Programmed polymeric integration of gold nanoparticles into multi-material 3D printed hydrogels

Gold nanoparticles (Au NPs), renowned for their localized surface plasmon resonance (LSPR) based optical properties, are widely used in myriad photonics and healthcare applications. They are utilized for targeted drug delivery, biological sensing, antimicrobial systems, and for plasmonic optical devices. Here, we report an in-situ synthesis method to initiate the pre-programmed targeted incorporation of Au NPs into multi-material geometries, including 3D-printed multi-material devices and contact lenses (made from hydrogels). The existing residual Olefinic groups (C = C) present in the pHEMA hydrogels matrix were used to label the target sections for producing Au NPs. Au NPs (with LSPR wavelength near 550 nm) were discriminately formed only within the regions that were 3D printed with pHEMA hydrogels, demonstrating a new technique of selectively doping 3D geometries with nanoparticles. We demonstrate selective functionalization (with plasmonic Au NPs) of targeted regions on several centimeter-scaled 3D-printed geometries. The gold precursor solutions used do not undergo reduction and can be reused. Hence, the innovative green chemistry process is relatively fast and economical and can produce devices with multi-composite material combinations and multifunctional properties.