Water-soluble/visible-light-sensitive naphthalimide derivative-based photoinitiating systems: 3D printing of antibacterial hydrogels

Abstract

Adaptability of hydrogels allows these structures to be used in a variety of industries, including biomedicine, soft electronics, and sensors. In this study, 10 different naphthalimide derivatives (five of them, dyes 5–9, never synthesized before) were prepared. More particularly, two naphthalimide salts (dyes 8 and 9) were specifically designed and exhibited excellent water solubility values of at least 6% for dye 9 and up to 10% for dye 8 in deionized water, thus exceeding the solubility of the typical photoinitiator Irgacure 2959 (I2959) used in water-based systems by 12- to 20-fold. When paired with co-initiators, such as arginine (L-Arg) or triethanolamine (TEA) as electron donors and an iodonium salt (Iod) as an electron acceptor, these two dyes might be utilized especially as high-efficiency water-soluble photoinitiators. Antibacterial hydrogels containing silver nanoparticles could be prepared using a dyes/Iod/amine based three-component photoinitiating system (PIS) upon exposure to a visible light source (LED@405 nm). It thus enabled responding to the growing demand for radiation-curable waterborne products such as hydrogels. Real-Time Fourier Transform Infrared (FTIR) spectroscopy proved that the dyes/Iod/TEA based three-component PISs achieved more than 90% double bond conversions of poly(ethylene glycol)diacrylate (PEG-DA) under LED@405 nm irradiation, comparable to that obtained with conventional water-soluble photoinitiators. Using the proposed water-soluble photoinitiators, 3D printed hydrogels could be prepared and the introduction of silver salts into the solution enabled silver cations to be reduced in situ into silver nanoparticles and antibacterial hydrogels were produced. Finally, Escherichia coli was selected to investigate the effect of the antibacterial activity of hydrogels containing different concentrations of AgNPs.