Marine alkaloid rigidins are cytotoxic compounds known to kill cancer cells at nanomolar concentrations by targeting the microtubule network. Here, a rigidin analogue containing a thioether group was "caged" by coordination of its thioether group to a photosensitive ruthenium complex. In the dark, the coordinated ruthenium fragment prevented the rigidin analogue from inhibiting tubulin polymerization and reduced its toxicity in 2D cancer cell line monolayers, 3D lung cancer tumor spheroids (A549), and a lung cancer tumor xenograft (A549) in nude mice. Photochemical activation of the prodrug upon green light irradiation led to the photosubstitution of the thioether ligand by water, thereby releasing the free rigidin analogue capable of inhibiting the polymerization of tubulin. In cancer cells, such photorelease was accompanied by a drastic reduction of cell growth, not only when the cells were grown in normoxia (21% O 2 ) but also remarkably in hypoxic conditions (1% O 2 ). In vivo, low toxicity was observed at a dose of 1 mg•kg −1 when the compound was injected intraperitoneally, and light activation of the compound in the tumor led to 30% tumor volume reduction, which represents the first demonstration of the safety and efficacy of ruthenium-based photoactivated chemotherapy compounds in a tumor xenograft.
In the present work, we report on the synthesis of cellulose cotton fibers bearing different types of photosensitizers with the aim to prepare new efficient polymeric materials for antimicrobial applications. Anionic, neutral, and cationic amino porphyrins have been covalently grafted on cotton fabric, without previous chemical modification of the cellulosic support, using a 1,3,5-triazine derivative as the linker. The obtained porphyrin-grafted cotton fabrics were characterized by infrared (ATR-FTIR), diffuse reflectance UV-vis (DRUV) spectroscopies, and thermogravimetric analysis (TGA) to confirm the triazine linkage. Antimicrobial activity of porphyrin-cellulose materials was tested under visible light irradiation against Staphylococcus aureus and Escherichia coli . The results showed excellent activity on the Gram-positive bacterium, showing structure-activity relationship, although no photodamage of the Gram-negative microorganism was recorded. A mechanism of bacterial inactivation by photosensitive surfaces is proposed.
International audienceWe describe a new approach to the formation of silver nanoparticles (Ag NPs) using cellulose nanocrystals. The process involves periodate oxidation of cellulose nanocrystals, generating aldehyde functions which, in turn, are used to reduce Ag+ into Ag0 in mild alkaline conditions. The nanoparticles were characterized using transmission electron microscopy (TEM) and ultraviolet-visible absorption spectroscopy. From the microscope studies (TEM) we observed that Ag NPs have spherical shape with a size distribution comprise between 20 and 45 nm. The antibacterial activity was assessed using the minimum inhibitory concentration. The antibacterial assays compare favourably with most of other experiments conducted with the same species
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