Fabrication of pH responsive coacervates using a polycation-b-polypropylene glycol diblock copolymer for versatile delivery platforms

Abstract

A new poly (3-arginylamino propylene succinate-b-polypropylene glycol) (PAPS-PPG) diblock copolymer was synthesized by one-pot ring opening polymerization (ROP) technique. H-1 NMR spectral technique was used to determine arginine conjugation efficiency and molecular weight of final polycations by using 4,4-dimethyl-4-silapentane-1-ammonium trifluoroacetate (DSA) as an internal standard. The PAAPS-PPG polycation was electrostatically complexed with heparin (HEP) at an isoelectric point to obtain PAAPS-PPG/HEP coacervate microparticles (Coa MPs). The PAAPS-PPG/HEP Coa MPs exhibit acid induced dissociation at pH 5, but PAAPS/HEP Coa MPs without PPG block do not show acid induced dissociation. The PPG block in PAAPS-PPG/HEP Coa MPs increased 20 folds of cell attachment efficiency on human mesenchymal stem cells (hMSCs). The PAAPS-PPG/HEP Coa MPs could effectively encapsulate siRNA and exhibit more than 95% cell viability up to 200 mu g/mL. Hence, the pH responsive PAAPS-PPG/HEP Coa MPs platform with enhanced stem cell attachment ability would find potential application in gene delivery. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.