Covalently linked Au nanoparticles to a viral vector: potential for combined photothermal and gene cancer therapy

Immuno gold nanocages with tailored optical properties for targeted photothermal destruction of cancer cells

Gold nanocages with a relatively small size (e.g., approximately 45 nm in edge length) have been developed, and the structure of these nanocages was tailored to achieve strong absorption in the near-infrared (NIR) region for photothermal cancer treatment. Numerical calculations show that the nanocage has a large absorption cross section of 3.48 x 10(-14) m(2), facilitating conversion of NIR irradiation into heat. The gold nanocages were conjugated with monoclonal antibodies (anti-HER2) to target epidermal growth factor receptors (EGFR) that are overexpressed on the surface of breast cancer cells (SK-BR-3). Our preliminary photothermal results show that the nanocages strongly absorb light in the NIR region with an intensity threshold of 1.5 W/cm(2) to induce thermal destruction to the cancer cells. In the intensity range of 1.5-4.7 W/cm(2), the circular area of damaged cells increased linearly with the irradiation power density. These results suggest that this new class of bioconjugated gold nanostructures, immuno gold nanocages, can potentially serve as an effective photothermal therapeutic agent for cancer treatment.

Thermal scalpel to target cancer

Nanotechnology is increasingly applied to the field of medicine, particularly for the treatment of cancer. In this regard, gold nanoparticles can mediate hyperthermia induction and kill tumor cells upon laser irradiation, thereby functioning as a 'thermal scalpel'. Recent developments in gold nanoparticle design have resulted in their absorption of energy in the near-infrared wavelength spectrum, which is best suited to tissue penetration and, thus, clinical application. Furthermore, to ensure accumulation of nanoparticles in neoplastic tissue, targeting ligands are being incorporated into the thermal scalpel schema. Examples of targeting ligands include antibodies and targeted gene therapy vectors. Therapeutic efficacy has been established in cell culture models for several developed thermal scalpel systems and a small number have demonstrated a therapeutic effect in animal models of cancer. Future considerations include analysis of the biodistribution and therapeutic efficacy of thermal scalpels using stringent models of cancer. Furthermore, the immunogenicity and toxicity of thermal scalpels must be established before clinical translation can be achieved.

Advances in small animal mesentery models for in vivo flow cytometry, dynamic microscopy, and drug screening

Using animal mesentery with intravital optical microscopy is a well-established experimental model for studying blood and lymph microcirculation in vivo. Recent advances in cell biology and optical techniques provide the basis for extending this model for new applications, which should generate significantly improved experimental data. This review summarizes the achievements in this specific area, including in vivo label-free blood and lymph photothermal flow cytometry, super-sensitive fluorescence image cytometry, light scattering and speckle flow cytometry, microvessel dynamic microscopy, infrared (IR) angiography, and high-speed imaging of individual cells in fast flow. The capabilities of these techniques, using the rat mesentery model, were demonstrated in various studies; e.g., real-time quantitative detection of circulating and migrating individual blood and cancer cells, studies on vascular dynamics with a focus on lymphatics under normal conditions and under different interventions (e.g. lasers, drugs, nicotine), assessment of lymphatic disturbances from experimental lymphedema, monitoring cell traffic between blood and lymph systems, and high-speed imaging of cell transient deformability in flow. In particular, the obtained results demonstrated that individual cell transportation in living organisms depends on cell type (e.g., normal blood or leukemic cells), the cell’s functional state (e.g., live, apoptotic, or necrotic), and the functional status of the organism. Possible future applications, including in vivo early diagnosis and prevention of disease, monitoring immune response and apoptosis, chemo- and radio-sensitivity tests, and drug screening, are also discussed.

Biomedical applications of plasmon resonant metal nanoparticles

The strong optical absorption and scattering of noble metal nanoparticles is due to an effect called localized surface plasmon resonance, which enables the development of novel biomedical applications. The resonant extinction, which can be tuned to the near-infrared, allows the nanoparticles to act as molecular contrast agents in a spectral region where tissue is relatively transparent. The localized heating due to resonant absorption, also tunable into the near-infared, enables new thermal ablation therapies and drug delivery mechanisms. The sensitivity of these resonances to their environment leads to simple affinity sensors for the detection of low-level molecular analytes. Coupled with their general lack of toxicity, these applications suggest that noble metal nanoparticles are a highly promising class of nanomaterials for new biomedical applications.