Preparation And Applications Of Sericin Protein-based Hydrogels

Part one Exploring natural silk protein sericin for regenerative medicine:an injectable, photoluminescent, cell-adhesive3D hydrogelObjective:To study the value of a native sericin and its potential application in regenerative medicine.Methods:To the beginning, we used a convenient, chemically gentle method (LiBr based extraction method) to extract sericin from cocoons of a natural fibroin-deficient mutant silkworm, Bombyx mori,185Nd-s. Next, the sericin was cross-linked by glutaraldehyde to fabricate a novel pure sericin hydrogel. Furthermore, the physicochemical property, control releasing and biocompatibility of the sericin hydrogel were evaluated comprehensively.Results:Firstly, A native sericin was obtained from cocoons of silkworm, Bombyx mori,185Nd-s. Secondly, the successful fabrication of a covalently-crosslinked3D pure sericin hydrogel was reported. Thirdly, the sericin hydrogel was characterized for delivery of cells and drugs. Finaly, we find that the hydrogel have many unique properties.(1)The hydrogel is injectable, enabling its implantation through minimally invasive approaches.(2) The hydrogel is found to exhibit photoluminescence, allowing bioimaging and in vivo tracking.(3) The hydrogel possesses excellent cell-adhesive capability, effectively promoting cell attachment, proliferation and long-term survival of various types of cells.(4) The sericin hydrogel releases bioactive reagents in a sustained manner.(5) The hydrogel reveals good elasticity, high porosity, and pH-dependent degradation dynamics, which are advantageous for the sericin hydrogel to use as a delivery vehicle for cells and therapeutic drugs.Conclusion:It is concluded that the sericin hydrogel will have wide utility in the areas of tissue engineering and regenerative medicine. Part two A new photoluminescent sericin-alginate hydrogel with interpenetrating networks for cell and drug deliveryObjective:Aiming to improve the property of alginate hydrogel including mechanical strength, drug release, and adhesive ability.Methods:We employ the interpenetrating hydrogel design rationale. Using alginate and sericin, we develop an interpenetrating polymer network (IPN) hydrogel comprising interwoven sericin and alginate double networks. A native sericin was isolated from a fibroin-deficient silkworm cocoons (185Nd-s) using LiBr method. The sericin was employed to form composite hydrogels by blending with alginate, glutaraldehyde and CaCl2. The microstructure of sericin-alginate hydrogels was observed by SEM. The porosity of the constructs was measured by the liquid displacement. FTIR spectra of sericin scaffolds were measured with a Fourier transformation infrared Spectroscopy. A Universal Testing Machine was used to measure the mechanical properties of sericin-alginate hydrogels. The swelling and degradation behaviors of the hydrogels were evaluated by gravimetric measurement. Horse radish peroxidase (HRP) used as a mold drug for evaluating a possibility for the hydrogels to be used as a drug delivery vehicle. The interpenetration network and photoluminescent properties of the lyophilized hydrogels were observed by fluorescence microscope and confocal laser scanning microscope, respectively. Small animal imaging system was used to track the hydrogels in mice. The adhesive, proliferation, migration, and survival of cells (C2C12) loaded on the hydrogels were measured by CCK8, observed or cell counting.Results:(1) we successfully fabricated sericin-alginate hydrogels with dual interpenetration networks crosslinked using glutaraldehyde and CaCl2.(2) The sericin-alginate hydrogels with photoluminescent property enable in vivo detection and tracking.(3) The elastic modulus, degradation dynamics, and sustained drug release kinetics of the hydrogels can be tuned by altering the ratios of sericin to alginate.(4) The porosity of the hydrogels is very high.(5) The hydrogels are biocompatible and suitable for extracellular matrix, which supply cells survival and proliferation for a long time and facilitate cells migration.Conclusion:This study reveals that sericin-alginate hydrogel potential as a valuale platform for delivering cells and drugs for various tissue regeneration. This work provides a rational for the future exploration of sericin’s potential as a building block with other polymers to obtain novel IPNs with improved properties.