Cancer Nanotheranostics - Cancer Nanotheranostics - page 24

Fig. 13 QUaPS as an inducer and ratiometric sensor of caspase activation. a Fluorometric con-
focal microscope image of a 2 ʼ M QUaPS solution, with or without proteolytic digestion. Num-
bers represent the Rox:Pyro average intensity ratio for the solution. FRET ratio legend is indi-
cated. Scale bars represent 20 ʼ m. b Induction of cell death and ratiometric imaging of caspase
activation. Cells were incubated with 5 ʼ M QUaPS and treated as indicated. Confocal micros-
copy was used to image the cells 2 h later. c Single cell analysis of caspase activation. Error bars
show mean std. dev. for 30 cells for each group from 3 separate experiments. Adapted from
Lovell et al., with permission from American Chemical Society. Copyright 2011
which leads to the switching of light into heat. Excessive off-target damage
was prevented by excellent spatial control due to localized heating given to the
areas into which the Photothermal therapy (PTT), agent and applied light over-
lap (Welch 1984). PTT, a hyperthermia based cancer therapeutic methodology,
has become one of the research interest due to its minimal invasiveness, reason-
able penetrating depth, and good controllability as shown in Fig. 15 (Chen et al.
2005, 2007). With the help of photo-absorbing agents, near-infrared (NIR) light
penetrating into the tumor region can be converted into heat for specific ablation
of cancer cells without damaging nearby healthy tissues. Another method for
controlling PTT damage is via the directed application of light. Light is applied
typically through laser fibres for PTT. Proper positioning of the laser fibers is of
the principle importance to maximize the deposition of energy in target tissues
while minimizing off target heating.
In the area of nanomedicine PTT has received attention seeking to exploit
its effect. Majority of the PTT agents explored to date are based on inorganic