Thiol Ligand Adsorption on Gold Nanoparticle Surfaces: Mathematical Models to Predict Optimal Concentration of Heterobifunctional Polyethylene Glycol for Horseradish Peroxidase Immobilization

摘要

Gold nanoparticles (GNPs) are often used in numerous applications, including diagnostics, drug delivery and treatment of diseases, given its physical features and excellent biocompatibility, where factors such as dispersion and stability are directly related to the its performance andefficiency. Mathematical models for experimental design can be very useful and contribute to predict optimal functionalization strategies. Therefore, the purpose of this work was to stabilize and functionalize GNPs of 40 nm and 80 nm and determine optimal concentrations of heterobifunctionalpolyethylene glycols (HS-PEG-NH2 3500 and 7500 g/mol). Mathematical models relating particle diameter, initial concentration and quantification of the polymers adsorbed for both varieties of thiol PEG was predicted. GNP were modified and subjected to the four different strategies employedin this study (strategy I and III with HS-PEG-NH2 3500; II and IV with HS-PEG-NH2 7500). Solutions with concentrations ranging from 30 to 200 ng/ml of enzyme horseradish peroxidase (HRP) were used as an alternative to gauge the efficiency of the evaluated strategies. A superior yield and efficacyof strategies I and II was observed, since the former had a capture capacity of up to 5 times when stabilized for 2 h and up to 6 times for 12 h. Regarding stability, the most promising strategy observed was number II for nanoparticles of 40 nm. Moreover, the mathematical models highlightedin this study were efficient in predicting behavior of colloidal solutions with sizes of 40 nm and 80 nm when in contact with different varieties of thiol PEG and may exempt new kinetic tests.