Biomedical Engineering Reference
In-Depth Information
ZnO-(L-cysteine)-H
2
TPP(NH
2
) and ZnO-H
2
TPP(NH
2
), and the efficiency became
smaller by diluting the system by adding diethylene glycol. This clearly indicates
that the energy transfer occurs by the collisions of the ZnO particles with porphy-
rins in the dispersion. ZnO and TPP do not bound with each other because
L-cysteine is not bound to the ZnO particles.
When ZnO nanoparticles are combined with drugs or photosensitizers, the
related cytotoxicity of anticancer agents on cancer cells seems enhanced, suggest-
ing that ZnO nanoparticles could play an important role in drug delivery. This may
offer the possibility of the great potential and promising applications of the ZnO
nanoparticles in clinical and biomedical areas like photodynamic cancer therapy
and others.
7
Miscellaneous
7.1
Mg-Al Hydroxides
Kantonis et al. (
2007
) proposed Mg-Al layered double hydroxides nanohybrids to
produce biocompatible nanomaterials for application in PDT. Protoporphyrin IX
(Fig.
7
) was thus encapsulated and used as the PDT drug. To maintain high oxygen
concentration in solution, the authors have also co-encapsulated perfluoroheptanoic
acid (PFHA), a non-toxic perfluorocarbon rapidly eliminated from the body.
Indeed, perfluorocarbons can dissolve 20 times more oxygen than water. PFHA
formed a bilayer between the inorganic layers of the nanohybrid, in addition to the
intercalation of PpIX. 10% (w/w) of PpIX were immobilized in the nanohybrid.
The photocatalytic activity was shown by oxidation of imidazole, 2,3-dimethyl-2-
butene and linoleic acid. The oxidation of hydrophobic linoleic acid was much
faster with PFHA-PpIX-modified nanohybrid than PpIX alone whereas the oxida-
tion of water soluble imidazole was much faster with PpIX. Thus, Mg-Al layered
double hydroxides nanohybrids are promising for PDT.
7.2
Calcium Phosphate
Epple's group (Epple et al.
2010
) have functionalized Ca-phosphate nanoparticles
with different polymers and photosensitizers were incorporated into that layer.
The calcium phosphate nanoparticles were prepared by rapid precipitation from
water with polymers to stabilize the nanoparticles. The polymers used were poly-
styrene sulfonic acid (PSS), polyallylamine hydrochloride, carboxymethylcellu-
lose (CMC), polyethylene imine. The layer by layer technique was used to coat
the negatively charged nanoparticles (PSS and CMC) with polyallylamine hydro-
chloride in the case of PSS, polyethylene imine in the case of CMC. mTHPP
(Fig.
43
) and Methylene Blue (Fig.
11
) were used as photosensitizers. Whatever
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