A novel platform for high sensitivity determination of PbP2a based on gold nanoparticles composited graphitized mesoporous carbon and doxorubicin loaded hollow gold nanospheres.

Gold nanoparticles composite graphitized mesoporous carbon nanoparticles (GMCs@AuNPs) biocomposite with the signal amplification capability was successfully synthesized for use in an immunoassay for penicillin binding protein 2 a (PbP2a). The polyamidoamine (PAMAM) dendrimers were first electrodeposited onto the Au electrode can greatly increase the amount of the captured antibodies. Protein A was used to properly orientate immobilized antibody against PbP2a, which strongly improved specificity of the antigen-antibody binding. Hollow gold nanospheres (HGNPs) as effective nanocarriers have been synthesized by sacrificial galvanic replacement of cobalt nanoparticles capable of encapsulating doxorubicin (Dox). The obtained HGNPs@Dox bionanocomposite was used for further loading of detection antibody (Ab2) to form the HGNPs@Dox@Ab2 bioconjugate. Then, the differential pulse voltammetric signals related to the concentration of PbP2a for Dox could be detected, and the immunosensor exhibited a detection limit as low as 0.65 pg mL(-1) (at an S/N ratio of 3). The proposed method with an excellent differentiation ability showed high sensitivity and specificity. The morphologies and electrochemistry properties of the composites were investigated by scanning electron microscopy, electrochemical characterization, UV-visible absorption spectroscopy, fluorescence spectrophotometer and Malvern laser particle size analyzer, respectively. In addition, the basic approach described here would be applicable towards developing biodetection assays against other important targets. Moreover, the bioconjugate of HGNPs@Dox is also a promising pattern to delivery Dox in vivo for anticancer therapy.