Study On The Film-forming Mechanism Of Photo-crossling Gelatin And Film-coating Preparation

Gelatin is a denatured product of collagen produced under physical or chemical conditions.It is mainly composed of eighteen amino acids.Gelatin has side groups with good chemical reactivity,which provide the possibility of chemical modification of gelatin.On the other hand,gelatin has good biodegradability and biocompatibility in terms of biological properties.In addition,gelatin has abundant sources,which make it a good natural polymer material and can be widely used in biomedical medicine and other fields.However,as a choice of macromolecule materials,the mechanical properties of gelatin are poor and can not meet the needs of different materials.In addition,gelatin also has some shortcomings,such as poor water resistance and easy to grow bacteria.Blending gelatin with other polymer materials is an important method to improve the physical and chemical properties of gelatin.Crosslinked gelatin has many properties of natural polymer materials,among which the film-forming property with significantly improved mechanical properties is one of the important properties of crosslinked gelatin.The modification of gelatin can not only retain the good biological properties of gelatin as a natural macromolecule material,but also improve its mechanical properties and obtain new biological properties.Chemical cross-linking and optical cross-linking are two-minute methods to obtain cross-linked gelatin.Chemical crosslinking method needs to introduce chemical crosslinking agents,such as glutaraldehyde,etc.Photocrosslinking method needs to be completed under the combined action of photosensitizer and light source.Photocrosslinking is usually carried out in the presence of ultraviolet light,photosensitizer compounds and biopolymers.Ultraviolet irradiation photosensitizers produce various free radical compounds,which react and cross-link between the chains of biopolymers and between biopolymers and sensitizers.Riboflavin is a common photosensitizer.Studies have shown that the functional groups in riboflavin molecules can directly participate in the cross-linking process of gelatin under the conditions of photoinitiation.Therefore,a series of water-soluble riboflavin derivatives were prepared by chemical modification.They were added into gelatin aqueous solution,and different cross-linked gelatin solutions were obtained under light conditions.The cross-linked gelatin obtained by solvent evaporation has good film-forming properties.In this paper,the mechanism of gelatin crosslinking with riboflavin derivatives was preliminarily discussed,and the best film-forming riboflavin photocrosslinking gelatin was screened out.In addition,a drug-loaded particle with montmorillonite as drug-loaded medium and cross-linked gelatin as coating material was designed and prepared.The drug release characteristics in vitro were tested,and the morphology and appearance of the particle were tested by scanning electron microscopy.