Synthesis of macrocyclic molecular brushes with amphiphilic block copolymers as side chains

End-functionalized polymers by controlled/living radical polymerizations: synthesis and applications

This review focuses on end-functionalized polymers synthesized by controlled/living radical polymerizations and the applications in fields including bioconjugate formation, surface modification, topology construction, and self-assembly.

Synthesis of cyclic graft polymeric prodrugs with heterogeneous grafts of hydrophilic OEG and reducibly conjugated CPT for controlled release

Fabrication of cyclic graft (cg) copolymer-based polymeric prodrugs by conjugation of drug molecules to cg copolymers via a dynamic covalent bond capable of responding to biorelevant signals integrates simultaneously the merits of cg copolymers and polymeric prodrugs for enhanced stability of nanocarriers and precise modulation of drug release kinetics. To completely eliminate the compromised drug conjugation efficiency due to the steric hindrance of hydrophilic grafts, it will be useful to develop cg polymeric prodrugs with heterogeneous grafts composed of hydrophilic polymers and drug species, respectively. For this purpose, we reported in this study the synthesis of cyclic graft polymeric prodrugs with heterogeneous grafts of hydrophilic oligo (ethylene glycol) (OEG) and reducibly conjugated camptothecin (CPT), cg-poly(oligo(ethylene glycol) monomethyl ether methacrylate)-b-poly((2-hydroxyethyl methacrylate)-disulfide link-camptothecin) (cg-P(OEGMA)-b-P(HEMA-SS-CPT), cg-prodrugs), via an integrated strategy of a previously reported diblock copolymer-based template and post-polymerization intermolecular click conjugation of a reducible CPT prodrug. The micelles self-assembled from cg-prodrugs on one hand had sufficient salt stability due to the branched cg structure, and on the other hand showed a reduction-triggered cleavage of the disulfide link for a promoted CPT release. Most importantly, we uncovered two interesting phenomena of the cg-based polymeric prodrugs as delivery vehicles: (i) the dimensions of both self-assemblies formed by the cg and bottlegraft (bg) polymers depend substantially on the molecular size of the cg and bg polymers likely due to the steric hindrance of the grafted structures of the cg and bg molecules and relatively low aggregation number of the self-assembled structures, and (ii) cg-prodrug-based micelles exhibited greater in vitro cytotoxicity against cancer cells despite the lower drug loading content (DLC) than the bg-based analogues, which results primarily from the faster reduction-triggered degradation and drug release as well as the greater cellular uptake efficiency of the former micelle prodrugs. Taken together, the developed cg-prodrugs provide great potential for chemotherapy, and the aforementioned interesting results will definitely inspire more upcoming studies on the future design and development of novel cg polymers for biomedical applications.

Amphiphilic multicomponent molecular brushes

Multicomponent molecular brushes containing amphiphilic polymer moieties are promising objects of research of macromolecular chemistry. The development of stimulus-responsive systems sensitive to changes in environmental parameters, based on the molecular brushes, opens up new possibilities for their applications in medicine, biochemistry and microelectronics. The review presents the current understanding of the structures of main types of amphiphilic multicomponent brushes, depending on the chemical nature and type of coupling of the backbone and side chains. The approaches to the controlled synthesis of multicomponent molecular brushes of different architecture are analyzed. Self-assembly processes of multicomponent molecular brushes in selective solvents are considered.

The bibliography includes 259 references.

Design and Synthesis of a Cyclic Double-Grafted Polymer Using Active Ester Chemistry and Click Chemistry via A "Grafting onto" Method

Combing active ester chemistry and click chemistry, a cyclic double-grafted polymer was successfully demonstrated via a "grafting onto" method. Using active ester chemistry as post-functionalized modification approach, cyclic backbone (c-P2) was synthesized by reacting propargyl amine with cyclic precursor (poly(pentafluorophenyl 4-vinylbenzoate), c-PPF4VB6.5k). Hydroxyl-containing polymer double-chain (l-PS-PhOH) was prepared by reacting azide-functionalized polystyrene (l-PSN₃) with 3,5-bis(propynyloxy)phenyl methanol, and further modified by azide group to generate azide-containing polymer double-chain (l-PS-PhN₃). The cyclic backbone (c-P2) was then coupled with azide-containing polymer double-chain (l-PS-PhN₃) via CuAAC reaction to construct a novel cyclic double-grafted polymer (c-P2-g-Ph-PS). This research realized diversity and complexity of side chains on cyclic-grafted polymers, and this cyclic double-grafted polymer (c-P2-g-Ph-PS) still exhibited narrow molecular weight distribution (Mw/Mn < 1.10).

Recent advances in the construction of cyclic grafted polymers and their potential applications

Three main strategies used for the construction of cyclic grafted polymers, “grafting through”, “grafting onto”, and “grafting from”, are summarized.

Facile synthesis of RGD-conjugated unimolecular micelles based on a polyester dendrimer for targeting drug delivery

Arginyl-glycyl-aspartic acid (RGD)-conjugated core–shell amphipilic copolymers were synthesized as unimolecular micelles for targeted drug delivery.

Nano-Sized Sunflower Polycations As Effective Gene Transfer Vehicles

The architecture of polycations plays an important role in both gene transfection efficiency and cytotoxicity. In this work, a new polymer, sunflower poly(2-dimethyl amino)ethyl methacrylate) (pDMAEMA), is prepared by atom transfer radical polymerization and employed as nucleic acid carriers compared to linear pDMAEMA homopolymer and comb pDMAEMA. The sunflower pDMAEMAs show higher IC50 , greater buffering capacity, and stronger binding capacity toward plasmid DNA than their linear and comb counterparts. In vitro transfection studies demonstrate that sunflower pDMAEMAs exhibit high transfection efficiency as well as relatively low cytotoxicity in complete growth medium. In vivo gene delivery by intraventricular injection to the brain shows that sunflower polymer delivers plasmid DNA more effectively than comb polymer. This study provides a new insight into the relationship between polymeric architecture and gene delivery capability, and as well as a useful means to design potent vectors for successful gene delivery.

Unimolecular micelles from graft copolymer with binary side chains

A novel amphiphilic binary graft copolymer was synthesized and used to prepare unimolecular micelles by intramolecular association.

Modular construction of macrocycle-based topological polymers via high-efficient thiol chemistry

Tadpole-, spiro-shaped, fused-dicyclic tadpole and other complex macrocycle-based topological polymers were modularly constructed via thiol-X chemistry.