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 357

PeG is a polymer of ethylene oxide. PeG has a low toxicity and is used in a
variety of products [60]. It is the basis of a number of laxatives (e.g., macrogol-
containing products, such as Movicol and PeG 3350, or SoftLax, MiraLAX, or
GlycoLax). It is the basis of many skin creams, frequently combined with glycerin.
When attached to various protein medications, PeG allows a slowed clearance of the
carried protein from the blood. This makes for a longer-acting medicinal effect and
reduces toxicity, and it allows longer dosing intervals. examples include PeG-
interferon alpha, which is used to treat hepatitis C, and PeG-filgrastim (Neulasta),
which is used to treat neutropenia. It has been shown that PeG can improve healing
of spinal injuries in dogs [61]. One of the earlier findings that PeG can aid in nerve
repair came from the University of Texas [62]. PeG is commonly used to fuse B cells
with myeloma cells in monoclonal antibody production. PeG has recently been
proved to give better results in constipation patients than tegaserod [63].
In research, PeG when labeled with an NIR fluorophore has been used in preclin-
ical work as a vascular agent, lymphatic agent, and general tumor imaging agent by
exploiting the ePR effect of tumors [64]. high-molecular-weight PeG, for example,
PeG 8000, has been shown to be a dietary preventive agent against colorectal cancer
in animal models [65]. The chemoprevention database shows it is the most effective
agent to suppress chemical carcinogenesis in rats. Cancer prevention in humans has
not yet been tested in clinical trials. The injection of PeG 2000 into the bloodstream
of guinea pigs after spinal cord injury leads to rapid recovery through molecular
repair of nerve membranes [66]. The effectiveness of this treatment to prevent para-
plegia in humans after an accident is not known yet. Research is being done in the use
of PeG to mask antigens on red blood cells. Various research institutes have reported
that using PeG can mask antigens without damaging the functions and shape of the
cell. PeG is being used in the repair of motor neurons damaged in crush or laceration
incidence in vivo and in vitro . When coupled with melatonin, 75% of damaged sciatic
nerves were rendered viable [67]. Most importantly, gene therapy vectors (such as
viruses) can be PeG coated to shield them from inactivation by the immune system
and to detarget them from organs where they may build up and have a toxic effect
[68]. The size of the PeG polymer has been shown to be important, with large poly-
mers achieving the best immune protection.

12.4.3 PeG-coated Gold nanoparticles in mice

There are no reports of any examples of toxicity associated with gold nanoparticles
at any dosage. Five published journal papers were found that studied the toxicology
of PeG-Au nanoparticles in mice. None found any signs of cytotoxicity. Organ
biodistribution depended heavily on size—35% clearance from major organs after
120 days.
In Reference [16], over 20 mice were used in the study and were injected with
100 μgAu/g of body weight. The biodistribution showed 57% spleen, 10% liver, less
than 5% in kidney, lung, heart, muscle, brain approximately 7% Id/g to tumor. The
mice showed no signs of neither stress nor weight loss up to and after 6 months after
injection.