Fabrication of pH/H2O2-responsive polyhedral oligomeric silsesquioxane self-assembled fluorescent vesicles for enhanced in vivo anti-tumor efficacy

Aim: The rational design of a fluorescence imaging-guided, highly efficient multiresponsive delivery system is important for improving drug delivery efficiency. Materials and methods: Herein, pH/H₂O₂-responsive polyhedral oligomeric silsesquioxane (POSS) molecule functionalized 4-(phenyl(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-phenyl)amino)benzaldehyde (OTB) copolymer (PEG-POSS-OTB) was synthesized to encapsulate doxorubicin (DOX) for precise drug delivery. Results: The self-assembly fluorescent vesicles exhibited excellent pH/H₂O₂-responsive drug release properties under physiological conditions and efficient drug-targeting ability. In vitro, compared with the DOX group, PEG-POSS-OTB fluorescent vesicles exhibited improved drug delivery and reduced toxicity. Importantly, we performed a proof-of-concept study demonstrating that PEG-POSS-OTB fluorescent vesicles were a high-efficiency nanoassembly drug-delivery platform for improving drug delivery efficiency. In vivo studies demonstrated that PEG-POSS-OTB vesicles with enhanced stability could be used in targeted drug delivery and controlled intelligent release.

Polyzwitterions with LCST Side Chains: Tunable Self-Assembly

Manipulation of self-assembly behavior of copolymers via environmental change is attractive in the fabrication of smart polymeric materials. We present tunable self-assembly behavior of graft copolymers, poly(sulfobetaine methacrylate)-graft-poly[oligo(ethylene glycol) methyl ether methacrylate)-co-di(ethylene glycol) methyl ether methacrylate] (PSBM-g-P(OEGMA-co-DEGMA)). Upon heating the aqueous solutions, the graft copolymers undergo a transition from micelles with PSBM cores to unimers (i.e., individual macromolecules) and then to reversed micelles with P(OEGMA-co-DEGMA) cores, thus demonstrating the tunability of the self-assembling through temperature change. In the presence of salt the temperature response of PSBM is eliminated, and the structure of the micelles with the P(OEGMA-co-DEGMA) core changes. Moreover, for the graft copolymer with long side chains, micelles with aggregation number ∼ 2 were formed with a PSBM core at low temperature, which is ascribed to the steric effect of the P(OEGMA-co-DEGMA) shell.

Double hydrophilic block copolymers self-assemblies in biomedical applications

Double-hydrophilic block copolymers (DHBCs), consisting of at least two different water-soluble blocks, are an alternative to the classical amphiphilic block copolymers and have gained increasing attention in the field of biomedical applications. Although the chemical nature of the two blocks can be diverse, most classical DHBCs consist of a bioeliminable non-ionic block to promote solubilization in water, like poly(ethylene glycol), and a second block that is more generally a pH-responsive block capable of interacting with another ionic polymer or substrate. This second block is generally non-degradable and the presence of side chain functional groups raises the question of its fate and toxicity, which is a limitation in the frame of biomedical applications. In this review, following a first part dedicated to recent examples of non-degradable DHBCs, we focus on the DHBCs that combine a biocompatible and bioeliminable non-ionic block with a degradable functional block including polysaccharides, polypeptides, polyesters and other miscellaneous polymers. Their use to design efficient drug delivery systems for various biomedical applications through stimuli-dependent self-assembly is discussed along with the current challenges and future perspectives for this class of copolymers.

Poly(ε-caprolactone) with pH and UCST responsiveness as a 5-fluorouracil carrier

Stimuli-responsive polymers with excellent biocompatibility and biodegradability are highly demanded as carriers for controlled drug delivery.

Facile preparation of long-chain aliphatic polycarbonates containing block copolycarbonates via one-pot sequential organic catalyzed polymerization of macrocyclic carbonates and trimethylene carbonates

A universal and effective approach was reported to synthesize block copolycarbonates containing long-chain aliphatic polycarbonates and PTMC segments using the ROP differences between macrocyclic and small cyclic carbonates with TBD as catalyst.

“Smart” self-assembled structures: toward intelligent dual responsive drug delivery systems

In the current review, we summarized the polymer and peptide-based schizophrenic copolymers which could form micellar and vesicular (polymersome) systems providing novel structures with beneficial applications.

Chemo-Enzymatic Synthesis of Poly(4-piperidine lactone- b-ω-pentadecalactone) Block Copolymers as Biomaterials with Antibacterial Properties

With increasing troubles in bacterial contamination and antibiotic-resistance, new materials possessing both biocompatibility and antimicrobial efficacy are supposed to be developed for future biomedical application. Herein, we demonstrated a chemo-enzymatic ring opening polymerization (ROP) approach for block copolyester, that is, poly(4-benzyl formate piperidine lactone- b-ω-pentadecalactone) (PNPIL- b-PPDL), in a one-pot two-step process. Afterward, cationic poly(4-piperidine lactone- b-ω-pentadecalactone) (PPIL- b-PPDL) with pendent secondary amino groups was obtained via acidic hydrolysis of PNPIL- b-PPDL. The resulting cationic block copolyester exhibited high antibacterial activity against Gram negative E. coli and Gram positive S. aureus, while showed low toxicity toward NIH-3T3 cells. Moreover, the antibacterial property, cytotoxicity and degradation behavior could be tuned simply by variation of PPIL content. Therefore, we anticipate that such cationic block copolymers could potentially be applied as biomaterials for medicine or implants.

Synthesis of a ROS-responsive analogue of poly(ε-caprolactone) by the living ring-opening polymerization of 1,4-oxathiepan-7-one

A well-defined ROS-responsive block amphiphilic diblock copolymer PEO-b-POTO was synthesized to elucidate the oxidative degradation mechanism in assemblies.

pH-Responsive Schizophrenic Diblock Copolymers Prepared by Polymerization-Induced Self-Assembly

Polymerization-induced self-assembly (PISA) is used for the highly convenient and efficient preparation of ampholytic diblock copolymer nanoparticles directly in acidic aqueous solution. Cationic nanoparticles comprising a protonated polyamine stabilizer block and a hydrophobic polyacid core-forming block are formed at pH 2. Micelle inversion occurs at pH 10 to produce anionic nanoparticles with an ionized polyacid stabilizer block and a hydrophobic polyamine core-forming block. Macroscopic precipitation occurs at around pH 6-7, which lies close to the isoelectric point of this ampholytic diblock copolymer. Incorporation of fluorescein and rhodamine dye labels into the acid and amine blocks, respectively, leads to dual-color bifluorescent self-reporting pH-responsive nanoparticles.