Aqueous Cellulose Nanocrystal-Colloidal Au Inks for 2D Printed Photothermia

Abstract

The conventional fabrication of photothermally active materials involves expensive, time-consuming, or environmentally hazardous processes. A scalable and environmentally benign fabrication of free-standing photothermal materials through 2D printing is obtained using cellulose nanocrystal (CNC) aqueous shear-thinning inks containing plasmonic nanoparticles. Polyvinylpyrrolidone was used to stabilize 14.7 ± 1.1 nm spherical plasmonic AuNPs for enhanced compatibility with CNCs. The resulting inks, containing 1 wt % AuNPs to CNCs, were shaped into ∼100 μm-thick lines, where CNC colloidal stability ensured homogeneous AuNP distribution within the printed materials. The suitability of printed materials for photothermal applications is demonstrated by a temperature increase of 12 °C after exposure to λ = 520–525 nm light over areas of 5 × 5 cm2. Importantly, nondegradable synthetic petroleum-based polymers or multicomponent nanomaterials with serious environmental burdens are avoided. Printed materials show remarkable durability as evidenced by stable photothermia after 16 h of irradiation and no AuNP loss after immersion in stirring water for a week. Besides, given the nontoxicity of prepared materials, they may be disposed of at the end of their service life with negligible environmental impact. Therefore, this work provides cues to develop environmentally friendly photothermal microdevices that balance performance, material renewability, ease of processing, and degradability.