Search Results (3)

Amphiphilic dendritic copolymers of arborescent poly(γ-benzyl L-glutamate) (PBG) of generations G1 and G2, grafted at their chain ends with poly(ethylene oxide) (PEO) segments (PBG-eg-PEO) were synthesized, characterized, and evaluated as nanocarriers for doxorubicin (DOX). The copolymers were designed with hydrophobic PBG cores having three different branching densities and were characterized by proton nuclear magnetic resonance (¹H NMR) spectroscopy, size exclusion chromatography (SEC), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Dynamic light scattering (DLS) measurements revealed that these amphiphilic molecules behaved like unimolecular micelles without significant aggregation in aqueous media such as phosphate-buffered saline (PBS), with diameters in the 13–29 nm range depending on the generation number and the core structure. Efficient encapsulation of DOX by these unimolecular micelles was demonstrated with drug loading capacities of up to 11.2 wt%, drug loading efficiencies of up to 67%, and pH-responsive sustained drug release, as determined by UV spectroscopy. The generation number of the copolymers and the branching density of the dendritic PBG core were found to have influenced the encapsulation and release properties of the micelles. Given the tailorable characteristics, good water dispersibility, and biocompatibility of the components used to synthesize the amphiphilic arborescent copolymers, these systems should be useful as robust nanocarriers for a broad range of therapeutic and diagnostic agents. Full article

A series of amphiphilic arborescent copolymers of generations G1 and G2 with an arborescent poly(γ-benzyl L-glutamate) (PBG) core and poly(ethylene oxide) (PEO) chain segments in the shell, PBG-g-PEO, were synthesized and evaluated as drug delivery nanocarriers. The PBG building blocks were generated by ring-opening polymerization of γ-benzyl L-glutamic acid N-carboxyanhydride (Glu-NCA) initiated with n-hexylamine. Partial or full deprotection of the benzyl ester groups followed by coupling with PBG chains yielded a comb-branched (arborescent polymer generation zero or G0) PBG structure. Additional cycles of deprotection and grafting provided G1 and G2 arborescent polypeptides. Side chains of poly(ethylene oxide) were then randomly grafted onto the arborescent PBG substrates to produce amphiphilic arborescent copolymers. Control over the branching density of G0PBG was investigated by varying the length and the deprotection level of the linear PBG substrates used in their synthesis. Three G0PBG cores with different branching densities, varying from a compact and dense to a loose and more porous structure, were thus synthesized. These amphiphilic copolymers behaved similar to unimolecular micelles in aqueous solutions, with a unimodal number- and volume-weighted size distributions in dynamic light scattering measurements. It was demonstrated that these biocompatible copolymers can encapsulate hydrophobic drugs such as doxorubicin (DOX) within their hydrophobic core with drug loading efficiencies of 42–65%. Sustained and pH-responsive DOX release was observed from the unimolecular micelles, which suggests that they could be useful as drug nanocarriers for cancer therapy. Full article

Optic neuropathy is one of the leading causes of irreversible blindness caused by retinal ganglion cell (RGC) degeneration. The development of induced pluripotent stem cell (iPSC)-based therapy opens a therapeutic window for RGC degeneration, and tissue engineering may further promote the efficiency of differentiation process of iPSCs. The present study was designed to evaluate the effects of a novel biomimetic polybenzyl glutamate (PBG) scaffold on culturing iPSC-derived RGC progenitors. The iPSC-derived neural spheres cultured on PBG scaffold increased the differentiated retinal neurons and promoted the neurite outgrowth in the RGC progenitor layer. Additionally, iPSCs cultured on PBG scaffold formed the organoid-like structures compared to that of iPSCs cultured on cover glass within the same culture period. With RNA-seq, we found that cells of the PBG group were differentiated toward retinal lineage and may be related to the glutamate signaling pathway. Further ontological analysis and the gene network analysis showed that the differentially expressed genes between cells of the PBG group and the control group were mainly associated with neuronal differentiation, neuronal maturation, and more specifically, retinal differentiation and maturation. The novel electrospinning PBG scaffold is beneficial for culturing iPSC-derived RGC progenitors as well as retinal organoids. Cells cultured on PBG scaffold differentiate effectively and shorten the process of RGC differentiation compared to that of cells cultured on coverslip. The new culture system may be helpful in future disease modeling, pharmacological screening, autologous transplantation, as well as narrowing the gap to clinical application. Full article