Radiosensitizer-eluting nanocoatings on gold fiducials for biological in-situ image-guided
radio therapy (BIS-IGRT)
Image-guided radiation treatments (IGRT) routinely utilize radio-opaque implantable
devices, such as ﬁducials or brachytherapy spacers, for improved spatial accuracy.
The therapeutic efﬁciency of IGRT can be further enhanced by biological in situ
dose painting (BIS-IGRT) of radiosensitizers through localized delivery within the
tumor using gold ﬁducial markers that have been coated with nanoporous polymer matrices
loaded with nanoparticles (NPs). In this work, two approaches were studied: (i)
a free drug release system consisting of Doxorubicin (Dox), a hydrophilic drug,
loaded into a non-degradable polymer poly(methyl methacrylate) (PMMA) coating and
(ii) poly(D,L-lactic-co-glycolic acid) (PLGA) NPs loaded with ﬂuorescent Coumarin-6,
serving as a model for a hydrophobic drug, in a biodegradable chitosanmatrix. Temporal
release kineticsmeasurements in bufferwere carried out using ﬂuorescence spectroscopy.
In the ﬁrst case of free Dox release, an initial release within the ﬁrst few hours
was followed by a sustained release over the course of the next 3 months. In the
second platform, release of NPs and the free drug was controlled by the degradation
rate of the chitosan matrix and PLGA. The results show that dosage and rate of release
of these radiosensitizers coated on gold ﬁducials for IGRT can be precisely tailored
to achieve the desired release proﬁle for radiation therapy of cancer.