Effect of Gelatin on Secondary Structure, Crystallinity and Swelling Behavior of Silk Fibroin - Gelatin Hydrogels and its Application in Controlled Release of Nitrogen

Abstract

Utilization of natural polymer as biodegradable matrix for the controlled releasing fertilizer can improve the performance of the materials and make them environmentally friendly. In this work, the effect of gelatin on the properties of hydrogels was investigated. The silk fibroin (SF)-gelatin hydrogels were prepared by solvent casting and β-crystallization of SF was promoted via methanol treatment. The secondary structure and the crystallinity of the blended hydrogels were investigated using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction analysis (XRD), respectively. Moreover, the swelling ratio of the hydrogels and also their kinetics of nitrogen (N) release were also studied. Results from the FT-IR confirmed that no intermolecular interactions had taken place between SF and gelatin. Furthermore, the increase of gelatin content in the blended hydrogels caused the decrease of the SF crystallinity detected by XRD which corresponded to the swelling behavior of the hydrogel. The release rate of nitrogen (N) depends on the composition of SF and gelatin of which its value of diffusion exponent characteristics (n) determined from the Korsmeyer-Peppas model for all of the hydrogels are smaller than 0.5. This indicates that the release of N from the hydrogels is a quasi-Fickian diffusion. Moreover, the release rate (k) and diffusion coefficient (D) of the SF-gelatin hydrogels are lower than those of the SF itself indicating a potential to use the SF-gelatin hydrogel for nitrogen controlled release application.

Development of potentially biocompatible hydrogels with cylindrical pores prepared from polyvinyl alcohol and low‐molecular weight polyacrylic acid

“…It can be hypothesized that PAA prevents the formation of PVA crystallites, leading to a material having higher amounts of amorphous zones. Materials having more amorphous zones usually exhibit larger swelling capabilities . This was observed in the blend materials here developed: PVA/PAA Mw 5000 hydrogels being less crystalline than PVA/PAA Mw 1800 showed greater swelling degree values than those achieved by the materials prepared from lower PAA's Mw.…”

Role of Chitosan on Some Physical Properties and the Urea Controlled Release of the Silk Fibroin/Gelatin Hydrogel

“…This indicates that the release mechanism of diffused urea molecules from the SF/gelatin/CS hydrogels is a super case II transport [20] which reflects the influence of matrix relaxation of the SF/ gelatin/CS on molecular movement of urea in the matrix. Comparing to our previous work [6], the release mechanism of diffused urea in the SF/gelatin hydrogel is quasiFickian from which the urea molecules diffuses partially through a swollen matrix and water filled pores in the hydrogels. But for the case of SF/gelatin/CS hydrogel, the water molecules penetrate the matrix followed by relaxation and swelling of the hydrogel network.…”

“…However, few researches has focused on their applications in agricultural area, especially in the field of controlled release fertilizer. In our previous work [6], the SF/gelatin hydrogels at various weight ratios were prepared and the urea release kinetics was investigated. The results revealed that the SF/ gelatin hydrogel, of which the SF/gelatin at a weight ratio of 75:25, released the urea at the slowest rate but only within a week.…”

Spontaneously Micropatterned Silk/Gelatin Scaffolds with Topographical, Biological, and Electrical Stimuli for Neuronal Regulation

“…Swelling ratios of the hydrogel substrates were obtained by measuring the weight before and after immersion in water at time intervals. The swelling ratio was calculated with eq . Three samples of each hydrogel type were tested. where W 0 and W t are the weights of hydrogels at initial time and time t , respectively.…”

“…rGO was prepared from graphite using a modified Hammer’s method. , Briefly, 1 g of native graphite flakes was preoxidized by mixing with 1 g of P 2 O 5 , 1 g of K 2 S 2 O 8 , and 3 mL of H 2 SO 4 , and then incubated at 80 °C for 6 h. After washing with DI water and filtering, the preoxidized graphite was dried at 60 °C in an oven overnight. Subsequently, the preoxidized graphite powder was further oxidized in 23 mL of H 2 SO 4 with slow addition of KMnO 4 followed by stirring at 40 °C for 2 h. After 2 h, the reaction was terminated by adding 140 mL of distilled water.…”