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The use of radiopharmaceuticals for diagnostics in oncology allows for the detection of the disease at an early stage. Among diagnostic radionuclides, [sup.99m]Tc is a promising isotope that has been used to create several drugs for clinical use. One of the most effective [sup.99m]Tc chelators is 6-hydrazinylnicotinic acid (HYNIC), which, when combined with various vector molecules, can be used for targeted delivery of radionuclides to tumor tissues. At the same time, it is known that tetrapyrrole macrocycles are capable of selective accumulation in tumors, and thus can be used to target radiopharmaceuticals with [sup.99m]Tc. In this work, the conjugate of natural chlorin and HYNIC was obtained, and preliminary preclinical studies were carried out on its radiocomplex with [sup.99m]Tc.

In this work, we obtained the first selenium-containing chlorin with a chalcogen atom in exlocycle E. It was shown that the spectral properties were preserved in the target compound and the stability increased at two different pH values, in comparison with the starting purpurin-18. The derivatives have sufficiently high fluorescence and singlet oxygen quantum yields. The photoinduced cytotoxicity of sulfur- and selenium-anhydrides of chlorin p6 studied for the first time in vitro on the S37 cell line was found to be two times higher that of purpurin-18 and purpurinimide studied previously. Moreover, the dark cytotoxicity increased four-fold in comparison with the latter compounds. Apparently, the increase in the dark cytotoxicity is due to the interaction of the pigments studied with sulfur- and selenium-containing endogenous intracellular compounds. Intracellular distributions of thioanhydride and selenoanhydride chlorin p6 in S37 cells were shown in cytoplasm by diffusion distribution. The intracellular concentration of the sulfur derivative turned out to be higher and, as a consequence, its photoinduced cytotoxicity was higher as well.

We review the use of visible range spectroscopy (VRS) to measure concentrations of chlorophyll a and its degradation products (collectively classified as chlorins) from lake sediments. This method for reconstructing aquatic production offers a rapid and non-destructive alternative to wet-chemical techniques, which has led to VRS measurements of aquatic production to become a routine analysis in paleolimnological studies. Over the last decade, VRS has been used to measure paleo-production in a variety of lake types exposed to numerous stressors, including climate change, natural and anthropogenic eutrophication, and whole-lake manipulations. Here, we summarize some of these studies with the intent of demonstrating the utility and the consistency of VRS to track past trends in aquatic production. In all cases, VRS-derived measurements matched a priori predictions of production changes based on historical data of trophic status, or as inferred by multiple, independent proxies of primary production.

Graphene oxide (GO) is one of the most studied nanomaterials in many fields, including the biomedical field. Most of the nanomaterials developed for drug delivery and phototherapies are based on noncovalent approaches that lead to an unspecific release of physisorbed molecules in complex biological environments. Therefore, preparing covalently functionalized GO using straightforward and versatile methods is highly valuable. Phototherapies, including photothermal therapy (PTT) and photodynamic therapy (PDT), have shown great potential as effective therapeutic approaches against cancer. To overcome the limits of a single method, the combination of PTT and PDT can lead to a combined effect with a higher therapeutic efficiency. In this work, we prepare a folic acid (FA) and chlorin e6 (Ce6) double-functionalized GO for combined targeted PTT/PDT. This conjugate can penetrate rapidly into cancer cells and macrophages. A combined effect of PTT and PDT is observed, leading to a higher killing efficiency toward different types of cells involved in cancer and other diseases. Our work provides a simple protocol to prepare multifunctional platforms for the treatment of various diseases.

Details of the structural elucidation of the clinically useful photodynamic therapy sensitizer NPe6 (15) are presented. NPe6, also designated as Laserphyrin, Talaporfin, and LS-11, is a second-generation photosensitizer derived from chlorophyll-a, currently used in Japan for the treatment of human lung, esophageal, and brain cancers. After the initial misidentification of the structure of this chlorin-e6 aspartic acid conjugate as (13), NMR and other synthetic procedures described herein arrived at the correct structure (15), confirmed using single crystal X-ray crystallography. Interesting new features of chlorin-e6 chemistry (including the intramolecular formation of an anhydride (24)) are reported, allowing chemists to regioselectively conjugate amino acids to each available carboxylic acid on positions 131 (formic), 152 (acetic), and 173 (propionic) of chlorin e6 (14). Cellular investigations of several amino acid conjugates of chlorin-e6 revealed that the 131-aspartylchlorin-e6 derivative is more phototoxic than its 152- and 173-regioisomers, in part due to its nearly linear molecular conformation.

Microorganisms, usually bacteria and fungi, grow and spread in skin wounds, causing infections. These infections trigger the immune system and cause inflammation and tissue damage within the skin or wound, slowing down the healing process. The use of photodynamic therapy (PDT) to eradicate microorganisms has been regarded as a promising alternative to anti-infective therapies, such as those based on antibiotics, and more recently, is being considered for skin wound-healing, namely for infected wounds. Among the several molecules exploited as photosensitizers (PS), porphyrinoids exhibit suitable features for achieving those goals efficiently. The capability that these macrocycles display to generate reactive oxygen species (ROS) gives a significant contribution to the regenerative process. ROS are responsible for avoiding the development of infections by inactivating microorganisms such as bacteria but also by promoting cell proliferation through the activation of stem cells which regulates inflammatory factors and collagen remodeling. The PS can act solo or combined with several materials, such as polymers, hydrogels, nanotubes, or metal-organic frameworks (MOF), keeping both the microbial photoinactivation and healing/regenerative processes’ effectiveness. This review highlights the developments on the combination of PDT approach and skin wound healing using natural and synthetic porphyrinoids, such as porphyrins, chlorins and phthalocyanines, as PS, as well as the prodrug 5-aminolevulinic acid (5-ALA), the natural precursor of protoporphyrin-IX (PP-IX).

Photodynamic therapy (PDT) is a relatively non-invasive anti-cancer therapy that employs a photosensitizer with a specific wavelength of light, causing a photochemical reaction that releases free radicals, thereby inducing tumor cell necrosis via oxidative stress. The oxygen molecule reaches the singlet excited state through efficient energy transfer from an excited triplet state of the photosensitizer. Heavy atoms are frequently introduced in photosensitizers for efficiently generating reactive oxygen species (ROS) in PDT, known as the heavy atom effect. However, metal-complexed photosensitizers often show low water-solubility. To overcome this limitation and produce ROS effectively, we focused on the better solubility of photosensitizers with heavy metals bound within the chlorin skeleton and conjugated with glucose in this study. We established maltotriose (Mal )-conjugation with heavy metallochlorins [M (Mal -chlorin), M=Pt or Pd)] and evaluated its anti-tumor effect. M (Mal -chlorin) showed effective ROS production and singlet oxygen induction. Consequently, these cytotoxic factors caused effective anti-tumor effects and induced morphological changes, followed by cell death in vitro. In a xenograft tumor mouse model, PDT with M (Mal -chlorin) showed tumor growth suppression. M (Mal -Chlorin) might be an excellent glucose-conjugated chlorin because of its strong anti-tumor PDT effect.

Nowadays, cancer has become the leading cause of death worldwide, driving the need for effective therapeutics to improve patient prognosis. Photodynamic therapy (PDT) has been widely applied as an antitumor modality, owing to its minimal invasiveness, localized tumor damage, and high safety profile. However, its efficacy is limited by poor stability of photosensitizers, inadequate tumor accumulation, and a complex tumor microenvironment. To overcome these challenges, extensive endeavors have been made to explore the co‐assembly of the widely used photosensitizer chlorin e6 (Ce6) with various functional small molecules to enhance pharmacodynamic activity. This review provides a comprehensive overview of current studies on Ce6‐based nanoparticles for effective PDT and precise delivery of functional molecules. The self‐assembly mechanism will be discussed in detail, with a focus on potential strategies for combinational therapy with PDT.

Recent scientific research has shown the use of chlorin, phthalocyanines, and porphyrins derivatives as photosensitizers in photodynamic therapy in the treatment of various pathologies, including some of the major skin diseases. Thus, the main goal of this critical review is to catalog the papers that used these photosensitizers in the treatment of acne vulgaris, psoriasis, papillomavirus infections, cutaneous leishmaniasis, and skin rejuvenation, and to explore the photodynamic therapy mechanisms against these conditions alongside their clinical benefits.

Photodynamic therapy (PDT) is widely recognized as a promising way to cure cancer. However, the limited tumor homing property of currently available drug delivery systems (DDSs) is the bottleneck for the delivery of photodynamic agents. In our study, we decorated silica nanoparticles (SLN) with cell membrane (CM) derived from SGC7901 cells to construct carrier (CM/SLN) which was able to to specifically target the homogenous SGC7901 cells. Furthermore, the decent drug loading capability of CM/SLN was adopted to load photodynamic agent chlorins e6 (Ce6) to finally construct aDDS suitable for tumor-targeted PDT of gastric cancer. The experimental results suggested that CM/SLN/Ce6 was nano-sized particles with good dispersion and stability in physiological conditions. Moreover, due to the modification of CM,CM/SLN/Ce6 could specifically target the homogenous SGC7901 cells both in vitro and in vivo. Most importantly, further in vivo results demonstrated that the CM/SLN/Ce6 showed a better anticancer outcome compared to SLN/Ce6. CM/SLN/Ce6 might be a promising platform for effective tumor targeted PDT of gastric cancer.