X-ray CT and pneumonia inhibition properties of gold-silver nanoparticles for targeting MRSA induced pneumonia.

Non-invasive assay for the early stage diagnosis of methicillin resistant Staphylococcus aureus (MRSA) related pneumonia is of great clinical importance and still a great challenge. In this paper, we reported a novel kind of Au@Ag core-shell theranostic nanoparticles (NPs) conjugated with MRSA specific antibody on their surface. Compared with the raw Au@Ag NPs, these antibody modified NPs (AAMA NPs) showed 10.66 fold enhancement targeting to the MRSA in vitro. In vivo target efficacy was measured with rats bearing pneumonia induced by different pathogens. Computed tomography (CT) results revealed that these AAMA NPs had higher CT contrast enhancement (498 HU), than those of raw Au@Ag and Omnipaque (oth <100 HU). In addition, lesions labeled by AAMA NPs could be distinguished from lung parenchyma by taking advantage of spectra CT. Bio-distribution analysis confirmed that these AAMA NPs accumulated in the MRSA rich site. Both BAL and Elisa assays indicated that these AAMA NPs greatly alleviated the inflammation reaction by reducing bacterial proliferation and cytokine production. Pathological study showed that these NPs exerted negligible long term cytotoxicity in vivo.