Preparation And Properties Of Resveratrol-Loaded Silk Fibroin Nanospheres

Silk fibroin-based products have excellent plasticity due to their unique secondary structure.Among them,random coils with low stability and ?-helix structures can be transformed into ?-sheet structures with high stability under certain conditions.Nowadays,carrier products using silk fibroin as raw materials are constantly emerging.With the excellent biocompatibility and biodegradability of silk fibroin,there have been continuous application examples in the field of biomedicine.Resveratrol is a non-flavonoid polyphenol.Natural resveratrol is mainly enriched in plants such as grapes.Studies have shown that resveratrol performs well in anti-tumor,anti-cancer,antibacterial,and anti-inflammatory fields.However,due to its nature,it is highly susceptible to degradation due to external conditions,resulting in a much-reduced bioavailability.In this study,silkworm cocoon shells were used as necessary materials to prepare silk fibroin nanospheres through two types of green schemes.Resveratrol with lower stability was loaded into the nanospheres as a model drug to provide a way to load drugs or food.A feasible and efficient scheme and preliminary studies were conducted in the fields of anti-oxidation,bacteriostasis,sustained-release,and degradation.In this study,we used the self-assembly method and salting-out method to process silk fibroin solution into silk fibroin nanospheres.Among them,the respective advantages of the two schemes were compared from the aspects of material consumption(material addition ratio and concentration),morphology,particle size distribution,and yield.In the self-assembly method,silk fibroin nanospheres with particle size distribution ranging from 200 nm to 1 ?m can be prepared by adjusting the addition ratio of ethanol and silk fibroin solution(from 1:4 to 1:8).The yield of silk fibroin nanospheres prepared by this method is high,and the highest can reach 87.26% ± 2.61%.In the silk fibroin nanospheres prepared by salting out method,only when the concentration of the phosphate buffer solution is 1.25 mol /L,the highest yield can reach 62.04% ± 1.67%.The particle size distribution range is smaller than the self-assembly method,and the yield is relatively low.After loading resveratrol onto silk fibroin nanospheres by physical adsorption,the extension and protection of silk fibroin nanospheres on resveratrol's stability were investigated by controlling the light and temperature factors.The results show that silk fibroin nanospheres can significantly avoid the degradation of resveratrol caused by light.However,due to heat conduction,silk fibroin nanospheres do not have distinct protection for resveratrol's thermal stability.Also,this paper investigated the growth inhibitory effect of resveratrol-loaded silk fibroin nanospheres on Staphylococcus aureus ATCC 6538 and Escherichia coli DH5?.Finally,it determined that their minimum inhibitory concentrations were 504 ?g/m L and 444 ?g/m L.Antioxidant experiments confirmed that resveratrol has powerful antioxidant properties.The required concentration of resveratrol-loaded silk fibroin nanospheres for DPPH free radicals and ABTS free radical scavenging rate to reach 50% is 235.1 ?g/m L and 32.17 ?g/m L,respectively.In the simulated sustained-release experiment,the silk fibroin nanospheres loaded with resveratrol showed stable and long-term sustained-release characteristics in the simulated gastric fluid,and the silk fibroin nanospheres showed higher degradation efficiency in the enzyme-containing sustained-release solution.