Biomedical Engineering Reference
In-Depth Information
A modified form of PEG, PEAMA was utilized as pH responsive theranos-
tic nanogel for delivery of gold nanoparticles to mediate photodynamic cancer
therapy. The complexes were targeted to cancer cells by functionalizing its sur-
face with Asp-Glu-Val-Asp (DEVD) peptide. Apart from this a fluorescent dye
fluorescein iosothiiocynate (FITC) was also tagged to the terminal PEG chains
in the nanogel. The gold nanoparticle acted as FITC fluorescence quencher when
the system is intact whereas when predisposed to caspase-3 enzyme the peptide is
cleaved leading to release of FITC from the complex and simultaneous enhance-
ment in fluorescence is observed after being separated from quencher (gold nano-
particle) (Oishi et al. 2009).
Another PEG based micelle system for delivery of doxorubicin has been lately
reported by Lin et al. wherein an imaging agent (DiD) was also coupled for diag-
nosis and therapy of bladder cancer. In order to target the system efficiently a
cancer specific ligand (PLZ4) is also grafted onto the surface PEG moieties (Lin
et al. 2012).
In an attempt to generalize a specific PEG based carrier for various hydrophobic
anticancer drugs like doxorubicin, KRN 5500 and capmptothecin a poly(ethylene
glycol)-poly(bbenzyl L-aspartate) (PEG-PBLA) micellelar system is evaluated
separately for their anti-cancer efficacies (Kataoka et al. 2006; Opanasopit et al.
2004; Watanabe et al. 2006). Recently, a PEG based theranostic system for deliv-
ery of anticancer drug doxorubicin and MRI contrast iron oxide nanoparticles
(SPIONs) was reported by Karine et al. The targeting ligand, folic acid was also
conjugated to the PEG terminal on the surface of the theranostic system so as to
improve its efficacy. A complete study of physiochemical characteristics of thus
synthesized theranostic system confirmed the distribution and interaction between
different components of the system. The presence of folic acid on the surface
enhanced drug internalization in MCF-7 (breast cancer cells) which was also com-
plemented by SPION mediated localized hyperthermia (Karine et al. 2012).
In a different approach double emulsion technique was utilized to fabricate
nanocapsules for combined delivery of ZnS:Mn QDs and an anticancer drug
camptothecin to A549 cells. In order to render them specificity for cancer cells an
anti-EGF receptor antibody (cetuximab) was also functionalized to its surface. The
ZnS:Mn QDs luminescence of the system was employed for simultaneous imag-
ing of cells (Deepagan et al. 2012). In a recent article by Peng et al. PEG-PCL
micelles were used for delivery of IR-780 iodide and
188
Re which simultaneously
provided NIR fluorescence and nuclear imaging. The
188
Re complexes mediated
photothermal therapy at the cancer site and the therapeutic outcomes that follow
were monitored in real time by fluorescence studies (Fig.
1
) (Peng et al. 2011).
A pH dependant doxorubicin release system was devised by Zou et al. where
PEGylated superparamagnetic iron oxide (SPIO) nanoparticles were surface
functionalized with cancer specific HuCC49
ʔ
CH2 antibody and fluorescent dye
5-FAM. A modified version of doxorubicin i.e. azido-doxorubicin was entrapped
in the PEG moieties attached to the surface of SPIONs. The sessile pH depend-
ent azide bond introduced in the drug enables the theranostic system to release
