Drug Carrier for Photodynamic Cancer Therapy

Abstract

Photodynamic therapy (PDT) is a non-invasive combinatorial therapeutic modality using light, photosensitizer (PS), and oxygen used for the treatment of cancer and other diseases. When PSs in cells are exposed to specific wavelengths of light, they are transformed from the singlet ground state (S0) to an excited singlet state (S1–Sn), followed by intersystem crossing to an excited triplet state (T1). The energy transferred from T1 to biological substrates and molecular oxygen, via type I and II reactions, generates reactive oxygen species, (1O2, H2O2, O2*, HO*), which causes cellular damage that leads to tumor cell death through necrosis or apoptosis. The solubility, selectivity, and targeting of photosensitizers are important factors that must be considered in PDT. Nano-formulating PSs with organic and inorganic nanoparticles poses as potential strategy to satisfy the requirements of an ideal PDT system. In this review, we summarize several organic and inorganic PS carriers that have been studied to enhance the efficacy of photodynamic therapy against cancer.

Evaluation of Perylene Bisimide‐Based RuII and IrIII Complexes as Photosensitizers for Photodynamic Therapy

“…Therefore, the production of singlet oxygen should be strongly favored by these compounds. Firstly, we confirmed the stability and photostability of both complexes up to 72 h in a CH 3 50 in the nanomolar range and PIs from > 7.8 to > 23, depending on the cell line. The investigation of the cellular uptake and localization of the complexes based on ICP-MS analysis indicated a nuclear accumulation for 1 and a mitochondrial localization for 2.…”

“…Singlet Oxygen Determination [20] . Indirect Method: An air-saturated CH 3 I (absorbance correction factor) was obtained from Equation (2), where I 0 is the light intensity of the irradiation source in the irradiation interval and A λ is the absorbance of the sample at wavelength λ.…”

“…[1,2] Already applied in the clinic for several types of cancer, [3] PDT exploits the synergistic action of three components: a photosensitizer (PS), light, and molecular oxygen ( 3 O 2 ). In the first step, the PS is administered to the patient aiming at a preferential accumulation in cancer cells over healthy cells.…”

Photosensitizers Imprinting Intracellular Signaling Pathways in Dermato-Oncology Therapy

“…at the level of their electron-dense regions [57,60], while superoxide anion due to its low reactivity on direct biological target, will act mainly as a precursor for other reactive species (e.g. H 2 O 2 or • OH) that will cause cellular fatal injuries triggering cell death through necrosis or apoptosis [61]. Also it is important to notice that since singlet oxygen is a short-lived species, will act immediately upon intracellular targets close to the site where PS was accumulated, influencing thus the type of response upon intracellular localization [57].…”

Strategies for optimizing the delivery to tumors of macrocyclic photosensitizers used in photodynamic therapy (PDT)

“…Thus, photo-sensitization of normal tissue, which is one of the major drawbacks associated with PS administration, can be minimized with the so called "targeted PDT" using NPs for the delivery of the PSs [103]. Furthermore, the presence of the delivery system can (i) improve the solubility and the bioavailability of highly hydrophobic PSs, which can be encapsulated or entrapped in NPs through covalent or noncovalent interactions, (ii) limit PS aggregation and degradation in serum, (iii) control drug release and increase blood circulation after systemic administration [104]. In the context of PDT, many different kind of materials have been used to develop NPs as carriers of PSs but also as PSs itself or energy transducers of PSs [105].…”