Dendritic Quaternary-Encoded Oligourethanes for Data Encryption

Precision Sequence-Defined Polymers: From Sequencing to Biological Functions

Precise sequence-defined polymers (SDPs) with uniform chain-to-chain structure including chain length, unit sequence, and end functionalities represent the pinnacle of sophistication in the realm of polymer science. For example, the absolute control over the unit sequence of SDPs allows for the bottom-up design of polymers with hierarchical microstructures and functions. Accompanied with the development of synthetic techniques towards precision SDPs, the decoding of SDP sequences and construction of advanced functions irreplaceable by other synthetic materials is of central importance. In this Minireview, we focus on recent advances in SDP sequencing techniques including tandem mass spectrometry (MS), chemically assisted primary MS, as well as other non-destructive sequencing methods such as nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD), and nanopore sequencing. Additionally, we delve into the promising prospects of SDP functions in the area of cutting-edge biological research. Topics of exploration include gene delivery systems, the development of hybrid materials combining SDPs and nucleic acids, protein recognition and regulation, as well as the interplay between chirality and biological functions. A brief outlook towards the future directions of SDPs is also presented.

Label-Free Quantification of Digital Nanorods Assembled from Discrete Oligourethane Amphiphiles

Polymeric nanoparticles (NPs) have been extensively designed for theranostic agent delivery. Previous methods for tracking their biological behavior and assessing theranostic efficacy heavily rely on fluorescence or isotope labeling. However, these labeling techniques may alter the physicochemical properties of the labeled NPs, leading to inaccurate biodistribution information. Therefore, it is highly desirable to develop label-free techniques for accurately assessing the biological fate of polymeric NPs. Here, we create discrete oligourethane amphiphiles (DOAs) with methoxy (OMe), hydroxyl (OH), and maleimide (MI) moieties at the dendritic oligo(ethylene glycol) (dOEG) ends. We obtained four types of digital nanorods (NRs) with distinct surface functional groups through self-assembly of a single DOA (OMe and OH NRs) or coassembly of two DOAs (OMe-MI and OH-MI NRs). These unique NRs can be directly quantified in a label-free manner by using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Specifically, OMe-MI NRs exhibited the best blood circulation, and OH-MI showed the highest area under the curve (AUC) value after intravenous injection. Biodistribution studies demonstrated that MI-containing NRs generally had lower accumulation in the liver and spleen compared to that of MI-free NRs, except for the comparison between OMe and OMe-MI NRs in the liver. Proteomics studies unveiled the formation of distinct protein coronas that may greatly affect the biological behavior of NRs. This study not only provides a label-free technique for quantifying the pharmacokinetics and biodistribution of polymeric NRs but also highlights the significant impact of surface functional groups on the biological fate of polymeric NPs.

Emerging Trends in the Chemistry of End-to-End Depolymerization

Over the past couple of decades, polymers that depolymerize end-to-end upon cleavage of their backbone or activation of a terminal functional group, sometimes referred to as "self-immolative" polymers, have been attracting increasing attention. They are of growing interest in the context of enhancing polymer degradability but also in polymer recycling as they allow monomers to be regenerated in a controlled manner under mild conditions. Furthermore, they are highly promising for applications as smart materials due to their ability to provide an amplified response to a specific signal, as a single sensing event is translated into the generation of many small molecules through a cascade of reactions. From a chemistry perspective, end-to-end depolymerization relies on the principles of self-immolative linkers and polymer ceiling temperature (Tc). In this article, we will introduce the key chemical concepts and foundations of the field and then provide our perspective on recent exciting developments. For example, over the past few years, new depolymerizable backbones, including polyacetals, polydisulfides, polyesters, polythioesters, and polyalkenamers, have been developed, while modern approaches to depolymerize conventional backbones such as polymethacrylates have also been introduced. Progress has also been made on the topological evolution of depolymerizable systems, including the introduction of fully depolymerizable block copolymers, hyperbranched polymers, and polymer networks. Furthermore, precision sequence-defined oligomers have been synthesized and studied for data storage and encryption. Finally, our perspectives on future opportunities and challenges in the field will be discussed.

Macromolecular Information Transfer

Macromolecular information transfer can be defined as the process by which a coded monomer sequence is communicated from one macromolecule to another. In such a transfer process, the information sequence can be kept identical, transformed into a complementary sequence or even translated into a different molecular language. Such mechanisms are crucial in biology and take place in DNA→DNA replication, DNA→RNA transcription and RNA→protein translation. In fact, there would be no life on Earth without macromolecular information transfer. Mimicking such processes with synthetic macromolecules would also be of major scientific relevance because it would open up new avenues for technological applications (e.g. data storage and processing) but also for the creation of artificial life. In this important context, this minireview summarizes recent research about information transfer in synthetic oligomers and polymers. Medium- and long-term perspectives are also discussed.