Nanotechnology offers a targeted approach to both imaging and treatment of cancer, the leading cause of death worldwide. Previous studies have found nanoparticles with a wide variety of coatings initiate an immune response leading to sequestration in the liver and spleen. In an effort to find a nanoparticle platform which does not elicit an immune response we created 43/44 nm gold or silver nanoparticles coated with biomolecules normally produced by the body, α-lipoic acid and the Epidermal Growth Factor (EGF), and have used mass spectroscopy to determine their biodistribution in mouse models, 24 hours following tail vein injection. Relative to controls, mouse EGF (mEGF) coated silver and gold nanoprobes are found at reduced levels in the liver and spleen. mEGF coated gold nanoprobes on the other hand do not appear to elicit any immune response, as they are found at background levels in these organs. As a result they should remain in circulation for longer and accumulate at high levels in tumors by the enhanced permeability retention (EPR) effect.
The purpose of this study was to explore the use of surface-enhanced Raman spectroscopy (SERS) to image the distribution of epidermal growth factor receptor (EGFR) in cells. To accomplish this task, 30-nm gold nanoparticles (AuNPs) tagged with antibodies to EGFR (1012 per mL) were incubated with cells (106 per mL) of the A431 human epidermoid carcinoma and normal human bronchial epithelial cell lines. Using the 632.8-nm excitation line of a He-Ne laser, Raman spectroscopy measurements were performed using a point mapping scheme. Normal cells show little to no enhancement. SERS signals were observed inside the cytoplasm of A431 cells with an overall enhancement of 4 to 7 orders of magnitude. Raman intensity maps of the 1450 and 1583 cm−1 peaks correlate well with the expected distribution of EGFR and AuNPs, aggregated following uptake by endosomes and lysosomes. Spectral features from tyrosine and tryptophan residues dominate the SERS signals.
Our aim is to create and validate a novel SERS-based nanoprobe for optical imaging of the epidermal growth factor
receptor (EGFR). Gold and silver nanoparticles (Au/AgNPs) of various sizes were synthesized and coupled to epidermal
growth factor (EGF) via a short ligand, α-lipoic acid (206 g/mol), which binds strongly to both Au and Ag nanoparticles
via its disulfide end group. We used carbodiimide chemistry to couple EGF to α-lipoic acid. These nanoprobes were
tested for binding affinity using Enzyme Linked ImmunoSorbent Assay (ELISA) and, in-vitro, using EGFRoverexpressing
A431 cells. The nanoprobes show excellent EGFR-specific binding. Time of Flight Mass Spectrometry
demonstrate the carbodiimide based linking of the carboxylic acid end-group of α-lipoic acid to one or more of the three
(terminal, or 2 lysine) amine groups on EGF. ELISA confirms that the linked EGF is active by itself, and following
conjugation with gold or silver nanoparticles. Compared with bare nanoparticles, UV-Vis spectroscopy of Ag-based
nanoprobes exhibit significant plasmon red-shift, while there was no discernable shift for Au-based ones. Dark field
microscopy shows abundant uptake by EGFR overexpressing A431 cells, and serves to further confirm the excellent
binding affinity. Nanoprobe internalization and consequent aggregation is thought to be the basis of enhanced light
scattering in the dark field images, supporting the notion that these nanoprobes should provide excellent SERS signals at
all nanoprobe sizes. In summary, novel EGFR-specific nanoprobes have been synthesized and validated by standard
assay and in cell culture for use as SERS optical imaging probes.
The purpose of this study is to explore the feasibility of using Surface Enhanced Raman Spectroscopy (SERS) to image
the distribution of Epidermal Growth Factor Receptor (EGFR) in cells. To accomplish this task, 30 nm gold
nanoparticles (AuNPs) tagged with antibodies to EGFR (10<sup>12</sup> per ml) are incubated with cells (10<sup>6</sup> per ml) of the A431
human epidermoid carcinoma cell line and normal human bronchial epithelial (NHBE) cells. Using the 632.8 nm
excitation line of a He-Ne laser, Raman spectroscopy measurements are performed using a point mapping scheme.
SERS signals are observed with an overall enhancement of 4-7 orders of magnitude. Raman intensity maps of the 1480
and 1583 cm<sup>-1</sup>
peaks correlate well with the expected distribution of AuNPs and EGFR. Normal cells show little to no
enhancement. The results therefore present a simple yet effective means to image EGFR over-expression.
We report a non-destructive in-line monitoring method developed for Cd diffusion into InP on SACM-APD structure. Photocurrent vs voltage measurement are taken directly via proving diffused diodes on a wafer. We demonstrate that there is linear correlation between punch-through voltages Vpt on the photo I-V curves and diffusion depth measured by SIMS and Polaron profiles. It has been established that Vpt can be extracted easily from I-V curves and used for re-diffusion to approach target depth.