In this present work, physical hydrogels were prepared by the reaction between pectin and bis (3-aminopropyl) amine (APA) using N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as catalysts. These pectin-graft-bis (3-aminopropyl) amine (pec-g-APA) copolymers exhibited the electrostatic induced sol-gel phase transition at the predetermined pH values. Sol-gel phase diagrams demonstrated both lower- and upper- phase boundaries, corresponding to sol-gel phase transition and gel-sol phase transition, respectively, upon varying pH of the system. The phase transition depended on the APA composition as well as the copolymer concentration so that the gelation can be manipulated. The hydrogels were non-cytotoxic and exhibited the potential use for controlled release of gentamicin. Also, the antimicrobial activity of released gentamicin remained unaffected by the hydrogels. Graphical Abstract

Rapid release and diminished stability are two of the limitations associated with the growth factors that are essentially used in dental applications. These growth factors are employed to enhance the quality and quantity of tissue or bone matter during regeneration. Therefore, drug delivery devices and systems have been developed to address these limitations. In this study, bovine serum albumin (BSA), as a representative growth factor, was successfully sustained by encapsulation with the medium-absorbable copolymer, poly(L-lactide-co-glycolide) (PLG) 70:30% mol, via the multiple emulsion method. Different PLG, PVA, and BSA concentrations were used to investigate their effects on the BSA encapsulation efficiency. The suitable ratios leading to a better characterization of microparticles and a higher encapsulation efficiency in producing encapsulated PLG microparticles were 8% (w/v) of PLG, 0.25% (w/v) of PVA, and 8% (w/v) of BSA. Furthermore, an in vitro release study revealed a bursting release of BSA from the encapsulated PLG microsphere in the early phase of development. Subsequently, a gradual release was observed over a period of eight weeks. Furthermore, to encapsulate LL-37, different proteins were used in conjunction with PLG under identical conditions with regard to the loading efficiency and morphology, thereby indicating high variations and poor reproducibility. In conclusion, the encapsulated PLG microparticles could effectively protect the protein during encapsulation and could facilitate sustainable protein release over a period of 60 days. Importantly, an optimal method must be employed in order to achieve a high degree of encapsulation efficiency for all of the protein or growth factors. Accordingly, the outcomes of this study will be useful in the manufacture of drug delivery devices that require medium-sustained release growth factors, particularly in dental treatments.