direct polymerization of L-malic acid in vivo. Chemically versatile and biologically compatible, PMLA can be used as an ideal carrier for several molecules, including nucleotides, proteins, chemotherapeutic drugs, and imaging agents, and can deliver multimodal theranostics through biological barriers such as the blood–brain barrier. We focus on PMLA biosynthesis in microorganisms, summarize the physicochemical and physiochemical characteristics of PMLA as a naturally derived polymeric delivery platform at nanoscale, and highlight the attachment of functional groups to enhance cancer detection and treatment.

聚（β-L-苹果酸）（PMLA）是由多种微生物产生的天然聚酯。关于其生物合成机制，提出了一种非核糖体肽合成酶 (NRPS) 来指导 L-苹果酸在体内的聚合。PMLA 具有化学通用性和生物相容性，可用作多种分子的理想载体，包括核苷酸、蛋白质、化学治疗药物和显像剂，并且可以通过血脑屏障等生物屏障提供多模式治疗诊断。我们专注于微生物中的 PMLA 生物合成，总结了 PMLA 作为纳米级天然衍生聚合物递送平台的物理化学和理化特性，并强调了功能基团的附着以增强癌症检测和治疗。