Two Oligopeptide-Based Amphiphiles:Design,Synthesis And Properties

Oligopeptides are a class of compounds consisting of 2-10 amino acids bound by peptide bonds.They have the advantages of easy synthesis,low synthesis cost,and easy regulation of molecular structures.In this thesis,two oligopeptide-based amphiphilic molecules were designed and synthesized,and the properties and their applications were systematically investigated.This thesis mainly includes the following contents:1.A L-glycyrrhodipeptide-modified dansyl fluorescent probe（D-TG）was designed and synthesized,which showed good detection performance for Cu²⁺in aqueous solutions.In HEPES buffer solution（10 m M,pH 7.4）,the fluorescent probe D-TG itself has strong fluorescence emission and undergoes significant fluorescence quenching upon coordination with Cu²⁺,thus allowing efficient and sensitive detection of Cu²⁺.D-TG is also responsive to pH due to the protonation of dimethylamine and deprotonation of sulphonamide.The applicable pH range was determined to be 6-12 for the detection of Cu²⁺.The binding constant between D-TG and Cu²⁺was determined to be 6.47×10⁴M^-1.The detection limit for Cu²⁺in HEPES buffer solution（10 m M,pH 7.4）was 0.69μM,which is much lower than the requirement of the Chinese national standard for copper ions in drinking water（15.7μM）.In addition,the probe can detect Cu²⁺in real water samples and living HepG2 cells,indicating that the probe can be applied in complex environments.2.An amphiphile based on oxidized glutathione（AZO-GSSG）was designed and synthesized,and it formed hydrogels in DMF samples with 50%-90%（v/v）water.The hydrogel exhibited triple responsiveness to light,temperature,and redox.The morphologies of the self-assemblies were observed by transmission electron microscopy（TEM）and scanning electron microscopy（SEM）;the modulus and viscosity in different states were investigated by rheometry.Interestingly,the gel starts to collapse at 38℃,a temperature that is close to the physiological temperature,suggesting a possible biomedical application.The hydrogel can be re-formed by the addition of glutathione followed by H₂O₂.Due to the high concentration of glutathione in the pathological site,this glutathione responsive breakdown of the hydrogel suggests a potential application of the hydrogel as a drug carrier.