Synthesis And Properties Of Temperature-sensitive Polypeptides With Single-chain Folding

Temperature-responsive polymer refers to a type of polymer whose physical or chemical properties will change with the change of external temperature.Polypeptide is a type of material with good biocompatibility,and temperature-responsive polypeptide as a temperature-responsive Polypeptides with good properties have great application value in many fields because of their unique properties.Therefore,research on the structure and performance of temperature-responsive polypeptides has been widely concerned by researchers.In this paper,two different structures of single-chain folded temperature-responsive polypeptides were designed.We used ¹H NMR,GPC,CD,and DLS instruments to characterize the molecular structure,and temperature-dependent UV-vis and DLS were used to characterize the temperature response.In testing,we compared the UCST properties of single-chain folded and linear-temperature-responsive polypeptides.In addition,this article also tested and compared the cytotoxicity of single-chain folding and linear temperature.We found that the UCST properties of the polypeptide material after single-chain folding have a high cloud point,and we found that single-chain The folded polypeptide is much less cytotoxic than its corresponding linear polypeptide.Our work synthesized two different single-chain folded temperature-responsive polypeptides,which not only enriched the types of temperature-responsive polypeptides,but also provided guidance for future related research.The specific contents of this article are as follows:In the second chapter,we first initiated the ring-opening polymerization of N-amide anhydride?hereinafter referred to as MTP-NCA?of?-3-methylthiopropyl-L-glutamic acid ester with PEG4000 with double-ended amino groups as the initiator.Block polypeptide,and then we react this linear triblock polypeptide with 1,4-diiodobutane at very dilute concentration to obtain single chain folded polypeptide.We confirmed the successful synthesis of single-chain folded polypeptide using ¹H NMR,GPC,DLS,etc.We then reacted the linear and single chain folds with 3-bromopropyne to obtain a reactive polypeptide with a triple bond,and then obtained a temperature-responsive polypeptide through a click chemical reaction.We prepared the self-assembly solutions of these two polypeptide samples,and found that the self-assembly solutions of these two polypeptide samples had UCST properties in deionized water and PBS buffer solution?p H 7.1-7.4?,and the single-stranded folding The cloud point of the subsequent samples is not less than that of the straight chain samples.The cloud point of the UCST property of the sample with a large degree of folding is higher than that of the sample with a small degree of folding.In addition,we also tested the cytotoxicity of these two samples,and we found that the cytotoxicity of the single-stranded folded sample also decreased significantly.The third chapter uses double-terminal PEG₄₀₀₀as the initiator to initiate MTP-NCA polymerization to obtain triblock polypeptide,and then continue to add?-4-?propargyloxycarbonyl?benzyl-L-glutamate N-Amidic anhydride?hereinafter referred to as PBLG-NCA?is polymerized to obtain a five-block polypeptide.We will fold this five-block polypeptide at a very dilute concentration to obtain a single-chain folded five-block polypeptide,and then click the chemical reaction Obtaining ionic polypeptide,we characterized the structure of all intermediates and target products,confirming that we successfully synthesized a single-chain folded pentablock ionic polypeptide.Both straight-chain and single-chain folded ionic liquids have reversible UCST properties in deionized aqueous solutions.We obtained the temperature-transmittance curve using variable temperature UV-vis test.We found that the pentablock single-chain folds at the same concentration The cloud point of ionic liquids is higher than that of straight chains.