Pandia: Gold Nanorods and Their Applications in Cancer Therapy and In Vivo Imaging in Companion Animals and Their Potential Application to Humans - Nanotechnology for Biomedical Imaging and Diagnostics - page 349

12.3 PhoToThermal imaGinG and TheraPy In VIVo

12.3.1 efficacy in mice

There have been a number of studies conducted using Nanopartz AuNRs that have
shown efficacy in cancer tumor therapy [16, 29]. Using PeGylated Nanopartz AuNRs
(PeG-NRs), Maltzahn et al. [10] determined that:

1. PeG-NRs were highly stable in vitro , showing minimal spectral shifting
(which would indicate particle destabilization and aggregation) even after
greater than 1000 h in 0.15 mol/l NaCl or 10% human serum and highly
biocompatible.
2. PeG-NRs exhibited less than 1/3 of the spectral bandwidth and approximately
three times higher extinction coefficient per gram of gold than PeG-
nanoshells. Additionally, under identical experimental conditions, irradiated
PeG-NR solutions generated heat greater than six times more rapidly than
PeG-nanoshells per gram of gold.
3. In order for PeG-NRs to passively target tumors via the enhanced permeability
and retention (ePR) effect and act as nanoantennas for photothermal therapy,
they must be able to traverse the systemic circulation, deter protein opsonization
and reticuloendothelial system (ReS) clearance, permeate through transendothe-
lial pores in tumor blood vessels, and be retained in the tumor interstitium. After
IV administration to tumor-bearing mice (20 mg Au/kg), Nanopartz PeG-NRs
were found to exhibit blood half-lives of approximately 17 h and to maintain
their 810 nm longitudinal plasmon resonance throughout this period, allowing
spectrophotometric detection in the serum over time (Fig. 12.7).

1

0.9

0.1 h
1 h
3 h
7 h
22 h

0.8

0.7

0.6

Hemoglobin

0.5 Ntracker TM Nanorods

Water

0.4

0.3

0.2

0.1

0

450 550 650 750

Wavelength (nm)

850 950

FiGure 12.7 UV-Vis absorption of mice blood over 22 h after IV injection of Nanopartz

nanorods.