Posted by Cyclodextrin polymers (CDPs) are a class of polymers that have been extensively used in diverse scientific and technological fields, can be designed to bring biocompatibility, organ testing and stimuli responsiveness. Also, CDPs can be promising candidates for drug delivery systems, because of their ability to encapsulate and release guest molecules. The unique structure of CDs has enabled the synthesis of CDPs using multifunctional reagents, resulting in an enormous variety of CDPs with diverse structures and properties.
This review article focuses on a key subclass of CDPs, namely those containing ionizable and ionic groups (I-CDPs). Based on the presence of positive and negative charges, I-CDPs can be classified into three classes: cationic, anionic and ampholytic polymers (Fig. 1). These groups can be located on the polymer backbone or side chains to impart desirable properties, such as adjustable complexation, enhanced solubility, and improved cytocompatibility. The authors highlight the I-CDPs and their preparation methodologies and summarize the critical types of I-CDPs based on their structural similarities, highlighting their distinct features and potential advantages. Furthermore, in this article the significant development in this field made over the past decades is also summarized. Overall, this is the first comprehensive review that provides the classification of I-CDPs and synthesis procedures for all the classes.
Figure 1. Schematic representation of cyclodextrin polymers containing ionic moieties (I-CDPs) forming (a) cationic, (b) anionic, and (c) ampholytic CDPs.
Conclusion
Cyclodextrin polymers (CDPs) containing ionizable or ionic groups, referred to as I-CDPs, have emerged as a versatile class of materials with cationic, anionic, and ampholytic characteristics. This review provides a comprehensive overview of the current state of knowledge on I-CDPs. Specifically, it delves into the existing library of such polymers, discussing recent advancements in the synthesis of all groups and subgroups of I-CDPs, as well as various strategies for incorporating ionizable or ionic groups into these polymers. Additionally, the review explores the structure-to-properties relationships of I-CDPs, presenting their unique characteristics. I-CDPs represent a distinct class of materials with diverse applications due to their cyclodextrin cavities, polymeric network, and ionic motifs. These materials exhibit strong ionic interactions with oppositely charged molecules and can absorb a large amount of water through swelling. Notably, the ionic interactions of ionic CDPs are pH-independent, while ionizable CDPs can respond to changes in pH by breaking and reforming their ionic motifs. In the design of I-CDPs, the selection of an appropriate crosslinker and crosslinking approach is a crucial parameter for introducing ionizable or ionic moieties into the CDP structure.
Elmira Kashani, Saeid Maghsoudi, Hamid Rezania, Mina Yarazavi, Maryam Hajiabbas, Gábor Benkovics, Erem Bilensoy, Igor Lacík, Abolfazl Heydari (2024) Cyclodextrin polymers containing ionizable and ionic groups: A comprehensive review from classifications and synthesis methods to applications. Materials Today Chemistry 39(21):102186. https://doi.org/10.1016/j.mtchem.2024.102186