Polymers for enhanced photodynamic cancer therapy: Phthalocyanines as a photosensitzer model

Abstract

The use of photosensitizers (PSs) in cancer therapy opened new avenues for developing minimally‐invasive treatment of cancer. However, problems related to lack of biocompatibility and tumor targeting of many photosensitizers limited their clinical use for many years. Tailor‐made polymeric nanoparticles can significantly enhance the biocompatibility of the photosensitizers, achieve high cellular internalization and prolonged blood circulation. Further, attachement of the photosensitizer to bifunctional polymeric chains can be used for building novel nano‐constructions such as combination therapy and image‐guided therapy. This review describes the innovations pertaining to polymeric drug delivery systems of laser‐based cancer therapeutics as disclosed in recent literature. Phthalocyanines were considered a model of photosensitizers and photodynamic therapy (PDT) as a model of phototherapy. Interestingly, these models are applicable to other biomedical photoreceptors such as porphyrins, Chlorin e6, gold nanoparticles, quantum dots, carbon dots, etc.

Chlorophenyl thiophene silicon phthalocyanine: Synthesis, two-photon bioimaging-guided lysosome target, and in vitro photodynamic efficacy

“…Silicon phthalocyanines with two axial substitutions reduce aggregation in solution and can be synthetically designed, thereby creating wide scope for modulation of their optical, chemical, and electronic properties ( Li et al, 2019 ). However, their drawbacks include the easy formation of aggregates in aqueous solutions, leading to the low production of reactive oxygen species (ROS) and a lacking of targeting of cancer cells ( Darwish, 2020 ). Many efforts have been focused on improving the PDT efficacies of Pcs by inducing various substitutions to their axial/peripheral positions ( Chen Y. et al, 2018 ; Almeida-Marrero et al, 2021 ).…”

“…PDT efficacy has recently been shown to be associated with the amount of cancer cell uptake and subcellular localization of photosensitizers ( Ming et al, 2021 ). Because the ROS lifetime is short and the action radius is limited ( Luo et al, 2021 ), only photosensitizers proximal to the organelle are directly affected by PDT ( Darwish, 2020 ).…”

Zinc(II) Sulfanyltribenzoporphyrazines with Bulky Peripheral Substituents—Synthesis, Photophysical Characterization, and Potential Photocytotoxicity

“…This is because the non-polar macrocyclic core of Pzs decreases their solubility in water, thus increasing their ability to form aggregates in polar solvents, which in turn hampers their ability to produce ROS. The increase in the solubility of Pzs can be indirectly achieved by incorporating these macrocycles into different drug-delivery systems, such as liposomes [10][11][12][13] or polymers [14][15][16][17]. Nevertheless, the direct and practical possibility of solubility improvement of these compounds is possible due to the substitution of the Pz core in the peripheral positions.…”

Design of smart nanodevices based on N‐vinyl caprolactam nanogels for photosensitizers

“…Biocompatible and biodegradable polymers are excellent nano vehicles for PSs in PDT. This is because, some polymers can accommodate drugs with different degrees of hydrophobicity 23 …”