Synthesis And Applications Of Novel Environmental-responsive Polymers

The applications of environment-responsive polymer have been a hot topic in the field of biomedicine and nanotechnology.The stimuli from the external environment include both physical and chemical types,such as pH,temperature,ionic strength,light,electricity,or magnetic fields etc.For environment-responsive polymer,different response groups are introduced in polymers in order to meet different needs by polymerization or other chemical means.This method can not only control the shape of the responsive polymers more accurately when the external stimuli changes,but also can adjust different kinds and quantities of the groups according to the actual demands.Therefore,the study of new environment-responsive polymers has been a hot and important topic.Herein,four kinds of novel environment-responsive polymers were obtained,and the influence of external stimuli on the changes of the structure of these polymers were studied in detail.The contents are divided into four aspects:1.Herein,we design a polyethylene glycol(PEG)based hydrogel combined with caging chemistry,which could achieve the light-triggered local control of hydrogel.The crosslinking density of the hydrogel could be tuned with UV exposure by decomposing the structure of hydrogel.Meanwhile,by introduction of the releasable Rhodamine 110 molecule,we could conveniently monitor the changing of the crosslinking density of hydrogels via fluorescence.By this approach,the adjustable user-defined stiffness patterns with different fluorescence intensity in a range of soft tissue microenvironments have been obtained.This novel design of hydrogel could be useful for the manipulation of cell fate in various other contexts.2.We have reported a new strategy to synthesis a photo-cleavable poly(?-caprolactone)(PCL)with a photochemical switching on the basis of the attachment of a photo-cleavable moiety.With controlled ratio of initiator and monomer,different molecular weights of photo-cleavable polymers were successfully synthesized.With different time of UV exposure,the decopositon degree of PCLs changed regularly.By comparison of UV absorption spectra and molecular weights of PCLs,it could be found that there was a close relationship between photo-chromic and photo degradation,which provided a convenient tool in the study of photo-cleavable polymers.3.Nitrogen-doped carbon dots are introduced as a novel substrate suitable for enzyme immobilization in electrochemical detection,which are easily synthesized from polyacrylamide by one pot hydrothermal pyrolysis.With the help of the amino group on chitosan,glucose oxidase is immobilized on nitrogen-doped carbon dots-modified carbon glassy electrodes by amino-carboxyl reactions.The nitrogen-induced charge delocalization at nitrogen-doped carbon dots can enhance the electrocatalytic activity toward the reduction of O2.The specific amino-carboxyl reaction provides strong and stable immobilization of GOx.Based on that,with the help of chitosan to immobilize the GOx,we modified this glucose responsive polymer film onto the electrode to build a simple and sensitive glucose electrochemical sensor.4.A novel application in the determination of glucose by ultrasonic detection with the using of force-responsive molecule spiropyran(SP)was developed.Firstly,we synthesized a two armed boronic acid functional SP,which has a good response towards glucose by the specific reaction of boronic acid group and glucose.Next,we used this boronic acid functional SP to react with polysaccharide and glucose at the same time.In the absence of glucose,this SP could react with polysaccharide to form a force responsive polymer chain,and under the condition of ultrasonic,the color of solution will soon change to purple.However,when glucose is exsistent,the competition reaction between the glucose and polysaccharide would hinder the formation of force response polymers,so that the concentration of glucose could be easily measured by the color change of the solution after ultrasound.This work not only expands the application of force chemistry,but also effectively improves the sensitivity of the detection of glucose.