Construction And Properties Of Polysaccharide Hydrogels Loaded With Dendrobium Officinale

Dendrobium officinale Kimura et Migo belongs to the genus Dendrobium in the Orchidaceae,and its main biologically active components are polysaccharides.The functions of antioxidant,moisturizing,bacteriostatic and antitumor can be attributed to Dendrobium officinale polysaccharides（DOPs）.In the present study,DOPs were isolated from Dendrobium officinale.DOPs were incorporated into sodium alginate（SA）for the development of SA/DOPs films.The ability of SA/DOPs composite films to preserve fresh fruits were investigated.DOPs were incorporated into sodium alginate（SA）/polydopamine（PDA）for development of（SA/PDA/DOPs）hydrogel.The drug-loading and drug-releasing properties of SA/PDA/DOPs hydrogel were investigated which expanded the application scope of DOPs in the field of biomaterials.The main research results are as follows:1)1)The effects of different solid-liquid ratio,extraction time and temperature on the extraction rate of DOPs were explored and the response surface optimization was carried out.The optimal extraction conditions were as follows:solid-liquid ratio 1:10 g/m L,temperature80℃and time 90 min,the extraction rate of DOPs reached 11.86±0.44%.The content of polysaccharide was determined by phenol-sulfuric acid method to 78.64±0.28%.The molecular weight and monosaccharide composition characteristics of DOP1-1 were detected by GPC-gel permeation chromatography and HPLC respectively.The molecular weight of DOP1-1 was 3.08×10^-5D.It was composed of mannose（79.80%）,glucose（19.74%）,glucuronic acid（0.28%）and galacturonic acid（0.19%）.2)DOPs were incorporated into SA for the development of SA/DOPs films.The physical,mechanical and functional properties of SA/DOPs composite films and their ability to preserve fresh grapes were investigated.The results showed that the addition of DOPs significantly increased the thickness,swelling rate,tensile strength,elongation at break and thermal stability of the films（p<0.05）,and decreased the water solubility and water vapor permeability of the films.Fourier transform infrared（FT-IR）spectra reflect the interaction of chemical groups and chemical bonds between SA and DOPs.The results of electron microscopy showed that the SA/DOPs films were smooth,while the control films were rough.SA/DOPs membranes have potential antioxidant effects on DPPH and ABTS free radicals.In addition,the composite membrane had significant inhibitory effect on the growth of E.coli and S.ureus（p<0.05）.In addition,SA/DOPs coating can effectively reduce the weight loss of grapes,inhibit the activity of polyphenol oxidase and extend the shelf life of grapes for 14 days at room temperature（25±1℃）.These results indicate that SA/DOPs edible coatings have broad application prospects in food preservation industry.3)DOPs were incorporated into sodium alginate （SA）/polydopamine（PDA）for development of（SA/PDA/DOPs）hydrogel.The drug-loading and drug-releasing properties of SA/PDA/DOPs hydrogel on doxorubicin（DOX）were investigated.The results showed that the swelling,water retention and biocompatibility increased with the increase of DOPs,and the cytocompatibility of hydrogels with DOPs was better than that without DOP_S.The drug in the hydrogel is best released at a p H of 7.4 and the Korsmeyer Peppas model can describe the release process of DOX in the hydrogel.The effect of inhibiting the proliferation of osteosarcoma cell K7M2WT showed that the addition of DOPs enhanced the DOX release performance of gel.DOPs could also inhibit the proliferation of osteosarcoma cell K7M2WT,and the inhibitory effect of SA/PDA/DOPs+DOX was stronger at the same concentration of DOX.The research results suggested that DOPs can play a synergistic role in combination with DOX,a clinical chemotherapy drug.