Preparation And Antibacterial Investigation Of Enzyme-Responsive Antibacterial Interface Materials

Microorganisms,such as bacteria,widely exist in air,water,soil,animal and human body.Bacterial attachment,accumulation and colonization on materials surfaces have serious impacts in daily life and industry production.However,some of these materials do not have intrinsic ability to resist of bacterial contamination.Silver(Ag)-based materials,such as silver nanoparticles(Ag NPs),have attracted extensive studies to be used as antimicrobial materials in numerous consumer products and medical instruments due to broad-spectrum antimicrobial,antifungal and antiviral activities.Generally,Ag ions are regarded to be safe at low concentration.However,high doses of Ag release in a short time can induce cytotoxicity.Therefore,a negative impact of Ag NPs on surrounding environment and human body must be avoided.In this study,two different bacterial enzyme responsive antimicrobial interface materials were constructed by using layer-by-layer self-assembly(LBL)technique.Silver nanoparticles or silver ions can be released under the condition of bacterial secretase,which can quickly and efficiently kill the bacteria around the surface of the material and inhibit the bacterial biofilm on the surface of the material.This new enzyme-responsive antibacterial material has the advantages of environmental friendliness,human safety,broad spectrum,no toxic side effects,long effect and low cost.The work and results can be summarized as follows:(1)Preparation and Investigation of Hyaluronidase Enzyme-ResponsiveAntibacterial Interface MaterialsUsing chitosan as modifier and ascorbic acid as reducing agent,chitosan-silver composite nanoparticles(CS@Ag NPs)were synthesized by using liquid-phase chemical reduction method,and then dopamine was deposited on the surface of the material.CS@Ag NPs with positive charge and hyaluronic acid with negative charge were assembled by using layer-by-layer technique,and enzyme responsive multilayers were constructed on three typical materials(polyethylene,glass,metal).Transmission electron microscopy(TEM)analysis showed that the average particle size of CS@Ag NPs was about 20 nm.UV-Vis spectra showed that CS@Ag NPs had an enhanced peak at 400 nm.X ray diffraction(XRD)analysis showed that CS@Ag NPs had five characteristic peaks in 111,200,220,311 and 222 nm,there were no heterogeneity peak observed in the spectrum.Therefore,CS@Ag NPs had high purity and face-centered cubic crystal structure.X-ray photoelectron spectroscopy(XPS)showed that ascorbic acid as a reductant could completely reduce silver ions to silver elements.Inductively coupled plasma spectrometry(ICP)showed that hyaluronidase could rapidly disintegrate the multilayer films and release Ag ions rapidly.The results of SEM and contact angle measurements showed that the CS@Ag NPs/HA multilayer films were successfully constructed on the surface of the materials.The bacteriological activity of the material was measured by MTT method,and the antibacterial rate of the material stored for 1 and 28 days was determined by using coated plate method.The results showed that the interface of the prepared CS@Ag NPs/HA multilayer film showed good antibacterial capability.Confocal laser scanning microscopy and bacteriostatic circle detection showed that the antibacterial interface not only demonstrated highantibacterial properties,but could also resist bacterial adhesion.(2)Preparation and Investigation of Glutamyl endopeptidase(V8)EnzymeResponsive Antibacterial Interface MaterialsThe silver loaded MCM-41 mesoporous silica nanoparticles(Ag-MSN)were synthesized by one-step method,and then poly-L-glutamic acid(PLGA)/polyallylamine hydrochloride(PAH)were assembled by using LBL method on Ag-MSN to construct the enzyme responsive Ag-MSN@LBL nanoparticles.Ag-MSN@LBL nanoparticles were deposited on the surface of polydopamine-modified materials to prepare glutamyl endopeptidase responsive interfacial materials.The TEM results showed that the synthesized Ag-MSN nanoparticles were spherical in diameter 200-300 nm.After being dispersed in mesoporous silica layer,Ag-MSN nanoparticles had a diameter of about 10 to 20 nm.The UV-Vis showed that the Ag-MSN nanoparticles had enhanced absorption peak in 416.5 nm.Zeta potential,Hydrodynamic diameter,XPS and XRD showed that Ag nanoparticles were successfully loaded onto the surface of mesoporous silicon to form Ag-MSN@LBL nanoparticles.The results of bacterial activity,bacterial adhesion and antibacterial rate tests showed that Ag-MSN@LBL particles deposited on the surface of the material had higher antibacterial rate and lesser bacterial adhesion.Polymerase chain reaction(PCR)technique and Scanning electron microscopy(SEM)were used to observe the antibacterial mechanism of the interface,which was mainly based on the function of Ag ion destroying membrane,interfering with the production of adhesion mediated protein and producing reactive oxygen species(ROS).To sum up,the two enzymes response to the antibacterial interface material is based on the controlled release of silver ions to achieve bactericidal effect.The release of high dose silver ions can achieve efficient sterilization,but at the same time a large number of silver ions can bring great side effects in the accumulation of human body.Therefore,its utilization can only be limited to some facilities in the body.Such as public facilities and external medical facilities.