Preparation And Characterization Of Fish Skin Gelatin Microspheres Containing Vitamin D₂

In this paper,silver carp skin was used as raw material for gelatin extraction,and the basic chemical components of fish skin gelatin were analyzed.Besides,the crude protein content of dry matter content can reach up to 87%,which indicates that silver carp skin is good source of gelatin.Based on extracted fish skin gelatin,the gelatin microspheres containing vitamin D₂ were prepared by the method of simple coacervation and emulsion cross-linking.The physical and chemical properties,release in vitro and stability of microspheres were studied.Firstly,the blank gelatin microspheres?unencapsulated vitamin D₂,D-GMS?were prepared by simple coacervation method.And the optimum preparation technology was obtained by single factor experiment and orthogonal experiment.The optimum preparation conditions were listed as follows: gelatin concentration 3%,coagulant concentration 5%,emulsifying temperature 50°C and stirring speed1000r/min.The average particle size of gelatin microspheres was 45.62?m.Based on the optimal conditions,the drug loading and encapsulation efficiency of vitamin D₂ gelatin microspheres?D-VD₂-GMS?with core-wall ratio?Vitamin D₂ and gelatin mass ratio?of 15:1?mg/g?can reach up to 9.49mg/g and 64.25%,respectively.Moreover,the average particle size of vitamin D₂ gelatin microspheres was 47.39?m.Secondly,the vitamin D₂ gelatin microspheres?R-VD₂-GMS?were prepared by emulsion cross-linking method.And the optimum preparation technology was obtained by single factor experiment and orthogonal experiment.The optimum preparation conditions were listed as follows: gelatin concentration 12%,emulsifier dosage 1.5%,water/oil ratio?v/v?1/3 and the mass ratio of VD₂/gelatin?mg/g?20/1.Based on the optimal conditions,the drug loading and encapsulation efficiency of vitamin D₂ gelatin microspheres can reach up to 15.74 mg/g and 80.28 %,respectively.Moreover,the average particle size of vitamin D₂ gelatin microspheres was 11.58?m.Finally,the physical and chemical performances,releasing behavior in vitro and stability of D-VD₂-GMS and R-VD₂-GMS were studied.The experimental results indicated that both D-VD₂-GMS and R-VD₂-GMS were spherical and well dispersed.And the swelling degrees of the samples could reach to 316 % and 353 %,respectively.The results of DSC,FT-IR and XRD showed that vitamin D₂ was encapsulated in gelatin microspheres.The results of releasing behavior in vitro declared that both D-VD₂-GMS and R-VD₂-GMS had an excellent sustained releaseeffect,and the releasing profiles in vitro of both samples were in accordance with Higuchi equation.The two kinds of vitamin D₂ gelatin microspheres showed an eminent stability at 4°C and 25°C,and the loss was severe at high temperature.The microspheres were not stable in high humidity environment?RH = 90%?.Accelerated test showed that the vitamin D₂ gelatin microspheres could be stored well at room temperature for 6 months.