A quantitative comparison was made of the efficiency of conjugation of immunoglobulins G and gold nanoparticles obtained by the Turkevich-Frens method. The conjugates were synthesized by physical adsorption and covalent immobilization using orthopyridyl disulfide polyethylene glycol succinimidyl ester (OPSS-PEG-NHS). The study is conducted using an original method of determining the composition of protein nanoconjugates based on measuring the intrinsic fluorescence of tryptophan in the protein. The percentage of bound immunoglobulins was higher when using OPSS-PEG-NHS: 43% versus 22% for adsorption conjugation at an added IgG concentration of 2.3 μg/ml. After increasing the IgG concentration to 4.6 μg/ml, the percentage of binding immunoglobulins was close for the two methods of the conjugation: 26% and 22%, respectively, which may indicate the filling of the surface of the particles.Keywords: Gold nanoparticles, conjugates, tryptophan fluorescence, immunoglobulin
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