Guanidinated multi-arm star polyornithines with a polyethylenimine core for gene delivery

Guanylated Hyperbranched Polylysines with High In Vitro and In Vivo Antifungal Activity

With the rapid growth of fungal infections and the emergence of multi-drug resistant (MDR) fungal strains, new antifungals with novel mechanisms are a pressing need to tackle this emerging health problem. Herein it is reported for the first time that hyperbranched polylysine (HPL) shows antifungal activities against Candida, especially for drug-sensitive and MDR C. albicans strains, and broad-spectrum antibacterial activities against both Gram-negative and Gram-positive bacteria. The high antimicrobial activities are ascribed to the high charge density and compact size of the globular structure of HPL. The in vitro antifungal activities of HPL3 are further enhanced by the modification of amine groups to form guanylated polylysines (HPL3-Gxs). Similar to antimicrobial peptides (AMPs), HPLs and HPL3-Gxs interact with and lyse the membranes of microbes, which mitigates the emergence of drug resistance. HPLs and HPL3-Gxs demonstrate excellent in vivo antimicrobial efficacies against both lethal C. albicans challenge in the invasive candidiasis model and lethal Methicillin resistant Staphylococcus aureus challenge in the peritonitis model, and have potentials as broad-spectrum antimicrobials.

Star Polymers

Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

Targeted Gene Delivery to Macrophages by Biodegradable Star-Shaped Polymers

In this report, two biodegradable star-shaped polyasparamide derivatives and four analogues modified with either mannose or folic acid moiety for preferential targeting of a difficult-to-transfect immune cell type, i.e., macrophage, have been synthesized. Each of the prepared star polymers complexes with plasmid DNA to form nanosized particles featuring a core-shell-like morphology. Mannose or folate functionalized star polymers can greatly improve the transfection performance on a macrophage cell line RAW 264.7. As a result, a combination of targeting ligand modification and topological structures of gene carriers is a promising strategy for immune cells-based gene therapy.

Guanidinated Thiourea-Decorated Polyethylenimines for Enhanced Membrane Penetration and Efficient siRNA Delivery

RNA interference (RNAi) provides the promising treatments of gene-related diseases while hindered by the lack of highly efficient delivery platform with low cytotoxicity. Moreover, the intracellular fates of nonviral gene carriers are closely related to their internalization pathway, and eventually influence their RNAi efficiency. Herein, a series of guanidinated thiourea-modified polyethylenimines (PEI-MTU-Gs) are synthesized and utilized as the efficient carriers of small interfering RNA (siRNA) with up to 71.6% inhibition of luciferase activity in the luciferase-expressing cell lines (i.e., HeLa/Luc cells). The introduction of noncationic hydrogen bond donors, that is, thiourea groups, provides the carriers with much lower cytotoxicities and relatively looser complex structures that facilitate the intracellular release of siRNAs. Furthermore, the multiguanidino structures endow the PEI-MTU-G/siRNA complexes with the ability to directly penetrate cell membrane, which facilitates the cellular internalization while avoiding them suffering from the rigorous lysosomes. The results demonstrate PEI-MTU35 -Gs as promising siRNA carriers for further gene therapy.