Page 145 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

6.3 Photodynamic therapy 143

of PDT on carcinoma cells using chlorins photosensitizers in animal models. Their
results demonstrated complete cell ablation in in vitro model and tumor shrinkage in
in vivo model a week after PDT [45]. Despite having very good features in PDT ther-
apy, chlorins need to be incorporated in a delivery system to improve its accumula-
tion and blood circulation time such as chitosan, silica, and polymeric nanoparticles.

6.3.4 Curcumin
Curcuma longa L. dived polyphenolic compound, curcumin has been investigated for
a variety of applications including cancer treatment, antimicrobial diseases, wound
treatment, and joint inflammation. Curcumin with a wide absorption spectrum from
300 to 500 nm has a strong potential as a photosensitizer especially for superficial
infections [46] and superficial tumors such as oral cavity and skin [46]. Owing to
poor penetration depth, curcumin is not a good photosensitizer for deeper lesion.
One of the main drawbacks of using curcumin in PDT is its poor solubility leading
to poor bioavailability and low pharmacological outcomes. To tackle this challenge,
nanotechnology has been applied to improve aqueous solubility. In 2012, Mohan Yal-
lapu et al. encapsulated curcumin into cellulose nanoparticles and studied the effect
of curcumin assisted PDT in prostate cancer treatment [47].

6.3.5 Phthalocyanines
Phthalocyanines are one of the second generations of photosensitizers consists of
four isoindole groups attached together in a larger ring. It has unique properties
including ease of synthesis and modification, high stability, long and strong absorp-
tion wavelength and high yield of free radical production. The physiochemical prop-
erties can be modified either by substitution of cationic metals in the core or by
peripheral modifications to synthesis hybrid photosensitizer. Although phthalocya-
nines have great potentials for photosensitizer, they suffer from lack of tumor specify
which can be tackled by conjugating to tumor-targeting peptides or incorporating
into nanoparticles. Muehlmann et al. incorporated aluminum-phthalocyanine chlo-
ride into poly(methyl vinyl ether-co-maleic anhydride) nanoparticles leading to 10
times increase in PDT potential compared to its free form [48].

6.3.6 Hypericin
Hypericin is a red plant pigment being applied in traditional medicine for centuries.
There is an evidence indicating hypericin has a potential to treat cancer, depression,
and viral. Hypericin can be considered for PDT due to several excellent properties,
including light absorption spectrum near to NIR, high yield of free radical produc-
tion and tumor selectively, low toxicity, high stability. Several studies examined
the application of hypericin for PDT. Kleeman et al. studied the application of
hypericin assisted PDT for destroying melanoma cells [49]. In another study, Bara-
than et al. examined the effect of hypericin to kill hepatocellular carcinoma cells