Nanoparticles for Photodynamic Therapy Applications - Intracellular Delivery: Fundamentals and Applications - page 520

Fig. 8 Indocyanine green

N N

SO 3 SO 3

Fig. 9 Toluidine blue O

H 3 C N

CH 3

H 2 N S N

CH 3

Cl

bromide surfactant coating and conjugated indocyanine green (Fig. 8 ) or toluidine
blue O (Fig. 9 ) on the surface of the Au via respectively PSMA (poly(styrene- alt -
maleic acid)) or PAA (polyacrylic acid). In both cases, the authors showed that the
nanorods have been successfully prepared and can be used as photodynamic and
hyperthermia agents with improved photodestruction efficacy compared to PDT or
hyperthermia alone.

3 Silica Nanoparticles

3.1 Non Covalent Encapsulation of PS in Silica Nanoparticles

3.1.1 Silica Nanoparticles for PDT

Following the pioneering work of Prasad and Kopelman groups (Roy et al. 2003 ;
Yan and Kopelman 2003 ), several researchers have tried to encapsulate PS inside
silica nanoparticles in order to vectorize them in cancer cells. In 2003, the precursor
work of Kopelman lead to the encapsulation of meso meta-tetra(hydroxyphenyl)
chlorin ( m- THPC, Fig. 10 ), or Foscan®, a medicinal product used clinically, into
silica nanoparticles (Yan and Kopelman 2003 ).
To avoid the leaching of the PS from the silica matrix, the synthesis was per-
formed by first using aminopropyltriethoxysilane as the reagent, then by initiating
hydrolysis polycondensation of tetramethylorthosilicate. Increased amount of
hydrogen bonds between PS and amino groups were probably involved to explain
the higher efficiency of the encapsulation process than the Stöber procedure. An
average nanoparticle diameter of 180 nm was calculated by SEM. A good spectral
(UV-vis) correspondance between free and embedded m -THPC was observed. To