Facile functionalization of polyesters through thiol-yne chemistry for the design of degradable, cell-penetrating and gene delivery dual-functional agents

New bio-renewable polyester with rich side amino groups from l-lysine via controlled ring-opening polymerization

Lysine, a renewable resource from biomass fermentation, was converted to pure O-carboxyanhydride monomer, then well-defined polyester with amino groups was prepared via controlled ring-opening polymerization.

Spiropyran-decorated light-responsive amphiphilic poly(α-hydroxy acids) micelles constructed via a CuAAC reaction

Light-responsive amphiphilic poly(α-hydroxy acids) with pendent spiropyran chromophore was synthesized and the resultant micelles assembled in aqueous solution presented excellent light-response.

Synthesis and biomedical applications of functional poly(α-hydroxyl acid)s

This review highlights the recent progress in the synthesis and biomedical applications of poly(α-hydroxyl acid)s with pendent functional groups.

Ring-opening polymerization of L-lactic acid O-carboxyanhydrides initiated by alkoxy rare earth compounds

The ring-opening polymerization of l-lactic acid O-carboxyanhydrides was initiated by triisopropoxyneodymium in toluene-THF mixtures. Typically, high yields and relatively high molecular weight PLAs were obtained within 4 h at 25 °C. The reaction was highly controllable and easy to conduct, and the molecular weight distribution of the PLAs was rather narrow (Mw/Mn = 1.10–1.36). NMR analysis showed that one end of the PLA chain consisted of an isopropoxy group, while the other end of the chain contained a hydroxyl group. Due to their availability and high polymerizability, Lac-OCAs are promising monomers for the preparation of tailored architectures derived from well-defined PLAs.

Redox-responsive, core-cross-linked micelles capable of on-demand, concurrent drug release and structure disassembly

We developed camptothecin (CPT)-conjugated, core-cross-linked (CCL) micelles that are subject to redox-responsive cleavage of the built-in disulfide bonds, resulting in disruption of the micellar structure and rapid release of CPT. CCL micelles were prepared via coprecipitation of disulfide-containing CPT-poly(tyrosine(alkynyl)-OCA) conjugate and monomethoxy poly(ethylene glycol)-b-poly(tyrosine(alkynyl)-OCA), followed by cross-linking of the micellar core via azide-alkyne click chemistry. CCL micelles exhibited excellent stability under physiological conditions, while they underwent rapid dissociation in reduction circumstance, resulting in burst release of CPT. These redox-responsive CCL micelles showed enhanced cytotoxicity against human breast cancer cells in vitro.

Poly(ethylene glycol)-block-cationic polylactide nanocomplexes of differing charge density for gene delivery

Representing a new type of biodegradable cationic block copolymer, well-defined poly(ethylene glycol)-block-cationic polylactides (PEG-b-CPLAs) with tertiary amine-based cationic groups were synthesized by thiol-ene functionalization of an allyl-functionalized diblock precursor. Subsequently the application of PEG-b-CPLAs as biodegradable vectors for the delivery of plasmid DNAs (pDNAs) was investigated. Via the formation of PEG-b-CPLA:pDNA nanocomplexes by spontaneous electrostatic interaction, pDNAs encoding luciferase or enhanced green fluorescent protein were successfully delivered to four physiologically distinct cell lines (including macrophage, fibroblast, epithelial, and stem cell). Formulated nanocomplexes demonstrated high levels of transfection with low levels of cytotoxicity and hemolysis when compared to a positive control. Biophysical characterization of charge densities of nanocomplexes at various polymer:pDNA weight ratios revealed a positive correlation between surface charge and gene delivery. Nanocomplexes with high surface charge densities were utilized in an in vitro serum gene delivery inhibition assay, and effective gene delivery was observed despite high levels of serum. Overall, these results help to elucidate the influence of charge, size, and PEGylation of nanocomplexes upon the delivery of nucleic acids in physiologically relevant conditions.

Synthesis of cationic polylactides with tunable charge densities as nanocarriers for effective gene delivery

Well-defined cationic polylactides (CPLAs) with tertiary amine groups were synthesized by thiol-ene click functionalization of an allyl-functionalized polylactide to yield polymers with tunable charge densities. CPLAs have not previously been utilized in the context of DNA delivery. Thus, plasmid DNA (pDNA) encoding luciferase was delivered to two physiologically distinct cell lines (macrophage and fibroblast) via formation of CPLA/pDNA polyplexes by electrostatic interaction. The formulated polyplexes demonstrated high levels of transfection with low levels of cytotoxicity when compared to a positive control. Biophysical characterization of charge densities at various CPLA/pDNA weight ratios revealed a positive correlation between surface charge and gene delivery. Overall, these results help to elucidate the influence of polyplex charge and size upon the delivery of nucleic acid and support future gene delivery applications using this next-generation biomaterial.