Nanoparticles in photodynamic therapy: an emerging paradigm

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Photochemistry

Background:

• Photodynamic therapy (PDT) is a key cancer treatment, but photosensitizers' hydrophobicity necessitates effective delivery systems.
• Existing classifications for PDT delivery systems focus on surface targeting molecules.
• Recent advancements include nanoparticles with active roles beyond simple carrier functions.

Purpose of the Study:

• To introduce a functional classification for nanoparticles used in photodynamic therapy.
• To distinguish between passive carriers and active participants in photosensitizer excitation.
• To categorize active nanoparticles based on their mechanistic roles in PDT.

Main Methods:

• Proposed a functional classification for nanoparticles in PDT.
• Differentiated nanoparticles into passive carriers and active participants.
• Sub-classified active nanoparticles into photosensitizer nanoparticles, self-illuminating nanoparticles, and upconverting nanoparticles.

Main Results:

• Introduced a novel classification system for PDT nanoparticles.
• Identified active nanoparticles as distinct from non-biodegradable carriers with extraneous functions.
• Highlighted three mechanistic sub-classes of active nanoparticles: photosensitizer, self-illuminating, and upconverting nanoparticles.

Conclusions:

• Active, second-generation PDT nanoparticles offer enhanced therapeutic potential.
• These nanoparticles may overcome limitations of traditional PDT, particularly for deep-seated tumors.
• Further research is needed to address challenges for clinical adoption of these advanced nanoparticles.