Tetramethacrylic benzylidene cyclopentanone dye for one- and two-photon photopolymerization

Poly(3-hexylthiophene) nanoparticles as visible-light photoinitiators and photosensitizers in 3D printable acrylic hydrogels for photodynamic therapies

The design of smart photoelectrodes capable of stimulating the localized production of reactive oxygen species (ROS) on demand is of great interest for redox medicine therapies. In this work, poly(3-hexylthiophene) semiconducting polymer nanoparticles (P3HT SPNs) are used with a dual role to fabricate light-responsive hydrogels. First, P3HT SPNs act as visible-light photoinitiators to induce the photopolymerization of acrylic monomers such as acrylamide (AAm), 2-(hydroxyethyl) acrylate (HEA), and poly(ethylene glycol) diacrylate (PEGDA). This leads to the formation of acrylic hydrogels loaded with the P3HT SPNs, as demonstrated by photo-rheology and infrared spectroscopy. Furthermore, P3HT SPNs are also successfully used as photoinitiators for digital light processing (DLP) 3D printing purposes to fabricate shape-defined intelligent hydrogels. Interestingly, P3HT SPNs retain their photoelectrochemical properties when embedded within the polymer hydrogels, showing photocurrent densities that range from ∼0.2 to ∼1.1 μA cm-2 depending on the intensity of the visible light-lamp (λ = 467 nm). Second, they can be used as photosensitizers (PS) to generate reactive oxygen species (ROS), 12-15 μM H2O2, on demand. The acrylic hydrogels containing P3HT SPNs do not exhibit cytotoxic effects under normal physiological conditions in the darkness against mouse glioma 261 (GL261) cells and S. aureus bacteria. However, they induce a ∼50% reduction GL261 cancer cell viability and a ∼99% S. aureus cell death in contact with them upon illumination (λ = 467 nm) due to the localized overproduction of ROS, which makes them attractive candidates for photodynamic therapies (PDT).

Benzylidene Cyclopentanone Derivative Photoinitiator for Two-Photon Photopolymerization-Photochemistry and 3D Structures Fabrication for X-ray Application

Micron- and submicron-scale 3D structure realization nowadays is possible due to the two-photon photopolymerization (TPP) direct laser writing photolithography (DLW photolithography) method. However, the achievement of lithographic features with dimensions less than 100 nm is in demand for the fabrication of micro-optical elements with high curvature values, including X-ray microlenses. Spectroscopic and photochemical study of a photoinitiator (PI) based on a methyl methacrylate derivative of 2,5-bis(4-(dimethylamino)benzylidene) cyclopentanone was performed. Enhanced intersystem crossing in the methyl methacrylate derivative results in increased radical generation for the subsequent initiation of polymerization. A comprehensive study of the new photocompositions was performed, with particular emphasis on photochemical constants, the degree of photopolymerization, and topology. The optimal parameters for the fabrication of mechanically stable structures were determined in this research. The threshold dose parameters for lithography (radiation power of 5 mW at a speed of 180 µm/s) when trying to reach saturation values with a conversion degree of (35 ± 1) % were defined, as well as parameters for sub-100 nm feature fabrication. Moreover, the 45 nm feature size for elements was reached. Fabrication of X-ray lens microstructures was also demonstrated.