Spotlight on the delivery of photosensitizers: different approaches for photodynamic-based therapies

ABSTRACT

Introduction: Nanomedicine development allowed the discovery of new photosensitizers (PS) and drug delivery systems (DDS) to overcome current issues on phototherapy. Nano-engineered materials have the potential to improve the solubility of PS, control drug pharmacokinetics, decreasing side effects, increasing bioavailability, and overcoming multidrug resistance. A recent approach is the co-delivery of PS with other therapeutic agents in a multimodal platform for synergic and improved results.

Areas covered: This paper discusses the delivery of PS-nanostructured platforms for conventional, photothermal, and antimicrobial photodynamic therapies, as well as in a recent therapeutic modality for photobiomodulation, covering applications of cancer diagnosis, targeting to skin pathogens, photoregeneration and wound healing. The focus of the present review is to describe the use of different DDS to enhance the therapeutic outcomes triggered by the combination of delivered PS, light, and oxygen.

Expert opinion: Nanotechnology allowed the development of site-specific delivery of PS molecules, expanding possibilities poorly explored before to enhance photodynamic efficacy and extrapolate the concept to other treatment protocols. Research in this area embraces potential and pitfalls of PS delivery, allowing new clinical phase outcomes and long-term issues to be established, which will impact on several biomedical applications.

KEYWORDS:

• Drug delivery systems
• nanotechnology
• photoprocesses
• photosensitizers

Article highlights

• Nanotechnology strategies for photosensitizer delivery consist on rational design of systems with special ligands and specific functions for selective delivery and enhanced therapeutic outcomes.

• In Photodynamic Therapy, recent development has focused on ‘all-in one approach’ aiming the use of multifunctional nanostructures for multimodal therapies applications;

• Similar strategy has been used in Phototermal Therapy with single photosensitizer-based theranostic nanoplatforms for simultaneous PDT/PTT agents excitation;

• Photosensitizing agents/DDS for Antimicrobial Photodynamic Inactivation are based on cationic character and other favorable characteristics to increase permeability in microbial membrane;

• In Regenerative Medicine, Low Power Photodynamic Therapy uses photo-agents to allow maximum tissue penetration of light and increase cells proliferation.

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Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Additional information

Funding

ACT research supported by grants from the Brazilian agencies Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP Thematic Project [# 2013/50181-1] and [FINEP 01.10.0758.01], and CNPq Universal [472423/2013-4].