Fabrication And Applications Of Layer-by-Layer Assembly Multilayered Films With Controllable Adhesion

Inspired by the adhesive phenomenon in nature,a variety of intelligent adhesive materials have been gradually developed and play an important role in many fields,such as navigation,medical treatment,architecture,electronics,electricity and so on.However,at present,the preparation of interface adhesion materials still depends on the simple micro/nano multi-level structure and traditional surface modification methods.There are some defects,such as cumbersome and complex process,long time-consuming,high cost,weak adjustability and poor stability,which seriously hinder the research and application of intelligent controllable adhesion materials.To solve these problems,based on the layer-by-layer assembly(LBL)technology with the unique advantages in fabricating interface methods and diversified structures and functions,from the perspective of enhancing adhesion,inhibiting adhesion and selective adhesion,we designed and prepared a series of controllable adhesion multilayered film materials to realize full potential of economic effectiveness,reliability,durability,performance stability and intelligent responsiveness,expanding application in cell culture and sorting,wound repair,medical protection and intelligent sensing.The main research contents are as follows:(1)Based on the specific recognition interaction of biomolecules,the oxidized alginate /linear RGD(Arg-Gly-Asp sequence)grafted carboxymethyl chitosan multilayered film was prepared with the enhanced adhesion property via the LBL technology,and then integrated with the the LBL anti-cell adhesion film composed of biomimetic cell membrane phosphorylcholine analogues to form a novel microfluidic biochip.As an extracellular culture matrix,the chip is used for cell culture and efficient sorting.It can release cells in a highly active state on-demand triggered by amino acids after capture,without external physical or chemical noxious stimulation.(2)Inspired by the phenomenon of mussel adhesion,polydopamine-iron nanoparticles were loaded into quaternary ammonium chitosan / alginate multilayered films were fabricated through the LBL technology,high self-adhesion to biological tissues was realized and the adhesion mechanism was explained.Because the nanoparticles have the p H response to physiological environment and can remove free radicals of reactive oxygen species,they can alleviate the oxidative damage of cells in vitro.In addition,the motion driven triboelectric nanogenerator that generates continuous electric energy was introduced into the system to repair the wound in the active-treatment manner and its repair mechanism was clarified.In the healing experiment of rat wounds,this LBL film-based medical device can not only promote the proliferation and migration of fibroblasts through electrical stimulation,but also alleviate the oxidative stress of wound in the inflammatory stage,and facilitate the formation of neovascularization with no obvious inflammatory.(3)Taking the full advantage of the high hydrophilicity of natural polysaccharides,the LBL film was used to repel oil and resist bacterial adhesion.Humidity responsive polydopamine nanoparticles and conductive polymer doped temperature sensitive poly(N-isopropylacrylamide)were loaded on both sides of the film respectively to prepare an environmental dual-response unidirectional bending actuator.By measuring the effect of the film actuator on the temperature and humidity of the skin surface,oil resistance and bacterial anti-adhesion,we found that the film possessed high hydrophilicity and oil repellent.The sensitivity of the resistance of the conductive film to humidity,the monitoring of harmful volatile organic compounds(VOCs),the electromagnetic interference suppression and the post-damage tolerance were further studied.The experimental results illustrated that we integrated the adjustment comfort of temperature and humidity,the respiratory detection,the oil displacement of antibacterial adhesion,the visual monitoring of VOCs,electromagnetic shielding and self-healing into a single actuator,as a new multi-functional protection system,giving full play to the advantages of multi-modal protection and expanding the applications of intelligent responsive films with oil / bacterial anti-adheison in medical protection.(4)Based on Schiff base system,we skillfully used the ‘molecular suture technology’,sutured the LBL multilayered film-patch composed of succinimide alginate / tannic acid /polyethyleneimine and adhered it to wet biological tissue through the suture polyethyleneimine.And high adhesion state could be switched to non adhesion state under the trigger of glycine,so as to achieve the selective regulation of interface adhesion and realize peeling-on-demand without damage.Meanwhile,the mixed p H indicator was loaded on the multilayered film,and the smartphone APP was used to identify and monitor the p H value of the skin physiological environment.Further,the contact-separation self powered triboelectric nanogenerator prepared in the previous work was combined into the film as a bio-inspired skin receptor for visual electrical signal monitoring of skin surface damage.In addition,we embedded the drug-loaded micro-needle module into the film patch.The potential effect of the patch on wound closure was demonstrated by the results of drug release kinetics,cell proliferation in vitro and wound healing in vivo.This switchable adhesive film patch based on micro-needles not only has the characteristics of p H tactile dual sensing,but also has the ability to accelerate wound healing,which is expected to bring good news to trauma patients with sensory disorders.