Synthesis, Micellezation And Enzymatic Controlled Drug Release Of Mpeg-cys-afc Conjugate

The antitumor drug molecules often have low water-solubility and targeting for tumor is unobvious, which often cause many side effects on the normal organs and tissues, reducing the immunity of human body in clinical treatment, that is disadvantageous for tumor patients. In recent years, the technology of nano drug carrier developed rapidly, wherein amphipathic polymer micelles as drug carriers can enhance water-solubility of drug, decrease toxic and side effect and prolong circulation time. Based on the modifications in structure, intelligent targeting controlled drug release can be realized, and anticancer drug bioavailability is improved effectively, therefore nano micelles as drug carriers in anticancer drug and gene therapy drug carrier for drug delivery has broad application prospects.At first, a kind of amphiphilic drug carrier compound mPEG-Cys-AFC was designed and synthetized, and L-cysteine was selected as a central core, connecting phenylacetyl which is sensitive to PGA enzyme,7-amino-4-trifluoromethylcoumarin (AFC) which is convenient for fluorescence tracking and polyethylene glycol (PEG) which can enhance water solubility through stable chemical bonds (amide, phenolic ester, amino ester) at amino, carboxyl and sulfydryl respectively, resulting in the amphiphilic compound which can release AFC triggered by PGA enzyme.The structure of all compounds was characterized by1H NMR,13C NMR and MALDI-TOF-MASS, and its1H NMR spectrum chart suggests that the target compound shows different patterns in aqueous and organic solutions. In order to confirm that the carrier compounds can self-assemble to form nanoparticles in aqueous solutions, the critical micelle concentration (CMC) was measured to be92.8mg/L(6.02×10-5mol/L) by pyrene fluorescence probe method.; dynamic light scattering (DLS) test results showed that the hydrodynamic diameter were87.7nm,55.3nm,39.5nm when the concentration of the water solution were0.5mg/mL,l mg/mL,1.5mg/mL, and the polydispersity index were0.350,0.342and0.355respectively.Then, the vitro enzymatic release experiment research was carried on. The carrier compound was prepared by the concentration of7.36×10-6mol/L (under the CMC)in phosphate buffer solution (pH=7.4), and we added PGA enzymes under the condition of37℃, traced the release process by fluorescence spectrometry, resulted in the successful release of fluorescent molecule coumarin (AFC), and it was remain stable in the absence of enzymes. And we determined the Km constant of PGA enzyme on the drug carrier which was27.3μM.The mPEG-Cys-AFC carrier compounds we synthesized have good solubility in water, which can self-assemble to form different sizes of nano micelle in aqueous solution, can also to achieve the purpose of intelligent targeting controlled release drug molecules by controlling enzyme, which have potential application value as drug carriers.