Utilisation of Targeted Nanoparticle Photosensitiser Drug Delivery Systems for the Enhancement of Photodynamic Therapy

Abstract

The cancer incidence world-wide has caused an increase in the demand for effective forms of treatment. One unconventional form of treatment for cancer is photodynamic therapy (PDT). PDT has 3 fundamental factors, namely a photosensitiser (PS) drug, light and oxygen. When a PS drug is administered to a patient, it can either passively or actively accumulate within a tumour site and once exposed to a specific wavelength of light, it is excited to produce reactive oxygen species (ROS), resulting in tumour destruction. However, the efficacy of ROS generation for tumour damage is highly dependent on the uptake of the PS in tumour cells. Thus, PS selective/targeted uptake and delivery in tumour cells is a crucial factor in PDT cancer drug absorption studies. Generally, within non-targeted drug delivery mechanisms, only minor amounts of PS are able to passively accumulate in tumour sites (due to the enhanced permeability and retention (EPR) effect) and the remainder distributes into healthy tissues, causing unwanted side effects and poor treatment prognosis. Thus, to improve the efficacy of PDT cancer treatment, research is currently focused on the development of specific receptor-based PS-nanocarrier platform drugs, which promote the active uptake and absorption of PS drugs in tumour sites only, avoiding unwanted side effects, as well as treatment enhancement. Therefore, the aim of this review paper is to focus on current actively targeted or passively delivered PS nanoparticle drug delivery systems, that have been previously investigated for the PDT treatment of cancer and so to deduce their overall efficacy and recent advancements.

Targeted Photodynamic Therapy as Potential Treatment Modality for the Eradication of Colon Cancer

“…PDT treatment is a coordinated process, which begins with the intravenous administration of a photosensitizer (PS) drug [8]. Once the PS drug enters the blood stream it is then either passively or actively absorbed in tumor site, depending on the PS drug delivery mechanism that is involved [26]. Within standard conventional PS drug delivery mechanisms the advantage is that the PS drug tend to preferentially localize in diseased tissue via the enhanced permeability retention (EPR) effect and so is passively absorbed, promoting PDT induced tumor destruction with only slight healthy tissue damage [26].…”

“…Once the PS drug enters the blood stream it is then either passively or actively absorbed in tumor site, depending on the PS drug delivery mechanism that is involved [26]. Within standard conventional PS drug delivery mechanisms the advantage is that the PS drug tend to preferentially localize in diseased tissue via the enhanced permeability retention (EPR) effect and so is passively absorbed, promoting PDT induced tumor destruction with only slight healthy tissue damage [26]. However, current research studies are focused on improving PS passive drug uptake via chemical or functional modifications in order to promote a more specific and actively targeted PS delivery in cancer cells only, so that photosensitivity, localized healthy tissue destruction and other additional unwanted side effects can possibly be eliminated [26].…”

“…Within standard conventional PS drug delivery mechanisms the advantage is that the PS drug tend to preferentially localize in diseased tissue via the enhanced permeability retention (EPR) effect and so is passively absorbed, promoting PDT induced tumor destruction with only slight healthy tissue damage [26]. However, current research studies are focused on improving PS passive drug uptake via chemical or functional modifications in order to promote a more specific and actively targeted PS delivery in cancer cells only, so that photosensitivity, localized healthy tissue destruction and other additional unwanted side effects can possibly be eliminated [26]. Since, PS drugs are light absorbing molecules their activation is achieved when they are Targeted Photodynamic Therapy as Potential Treatment Modality for the Eradication of Colon… DOI: http://dx.doi.org/10.5772/intechopen.84760 exposed to laser irradiation light at a specific wavelength [26].…”

“…However, current research studies are focused on improving PS passive drug uptake via chemical or functional modifications in order to promote a more specific and actively targeted PS delivery in cancer cells only, so that photosensitivity, localized healthy tissue destruction and other additional unwanted side effects can possibly be eliminated [26]. Since, PS drugs are light absorbing molecules their activation is achieved when they are Targeted Photodynamic Therapy as Potential Treatment Modality for the Eradication of Colon… DOI: http://dx.doi.org/10.5772/intechopen.84760 exposed to laser irradiation light at a specific wavelength [26]. Thus when a tumor (which contains the localized PS drug) is exposed to laser irradiation light, the PS absorbs the photons and becomes excited [2].…”

Photodynamic Therapy for the Treatment of Glioblastoma

“…Selective drug delivery using nanotechnology is an area of active research that may provide functional tumor cell type specific delivery capabilities as well as provide improved systemic pharmacokinetics of photosensitizer molecules (73)(74)(75). For example, nanoparticleconjugated photosensitizers are in development to exploit tumor specific cell surface receptors which would deliver the photosensitizer directly to the tumor cell (76). The goal is to develop nanoparticles that are able to cross the BBB and selectively enter tumor cells.…”