Functionalized hollow carbon spheres: A light-triggered smart material for controlled release of drugs in peanut growth regulation

Intelligent responsive controlled release systems have demonstrated considerable potential for enhancing pesticide utilization efficiency and mitigating environmental pollution. In this study, hollow carbon spheres (HCMS) with different internal structures were synthesized, exhibiting excellent drug loading capacity and remarkable photothermal conversion performance. The PNIPAm@HCMS was successfully synthesized by encapsulating mepiquat chloride (DPC) within HCMS using the temperature-sensitive polymer poly-isopropylacrylamide(PNIPAm) as an intelligent encapsulation layer. The internal structure of HCMS, the successful loading of DPC drug and coating of PNIPAm thermosensitive shell were proved by SEM, TEM and FT-IR analysis. The release behavior study indicates that the release model of the composites at varying temperatures adheres to the Ritger-Peppas model, with the release mechanism mainly controlled by the internal diffusion of the particles. Furthermore, near-infrared (NIR) irradiation experiments confirmed that the PNIPAm@HCMS nanocomposites possess light controlled release properties. Among them, HCMS functions as an antenna for photothermal conversion, while PNIPAm serves as an intelligent regulator of drug release. The anti-scouring experiment and contact angle measurement indicated that PNIPAm also enhanced the washing resistance of the composites. The practical application of the composite was verified by pot experiment of peanut. This research offers novel perspectives for the development of photo responsive intelligent controlled release pesticides.