Engineering discrete synthetic macromolecules for biomedical applications.

Synthetic polymers have been extensively used in biomedical fields for imaging and therapeutic purposes. These macromolecular nanomedicines have shown unique advantages, such as increased blood circulation time, decreased systemic toxicity, and improved therapeutic outcomes. However, the polydisperse molecular weight of conventional polymers greatly hampers the reproducibility and clinical translations of macromolecular nanomedicines. Unlike conventional polymers with molecular weight distributions, discrete polymers are characterized by precise molecular weight and no molecular weight distribution (Ɖ = 1.0). Although discrete polymers have similar chemical structures and compositions to those of their disperse counterparts, they can show drastically distinct physiochemical properties and thus different biomedical performance. In this review, we summarize the recent achievements of discrete polymers in optical imaging, magnetic resonance (MR) imaging, and therapeutic applications. In addition, the representative methods used to synthesize discrete polymers are briefly discussed. Although this field represents an emerging research direction, preliminary results are encouraging and promising in many aspects. Due to the structural similarity of discrete and disperse polymers, their precise structures and improved performance may greatly facilitate their clinical translation into precision nanomedicines. We hope that more effort will be devoted to the development of highly efficient synthetic strategies and the conduction of (pre)clinical studies of discrete polymers. An in-depth understanding of the structure-property relationships of discrete polymers can be advantageous to boost their practical applications. [Display omitted] • Discrete polymers show distinct physicochemical properties compared to their disperse counterpart. • Molecular weight distribution has a critical role in the biological performance of synthetic polymers. • It is possible to decode the chain sequence of discrete polymers and quantify their biodistribution in a label-free manner. • Discrete polymers provide an excellent platform for precise nanomedicines. [ABSTRACT FROM AUTHOR]