| The attachment of bacteria and subsequent formation of biofilm on the surface of implant metal pose bacterial infection and a series of complications which threated human health.To solve this problem,considerable efforts have been directed toward the surface modification to prepare contact-based or release-based antibacterial coatings.Contact-based antibacterial coatings can kill bacteria and prevent the formation of biofilm through contacting with bacterias,but this kind of coating will still be contaminated by remaining dead bacteria,which may trigger immune responses and a series complications,such as inflammation,fever and pain.Release-based antibacterial coatings can prevent or reduce the initial attachment of bacteria via releasing antibacterial drugs.However,the releasing rate and amount of antibacterial drugs cannot be controlled,which will affect the long-time antibacterial property of coatings.The stimuli-responsive polymers are a kind of functional polymer that can respond to external small changes to trigger significantly physical and chemical changes.The colloidal particles based on stimuli-responsive polymer can change their own structure,hydrophilicity and hydrophobicity in response to the stimulation of temperature,pH,light,reducing agent,etc.So the colloidal particles can apply to load drugs and control the release of drugs.Among all colloidal particles,the redox-responsive colloidal particles,which are widely used as drug carrier,can reapond to glutathione?GSH?to load drugs and control their release in vivo.Therefore,using redox-responsive drug-loaded colloidal particles as building blocks,drug-loaded antibacterial coatings were prepared through electrodeposition to improve the question of contact-based or release-based antibacterial coatings.The research content is as follows:1.Preparation and properties of contact-based antibacterial coating with redox-resonsive drug releasing propertyFirstly,redox-responsiveamphiphilicrandomcopolymer poly-1-bromododecylmethylethylenediethacrylate quaternary ammonium salt-co-N-[2-?pyridine-2-disulfonyyl?-ethyl]-acrylamide-co-Methyl acrylate?PPDM?was synthesized by free radical polymerization.The structure of PPDM was characterized by FTIR and 1H-NMR.Then PCTM-loaded colloidal particles were prepared using selective solvent method.The particle size,morphology and drug-loaded efficiency of the colloidal particles were characterized by Zeta potential and nanoparticle size analyzer,transmission electron microscope?TEM?and UV-visibile spectrometer?UV-vis?.Finally,the contact-based antibacterial coatings with redox-responsive drug-released property was prepared on the surface of 316L stainless steel via the electrodeposition using PCTM-loaded CPs as building blocks.The effects of voltage and time on the structure and morphology of the antibacterial coating were studied.The chemical composition and morphology of the obtained coating were analyzed using FTIR and scanning electron microscope?SEM?.And the drug release test,antibacterial activity and cytotoxicity of PPDM coatings were studied.The results show that by changing the proportion of copolymer monomers,three copolymers PPDM-1,PPDM-2and PPDM-3 with different hydrophilic and hydrophobic ratio were synthesized.PPDM-2 and PPDM-3 could be self-assembled into colloidal particles with the particle size of 140 nm and179 nm,respectively.The PCTM-loaded efficiency of colloidal particles could come to 30%.Electrodepositon was carried on at 15 V and 3 min to prepare antibacterial coatings.The drug release test showed that the trigger release of PCTM can be realized when glutathione?GSH?were existed.Also,the coatings have better contact-based antibacterial activity and lower cytotoxicity.2.Preparation and properties of redox-responsive drug-released antibacterial coatingRedox-responsive 2-Pyridyldithioethylamine hydrochloride?PDA?and dopamine?DA?were used to modify?-polyglutamic acid??-PGA?to obtain?-PGA-PDA and?-PGA-PDA-DA.FTIR,1H-NMR and EDS were used to verify the structure of the modified polypeptide.Then?-PGA-PDA and?-PGA-PDA-DA were self-assembled with antibacterial agent ofloxacin?Oflo?to prepare drug-loaded colloidal particles in selective solvent.The particle size,morphology,zeta potential and drug-loaded efficiency were characterized by Zeta potential and nanoparticle size analyzer,TEM and UV-vis.The redox-responsive drug-released anbacterial coatings were prepared by the electrodeposition of Oflo-loaded colloidal particles on surface of 316L stainless steel.The drug release test,inhibition zone test and cell test were carried on to study the property of coatings.Meanwhile,the effect of DA on the long-term stability of the coating was studied by immersion test.The results showed that modification rate of PDA and DA in?-PGA-PDA and?-PGA-PDA-DA were 24%and 13.8%,respectively.Two kinds of Oflo-loaded colloidal particles were successfully formed,and the Oflo-loaded efficiency was 90%.The coatings,which were prepared at 150 V and 15 min,could realize the trigger release of Oflo when GSH at the concentration of 10 mM was added.The coatings could kill bacteria with responsiveness and improve cell compatibility.The presence of DA increased long-term stability of coatings in SBF.3.Preparation and properties of dual contact-based and redox-responsive drug release-based antibacterial coatingThe contact-based antibacterial prepared in the first chapter could kill bacterias via quaternary ammonium cations and achieve the responsive release of PCTM,but the coatings showed cell cytotoxicity because of a large number of quaternary ammonium cations.While,the responsive drug-released antibacterial coatings prepared in the second chapter could kill bacterias via the responsive release of Oflo,but the responsiveness was poor.To improve these problems,a dual contact-based and redox-responsive drug release-based antibacterial coating was prepared in this chapter.Firstly,copolymers poly?1-bromododecyl methacrylic acid dimethylaminoethyl ester quaternary ammonium salt-co-isobornyl acrylate?(P(ISA-co-DMAC12))were synthesized.The structure of copolymer was characterized by FTIR and 1H-NMR.Then,?-PGA-PDA,P(ISA-co-DMAC12)and Oflo were assembled together into Oflo-loaded colloidal particles.The particle size,morphology and Zeta potential were characterized by Zeta potential and nanoparticle size analyzer and TEM.Then,the antibacterial coatings were prepared by electrodeposition of Oflo-loaded colloidal particles on the surface of 316L satinless steel.FTIR,EDS,SEM and ultra-deep depth microscope analyses were used to confirm the presence of coatings on the surface of 316L stainless steel.Dual contact-based and responsive drug-release based antibacterial activity were investigated by antibacterial tests.The cell cytotoxicity of coatings was also characterized.The results indicated that the ratio of two monomers in the copolymer P(ISA-co-DMAC12)was ISA:DMAC12=1:1.2.CP1,CP2 and CP5 drug-loaded colloidal particles were successfully prepared through changing the concentration of P(ISA-co-DMAC12).Using electrodeposition at 100 V and 15 min,the colloidal particles could be assembled onto the surface of 316L stainless steel to form antibacterial coatings.Antibacterial test indicated the coatings had better antibacterial activity via contact and drug-release,and the coatings based on CP1 and CP2 colloidal particles could improve cell compatibility,while the coating based CP5 had higher cell cytotoxicity due to more quaternary ammonium salts. |
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