Phytochemical-coated nanoparticles for indoor-light photocatalysis

Overview

Traditional photocatalysts such as TiO2 and ZnO only absorb ultraviolet light below 400 nm and show little to no activity under typical indoor illumination (white LEDs, fluorescent lamps). This proposal introduces a new class of photocatalytic coatings based on phytochemical-coated silver or gold nanoparticles. Herbal photoredox compounds such as hypericin absorb indoor light strongly, and when coated onto plasmonic nanoparticles tuned to surface plasmon resonances near 470 nm (for LEDs) or 520 nm (for fluorescent lamps), the combination both quells the visible pigment color and enhances catalytic and antibacterial performance. The result is a practical, spray-applied disinfectant coating that works under ordinary indoor lighting on fabrics and hard surfaces.

Technical specifications

• Core innovation: Ag or Au nanoparticles coated with phytochemicals such as Breynia rhamnoides extract or hypericin, with surface plasmon resonance tuned to indoor light spectra
• Tuned plasmon resonances: ~470 nm for white LED lighting and ~520 nm for fluorescent lamp lighting
• Photocatalytic activity: Demonstrated reduction of 4-nitrophenol using Breynia-coated Ag/Au nanoparticles
• Antibacterial functionality: Surface functional chemistries developed to selectively target bacteria such as E. coli
• Toxicity profile: Evaluated in published toxicological studies on coated nanoparticle systems
• Application method: Spray coating onto fabrics and surfaces at varying concentrations
• Planned characterization: Hyperspectral imaging for particle distribution, abrasion testing per ASTM D4157, D4060, and D1044, photocatalytic testing per ISO 27447:2019, and antibacterial testing per ASTM E2274 and ASTM E2149, substituting white LED or fluorescent lamps for the UV source
• Analytical method: Chromatographic quantification of active photoredox phytochemicals on coated surfaces

Technology readiness level

The underlying components have been individually validated: plasmonic nanoparticle synthesis with plant extracts, photocatalytic reduction of model pollutants, antibacterial surface functionalization, and toxicity assessment. The team now plans a one-year integration effort to synthesize two formulations tuned to LED and fluorescent spectra, optimize spray-coating parameters, and validate performance against industry-standard abrasion, photocatalytic, and antibacterial protocols under realistic indoor lighting. The technology is at an early-to-mid stage, moving from demonstrated laboratory results toward application-ready coatings suitable for pilot evaluation with industry partners.