Paper Number
PO64
Session
Poster Session
Title
3D printing of thermoresponsive nanoemulsions for the diffusion of active ingredients
Presentation Date and Time
October 12, 2022 (Wednesday) 6:30
Track / Room
Poster Session / Riverwalk A
Authors
- Dowdy-Green, Riley E. (North Carolina State University, Chemical & Biomolecular Engineering)
- Hsiao, Lilian (North Carolina State University, Chemical and Biomolecular Engineering)
Author and Affiliation Lines
Riley E. Dowdy-Green and Lilian Hsiao
Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27606
Speaker / Presenter
Dowdy-Green, Riley E.
Keywords
colloids; composite rheology; emulsions; gels; microscopy; pharmaceuticals; polymer blends; surfactants
Text of Abstract
The rheology of precursors used to assemble functional organohydrogels is key to controlling the microstructure and transport kinetics of active ingredients. Here, we use a thermoresponsive nanoemulsion system with a yield stress and shear thinning rheology to investigate how drug delivery kinetics are influenced by processing conditions used in 3D printing. The thermoresponsive nanoemulsion is crosslinked into an organohydrogel capable of holding and releasing hydrophilic and hydrophobic molecules. The nanoemulsion precursor contains 20 vol% poly(dimethylsiloxane) droplets (diameter 2a = 46.3 nm ± 10%) dispersed in a continuous phase comprising 33 vol% of the gelator poly(ethylene glycol) diacrylate (molecular weight = 700 Da) and 200 mM of the surfactant sodium dodecyl sulfate. The dispersed and the continuous phases are loaded with hydrophobic coumarin-6 and hydrophilic methylene blue at a concentration of 0.1 mg/mL. At temperatures above gelation (Tgel = 35.5 ± 1.8°C), the cargo-laden nanoemulsions undergo self-assembly and generates different types of bicontinuous network with tunable morphology. The gelled nanoemulsions are crosslinked with ultraviolet light into composite organohydrogels, both in bulk and using an extrusion-based 3D printer operating at various temperatures (T = 2, 10, and 15°C above Tgel) and shear rates (398, 615, and 723 s-1). Confocal microscopy is used to visualize and quantify the bicontinuous network structures in the hydrogels. The functionalized hydrogels are placed in a custom-built diffusion apparatus to determine the release rates of coumarin-6 and methylene blue over a period of 12 days. The effective diffusion coefficient of these molecules from the samples will be modeled using a mass balance analysis and Fick’s Law of diffusion.