Degree

Doctor of Philosophy (PhD)

Department

Biological and Agricultural Engineering

Document Type

Dissertation

Abstract

Conventional agricultural practices suffer from poor targeting efficiency, environmental accumulation, and phytotoxicity at high application rates. Engineered nano-delivery systems offer a transformative strategy for improving the precision, efficacy, and environmental sustainability of agricultural inputs. This dissertation focused on the rational design, development, and optimization of multifunctional surfactant-free anionic and cationic lignin-graft-poly(lactic-co-glycolic acid) (LN-g-PLGA) core-shell nanoparticles ((a/c)LNPs) with controlled size and surface charge for the delivery of in-house synthesized nanoscale copper sulfide (nCuS), an antimicrobial and micronutrient complex. LN-g-PLGA was further modified by successful attachment of the plant growth hormone gibberellic acid (GA3) to create a nanoparticle platform for co-delivery of the GA3 and nCuS. Systematic adjustment of synthesis parameters enabled the production of colloidally stable (|ζ|≥38 mV) nanoparticles (~100-200 nm) with tunable physicochemical properties and reproducible performance. FTIR and NMR confirmed polymer grafting, and NP size was characterized using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). Scanning and transmission electron microscopy (S/TEM) and inductively coupled plasma (ICP) spectroscopy verified nCuS incorporation into the NPs and nutrient quantification in plant tissues, respectively, while X-ray photoelectron spectroscopy (XPS) confirmed the speciation of Cu and S after release from the nanocarrier matrix. The interaction of unloaded and nCuS-loaded (a/c)LNPs with lettuce (Lactuca sativa) in hydroponic systems was evaluated to assess delivery efficiency and metabolic activity. Results demonstrated plant compatibility of the LNPs with minimal phytotoxic or stress effects and showed that surface charge plays a decisive role in nanoparticle-plant interactions, with significant copper accumulation in roots for both (a/c)LNPs and selective systemic translocation to leaves for aLNPs. Metabolic variation was primarily attributed to the leaf developmental stage rather than nanoparticle treatments. Altogether, this work establishes lignin-based nanocarriers as a versatile, bio-based platform that integrates nutritional, antimicrobial, antioxidant, and growth-regulatory functionalities. Our findings advance nano-enabled strategies for sustainable agriculture and contribute to the development of plant-compatible agrochemical delivery and circular economy systems.

Date

4-13-2026

Committee Chair

Cristina Sabliov

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

Download

Available for download on Friday, April 09, 2027

Share

COinS