Sectioning of cultured cell monolayer using photo-acid-generating substrate and micro-patterned light projection

Photoacid Generators for Biomedical Applications

Photoacid generators (PAGs) are compounds capable of producing hydrogen protons (H+ ) upon irradiation, including irreversible and reversible PAGs, which have been widely studied in photoinduced polymerization and degradation for a long time. In recent years, the applications of PAGs in the biomedical field have attracted more attention due to their promising clinical value. So, an increasing number of novel PAGs have been reported. In this review, the recent progresses of PAGs for biomedical applications is systematically summarized, including tumor treatment, antibacterial treatment, regulation of protein folding and unfolding, control of drug release and so on. Furthermore, a concept of water-dependent reversible photoacid (W-RPA) and its antitumor effect are highlighted. Eventually, the challenges of PAGs for clinical applications are discussed.

Automated adherent cell elimination by a high-speed laser mediated by a light-responsive polymer

Conventional cell handling and sorting methods require manual labor, which decreases both cell quality and quantity. To purify adherent cultured cells, cell purification technologies that are high throughput without dissociation and can be utilized in an on-demand manner are expected. Here, we developed a Laser-induced, Light-responsive-polymer-Activated, Cell Killing (LiLACK) system that enables high-speed and on-demand adherent cell sectioning and purification. This system employs a visible laser beam, which does not kill cells directly, but induces local heat production through the trans-cis-trans photo-isomerization of azobenzene moieties. Using this system in each passage for sectioning, human induced pluripotent stem cells (hiPSCs) maintained their pluripotency and self-renewal during long-term culture. Furthermore, combined with deep machine-learning analysis on fluorescent and phase contrast images, a label-free and automatic cell processing system has been developed by eliminating unwanted spontaneously differentiated cells in undifferentiated hiPSC culture conditions.

Yohei Hayashi et al. present a method for high-speed adherent cell sectioning and purification, along with a label-free and automatic cell processing system. They show that this method is able to section human induced pluripotent stem cells without losing pluripotency and viability.

Fabrication of pocket-like hydrogel microstructures through photolithography

Photolithographic fabrication of unique microstructures composed of flexible hydrogel sheets is proposed and demonstrated by using photo-acid-generating poly(methyl methacrylate). Crosslinking of a hydroxyl-rich polymer and lifting off of the crosslinked polymer layer from the substrate are controlled respectively in an area-selective manner upon micropatterned light irradiation, and various pocket-like microstructures are fabricated resultantly.