The Construction Of Dnase-Mimetic Artificial Enzyme Based On Cerium(?) Complexes For Combating Bacterial Adhesion

Most hospital-acquired infections are initiated by bacterial,which is not only cause high incidence and mortality but also bring about other related economic burdens.The contamination of bacteria on medical devices is the main cause of nosocomial infections.Bacterial attachment and the subsequent proliferation and colonization of bacterial on the surfaces of medical devices usually result in the formation of biofilm.The biological properties of the material surface play an important role in the interaction with bacteria.Therefore,constructing an anti-infective surface is an important strategy for combating infection-related biological materials.There is increasing evidence that extracellular DNA?eDNA?plays a crucial role in the bacterial adhesion and biofilm formation.The material surface modified with the natural DNase has been proved as an effective method to prevent bacterial adhesion and biofilm formation in a short time?within 24 h?.In this work,DNase-mimetic artificial enzyme was constructed on the material surface based on cerium ions complexes which could accelerate the hydrolysis of DNA under physiological conditions as catalysts.More importantly,due to their inherent stability,DNase-mimetic artificial enzyme presented the much better performance in inhibiting bacterial biofilm development for prolonged periods of time,as compared to the natural DNase.?1?A layer of bioactive polymer brush mimetic enzyme was constructed on poly?styrene-b-?ethylene-co-butylene?-b-styrene??SEBS?film surfaces by UV grafting.In this work,the construction of the unique polymer brush structure mimic enzyme benefits the DNA-cleavage activity.First,the flexible copolymer backbones enhance the catalytic activity of the cesium ions.Second,the catalytic active site were enhance due to the enrichment of catalytic sites on the polymer brush.The surface analysis of the samples was conducted by the attenuated total reflection?ATR?mode of the Fourier transform infrared spectrometer.X-ray photoelectron spectroscopy?XPS?was used to analyze the elemental composition of the surfaces.Static water contact angle?WCA?was used to measure the wettability of the samples with a drop shape analysis instrument at room temperature.All of the surface characterization confirmed the successful construction of the polymer brushes and subsequent anchoring Ce^IV complexes to the macromolecular scaffolds.The antibacterial adhesion ability of the material surface were evaluated using S.aureus and E.coli,which represented of the Gram-positive and negative bacteria models respectively.The results proved that the material surfaces modified with the polymer brush mimics have excellent long-term antibacterial adhesion and biofilm formation resistance ability.?2?A bioactive antimicrobial surface was prepared on the surface of the material via a coating method.In this work,tannic acid?TA?is used as the matrix and backbone of the coating to bond directly with the substrate material.The cesium ions,on the one hand,serve as cross-linking points for the coating to connect different TA molecules,to allow the coating form rapidly and to maintain the stability of the coating,and on the other hand to act as a biologically active enzyme for cleaving the eDNA.UV spectrophotometer was used to detect changes in coating thickness with increasing coating times.The gradually increased absorbance values of the films evidently proved the growth of the film thickness as the dip-coating cycles increased.In addition,the stability of the coating was also examined.The pH-dependent disassembly of Ce?IV?-TA coatings was investigated via UV-Vis absorption spectroscopy.These results clearly demonstrated that the assembled Ce?IV?-TA networks on the SEBS surface were stable enough to undergo long-term incubation time under physiological conditions.Surface elements were analyzed using XPS.The surface composition of the sample was analyzed using the attenuated total reflectance?ATR?mode of the Fourier infrared spectrometer.Surface characterization techniques verified the successful fabrication of Ce?IV?-TA films on different model substratesThe antibacterial adhesion of the material surfaces were conducted by using S.aureus and E.coli as Gram-positive and negative bacterial models.Compared to the unmodified samples,he anti-biofilm formation efficiency of TA-Ce?IV?coated samples was 82.1%to S.aureus and 84.1%to E.coli,respectively.