Study On Preparation Of Polygonatum Polysaccharide And Its Application In Antibacterial Materials

Polygonatum sibiricum is a yin-nourishing medicine with anti-aging effects.It is often used in traditional Chinese medicine to treat age-related diseases,diabetes,lung diseases,fatigue,and weakness.However,Polygonatum sibiricum is raw edible hemp mouth,so the extraction of Chinese medicinal herbs is a new way besides processing medicinal herbs.The main active ingredients in Polygonatum Polysaccharide,steroidal saponins,flavonoids,polyphenols,lignins,and amino acids.Polygonatum Polysaccharide have been shown to have antioxidant,antitumor,antiviral,blood sugar and lipid-lowering properties.In this paper,the extraction and bioactivity of Polygonatum Polysaccharide were studied using Polygonatum sibiricum rhizome as raw material,and the effects of Polygonatum sibiricum Polysaccharide on nanomaterial synthesis were investigated.The main studies are as follows:（1）The fermentation method was used to extract PSP,and the yield of PSP was used as the index.Single factor and response surface experiments were used to optimize the fermentation conditions of PSP.The morphology and infrared spectrum characteristics of PSP by fermentation and water extraction were compared and analyzed.The results showed that the optimum conditions of PSP microbial fermentation were as follows:inoculation amount was 2.5%,bacteria ratio was 2.2:1,the solid-liquid ratio was 1:40,fermentation time was 36 h,and fermentation temperature was 41℃.Under these conditions,the actual extraction rate of PSP was10.07%,which was significantly higher than that of water extraction.Scanning electron microscopy（SEM）analysis showed that the polysaccharide was massive with a smooth surface.Enzymatic hydrolysis was fibrous with folds;Ultrasonic method is fragmentary,and small spherical;There were obvious holes on the surface of PSP formed by fermentation.The infrared spectrum analysis showed t the fermentation and water extraction methods had obvious characteristic peaks of PSP.The water extraction method had anα-glycoside bond characteristic peak.In contrast,the fermentation method hadβ-glycoside bond characteristic peaks,but the peaks of the enzyme hydrolysis method and ultrasonic method were not obvious.（2）Silver nanoparticles（Ag NPs）have good antibacterial activity and are not easy to produce drug resistance,however the lower solution stability and poor biocompatibility limit their wide application.In this study,Ag NPs were modified with PSP to synthesize the PSP@Ag NPs with a good stability,biocompatibility,and antibacterial activity.The results showed that when the reaction time is 70 min,the reaction temperature is 35°C,and the volume ratio of Ag NO₃ to PSP is 1:1,the synthesized PSP@Ag NPs has the best performance.The synthesized PSP@Ag NPs were more regular and uniform than Ag NPs,and their particle size was around 10nm.The cytotoxicity,hemolysis,and bacteriostatic activity of PSP@Ag NPs were improved significantly after PSP modification.PSP@Ag NPs can destroy the integrity and internal structure of cells,resulting in the leakage of intracellular nucleic acids and proteins.The cell membrane damage rate of E.coli and S.aureus treated by PSP@Ag NPs increased by 38.52%and 43.75%compared with that of Ag NPs.Meanwhile,PSP@Ag NPs can inhibit the activities of key enzymes related to antioxidant,energy and substance metabolism in cells,and its inhibitory effects on the enzyme activities of SOD,CAT,ATP,MDH,and SDH in E.coli and S.aureus cells were significantly more than those of Ag NPs.In addition,compared with Ag NPs,PSP@Ag NPs have a better effect on promoting the healing of infected wounds.Therefore,PSP@Ag NPs is expected to develop into a potential antibacterial agent for wound infections.（3）On the basis of the preparation of PSP@Ag NPs,a SA/SS/GI/PSP@Ag NPs film with antioxidant and antibacterial functions was prepared.Sodium alginate/silk film（SA/SS）was modified by glycerin（GI）,and the effect of PSP@Ag NPs on the performance of the SA/SS film was investigated.The release characteristics and antibacterial activity of PSP@Ag NPs in SA/SS/GI/PSP@Ag NPs composite film were analyzed The results showed that the optimal preparation parameters of SA/SS/GI/PSP@Ag NPs composite membrane were 2%SA,2%SS,20%GI and 40μg/m L PSP@Ag NPs.The SA/SS film surface structure becomes flatter and tension performance is improved by adding proper GI.On this basis,the addition of 40μg/m L PSP@Ag NPs did not significantly change the surface morphology and structure of the composite film,and the hemolytic activity was low.The characteristic peaks of the infrared spectra of the three composite films are similar,indicating that GI and PSP@Ag NPs are physically combined with SA/SS.The addition of GI and PSP@Ag NPs reduced the water vapor permeability of SA/SS/GI and SA/SS/GI/PSP@Ag NPs by 0.25 g·mm/m²·h·k Pa,respectively.The water absorption rate increased by 29.13%and 8.25%,and the superior water absorption made the SA/SS/GI/PSP@Ag NPs composite film have a better ability to keep the wound moist.The release rate of PSP@Ag NPs in the SA/SS/GI/PSP@Ag NPs composite film is about 53%.Live/dead cell fluorescence staining showed that SA/SS/GI/PSP@Ag NPs composite film showed certain inhibitory effects on E.coli and S.aureus.Therefore,the SA/SS/GI/PSP@Ag NPs composite membrane has potential application value as a dressing for inhibiting skin wound infection and promoting wound healing.