Robert Granet

Triazinyl Porphyrin-Based Photoactive Cotton Fabrics: Preparation, Characterization, and Antibacterial Activity

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.

HEAVY METAL ADSORPTION BY CRUDE CONIFEROUS BARKS: A MODELLING STUDY

ABSTRACT Equilibria and mechanisms involved in the adsorption process of metal ions (Cr3+, Cu2+, Ni2+, Pb2+ and Zn2+) from aqueous solutions using coniferous barks as biosorbent substrate were investigated. Crude barks were used in this study since previous experiments showed a decreasing uptake for chemically treated barks in the considered granulometry. In our experimental conditions, the maximum binding capacity of barks followed the decreasing order Cr3+>Cu2+>Pb2+>Ni2+>Zn2+ whereas their general binding affinity decreased as: Pb2+>Cr3+> Ni2+>Zn2+>Cu2+. Adsorption isotherms at the optimal physico-chemical conditions were established and the adsorption phenomenon was described by the non-competitive Langmuir adsorption model which fitted well the experimental data. An evaluation of adsorption capability was carried out using model parameters which were graphically determined. Models for removal of cations have been discussed; they represent efficient tools for predicting the behaviour of the biosorbents in metal ion adsorption systems.

Fungicidal properties of meso-arylglycosylporphyrins: influence of sugar substituents on photoinduced damage in the yeast Saccharomyces cerevisiœ

A series of neutral meso-arylglycosylporphyrins has been tested in order to evaluate their potency as antifungal agents against the yeast Saccharomyces cerevisiae. Photodynamic activity of these molecules results in intracellular damage as evidenced by the loss of clonogenicity and DNA fragmentation. The ability of these photosensitizers to permeate yeast cells is determined by microspectrofluorimetry and is correlated with their antifungal potency. Amphiphilic porphyrin derivatives are shown to exhibit the more pronounced photoactivity.

Rational design of sugar-based-surfactant combined catalysts for promoting glycerol as a solvent.

Thumbnail image of graphical abstract A sugary treat: Here we report the great efficiency of sugar-based-surfactant combined catalysts for conducting selective base-catalyzed organic reactions in glycerol. Close control of the reaction selectivity was successfully obtained owing to the formation of catalytic hydrophobic pockets in glycerol (see figure). The advantages of our catalytic processes and its similarities with catalysis in water are also highlighted.

Chlorin-PEI-labeled cellulose nanocrystals: synthesis, characterization and potential application in PDT.

This Letter reports the synthesis and characterization of a new series of water-stable and soluble photosensitizers (PS-CNCs) composed of cellulose nanocrystals (CNCs) bearing polyaminated chlorin p6. With a view to improve cancer cell targeting, these photosensitizers were assayed for their antitumor activity against HaCat cell line. IC(50) values fell within the nanomolar-range, making these photosensitizers promising for further in vitro and in vivo investigations.

Synthesis of tetraglucosyl- and tetrapolyamine-tetrabenzoporphyrin conjugates for an application in PDT.

This paper reports the synthesis and characterization of a new class of tetrabenzoporphyrins bearing glucosyl or polyamine units on meso positions to improve the targeting of cancer cells. Photocytotoxic activity of these photosensitizers was tested on cell lines HaCaT and MCF-7 and compared to Photofrin II.

Synthesis and biological evaluation of thioglycosylated porphyrins for an application in photodynamic therapy.

The aim of this work is the synthesis of a new family of glycosylated porphyrins in which the sugar moieties are linked to the tetrapyrrole ring by a thioglycosidic bond. Two series have been designed. The first one corresponds to meso-aryl porphyrin derivatives. The second one has been obtained from protoporphyrin IX derivatization. Aryl-porphyrins were prepared from tristolyl o- and p-hydroxyporphyrins followed by bromoallylation and thioglycosylation with peracetylated S-glucose, mannose and galactose and deprotection. The other series has been synthesized from protoporphyrin IX dimethylester with a regioselective glycosylation of terminal alkenyl carbon. The UV-visible, NMR and MALDI mass spectra are presented. Photocytotoxicities of the synthesized compounds against K562 chronic leukaemia cell line has been evaluated.

Synthesis and photobiocidal properties of cationic porphyrin-grafted paper.

We report on the synthesis of cellulose paper bearing a cationic porphyrin, designed for antimicrobial applications. Tricationic porphyrin has been covalently grafted on paper, without previous chemical modification of the cellulosic support, using 1,3,5-triazine derivative as linker. The obtained porphyrin-grafted paper was characterized by infrared (ATR-FTIR), UV-visible and diffuse reflectance UV-vis (DRUV) spectroscopies to confirm the triazine linkage. Thermogravimetric analysis (TGA) was used to investigate thermal properties of grafted paper. Antimicrobial activity of porphyrin-cellulose material was tested under visible light irradiation against Staphylococcus aureus and Escherichia coli. The two bacterial strains deposited on the resulting photosensitizing filter paper are efficiently killed after illumination.

Acidic activation of cellulose and its esterification by long‐chain fatty acid

Cellulose-enriched residues from wheat bran can be transformed in bioplastics after esterification of the cellulose by lauroyl chloride. Before the esterification reaction, an activation step with a swelling of the sample in dilute acid and subsequent drying was required. This activation had a marked influence on the amount of esterified product and its degree of substitution. Using pure cellulose as well as cellulose-enriched agricultural residues, we have shown that the cellulose was totally recovered after this pretreatment and that partial hydrolysis of cellulose chains occurred during the drying step, which probably improved the accessibility to chemical reagents. The possible role of sulfuric acid as catalyst for the esterification reaction of the cellulose by lauroyl chloride was discussed.

Photobactericidal plastic films based on cellulose esterified by chloroacetate and a cationic porphyrin.

The synthesis and characterisation of pyridinium porphyrinic chloroacetyl cellulose ester chlorides, where photosensitizing agents are covalently bounded to the polymeric chain, is presented in this paper. First, cellulose was homogenously converted into chloroacetate cellulose ester in DMAc/LiCl solvent by using chloroacetyl chloride. The complete substitution of cellulose was achieved using 7equiv of chloroacetyl chloride for a 2h reaction at room temperature. The absence of base did not prove detrimental to reaction. The grafting of monopyridyltritolylporphyrin onto chloroacetate cellulose ester was then realised by alkylation of the photosensitizer in DMF. These new plastic films were found to be thermostable up to 55 degrees C; higher temperatures led to progressive deacetylation. First results of their photobactericidal activity against Staphylococcus aureus and Escherichia coli strains are very encouraging. Such materials could find applications in medical environments as an alternative to overcome the rampant bacterial multiresistance to classical antibiotics.