Study On The Construction And Properties Of Anti-bioadhesion Surfaces Based On Functional Characteristics Of Anchor Molecules

The adverse bioadhesion phenomena are widely present in various fields such as biomedicine,food processing,fluid transportation,underwater equipment and shipbuilding industry,which can cause serious harm to people's production and life.According to studies on many biological surfaces with excellent anti-bioadhesion properties in nature,it has been found that special bioinspired surfaces with special wettability,including superhydrophobic/highly hydrophobic and superhydrophilic/highly hydrophilic surfaces,can effectively reduce or even eliminate the negative impact of adverse bioadhesion behaviors.With respect to the consrruction of anti-bioadhesion surfaces with special wettability,the grafting of right functional compounds onto the substrate surfaces is one of most effective strategies,and surface-initiated atom transfer radical(SI-ATRP)and surface-initiated reversible additionfragmentation chain transfer(SI-RAFT)polymerization are efficient and controllable surface modification methods for surface grafting.However,both ATRP and RAFT must be conducted under harsh anaerobic and anhydrous conditions;and trace amounts of residual additives in the product,including a transition-metal complex as a catalyst and dithioester as a chain transfer agent that have to be used in the reaction system of ATRP and RAFT,respectively,may also lead to adverse consequences.Besides,the performances of the anti-bioadhesion surfaces prepared via the present methods are usually unstrable and unsatisfactory particularly in the complicated aqueous environment,which makes their ability to resist bioadhesion difficult to maintain long-term stability,thereby inevitably exhibiting a significant downward trend.Therefore,we put forward a research thought of construcing the durable anti-bioadhesion surfaces via anchoring the compounds with an anchor group as anchor molecules onto the substrate surfaces so as to endow them with reactivity,and then grafting the functional monomer or macromolecules with different wetting characteristics onto the prepared reactive surfaces.The structure-activity relationship between the anti-bioadhesion performance of the prepared surfaces and their surface properties,including the chemical/physical characteristics and wetting properties of surfaces,can be studies and established by investigating and comparatively analyzing theirchemical compositions,morphologies,wettabilities and the antibioadhesion properties.Furthermore,the effect and mechanism of different anchor molecules and grafted compounds with different wetting characteristics on the construction and properites of anti-bioadhesion surfaces can be revealed,thus laying a theoretical and practical foundation for the construction of stable anti-bioadhesion surfaces.The main comtents and results of this work are described follows.1.Two types of anchor molecules,alkylated silane compounds(MN)and DOPA derivatives bearing a double bond(DMA),were designed and synthesized based on UV-induced thiol-ene click chemistry reaction and amidation reaction,respectively.The hydrophobic Si O2 nanoparticles were prepared via the thiol-ene click chemistry reaction between DMA-modified Si O2 nanoparticles and n-dodecyl mercaptan(NDM).A series of the organic/inorganic hybrid surfaces using MN and dopamine(DOPA)as anchor molecules,respectively,was fabricated by modifying the surface of a glass slide(Glass)as a substrate with the organic/inorganic hybrid solutions composed of MN and Si O2 sol in various proportions and modifying the surface of a DOPA-modified Glass as a substrate with the hydrophobic Si O2 nanoparticles,respectively,via the spray-deposition,heat treatment and dipping;and their surface physical and chemical characteristics were investigated.The results indicate that these two types of modified surfaces possess significantly greater roughness than the corresponding unmodified surfaces;and showing mico-nano hierarchical stuctures;the water contact angle(WCA)of both the modified surfaces using MN and DOPA as anchor molecules can reach 138.3° and 142.2°,respectively,so exhibiting high hydrophobicity;and after being immersed into water at 37 °C for 5 days,the WCA of the former is reduced to 35.6° and the WCA of the latter is 140.5°,only slightly decreased.It implies that the modified surfaces using DOPA as anchor molecules can possess better stability and durability than those using MN as anchor molecules.2.Inspired by the chemical composition and character of cell outer membrane,betaine zwitterionic compound,3-dimethyl(3-(N-methacrylamido)propyl)ammonium propane sulfonate(DMAPMAPS),was designed and synthesized;and then DMAPMAPS was polymerized into the zwitterionic polymers PMDAPMAPS via the reversible additionfragmentation chain transfer(RAFT)polymerization.The as-prepared PDMAPMAPS was converted by Na BH4 reduction into the zwitterionic polymer bearing a thiol group or a clickable reactive module,PDMAPMAPS-SH.The zwitterion-modified surfaces using a double bondcontaining silane coupling agent TMSPMA and DMA as anchor molecules,respectively,were successfully constructed on a glass substrate via the UV-induced thiol-ene interfacial click reaction between PDMAPMAPS-SH and anchor molecules;and their surface physical and chemical characteristics were measured.The results indicate that compared with the corresponding unmodified surface,the zwitterion-modified surfaces using TMSPMA and DMA as anchor molecules,respectively,possess an increased roughness and a decreased WCA value,which is 0° and 4°,respectively,showing excellent superhydrophilicity.Besides,the WCA of the prepared zwitterion-modified surfaces will decrease gradually with increasing the ammount of PDMAPMAPS grafted onto the substrate surface.3.DMA was first anchored onto the surfaces of Glass and PET sheets(PET)via a simple dipping-coating method,so endowing them with reactivity;and then the thio-terminated zwitterionic macromolecule poly(DMAPMAPS-co-BAC),which was synthesized by the freeradical copolymerization of DMAPMAPS and N,N'-bis(acryloyl)cystamine(BAC),was bonded onto the reactive surfaces via an UV-induced thiol-ene interfacial click reaction,thereby preparing a series of the modified surfaces,Glass-DMA-Pi and PET-DMA-Pi.Their morphology,wettability,anti-oil-fouling performance and antifogging property were characterized and analyzed.The studies show that the roughness of the as-prepared surfaces is greater than that of the corresponding unmodified surface as a control and they possess strong hydrophilicity and excellent underwater superoleophobicity.With an increase of the DMAPMAPS content in the copolymer poly(DMAPMAPS-co-BAC)macromolecular chains grafted onto the substrate surfaces,the roughness of the modified surfaces increases gradually;while the WCA values of Glass-DMA-Pi and PET-DMA-Pi decreases from 26° to 10° and from 20° to 12°,respectively,and the OCA values of Glass-DMA-Pi and PET-DMA-Pi increase from 150° to 156° and from 146° to 162°,respectively.Moreover,the modified surfaces possess obvious anti-oil-fouling and antifogging properties.4.A series of the nanocomposite hydrogels(NCx Ny Dz)was synthesized using clay Laponite XLG as a crosslinker through a thermally initiated polymerization of N,NDimethylaminopropyl acrylamide(DMAPAA)with N-isopropylacrylamide(NIPAM),and the surface of NCx Ny Dz was then modified by the use of the ring-opening reaction of 1,3-PS,so successfully preparing the zwitterion nanocomoposite hydrogels(NCx Ny Dz PS).The morphology,swelling properties,mechanical properties,thermodynamic properties and wettability of NCx Ny Dz and NCx Ny Dz PS were characterized and analyzed.The mechanical strength of NCx Ny Dz and NCx Ny Dz PS show a gradual increasing trend with an increase in the clay content.When the clay content is 4 wt %,the tensile strength,elongation at break and thermal decomposition temperature of NCx Ny Dz are 290 k Pa,1035 % and 175 °C,respectively,and the tensile strength,elongation at break and thermal decomposition temperature of NCx Ny Dz PS containing 25 wt % zwitterion are 90 k Pa,480 % and 297 °C,respectively.It indicates that the incorporation of zwitterion can improve the thermal stability of the nanocomoposite hydrogels NCx Ny Dz,but will lead to the deterioration of their mechanical properties.Furthermore,the WCA of NCx Ny Dz and NCx Ny Dz PS can reach 27° and 21°,respectively.The WCA of NCx Ny Dz PS will decrease gradually with increasing the zwitterion content and can reach 10° when the NIPAM/DMAPMAPS mass ratio in the feed is 25(25)75.5.Anti-bacterial adhesion behaviors of the anti-bioadhesion surfaces,which were constructed based on the functional characteristics of different anchor molecules,were measured by a bacterial adhesion experiment via using Gram-negative bacterium Escherichia coli and Gram-positive bacterium Staphylococcus aureus as test bacteria.The structure-activity relationship between the anti-bioadhesion performance of these surfaces and their surface properties,including chemical/physical characteristics and wetting properties,were studied by combining their chemical compositions,morphologies and wettabilities.The obtained experimental results are as follows:(a)The highly hydrophobic surfaces prepared by using MN or DOPA as anchor molecules can exhibit a certain resistance to bacterial adhesion.The bacteria adhered to them are much less than the corresponding unmodified surface although there is still a small amount of bacteria adhered to the surfaces.Under the same conditions,there are nearly no bacteria adhering to the superhydrophilic surfaces prepared by using TMSPMA and DMA as anchor molecules,respectively.It implies that the superhydrophiliic surfaces can possess better anti-bacterial adhesion performance than the highly hydrophobic surfaces.(b)The highly hydrophobic surfaces prepared by using MN or DMA as anchor molecules can exhibit a certain resistance to bacterial adhesion.The bacteria adhered to them are much less than the corresponding unmodified surface although there is still a small amount of bacteria adhered to the surfaces.Under the same conditions,there are nearly no bacteria adhering to the superhydrophilic surfaces prepared by using TMSPMA and DMA as anchor molecules,respectively.It implies that the superhydrophiliic surfaces can possess better anti-bacterial adhesion performance than the highly hydrophobic surfaces.(c)Compared with the corresponding nanocomposite hydrogels,the bacteria adhered to the zwitterion nanocomposite hydrogels prepared via the incorporation of zwitterionic molecular chains decrease remarkably.From the results of the bacterial adhesion experiments on various types of modified surfaces with different wettablilities,it is proved that the superhydrophilic and highly hydrophilic surfaces can possess better anti-bacterial adhesion performance than the hydrophobic surfaces.