Carbon Dots Embedded in Nanoporous SiO2 Nanoparticles for Enhancing Photosynthesis in Agricultural Crops

Nanoenable agriculture has been rapidly developed. However, foliar application of nanofertilizers results in them dripping off the leaves, which would effectively limit their bioavailability. Herein, a nanocarrier method of using nanoporous SiO2 (NanoSi) was found to enhance the adhesion of carbon dots (CDs) on crop leaf surfaces. Foliar application of NanoSi-CDs (10 mg·L–1) could significantly increase the net photosynthetic rate (Pn; 110.0–140.0%), fresh weight (327.1% in roots and 247.2% in shoots), and dry weight (212.0% in roots and 118.5% in shoots) of maize. Moreover, NanoSi-CDs showed a long-term promotion effect. Specifically, the Pn remained significantly increased on day 20 after spraying with NanoSi-CDs, whereas the CDs had no such effect at the same time. Furthermore, the rainfall simulation experiments demonstrated that the water resistances of NanoSi-CDs and CDs were 2.5 and 1.5 cm, respectively. Compared with the control, NanoSi-CDs could increase the Pn by 22.3% on the 20th day after rainfall. Collectively, NanoSi nanocarriers can be a promising method to improve the bioavailability of engineering nanomaterials in sustainable agriculture.