We sought to develop dual-modality imaging probes using functionalized silica nanoparticles to target human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer cells and achieve efficient target imaging of HER2-expressing tumors. Polyamidoamine-based functionalized silica nanoparticles (PCSNs) for multimodal imaging were synthesized with near-infrared (NIR) fluorescence (indocyanine green (ICG)) and technetium-99m (^99mTc) radioactivity. Anti-HER2 antibodies were bound to the labeled PCSNs. These dual-imaging probes were tested to image HER2-overexpressing breast carcinoma cells. In vivo imaging was also examined in breast tumor xenograft models in mice. SK-BR3 (HER2 positive) cells were imaged with stronger NIR fluorescent signals than that in MDA-MB231 (HER2 negative) cells. The increased radioactivity of the SK-BR3 cells was also confirmed by phosphor imaging. NIR images showed strong fluorescent signals in the SK-BR3 tumor model compared to muscle tissues and the MDA-MB231 tumor model. Automatic well counting results showed increased radioactivity in the SK-BR3 xenograft tumors. We developed functionalized silica nanoparticles loaded with ^99mTc and ICG for the targeting and imaging of HER2-expressing cells. The dual-imaging probes efficiently imaged HER2-overexpressing cells. Although further studies are needed to produce efficient isotope labeling, the results suggest that the multifunctional silica nanoparticles are a promising vehicle for imaging specific components of the cell membrane in a dual-modality manner.

We propose a new approach to facilitate sentinel node biopsy examination by multimodality imaging in which radioactive and near-infrared (NIR) fluorescent nanoparticles depict deeply situated sentinel nodes and fluorescent nodes with anatomical resolution in the surgical field. For this purpose, we developed polyamidoamine (PAMAM)-coated silica nanoparticles loaded with technetium-99m (99mTc) and indocyanine green (ICG).

We investigated the effects of targeted functionalized silica nanoparticles on the radiosensitivity of cancer cells. Better control of the local concentration of silica nanoparticles may facilitate their use as an adjuvant in conjunction with ionizing radiation to target cancer cells while preventing damage to normal cells. Hyperbranched polyamidoamine (PAMAM) was grafted onto the surface of amorphous silica nanoparticles to functionalize them. The PAMAM-coated silica nanoparticles (PCSNs) were then conjugated with fluorescent dyes. Anti-HER2 antibodies were covalently attached to the labeled PCSNs. The HER2-overexpressing SK-BR3 breast cancer cell line was incubated in medium containing the PCSN probes. After incubation; the cells were exposed to X-ray radiation. Cells were counted in all samples using cell proliferation assays; and apoptotic cells were detected. The cell survival results showed that the combination of the targeted PCSN probes and radiation reduced the survival rate of SK-BR3 cells to a greater extent than when either PCSN probes, PCSNs or radiation were applied individually. The results also showed an increase in apoptosis in the SK-BR3 cells that internalized the PCSN probes and were then irradiated. Based on these data, PCSN probes act as specific radiosensitizing agents for HER2-overexpressing cells.

We previously reported the basic performance of a prototype small cadmium telluride (CdTe) γ-camera (SSGC) intended for use in radioguided surgeries. In this study, we sought to confirm the favorable previous results and to extend the preliminary findings to examine the efficacy of the SSGC in an animal study and a clinical setting for sentinel lymph node biopsy. Methods: The prototype SSGC (1,024 pixels; field of view, 44.8 × 44.8 mm), equipped with a parallel-hole collimator, was used in both animal and clinical studies. ^99mTc-phytate (18.5 MBq) was injected into the tongues and legs of 6 rabbits. In the clinical study, 74 MBq of ^99mTc-phytate was injected into peritumoral regions in 8 patients with oral cancer. The detection of hot nodes by the SSGC was compared with that by a conventional scintillation γ-camera (CGC). Results: The SSGC detected 29 hot nodes in images of 6 rabbits after injection. The number of hot nodes was the same as the number seen in CGC studies, but the CGC required a longer acquisition time to produce comparable images. There were no differences between the SSGC and the CGC in terms of activity ratios and hot node-to-background ratios. The biodistribution of ^99mTc-phytate in removed tissues was evaluated by contact radiography, and radioactivity was assayed with a γ-well counter. The mean ± SD radioactivity in specimens was 0.15% ± 0.15%, with a range of 0.01%–0.62%. In the clinical study, the SSGC detected 30 hot nodes with a 5- to 60-s acquisition time at 4 h after injection. The SSGC documented all hot nodes depicted by the CGC at 4 h after injection. Conclusion: The SSGC showed significant potential for the detection of sentinel lymph nodes in lymphoscintigraphy. The results of the studies suggested that the SSGC facilitates the exploration of hot nodes in sentinel lymph node biopsy.