Confocal micro Raman system in conjunction with our EGF-nanoprobes to image breast cancer via SERS (Surface Enhanced Raman Spectroscopy)

A number of cancers are characterized by overexpression of the Epidermal Growth Factor receptor (EGFR), a membrane protein which mediates cell growth, proliferation and differentiation in multiple tissues. Many epithelial tumors express high numbers of EGF receptors, and receptor levels are associated with poor clinical prognosis in cancers of the bladder, breast and lung. Therapies that target these receptors have shown promise and a monoclonal antibody with the trade name Herceptin is currently being used to treat breast cancer. However, the treatment is also associated with cardiac arrest. Anti-EGFR tagged with fluorescent probes and white light scattering from gold nanoparticles have successfully been used to image EGFR overexpression but with a maximum contrast factor of 10:1. In place of Anti-EGFR we have developed a protein linker composed of Epidermal Growth Factor (EGF), the ligand for EGFR, and a molecule containing a group with high affinity for noble metals to mediate the attachment of the protein to gold or silver nanoparticles, and have shown that contrast of 100:1 at 1450 cm-1 is possible. Once the protein is attached to the nanoparticles, imaging of A431 cancer cells and Normal Human Bronchial Epithelial (NHBE) cells can take place with Raman Spectroscopy, an inelastic laser light scattering technique. Surface Enhanced Raman Spectroscopy (SERS), caused by the proximity of the nanoparticles, should be visualized through intensity and possibly signature differences in the observed signal to differentiate the cancerous and normal cells. Formation of the preliminary protein linker has been successful. Optimization of the protein linker to increase the recovery is underway. Reduced EGF is the smallest tag specific for EGRF, and so our particles should have larger diffusion coefficient and enhanced penetration than Ant-EGFR linked nanoparticles. We will use your Confocal Micro Raman system in conjunction with our EGF-nanoprobes to image breast cancer via Surface Enhanced Raman Spectroscopy measurements of tissue available in the Laboratório de Espectroscopia Vibracional Biomédica. If successful, gold nanoshells or nanorods can be used access the NIR excitation window for effective tissue penetration of more than 10 mm; with spatial information obtained by spatially offset Raman spectroscopy (SORS). The primary research question is to determine whether surface enhanced Raman spectroscopy can be used to image EGFR overexpression associated with breast cancer? If so, what is the corresponding depth resolution? (AU)