Adipose Tissue-Targeting Polypeptide-Verbascoside-Nanogold Particle Derivative, Preparation Method and Application Thereof

An adipose tissue-targeting polypeptide-verbascoside-nanogold particle derivative, wherein the derivative is prepared by a preparation method comprising:

• activating a carboxyl group of a cysteine residue at a C-terminus of an adipose tissue-targeting polypeptide to form an acyl chloride;
• wherein the adipose tissue-targeting polypeptide has an amino acid sequence of CKGGRAKDC;
• reacting a verbascoside with a sodium hydroxide to obtain a sodium phenolate;
• esterifying the acyl chloride with the sodium phenolate to form an adipose tissue-targeting polypeptide-verbascoside derivative;
• modifying nanogold particles with polyethylene glycol (PEG), mixing and reacting the adipose tissue-targeting polypeptide-verbascoside derivative with PEG-modified nanogold particles;
• wherein the sulfydryl of the cysteine residue at the C-terminus of the adipose tissue-targeting polypeptide is connected to the nanogold particles with an Au—S bond,
• wherein a first amino protecting group is connected to a side chain of a second amino acid residue of the adipose tissue-targeting polypeptide, and a second amino protecting group is connected to a seventh amino acid residue of the adipose tissue-targeting polypeptide;
• a guanidine protecting group is connected to the fifth arginine residue;
• a carboxyl protecting group is connected to the eighth amino acid residue;
• and a sulfhydryl protecting group is connected to the N-terminal amino acid residue;
• wherein the amino protecting group is a 9-fluorenylmethoxycarbonyl, the guanidine protecting group is an amantadyl-oxygen carbonyl, the carboxyl protecting group is a methyl ester, and the sulfhydryl protecting group is a triphenylmethyl;
• wherein a molar ratio of the adipose tissue-targeting polypeptide and the verbascoside is 1-5:1;
• wherein the step of modifying the nanogold particles with PEG further comprises:
• mixing the nanogold particles with SH-mPEG-COOH at 20-25° C.;
• stirring and incubating for 12-24 hours;
• and
• removing unreacted SH-mPEG-COOH after centrifugation and washing to obtain a precipitate, wherein the precipitate is the PEG-modified nanogold particles;
• and
• wherein a molar ratio of the adipose tissue-targeting polypeptide-verbascoside derivative and the PEG modified nanogold particles is 106:9−5.

A preparation method of an adipose tissue-targeting polypeptide-verbascoside-nanogold particle derivative, comprising:

• step (1), activating a carboxyl group of a cysteine residue at a C-terminus of an adipose tissue-targeting polypeptide to form an acyl chloride;
• wherein the adipose tissue-targeting polypeptide has an amino acid sequence of CKGGRAKDC;
• step (2), reacting a verbascoside with a sodium hydroxide to obtain a sodium phenolate;
• step (3), esterifying the acyl chloride with the sodium phenolate to form an adipose tissue-targeting polypeptide-verbascoside derivative;
• step (4), modifying nanogold particles with polyethylene glycol (PEG), mixing and reacting the adipose tissue-targeting polypeptide-verbascoside derivative with PEG-modified nanogold particles;
• wherein the sulfydryl of the cysteine residue at the C-terminus of the adipose tissue-targeting polypeptide is connected to the nanogold particles with an Au—S bond;
• the step (1) further including:
• dissolving the polypeptide in Dimethyl Sulfoxide (DMSO) to form a polypeptide solution;
• adding the polypeptide solution into a bottle, dripping N, N-dimethylformamide (DMF) and thionyl chloride into the bottle and stirring evenly;
• and reacting at 70-75° C. for 1-2 hours to obtain the acyl chloride.
• the step (2) further including:
• dissolving the verbascoside and the sodium hydroxide in methanol respectively to form two solutions;
• mixing the two solutions;
• reacting at room temperature to generate the sodium phenolate;
• wherein a chemical structure formula of the verbascoside is
• wherein a molar ratio of the verbascoside to the sodium hydroxide is 1:4;
• the step (3) further including:
• dissolving the sodium phenolate obtained in the step (2) in first deionized water to form a sodium phenolate solution;
• dripping the acyl chloride obtained in the step (1) into the sodium phenolate solution;
• stirring and reacting at 10-15° C. for 1.5-2 hours;
• washing, suction filtering and drying to obtain adipose tissue-targeting polypeptide;
• wherein a molar ratio of the adipose tissue-targeting polypeptide obtained in the step (1) to the verbascoside obtained in step (2) is 1-5:1;
• and
• the step of modifying the nanogold particles with PEG further including:
• mixing the nanogold particles with a SH-mPEG-COOH solution at 20-25° C., stirring and incubating for 12-24 hours;
• removing unreacted SH-mPEG-COOH by centrifugation and washing to obtain a precipitate;
• dissolving the precipitate in second deionized water;
• wherein a molar ratio of the adipose tissue-targeting polypeptide-verbascoside derivative to the PEG modified nanogold particles is 106:9−5.