Design and performance of a poly(vinyl alcohol)/silk fibroin enzymatically crosslinked semi-interpenetrating hydrogel for a potential hydrophobic drug delivery.

Chunqing Niu,Xiang Li,Xinyu Wang,Yiyu Wang,Jian Shi,Xinyu Liu

doi:10.1039/c9ra09344c

Abstract

In this study, in order to obtain hydrogels with good properties for sustained release of hydrophobic drugs or for tissue engineering, poly(vinyl alcohol) (PVA)/silk fibroin (SF) semi-interpenetrating (semi-IPN) hydrogels with varied ratios of PVA/SF were enzymatically cross-linked using horseradish peroxidase. A vial inversion test determined approximate gelation times of PVA/SF hydrogels ranging from 5 to 10 min. The hydrogels with varied ratios showed differences in pore size and morphology. Mass loss rate of hydrogels increased from 15% to 58% with increasing PVA concentration. Stable hydrogels with PVA/SF at 0.5 : 1 w/w showed the best swelling ratio values in distilled water (7.36). FTIR analysis revealed that silk fibroin in these hydrogels exhibited the coexistence of amorphous and silk I crystalline structures and the SF and PVA molecules interacted with each other well. The mechanical properties of the composite hydrogels were controlled by the SF content. From the cell viability results, it was found that the hydrogels exerted very low cytotoxicity. Paeonol was chosen as the hydrophobic drug model for release studies from the hydrogels. Paeonol can be uniformly loaded into the composite hydrogels using the emulsifying property of PVA and paeonol release from the hydrogels was dependent on the PVA/SF ratio. This study applied a novel type of enzymatically crosslinked semi-IPN hydrogel that may have potential applications in drug delivery.

Highlights

Hydrogels are three-dimensional networks composed of crosslinked hydrophilic polymers; they are water-insoluble while exhibiting a high degree of water uptake in aqueous environments.[1,2] Hydrogels are attractive for drug delivery and clinical application, as their properties can be ne tuned and they can encapsulate drugs, growth factors and other cell signaling factors to optimize treatment effect.[3,4] A semiinterpenetrating hydrogel is a combination of polymers in a network form, in which one of the matrix constituents forms the network while the linear chains of the other constituent physically interact with each other and with the network.[5]
We demonstrated the preparation of poly(vinyl alcohol) (PVA)/silk fibroin (SF) semi-IPN hydrogel using horseradish peroxidase (HRP) and H2O2
Formation of phenolic radicals between SF macromers leads to polymerization of the precursor hydrogel solutions with HRP and H2O2, which play a key role in gel formation

Summary

Introduction

Properties, like better elasticity and greater capacity to immobilize drugs.[6,7] Due to this versatility, numerous synthetic and natural polymers and their combined hydrogels have been studied, such as polyurethanes, poly(vinyl alcohol), polyacrylamide, poly(lactic acid), sodium alginate, gelatin, collagen, silk broin (SF), etc.[6,8,9,10,11,12,13,14]. 4 mg mLÀ1 of paeonol in 8% PVA solution was prepared by dissolving 400 mg of paeonol in 50 mL of 8% (w/v) PVA solution at 37 C and stirring for 40 min to obtain homogeneity and transferred to a 100 mL volumetric ask and brought to volume with 8% (w/v) PVA solution This solution was thoroughly mixed with SF (8% w/v) solution at equal volume and nally enzymatically crosslinked by HRP and H2O2. PVA/SF 0.5/1, 0.75/1, 1/1 and 1.25/ 1 semi-IPN hydrogels with the same paeonol concentration of 1.5 mg mLÀ1 were used to test the hydrophobic release behavior. In this case, we prepared 3 mg mLÀ1 of paeonol in 4%, 6%, 8% and 10% PVA solutions and mixed them separately with SF (8% w/v) solution at equal volume. As relatively short gelation time and mild conditions are used, biological molecules like growth factors and drug molecules can be encapsulated and loaded without losing their activity

Results and discussion

Conflicts of interest

Conclusion