Analysis and Characterization of Complex Compound Gadolinium-(1,4,7,10-Tetraazacyclododecane,1-4-7-10- Tetraacetic Acid)n-Poliamidoamine Generation 3- Trastuzumab as a Novel Contrast Agent for Magnetic Resonance Imaging

Currently, cancer is one of the leading causes of death
worldwide. One type of cancer that women fear is
breast cancer. One tool that can be used for early
cancer detection is Magnetic Resonance Imaging
(MRI). MRI can diagnose cancer quickly compared to
other diagnostic techniques. One of the contrasting
compounds used to produce a good image in MRI is
Gd-DOTA. Gd-DOTA is a complex compound that can
be used as a contrasting compound recommended by
the Food and Drug Administration and the European
Medicines Agency.
Gd-DOTA is known to be a contrasting compound with
low toxicity potential, so its chemical stability is better
than other contrast compounds, but it is still less
specific when used to diagnose cancer, especially
HER-2 positive breast cancer, therefore research into
improving its contrasting capability needs to be done.
The purpose of this research was to synthesize complex
compounds (Gd-DOTA)n-PAMAM G3-trastuzumab.
DOTA-NHS ligand was conjugated with the dendrimer
PAMAM G3, then conjugated with a protein
trastuzumab. The resulting DOTA-PAMAM G3-
trastuzumab was finally conjugated with gadolinium.
Characterization using the UV-Vis spectrophotometric
method obtained specific wavelength for (Gd-DOTA)nPAMAM
G3-trastuzumab at 254 nm.
The bounding functional groups were characterized
using FT-IR spectrophotometry, obtaining the specific
wavelengths for Gd-O at 500.26 cm-1
and Gd-N at
415.79 cm-1
. The number of Gd-DOTA attached to
PAMAM G3-trastuzumab was determined by HPLC to
be 2 pieces. The determination of free Gd3+ was done
using a UV-Vis spectrophotometer with xylenol orange
indicator and the result is 0.4594 ppm in (Gd-DOTA)nPAMAM
G3-trastuzumab.
Keywords: Cancer, DOTA, Magnetic Resonance Imaging,
PAMAM G3, Trastuzumab.