Purpurin derivatives as visible-light photosensitizers for 3D printing and valuable biological applications

We report the synthesis of new visible-light photosensitizers derived from purpurin (mono-allyl-and triallyl-purpurin), and their use as type II photoinitiating systems when associated with N-methyldiethanolamine, bis(4-methylphenyl) iodonium hexafluorophosphate or tri-functionalized thiol (trimethylolpropane tris(3-mercaptopropionate)) for cationic and free-radical photopolymerization, and the initiation of thiol-ene reactions. These photoinitiating systems showed good initiating properties in laminate or under air upon visible-light exposure, i.e. LED@405 nm, 455 nm, 470 nm, 530 nm, and a Xe lamp. Steady-state photolysis, electron paramagnetic resonance, fluorescence analysis and laser flash photolysis have clearly highlighted the photochemical properties of the different photoinitiating systems and proved that purpurin derivatives could act as electron donors or as proton/proton-coupled electron transfer promoters when associated with appropriate additives. For the first time, we also demonstrated the capability of triallyl purpurin to produce newly designed 3D objects by 3D photoprinting technology. Interestingly, the photosensitizers from new 3D materials incorporating triallyl-purpurin have undoubtedly shown tremendous antibacterial properties with more than 99% of inhibition of bacterial adhesion upon visible-light exposure, even after many antibacterial cycling experiments, thus showing their capability to be recycled. This journal i

Purpurin derivatives as visible-light photosensitizers for 3D printing and valuable biological applications

We report the synthesis of new visible-light photosensitizers derived from purpurin (mono-allyl-and triallyl-purpurin), and their use as type II photoinitiating systems when associated with N-methyldiethanolamine, bis(4-methylphenyl) iodonium hexafluorophosphate or tri-functionalized thiol (trimethylolpropane tris(3-mercaptopropionate)) for cationic and free-radical photopolymerization, and the initiation of thiol-ene reactions. These photoinitiating systems showed good initiating properties in laminate or under air upon visible-light exposure, i.e. LED@405 nm, 455 nm, 470 nm, 530 nm, and a Xe lamp. Steady-state photolysis, electron paramagnetic resonance, fluorescence analysis and laser flash photolysis have clearly highlighted the photochemical properties of the different photoinitiating systems and proved that purpurin derivatives could act as electron donors or as proton/proton-coupled electron transfer promoters when associated with appropriate additives. For the first time, we also demonstrated the capability of triallyl purpurin to produce newly designed 3D objects by 3D photoprinting technology. Interestingly, the photosensitizers from new 3D materials incorporating triallyl-purpurin have undoubtedly shown tremendous antibacterial properties with more than 99% of inhibition of bacterial adhesion upon visible-light exposure, even after many antibacterial cycling experiments, thus showing their capability to be recycled. This journal i

Methacrylated Quinizarin Derivatives for Visible-Light Mediated Photopolymerization: Promising Applications in 3D-Printing Biosourced Materials under LED@405 nm

The high initiating properties of mono- (Q-1Ac) and dimethacrylated (Q-2Ac) quinizarin derivatives under visible-light irradiation are reported here. Associated with various co-initiators, such as iodonium salt (electron acceptor), an amine derivative (electron donor), or thiol cross-linker (H-donor), the quinizarin-derived photosensitizers lead to high conversions by radical photopolymerization in laminate or under air. Mechanisms of photoinitiation were deeply investigated by fluorescence, laser flash photolysis (LFP) and electron paramagnetic resonance (EPR) experiments. The use of soybean oil acrylate (SOA) as biobased monomer leads to highly cross-linked materials under visible-light, with comparable mechanical properties than UV-induced ones previously described in literature. Copolymerization of the photosensitizer (PS) with the polymer matrix not only prevents leakage, but also ensures antiadhesion properties of SOA materials against Staphylococcus aureus (S. aureus) under visible-light activation. Finally, complex 3D biobased structures are successfully obtained by 3D-printing under visible-light irradiation (LED@405 nm), opening opportunities to design photoinduced biosourced materials

Photoinduced chitosan-PEG hydrogels with long-term antibacterial properties

International audiencePhotochemical processes offer the possibility to prepare functional hydrogels in green conditions that are compatible with both synthetic and natural polymers. Here hydrogels associating chitosan derivatives and poly(ethylene glycol) (PEG) have been successfully synthesized under light illumination in aqueous conditions. Kinetic studies under irradiation showed that less than 2 min were necessary to obtain fully cross-linked networks. Thermomechanical analyses and swelling experiments indicated that introduction of chitosan overall weakens the hydrogel network but can create domains of higher thermal stability than the PEG-alone structure. The resulting chitosan-PEG hydrogels demonstrated a tremendous inhibition (100%) of the bacterial growth (Escherichia coli and Staphylococcus aureus). After 6 months ageing, one of the hydrogel preserved a high antifouling activity against Escherichia coli. This interesting result, that could be correlated with the network features, demonstrates the strong potentiality of these photochemical methods to obtain robust bio-functional materials

Glycobiology on the fly: Developmental and mechanistic insights from Drosophila

Drosophila melanogaster offers many unique advantages for deciphering the complexities of glycan biosynthesis and function. The completion of the Drosophila genome sequencing project as well as the comprehensive catalogue of existing mutations and phenotypes have lead to a prolific database where many of the genes involved in glycan synthesis, assembly, modification, and recognition have been identified and characterized. Recent biochemical and molecular studies have elucidated the structure of the glycans present in Drosophila. Powerful genetic approaches have uncovered a number of critical biological roles for glycans during development that impact on our understanding of their function during mammalian development. Here, we summarize key recent findings and provide evidence for the usefulness of this model organism in unraveling the complexities of glycobiology across many species