Visualizing Polymer Carriers With Upper Critical Solution Temperature And Bacteria Recognition Characterization

The polymers featured with the upper critical solution temperatures(UCST)can undergo a transition from aggregation to dissociation with the increase of temperature,which will lead to a complete release as drug carriers.It's knowledge that the abuse of antibiotics and antibacterial agents is an important reason for the increasing number of drug-resistant bacteria.UCST polymer carriers have great potential in improving the utilization of antibacterial agents and solving the challenges of bacterial infections.However,the types of polymer carriers with UCST are very limited currently.What's more,the UCST carriers involves polymer aggregation state leading to strong aggregation-cause quenching(ACQ),which make traditional fluorescent molecules unable to be used for UCST carriers fluorescence tracing and bacterial imaging.In addition,most of the polymer carriers with UCST lack the function of recognizing bacteria,resulting in low utilization of loaded antibacterial agents.Therefore,the development of visualization polymer carriers with UCST and bacterial recognition functions has great application potential in the treatment of bacterial infections.Based on the above background,this article mainly develops an aggregation-induced emission(AIE)visualization polymer with UCST and bacterial recognition functions.The main research content is divided into two parts:(1)In the early UCST polymer(copolymer of acrylamide(AAm)and cholic acid modified acrylamide(CAA))was introduced tetraphenylethylene modified acrylamide(TPEA)monomer with AIE property via reversible addition fragmentation chain transfer(RAFT)polymerization to afford terpolymer PATC.The introduction of AIE fluorescent molecules is not only conducive to bacterial imaging and carrier tracing,but also helps to monitor the phase transition process of UCST polymers.The experimental results show that PATC possesses adjustable UCST above body temperature and typical AIE fluorescence properties,and can be used as a carrier to realize the loading and visual controlled release of hydrophobic drugs.Fluorescence imaging technology can be used to observe the phase transition process of PATC and monitor the drug release process.In vitro cytotoxicity evaluation proved the good biocompatibility of PATC.(2)The glycopolymer PATC-GlcN was block synthesized on the basis of PATC.The introduction of sugar-bearing blocks with bacterial recognition function can not only regulate the aggregation morphology of bacteria,but also can achieve the targeted drug delivery and killing of bacteria.Experimental results show that PATC-GlcN retains the AIE and UCST properties,has good biocompatibility and can realize the recognizing and fluorescence imaging of E.coli.The cluster glycoside effect of multiple glucose residues in the glycopolymer can agglutinate E.coli and reversible regulate the aggregation behavior of E.coli based on UCST property under fluorescence imaging.PATC-GlcN can be used as an UCST photothermal agent carrier,which can enhance the in-situ photothermal sterilization efficacy of the photothermal agent IR780.