Sunlight Broad Spectrum-Capturing Nanophotofertilizer for Plant Growth Multiregulation and Second Near-Infrared Imaging

Nanophotonic strategies offer promising routes to enhance plant photosynthetic efficiency but are often hindered by limited capacity for sunlight energy capture and inefficient electron transfer between Photosystem I and II. Herein, lanthanide-doped nanoparticles (LPs) with red upconversion and downconversion second near-infrared (NIR-II, 1525 nm) emissions were coated with Ce/Mn-doped mesoporous silica (SiO₂) to create a nanophotofertilizer (LPs@SiCeMn) for plant growth multiregulation. This nanophotofertilizer is based on LPs (NaErF₄:Tm@NaGdF₄:Yb,0.2Ce), which enables red emission for photocatalysis and 1525 nm emission for plant tissues imaging upon 980 nm laser excitation. Co-doping Ce and Mn into the SiO₂ shell reduces its band gap to 1.75 eV, allowing efficient absorption of the red light to improve photogenerated electron production. Meanwhile, the Ce and Mn ions released in response to pH serve as redox-active centers to scavenge reactive oxygen species. Following the foliar application concentration 100 μg mL^-1 of LPs@SiCeMn, the electron transport rate and net photosynthetic rate of N. benthamiana were respectively increased by 26.8% and 36.9%, with increases of fresh biomass 88.2% and dry biomass 43.7%. This study underscores the potency of sunlight broad-spectrum-capturing nanophotofertilizer for plant growth multiregulation and bioimaging, presenting a promising approach for precise and sustainable agriculture.