Julie A. Willoughby

Development of abamectin loaded plant virus nanoparticles for efficacious plant parasitic nematode control.

Plant parasitic nematodes are one of the worlds major agricultural pests, causing in excess of

Loading and Release Mechanism of Red Clover Necrotic Mosaic Virus Derived Plant Viral Nanoparticles for Drug Delivery of Doxorubicin

157 billion in worldwide crop damage annually. Abamectin (Abm) is a biological pesticide with a strong activity against a wide variety of plant parasitic nematodes. However, Abms poor mobility in the soil compromises its nematicide performance because of the limited zone of protection surrounding the growing root system of the plant. In this study, we manipulated Abms soil physical chemistry by encapsulating Abm within the Red clover necrotic mosaic virus (RCNMV) to produce a plant virus nanoparticle (PVN) delivery system for Abm. The transmission electron microscopic and dynamic light scattering characterization of Abm-loaded PVN (PVN(Abm)) indicated the resultant viral capsid integrity and morphology comparable to native RCNMV. In addition, the PVN(Abm) significantly increased Abms soil mobility while enabling a controlled release strategy for Abms bioavailability to nematodes. As a result, PVN(Abm) enlarged the zone of protection from Meloidogyne hapla root knot nematodes in the soil as compared to treating with free Abm molecules. Tomato seedlings treated with PVN(Abm) had healthier root growth and a reduction in root galling demonstrating the success of this delivery system for the increased efficacy of Abm to control nematode damage in crops.

Cyclodextrin facilitated electrospun chitosan nanofibers

Loading and release mechanisms of Red clover necrotic mosaicvirus (RCNMV) derived plant viral nanoparticle (PVN) are shown for controlled delivery of the anticancer drug, doxorubicin (Dox). Previous studies demonstrate that RCNMVs structure and unique response to divalent cation depletion and re-addition enables Dox infusion to the viral capsid through a pore formation mechanism. However, by controlling the net charge of RCNMV outer surface and accessibility of RCNMV interior cavity, tunable release of PVN is possible via manipulation of the Dox loading capacity and binding locations (external surface-binding or internal capsid-encapsulation) with the RCNMV capsid. Bimodal release kinetics is achieved via a rapid release of surface-Dox followed by a slow release of encapsulated Dox. Moreover, the rate of Dox release and the amount of released Dox increases with an increase in environmental pH or a decrease in concentration of divalent cations. This pH-responsive Dox release from PVN is controlled by Fickian diffusion kinetics where the release rate is dependent on the location of the bound or loaded active molecule. In summary, controllable release of Dox-loaded PVNs is imparted by 1) formulation conditions and 2) driven by the capsids pH- and ion- responsive functions in a given environment.

Oil-in-Water Emulsions Stabilized by Carboxymethylated Lignins: Properties and Energy Prospects

The use of chitosan, a cationic, biodegradable polysaccharide derived from sea-shells, in nanofibrous form offers a powerful platform to exploit its inherent benefits. However, chitosan nanofiber formation is difficult, requiring corrosive solvents or a carrier polymer blend to successfully electrospin. Our approach entails blending chitosan with a functional small molecule, cyclodextrin, to facilitate nanofiber formation of chitosan in acetic acid and trifluoroacetic acid. In this case the cyclodextrin, with its complexation properties, could serve to improve chitosan fiber formation, thus serving as a multi-functional blend. In this study, we examine the role of each component and the possibility of synergistic effects in nanofiber formation. Significant improvements in chitosan fiber formation were observed in concert with cyclodextrin at solvent concentrations not possible with just the individual components. Multiple fiber morphologies including three-dimensional fiber mats were also achieved. We examine the improved nanofiber formation in relation to solution viscosity, polymer entanglement, and chitosan–cyclodextrin associations. Rheological studies provide evidence of interactions between cyclodextrin and chitosan. NMR and FTIR studies further validate complexation between these two components.

Polymeric Systems Incorporating Plant Viral Nanoparticles for Tailored Release of Therapeutics

We take advantage of the amphiphilic properties of technical lignin macromolecules and their inherent high calorific values to formulate oil-in-water (O/W) fuel emulsions with high internal-phase ratios. For the oil phase, we used a combustible hydrocarbon (kerosene) with a measured equivalent alkane carbon number of 12. To adjust the balance of affinity with the oil and water phases and their surface activity, pine kraft lignins were carboxymethylated to different degrees, as quantified by (13) C NMR spectroscopy, potentiometric titrations, and zeta potential measurements. Carboxymethylated lignins (CMLs) with a degree of substitution of 30 % displayed a critical aggregation concentration of 3 %. The salinity and pH of the aqueous phase were chosen as formulation variables and adjusted within the Winsor framework. The O/W emulsions were produced by following standard protocols. The drop-size distributions of emulsions with varying pH, degree of substitution, and composition (water-to-oil ratio, WOR) were determined, and the long-term stabilities and rheological behavior of these emulsions were analyzed. Most of the obtained O/W fuel emulsions showed shear-thinning behavior with a drop size of approximately 2.5 μm and were stable for over 30 days. The combustion of the lignins and their respective emulsions was performed, and their higher heating values (HHVs) were quantified. The HHVs of CML and a high-internal-phase (WOR=30:70) O/W emulsion were 20 and 30 MJ kg(-1) , respectively. Overall, we propose the stabilization of O/W fuel emulsions by lignin as an important avenue in the utilization of this abundant biomacromolecule.

Carboxymethylated lignins with low surface tension toward low viscosity and highly stable emulsions of crude bitumen and refined oils

Therapeutic polylactide (PLA) nanofibrous matrices are fabricated by incorporating plant viral nanoparticles (PVNs) infused with fluorescent agents ethidium bromide (EtBr) and rhodamine (Rho), and cancer therapeutic doxorubicin (Dox). The native virus, Red clover necrotic mosaic virus (RCNMV), reversibly opens and closes upon exposure to the appropriate environmental stimuli. Infusing RCNMV with small molecules allows the incorporation of PVN(Active) into fibrous matrices via two methods: direct processing by in situ electrospinning of a polymer and PVNs solution or immersion of the matrix into a viral nanoparticle solution. Five organic solvents commonly in-use for electrospinning are evaluated for potential negative impact on RCNMV stability. In addition, leakage of rhodamine from the corresponding PVN(Rho) upon solvent exposure is determined. Incorporation of the PVN into the matrices are evaluated via transmission electron, scanning electron and fluorescent microscopies. Finally, the percent cumulative release of doxorubicin from both PLA nanofibers and PLA and polyethylene oxide (PEO) hybrid nanofibers demonstrate tailored release due to the incorporation of PVN(Dox) as compared to the control nanofibers with free Dox. Preliminary kinetic analysis results suggest a two-phase release profile with the first phase following a hindered Fickian transport mechanism for the release of Dox for the polymer-embedded PVNs. In contrast, the nanofiber matrices that incorporate PVNs through the immersion processing method followed a pseudo-first order kinetic transport mechanism.

Development of abamectin loaded lignocellulosic matrices for the controlled release of nematicide for crop protection

Kraft and organosolv lignins were subjected to carboxymethylation to produce fractions that were soluble in water, displayed a minimum surface tension as low as 34mN/m (25°C) and a critical aggregation concentration of ∼1.5wt%. The carboxymethylated lignins (CML), which were characterized in terms of their degree of substitution ((31)P NMR), elemental composition, and molecular weight (GPC), were found suitable in the formulation of emulsions with bitumens of ultra-high viscosity, such as those from the Canadian oil sands. Remarkably, the interfacial features of the CML enabled fuel emulsions that were synthesized in a very broad range of internal phase content (30-70%). Cryo-replica transmission electron microscopy, which was used here the first time to assess the morphology of the lignin-based emulsions, revealed the droplets of the emulsion stabilized with the modified lignin. The observed drop size (diameters<2μm) was confirmed by light scattering, which revealed a normal size distribution. Such characteristics led to stable emulsified systems that are amenable for a wide range of applications. Emulsification with CML afforded bitumen emulsions with very high colloidal stability (no change was noted for over one month) and with a strong shear thinning behavior. Both features indicate excellent prospects for storage, transport and spraying, which are relevant in operations for power generation, which also take advantage of the high heating value of the emulsion components. The ability of CML to stabilize emulsions and to contribute in their combustion was tested with light fuels (kerosene, diesel, and jet fuel) after formulation of high internal phase systems (70% oil) that enabled operation of a fuel engine. A significant finding is that under certain conditions and compared to the respective pure fuel, combustion of the O/W emulsions stabilized by CML presented lower NOx and CO emissions and maintained a relatively high combustion efficiency. The results highlight the possibilities in high volume application for lignin biomacromolecules.