Nano-Sized Delivery For Agricultural Chemicals

Transcription

1 Nano-Sized Delivery For Agricultural Chemicals Min Zhao 1, Lei Liu 1, Robert Ehr 1, Tom Kalantar 2, Dale Schmidt 2, Todd Mathieson 1, Mike Tolley 1, Kerrm Yau 1, Steven Wensing 1 1 Dow AgroSciences LLC., United States 2 Dow Chemical Company, United States June, 2011 Nanoformulation 2011

2 Outline I. Potential benefits to agricultural chemicals II. Nano-particle (NP) cellular uptake Can NP be taken up by model cell systems? III. Hydroponic nano-delivery study Can NPs enter root and move upward in xylem? How does NP size or surface functionality affect plant health? Can fungicide loaded NPs provide disease protection? IV. Nano-capsule pesticide formulation Can pesticide be delivered via nano-sized formulations? Can nano-sizing improve efficacy? V. Summary

3 I. Agrochemical Application Application Reaching the Target SPRAYING Cuticle Upper Epidermis Palisade Mesophyll Improving Efficiency Deposit Formation D R Y I N G Leaf Cross Section Xylem Phloem Sponge Mesophyll Lower Epidermis PENETRATION & UPTAKE Courtesy of Robert Wolf, Kansas State Univ.

4 Agrochemical Formulations Containing Solid Liquid Forms Solid Forms Suspension Concentrates (SC) Capsule Suspensions (CS) Oil Dispersions (OD) Suspo Emulsions (SE) Solid particles are within conventional size range (microns) Volume (%) Wettable Powders (WP) Water Dispersible Granules (WDG or WG) Particle Size (µm)

5 Nano-Technology vs. Agriculture Can nano-sizing delivery systems improve pesticide efficiency? Broadly applicable delivery system, small in size (50-300nm), possibly with designed surface functionality, to deliver active ingredients more efficiently/effectively than those in the conventional size range (microns). How could nano-sized formulations improve efficiency? Leaf Cross Section Cuticle Upper Epidermis Palisade Mesophyll Xylem Phloem Sponge Mesophyll Lower Epidermis Vascular Bundle Enhance penetration, uptake, and systemicity through biological systems (root, stem, foliar, insect guts, etc.) Enhance bio-availability (solubility, soil mobility) Improve or overcome undesirable phys-chem properties of AIs Control release

6 Types Of Pesticide Loaded Nano-Particles Homogeneous Matrix Capsule Gold or silica surface coupling

7 II. Nano-Particle Cellular Uptake The uptake of NP is surface-ligand dependent and an active process Folate for Chinese Hamster Ovarian (CHO) cells, Citrate for tobacco NT1 cells. Negative Surface Charge Citrate A. Au + B. O HN H 2 N N Folate-Cysteine N N HO O N H N H C 22 H 24 N 8 O 7 S Mol. Wt.: O H N O O OH SH Diameter = 30, 60, 150 nm 60nm Optimal size of functionalized particle was estimated at 60 nm, qualitatively determined by analysis of dark field images after a fix-time uptake procedure. (20 min incubation at 37 C, 5% CO 2 ) 30nm Uptake 150nm Particle Diameter

8 Nano-Particle Cellular Uptake Preliminary assay of citrate-au NP on tobacco leaf tissue demonstrated that the particle could penetrate quickly through epidermal cells into palisade cells.

9 III. Hydroponic Rice/Wheat Test System Rice Paddy Root Hair Epidermis Cortex Xylem Phloem Endodermis Root Cross Section

10 Q1: Can NPs Enter Root And Move Upward In Xylem? Testing Protocol NP (internally dyed with fluorescein) solution was injected into the hydroponic solution (1600 ppm NP concentration) Sap was collected every 15 minutes Fluorescence detection in the produced sap sap for collection

11 Q1: Can NPs Enter Root And Move Upward In Xylem? A B C D E Solutions Fluorescence in produced sap (threshold 8ppm) Y Y Y Y N N NP transport through the root barrier and the vascular system was confirmed by fluorescence of the produced sap.

12 Q2: Effects Of Nano-Particle Surface Functionality On Plant Health? Negatively Charged Sap Production Positively Charged At the chosen NP concentration (1600 ppm), positively charged particles clearly hinder root uptake of hydroponic solutions. Day 9 Healthy 150 nm (-) Dying 50 nm (+) Healthy Control 150 nm (+) 150 nm(-) 50 nm (+) DI H2O Control

13 Q2: Effects Of Nano-Particle Size On Plant Health? Sap Production Negatively Charged Samples Compared to Control 100 nm 150 nm 50 nm The size of nano-particles was not a major factor on plant health.

14 Q3: Can Fungicide Loaded NPs Provide Disease Protection? Bioassay Test Vials were spiked with nano-particle solutions then inoculated with brown rust disease of wheat. Assessments were done 6 days after inoculation. NP loaded with fungicide show disease protection. NP w/o fungicide NP w/ Fungicide Fungicide wettable powder, foliar applied

15 IV. Pesticide Formulation Pestcide active ingredient (AI) candidates for NP Model systems: Low water solubility (<1000 ppm) Performance limited due to restricted penetration/uptake Target for 25-50% efficacy enhancement Soluble in common organic solvent Nano-delivery systems: Oil Phase + Water/ Surfactant High Shear Homogenization AI + Solvent/ Monomer nm Shell Formation HO 2 C HO 2 C HO 2 C CO 2 H AI Solvent CO 2 H CO 2 H CO 2 H CO 2 H Miniemulsion process Particle size set here No particle growth Polyurea core/shell Nano-Capsule WO

16 Herbicide: Atrazine Control On Sicklepod (Cassia obtusifolia) Control% AAtrex Nine-O (μm) Nano CS (285 nm) Use Rate (g ai/ha) Nano capsule formulation provided superior weed control to conventional sized formulation.

17 Fungicide: Fenbuconazole Curative Effect On Wheat Leaf Blotch (Septoria tritici) Control% Indar (μm) Nano CS (107 nm) Use Rate (g ai/ha) Nano capsule formulation provided improved disease control compared to conventional sized formulation.

18 Insecticide: Indoxacarb Topical Control On German Cockroach (Blatella germanica) Mortality% SC Control (μm) Nano CS (123 nm) Day after Treatment Use rate: 0.1% Nano capsule formulation increased cockroach mortality compared to conventional sized formulation.

19 Size Dependence Of Fenbuconazole Efficacy In Green House % Disease (Mean of all rates) Nano-sized formulation Typical conventional formulation y = 5.06x R 2 = VMD (μm)

20 V. Summary Present 1. Demonstrated the penetration, uptake, and mobility of NP in model cell systems. 2. Proved that NPs transport through root and xylem. 3. Confirmed the adverse effect from positively charged NPs and size independence on plant health. 4. Demonstrated fungicide loaded NP showing disease protection. 5. Formulated nano-sized pesticide capsules. 6. Demonstrated enhanced efficacy in green house test with a herbicide, fungicide, and insecticide. 7. Confirmed size dependence over nm. 8. Continuing efforts of nano-sized delivery for agricultural chemicals.