A novel antimicrobial photosensitizer: hydroxyethyl Michler's ketone

Abstract

A new photoactive antimicrobial agent was synthesized by introducing a reactive functional group (-CH2CH2OH) to 4,4-bis(dimethylamino)benzophenone (Michler's ketone) that could enhance the fixation of benzophenone derivatives to cotton fabric. Cotton fabrics containing organic photosensitizers were investigated to demonstrate antimicrobial properties in the application to protective and germ-free clothing. Photosensitizers such as benzophenone, Michler's ketone and synthesized (4-(dimethylamino)phenyl)(4-((2-hydroxyethyl)(methyl)amino)phenyl)methanone (MK-EtOH) were applied on cotton fabrics through a pad-dry-cure method. The introduction of the reactive functional groups (-CH2CH2OH) enhanced the fixation of benzophenone derivatives to cotton fabrics as confirmed by Fourier transform infrared spectroscopy analysis and methylene blue staining method. No significant reductions of tensile strength and thermal degradation were observed with cotton fabrics treated with MK-EtOH. The scanning electron microscope morphology of the treated cotton showed that organic photosensitizers were evenly distributed and diffused to cotton fibers. After ultraviolet irradiation (365nm), the cotton fabrics treated with synthesized MK-EtOH photosensitizer provided more effective and durable antimicrobial properties than Michler's ketone and benzophenone, even after multiple washing.