Environmentally compatible bioconjugated gold nanoparticles as efficient contrast agents for inflammation-induced cancer imaging

Abstract

For many cancers, early detection is the key to improve survival and reduce the morbidity, which is associated with radical resections due to late diagnosis. Here, we describe the efficiency of primary antibody-conjugated gold nanoparticles (AuNPs) to specifically target chronic inflammatory processes, specially M2 macrophages, in tissue sections of ulcerative colitis (UC) and steatohepatitis in rats which may lead to colorectal cancer and liver carcinoma, respectively. In this study, we demonstrate that AuNPs synthesized by a simple, inexpensive, and environmentally compatible method can be easily conjugated with the antibodies anti-COX-2, anti-MIF, and Alexa Fluor® 488 (ALEXA) to perform immunofluorescence staining in inflamed tissues. Moreover, we showed that primary antibody-conjugated gold nanoparticles (AuNPs) can be used to target M2 macrophages by flow cytometry. We designed three immunofluorescence staining protocols of tissue section with AuNPs for 30 min and overnight incubation, as well as one flow cytometry protocol of M2 macrophage labeling with AuNPs for 30 min. Immunofluorescence and flow cytometry results suggest that conjugation was achieved by direct adsorption of antibodies on the AuNPs surface. When compared to the standard ALEXA protocol in immunofluorescence (IF) and flow cytometry (FC), our 30-min incubation protocol using AuNPs instead of ALEXA decreased from approximately 23 h to 5 h for IF and from 4 h to 1 h for FC, proving to be less laborious, which makes the method eligible for inflammation-induced cancer diagnostic.

Development of a Theoretical Model That Predicts Optothermal Energy Conversion of Gold Metallic Nanoparticles

“…This effect happening globally in a homogenous NP solution leads to an elevation in the temperature of the bulk solution harboring the NPs. 16−20 This physical property of the nanostructures has led to their applications in cancer imaging, 21 cancer cell ablation, 22 spectroscopic detection, 23 photothermal therapy, 24 and gene silencing. 25 In each one of these applications, depending on the desired conditions and aims, two forms of laser light [pulsed and continuous wave (CW)] have been used to supply optical energy at a specific wavelength.…”

“…Ultimately, this thermal energy produced causes an increase in the temperature of the surroundings of the nanostructure that diffuses away from the surface of the hot metallic NPs. This effect happening globally in a homogenous NP solution leads to an elevation in the temperature of the bulk solution harboring the NPs. − This physical property of the nanostructures has led to their applications in cancer imaging, cancer cell ablation, spectroscopic detection, photothermal therapy, and gene silencing …”