Structure-biocompatibility relationship of dendritic polyglycerol derivatives

Nanocarriers possess advanced physicochemical properties that improve bioavailability, enhance cellular dynamics, and control targetability in drug delivery. In particular, dendritic polyglycerol is a promising new biocompatible scaffold for drug delivery. The present explores the structure-biocompatibility relationship of dendritic polyglycerol (dPG) derivatives possessing neutral, cationic, and anionic charges. The effect of solution pH on the surface charge was studied in buffered aqueous solution between pH 4.8 and 7.4. Surface charge properties of dPG derivatives are discussed in terms of surface functionalities and compared with amine and hydroxyl terminated polyamidoamine (PAMAM) dendrimers. Zeta potential measurements and fluorescence quenching studies address the binding interactions of dPGs to bovine serum albumin in order to explore the applicability of dPG derivatives for systemic delivery. Cellular entry of dPG-dye conjugate was evaluated using A549 lung epithelial cells, while in vitro toxicity was studied for various dPGs and compared to PAMAM dendrimers, polyethyleneimine (PEI), dextran, and linear polyethylene glycol (PEG) using human hematopoietic cell line U-937. Cellular uptake studies of dye labelled dPGs inferred that the charged derivatives (dPG-sulfate and dPG-amine) are more rapidly internalized primarily inside the cytosol of A549 cells compared to the neutral dPG. The cell compatibility results show that the dendritic polyglycerols are as safe as linear PEG polymer or dextran, which indicates the suitability of dPG derivatives in delivering therapeutic agents systemically.