| Stimuli-responsive interfaces has been always one critucal challenge and hot topic in this field,because that it closely related to understanding the secret of life,preparing functional coating of biological implant,and realizing disease diagnostics with high sensitivity.Among the various stimulus,light-stimulus response system has promising potential because of its precise spatiotemporal control and convenient operation.Azobenzene is regarded as one of the most ideal photoswitch candidates due to its highly efficient reversible trans-to-cis photoisomerization,and as it has been widely used in the fields of information storage,functional interface and drug release.In this thesis,the cell or bacteria capture and release properties of azobenzene self-assembly layer-by-layer films were studied,and the trapping/release of cargoes were also studied.The reaearches and results are summarized as the following:(1)Two different photoresponsive azobenzene films are synthesized by chemisorption and electrostatic layer-by-layer(LbL)assembly techniques.The changes in trans/cis isomer ratio of the azobenzene moiety and the corresponding wettability of the LbL films were also studyed before and after UV light irradiation.Interestingly,the tendency for cell adhesion can be considerably increased on rough substrates,the roughness being introduced by use of photolithography and inductively coupled plasma deep etching techniques.The tendency for cell adhesion on the LbL films decreases markedly after UV light irradiation,whereas adhesion on the chemisorbed films decreases only slightly,because the azobenzene chromophores stay densely packed.(2)The substrates grafted with cyclodextrin were fabricated by the silanization reaction and a specific cell capture agent(aptamer)was connected to the azobenzene via bifunctional coupling agent to construct the aptamer modified surface(Si-CD/Azo-apt)which could capture the specific cells.The cell capture and release properties of the Si-CD/Azo-apt upon UV/visible light irradiation were studied,and the specific adhesion of cells on the aptamer-functionalized surface was demonstrated.Moreover,the Si-CD/Azo-apt substrate can be reconstruction due to the host-guest interaction between trans-azobenzene andβ-CD.The light-triggered cell release with high efficiency may afford the smart surface with significant potential applications for the isolation and analysis of cancer cells.(3)A facile method to construct reversible visible light-responsive switching for bacteria attachment and detachment was currently developed by host-guest self-assembly of β-cyclodextrin(β-CD)and azobenzene functionalized polycation(Azo-PDMAEMA)/polyanion(Azo-PAA).The bacterias adhesion properties on the surfaces were studied.At the same time,visible-light irradiation can changed the adhesion properties of the substrates.Moreover,the system can alterably switch surface properties from bacterial attachment to detachment upon visible light irradiation via alternate assembly of Azo-PDMAEMA and Azo-PAA.(4)A visible-light azobenzene polymeric was synthesized by quaternization reaction,and the inclusion complex Azo-PDMAEMA/β-CD-RhB was constructed via azobenzene/cyclodextrin-based host-guest interactions.Visible light responsive Azo-PDMAEMA was used as a polycation to combine with polyacrylic acid(PAA)for the construction of multilayers through the LbL electrostatic selfassembly technique,from which the trapping/release of cargoes could be realized upon light stimulation.It is noted that the loading capacity could be increased with the increase of the layer number,which might contribute to the delivery system loaded with the desired amount of target.Green light could induce the isomerization of azobenzene from trans to cis,resulting in the disassembly of the host-guest complex and release of the cargoes from the multilayers.Subsequent regeneration of the trans azobenzene by blue light irradiation enabled the retrapping of the cargoes into the multilayers. |
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