Preparation And Biomedical Research Of Novel Polydopamine Functional Materials

Polydopamine(PDA)is a major component of melanin in organisms and has been widely used in biomedical fields because of its good biocompatibility and safety.To date,polydopamine nanomaterials have shown a variety of nanostructures,such as colloids,capsules,microfilms,pore structures,one-dimensional structures,etc.In this thesis,twodimensional polydopamine nanosheets(PDA NSs)were prepared in a "top-down" method by optimizing the preparation conditions;the anti-oxidation effect of PDA NSs was explored,its scavenging effect on free radicals.A rat trauma model was established to further investigate its therapeutic effect on wound healing.The specific research content are as follows:1.Dopamine hydrochloride was selected as the precursor material.The morphology and size of the products under different temperature,different reaction time,different p H conditions and different ingredients ratio were measured by means of TEM and AFM,and the suitable size of PDA NSs was selected by graded centrifugation.The results showed that under the reaction conditions of p H 6.8,50°C,24 hours,ingredients ratio of 1:450,centrifugation was performed at 1500 rpm,the precipitate was discarded,and the supernatant was left to obtain PDA NSs with a size of about 200 nm and an average thickness of 3.85 nm.The stability of PDA NSs was evaluated by DLS.Test results indicate that the size of PDA NSs in the aqueous solution has negligible change within 24 hours,indicating that it has the good stability.2.Ultraviolet spectrophotometry was used to investigate the free radical scavenging effect of the synthesized PDA NSs.The results showed that when the concentration of PDA NSs was 35 μg/m L,50 μg/m L,210 μg/m L,respectively,the scavenging efficiency of DPPH radical(DPPH·),superoxide anion radical(O2·-),and ABTS radical(ABTS·+)reached the maximum,with their clearance rate of approximately 91.6%,96.0%,and 100.0%,respectively.These results suggested PDA NSs is a good free radical scavenger with remarkable antioxidant activity.3.The biocompatibility of PDA NSs was demonstrated on mouse fibroblast L929 cells in vitro and the effect of PDA NSs on wound healing was evaluated by establishing SD rat trauma models afterward.According to the results of naked eye observation and tissue staining analysis,the repairing effect of PDA NSs on non-intact skin was concentrationdependent.At the same time,the number of neovascular and collagen fibers in tissue sections were found increasing along with the increased dose of PDA NSs.This shows that PDA NSs can significantly promote wound healing and have good application prospects in the biomedical field.