# Nanoengineered polyglutamic acid fertilizers via self-assembly for efficient tomato growth

## TL;DR

Researchers developed a new type of eco-friendly nanofertilizer using polyglutamic acid that improves tomato growth and stress resistance.

## Contribution

A novel self-assembly method creates PGA nanofertilizers with better leaf retention and plant mobility.

## Key findings

- PGA nanofertilizers showed uniform spherical morphology and good water dispersibility.
- Fluorescence imaging confirmed bidirectional transport and vascular localization in plants.
- Nanofertilizers improved chlorophyll, root growth, and antioxidant activity in tomatoes.

## Abstract

Polyglutamic acid (γ-PGA) is a promising biostimulant for enhancing crop growth and stress resistance, while its agricultural application is limited by poor leaf retention, low mobility within plants, and susceptibility to rain wash-off.

This study developed PGA nanofertilizers via a facile one-step self-assembly strategy in crude γ-PGA aqueous solution without adding salt ions to overcome these limitations. SEM images show that the obtained nanoparticles appear uniform spherical morphology and good dispersibility in water with an average hydrodynamic diameter of 182 nm confirmed by DLS. XRD and DSC patterns indicate a strong reduction in crystallinity consistent with a largely amorphous or highly disordered state.

Fluorescence imaging of FITC-labeled PGA nanofertilizers (FITC@PGA) indicates systemic, vascular-localized signals consistent with bidirectional movement from absorption of both roots and leaves. Importantly, the PGA nanofertilizers exhibited superior rainfastness and leaf retention compared to crude γ-PGA. Physiological assessments showed that foliar application of PGA nanofertilizers significantly enhanced chlorophyll content, root development, and antioxidant enzyme activities compared to that of crude γ-PGA, which led to significant improvement for tomato growth and stress tolerance.

It is clear shown that the nano-engineering strategy will provide a promising approach for developing efficient and eco-friendly nanofertilizer.

TOC graphics.Illustration depicting the bidirectional transport in a plant. Labels indicate foliar and root absorption with cellular structures like epidermis, mesophyll, phloem, xylem. A red spray bottle suggests foliar application. The stoma is highlighted for foliar absorption. Arrows indicate movements of substances through the plant, including via roots and stems, with terms such as SOD, CAT, and POD.

TOC graphics.