ABSTRACT
Photoactivation has garnered tremendous interest in the last decade, with widespread applications ranging from medicine to energy harvesting and even wastewater treatment. This increasing interest stems from the fact that photoactivation allows the use of light-a noninvasive, spatially, and temporally controllable stimulus to achieve specic outcomes. This is particularly useful for therapeutic applications where specicity and safety are a major concern. With the use of light, therapy can be targeted, reducing side effects and improving efcacy of treatment. In addition, the ability to control
CONTENTS
9.1 Introduction: Need for NIR-Based Phototherapy .................................255 9.2 Photoinduced ROS Production ................................................................ 257
9.2.1 Photodynamic Therapy ................................................................. 257 9.2.1.1 PSs for PDT ...................................................................... 259 9.2.1.2 UCNPs for PDT: Host Matrix, Dopants, and
Surface Coatings .............................................................. 261 9.2.1.3 PS Loading Strategies .....................................................264 9.2.1.4 In Vitro and In Vivo PDT Using UCNPs ....................... 266
9.2.2 Photochemical Internalization ..................................................... 268 9.2.2.1 Photosensitive Chemicals for PCI ................................. 270
9.3 Photocontrolled Release of Molecules .................................................... 272 9.3.1 Photolabile Groups in Photocontrolled Delivery ...................... 272 9.3.2 UCNP-Based Phototriggered Release In Vitro and In Vivo ...... 274
9.4 Photothermal Therapy ..............................................................................277 9.4.1 UCNP-Based PTT ........................................................................... 278
9.5 UCNPs in Combination Therapy ............................................................. 279 9.6 Limitations of UCNPs ............................................................................... 281 9.7 Conclusion and Outlook ...........................................................................283 References .............................................................................................................284
parameters such as wavelength, intensity, and duration of exposure, provide an added degree of control. To this end, phototherapies such as photodynamic therapy (PDT), photothermal therapy (PTT), photocontrolled release of drugs/nucleic acids, and combination therapies involving synergistic use of two or more of the previous techniques have come to the fore.
