Hyperspectral molecular imaging of multiple receptors using immunolabeled plasmonic nanoparticles.

This work presents simultaneous imaging and detection of three different cell receptors using three types of plasmonic nanoparticles (NPs). The size, shape, and composition-dependent scattering profiles of these NPs allow for a system of multiple distinct molecular markers using a single optical source. With this goal in mind, tags consisting of anti-epidermal growth factor receptor gold nanorods, anti-insulin-like growth factor 1-R silver nanospheres, and human epidermal growth factor receptor 2Ab gold nanospheres were developed to monitor the expression of receptors commonly overexpressed by cancer cells. These labels were chosen because they scatter strongly in distinct spectral windows. A hyperspectral darkfield microspectroscopy system was developed to record the scattering spectra of cells labeled with these molecular tags. Simultaneous monitoring of multiple tags may lead to applications such as profiling of cell line immunophenotype and investigation of receptor signaling pathways. Single, dual, and triple tag experiments were performed to analyze NP tag specificity as well as their interactions. Distinct resonance peaks were observed in these studies, showing the ability to characterize cell lines using conjugated NPs. However, interpreting shifts in these peaks due to changes in a cellular dielectric environment may be complicated by plasmon coupling between NPs bound to proximal receptors and other coupling mechanisms due to the receptors themselves.