Stimuli-Free Transcuticular Delivery of Zn Microelement Using Biopolymeric Nanovehicles: Experimental, Theoretical, and <i>In Planta</i> Studies.

Abstract

This paper reports one-step synthesis of polysaccharide-based nanovehicles, capable of transporting ionic zinc <i>via</i> plant cuticle without auxiliary stimulation. Delivery of highly hydrophilic nutritive microelements <i>via</i> the hydrophobic cuticle of plant foliage is one of the major challenges in modern agriculture. In traditional nutrition <i>via</i> roots, up to 80% of microelements permeate to soil and get wasted; therefore, foliar treatment is an environmentally and economically preferable alternative. Carboxymethyl cellulose (CMC) was modified to amphiphilic <i>N</i>-octylamide-derivative (CMC-8), which spontaneously self-assemble to nanovehicles. It was found that hydrophobic substituents endow a biopolymer with unexpected affinity toward a hydrophilic payload. CMC-8 nanovehicles effectively encapsulated ionic zinc (ZnSO₄) and delivered it upon foliar application to pepper (<i>Capsicum annuum</i>) and tomato (<i>Solanum lycopersicum</i>) plants. Zinc uptake and translocation in plants were monitored by SEM-EDS and fluorescence microscopic methods. <i>In planta</i> monitoring of the carrier was done by labeling nanovehicles with fluorescent carbon dots. Three-dimensional (3-D) structural modeling and conformational dynamics explained the CMC-8 self-assembly mechanism and zinc coordination phenomenon upon introduction of hydrophobic substituents.