A triple-stimuli responsive hormone delivery system equipped with pillararene magnetic nanovalves†
Nanotechnology in agriculture and food industry has attracted significant attention over the past few decades. Benefiting from the introduction of controlled release capability, drug/cargo delivery systems possess great advantages for plants in delivering plant genes, hormones, pesticides, and fertilizers to mediate their growth. Herein, we construct a new smart multi-stimuli responsive hormone delivery system to regulate the release of gibberellin acid (GA3) for plant growth. Hollow mesoporous silica nanoparticles have been utilized as nanocarriers, upon which water soluble carboxylatopillararene ammonium (WPA) functionalized Fe3O4 nanoparticles (WPA-Fe3O4) are installed as nanovalves via host–guest interactions (WPA-Fe3O4 capped HMSNs are denoted as HMSN/Fe3O4). Bidirectional pH-responsive supramolecular nanovalves have been constructed for the first time, and under acidic or alkaline conditions hormones can be released out from GA3-loaded HMSN/Fe3O4 (GA3-HMSN/Fe3O4) to promote the growth of plants. Interestingly, the GA3-HMSN/Fe3O4 nanoparticles can also respond to other stimuli including 1,4-butanediamine (BDA) and ultrasound. This smart delivery system has been successfully applied in plants like Arabidopsis thaliana (A. thaliana) and cabbages, and our experimental results suggested that the GA3-HMSN/Fe3O4 hybrid nanomaterials can obviously promote the growth of both plants. Therefore, we envision that this magnetic multi-stimuli responsive system will hopefully play an important role in promoting agricultural industry development.