Light Technology for Efficient and Effective Photodynamic Therapy: A Critical Review

Abstract

Photodynamic therapy (PDT) is a cancer treatment with strong potential over well-established standard therapies in certain cases. Non-ionising radiation, localisation, possible repeated treatments, and stimulation of immunological response are some of the main beneficial features of PDT. Despite the great potential, its application remains challenging. Limited light penetration depth, non-ideal photosensitisers, complex dosimetry, and complicated implementations in the clinic are some limiting factors hindering the extended use of PDT. To surpass actual technological paradigms, radically new sources, light-based devices, advanced photosensitisers, measurement devices, and innovative application strategies are under extensive investigation. The main aim of this review is to highlight the advantages/pitfalls, technical challenges and opportunities of PDT, with a focus on technologies for light activation of photosensitisers, such as light sources, delivery devices, and systems. In this vein, a broad overview of the current status of superficial, interstitial, and deep PDT modalities—and a critical review of light sources and their effects on the PDT process—are presented. Insight into the technical advancements and remaining challenges of optical sources and light devices is provided from a physical and bioengineering perspective.

Photodynamic Therapy: A Compendium of Latest Reviews

“…To our knowledge, there is no dedicated review of implants for PDT. A section devoted to the description and critical review of selected implants can be found in a recent review of light technology for PDT [230].…”

Redox-Sensitive and Folate-Receptor-Mediated Targeting of Cervical Cancer Cells for Photodynamic Therapy Using Nanophotosensitizers Composed of Chlorin e6-Conjugated β-Cyclodextrin via Diselenide Linkage

“…Photodynamic therapy (PDT) is defined as phototherapy of abnormal cells using photosensitizers and light sources. Since PDT is composed of light, photosensitizers and oxygen species are believed to be the safe candidates for cancer treatment [ 16 , 17 , 18 ]. PDT using photosensitizers does not significantly affect the viability of surrounding normal cells or tissues in the absence of light because photosensitizers are only activated in the irradiation field, producing ROS and thus killing the abnormal cells [ 16 , 17 , 18 ].…”

“…Since PDT is composed of light, photosensitizers and oxygen species are believed to be the safe candidates for cancer treatment [ 16 , 17 , 18 ]. PDT using photosensitizers does not significantly affect the viability of surrounding normal cells or tissues in the absence of light because photosensitizers are only activated in the irradiation field, producing ROS and thus killing the abnormal cells [ 16 , 17 , 18 ]. Furthermore, PDT would be an adequate option for squamous phenotype of tumor because the irradiation depth of tissues is less than 15 mm [ 17 , 18 ].…”

“…PDT using photosensitizers does not significantly affect the viability of surrounding normal cells or tissues in the absence of light because photosensitizers are only activated in the irradiation field, producing ROS and thus killing the abnormal cells [ 16 , 17 , 18 ]. Furthermore, PDT would be an adequate option for squamous phenotype of tumor because the irradiation depth of tissues is less than 15 mm [ 17 , 18 ]. From these reasons, PDT is believed to be an efficient treatment option for cancers generated on the skin, epithelial tissue regions, or mucous layer [ 19 , 20 , 21 , 22 , 23 ].…”

Application of TD-DFT Theory to Studying Porphyrinoid-Based Photosensitizers for Photodynamic Therapy: A Review

“…In PDT, typically one uses visible light, which is able to penetrate tissues in the so-called therapeutic window to centimeters of depth [ 15 ], thereby reaching shallow tumors only. In order to overcome this limitation and target deeper tumors, other light sources have been tested [ 16 ]. Among them, electromagnetic radiation such as near infrared light [ 16 , 17 , 18 ], Cherenkov radiation [ 19 , 20 , 21 ], and X-rays [ 22 , 23 , 24 , 25 ] have been used.…”