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BODIPYs are photosensitizers activatable by light to generate highly reactive singlet oxygen (1O2) from molecular oxygen, leading to tissue damage in the photoirradiated region. Despite their extraordinary photophysical characteristics, they are not featured in clinical photodynamic therapy. This review discusses the recent advances in the design and/or modifications of BODIPYs since 2013, to improve their potential in photodynamic cancer therapy and related areas. [ABSTRACT FROM AUTHOR]

In photodynamic therapy (PDT), the low absorptivity of photosensitizers in an aqueous environment reduces singlet oxygen generation efficiency and thereby decreases photosensitizing efficacy in biological conditions. To circumvent this problem, we designed a phthalocyanine-poly-L-glutamic acid conjugate ( 1-PG ) made from a new phthalocyanine ( Pc 1 ) monofunctionalized to allow adequate conjugation to PGA. The resulting 1-PG conjugate retained high absorptivity in the near-infrared (NIR) region at its λ max 675 nm in an aqueous environment. The 1-PG conjugate demonstrated good singlet oxygen generation efficiency, increased uptake by 4 T1 breast cancer cells via clathrin-mediated endocytosis, and enhanced photocytotoxic efficacy. The conjugate also displayed a high light–dark toxicity ratio, approximately 1.5-fold greater than zinc phthalocyanine at higher concentration (10 μM), an important feature for the reduction of dark toxicity and unwanted side effects. These results suggest that the 1-PG conjugate could be a useful alternative for deep tissue treatment with enhanced anti-cancer (PDT) efficacy. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO)-based nanocarriers have been frequently studied due to their high drug loading capacity. However, the unsatisfactory biocompatibility of these GO-based nanocarriers hampers their use in clinical settings. This review discusses how each of the physicochemical characteristics ( e.g. , size, surface area, surface properties, number of layers and particulate states) and surface coatings on GO affect its in vitro and in vivo nanotoxicity. We provide an overview on the effect of GO properties on interactions with cells such as red blood cells, macrophages and cell lines, and experimental organisms including rodents, rabbits and Zebrafish, offering some guidelines for development of safe GO-based nanocarriers. We conclude the paper by outlining the challenges involving GO-based formulations and future perspectives of this research in the biomedical field. [ABSTRACT FROM AUTHOR]

Phthalocyanines are excellent photosensitizers for photodynamic therapy as they have strong absorbance in the near infra-red region which is most relevant for in vivo activation in deeper tissular regions. However, most phthalocyanines present two major challenges, ie, a strong tendency to aggregate and low water-solubility, limiting their effective usage clinically. In the present study, we evaluated the potential enhancement capability of glycerol substitution on the photodynamic properties of zinc (II) phthalocyanines (ZnPc). Three glycerol substituted ZnPc, 1–3, (tetra peripherally, tetra non-peripherally and mono iodinated tri non-peripherally respectively) were evaluated in terms of their spectroscopic properties, rate of singlet oxygen generation, partition coefficient (log P), intracellular uptake, photo-induced cytotoxicity and vascular occlusion efficiency. Tetrasulfonated ZnPc (ZnPcS4) was included as a reference compound. Here, we showed that 1–3 exhibited 10–100 nm red-shifted absorption peaks with higher molar absorptivity, and at least two-fold greater singlet oxygen generation rates compared to ZnPcS4. Meanwhile, phthalocyanines 1 and 2 showed more hydrophilic log P values than 3 consistent with the number of glycerol attachments but 3 was most readily taken up by cells compared to the rest. Both phthalocyanines 2 and 3 exhibited potent phototoxicity against MCF-7, HCT-116 and HSC-2 cancer cell-lines with IC50 ranging 2.8–3.2 µM and 0.04–0.06 µM respectively, while 1 and ZnPcS4 (up to 100 µM) failed to yield determinable IC50 values. In terms of vascular occlusion efficiency, phthalocyanine 3 showed better effects than 2 by causing total occlusion of vessels with diameter <70 µm of the chorioallantoic membrane. Meanwhile, no detectable vascular occlusion was observed for ZnPcS4 with treatment under similar experimental conditions. These findings provide evidence that glycerol substitution, in particular in structures 2 and 3, is able to improve the photodynamic properties of ZnPc. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is emerging as a significant complementary or alternative approach for cancer treatment. PDT drugs act as photosensitisers, which upon using appropriate wavelength light and in the presence of molecular oxygen, can lead to cell death. Herein, we reviewed the general characteristics of the different generation of photosensitisers. We also outlined the emergence of rhenium (Re) and more specifically, Re(I) tricarbonyl complexes as a new generation of metal-based photosensitisers for photodynamic therapy that are of great interest in multidisciplinary research. The photophysical properties and structures of Re(I) complexes discussed in this review are summarised to determine basic features and similarities among the structures that are important for their phototoxic activity and future investigations. We further examined the in vitro and in vivo efficacies of the Re(I) complexes that have been synthesised for anticancer purposes. We also discussed Re(I) complexes in conjunction with the advancement of two-photon PDT, drug combination study, nanomedicine, and photothermal therapy to overcome the limitation of such complexes, which generally absorb short wavelengths. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) has recently emerged as a potential valuable alternative to treat microbial infections. In PDT, singlet oxygen is generated in the presence of photosensitisers and oxygen under light irradiation of a specific wavelength, causing cytotoxic damage to bacteria. This review highlights different generations of photosensitisers and the common characteristics of ideal photosensitisers. It also focuses on the emergence of ruthenium and more specifically on Ru(II) polypyridyl complexes as metal-based photosensitisers used in antimicrobial photodynamic therapy (aPDT). Their photochemical and photophysical properties as well as structures are discussed while relating them to their phototoxicity. The use of Ru(II) complexes with recent advancements such as nanoformulations, combinatory therapy and photothermal therapy to improve on previous shortcomings of the complexes are outlined. Future perspectives of these complexes used in two-photon PDT, photoacoustic imaging and sonotherapy are also discussed. This review covers the literature published from 2017 to 2023. The review discussed the use of Ru(II) polypyridyl complexes with structural modifications as antibacterial photodynamic therapy agents together with recent advancements such as nanoformulations, combinatory therapy and photothermal therapy. The possible use of Ru(II) complexes in two-photon photodynamic therapy, photoacoustic imaging and sonotherapy in the future was also discussed. [Display omitted] • Antibacterial studies of Ru(II) photosensitisers with structural modifications. • Advancements in strategies - nanoformulations, combinatory and photothermal therapies. • Future use - two-photon photodynamic therapy, photoacoustic imaging and sonotherapy. [ABSTRACT FROM AUTHOR]

• Active targeted aza-BODIPY conjugates are promising photosensitizers for melanoma. • Ex vivo biodistribution assay showed conjugates 1a and 1b accumulated in the tumour. • 1b was found to reduce tumour volume and growth suppression after PDT up to 12 days. Active targeting compound, a non-iodinated derivative of IK-IK-I 2 -azaBODIPY (1a) was previously reported to preferentially bind melanoma over healthy cells. In this study, we evaluate the photodynamic therapy (PDT) efficiency on melanoma cells of 1a , together with its reversed sequence compound KI-KI-I 2 -azaBODIPY (1b) and a non-targeted control I 2 -azaBODIPY-NH 2 (2). All three test compounds possess absorption wavelengths in the near-infrared (NIR) region (λ max between 678 and 687 nm) which alleviate melanin interference and allow deeper tissue penetration. In vitro studies revealed 1a and 1b are promising photosensitizers with enhanced singlet oxygen generation, have increased uptake by B16-F10 melanoma cells via clathrin-mediated endocytosis and good photocytotoxic efficacies. Ex vivo biodistribution assays showed both 1a and 1 b accumulated in the tumour. In B16-F10 tumour bearing-C57BL/6 mice, 10 mg/kg of 1b and light irradiation was found to reduce tumour volume by up to 23% at day-3. Doubling the dosage of 1b (20 mg/kg) enhanced the antitumour effect, showing 96% maximum tumour volume reduction at day-7 and tumour growth suppression for up to 12 days. [ABSTRACT FROM AUTHOR]