Citation
PEG-Peptide Microparticles for Pulmonary Drug Delivery

Material Information

Title:
PEG-Peptide Microparticles for Pulmonary Drug Delivery
Series Title:
18th Annual Undergraduate Research Symposium
Creator:
Edwards, Camilla
Language:
English

Subjects

Subjects / Keywords:
Center for Undergraduate Research
Engineering
Genre:
Conference papers and proceedings
poster ( aat )

Notes

Abstract:
Because of their low cost, ease of processing, and biocompatibility, hydrogel particles offer an ideal medium for drug delivery. The hydrogel particles can be synthesized via emulsion polymerization, and additionally can be made enzyme-responsive by incorporating specific peptide sequences into the polymeric gel. In the case of lung disease, these enzyme-responsive hydrogels will then release drug only near diseased cells which overexpress matrix metalloproteinases (MMPs). But while the particles can be made site-specific, their drug release must be predictable. As hydrogels sit in a water-based medium, (such as lung fluid), they swell and release their contents due to a difference in osmotic pressure. This swelling, combined with the enzymatic degradation, releases the drug into the body. By using a peptide- conjugated polyethylene glycol (PEG) diacrylate and tuning the composition of the hydrogel, the degradation rate and thereby drug release rates of the particles can be controlled. This poster seeks to show the relationship between hydrogel composition and their resultant degradation properties. ( en )
General Note:
Research Authors: Camilla Edwards, Amanda Uhl, Jennifer Andrew (PI) - University of Florida
General Note:
University Scholars Program
General Note:
Faculty Mentor: Jennifer Andrew - Materials Science and Engineering, University of Florida

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Source Institution:
University of Florida
Rights Management:
Copyright Camilla Edwards. Permission granted to University of Florida to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.

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Microgel Particle Synthesis for Pulmonary Drug Delivery Camilla Edwards, Amanda Uhl Jennifer Andrew, PhD Department of Materials Science & Engineering, University of Florida, Gainesville, FL Methodology Conclusions References Introduction Results Acknowledgements Figure 3 Dry, water swollen, and cell culture swollen microparticles Because of their low cost, ease of processing, and biocompatibility, hydrogel particles offer an ideal medium for drug delivery. The hydrogel particles can be synthesized via emulsion polymerization, and additionally can be made enzyme responsive by incorporating specific peptide sequences into the polymeric gel [1] In the case of lung disease, these enzyme responsive hydrogels will then release drug only near diseased cells which overexpress matrix metalloproteinases (MMPs) [2] But while the particles can be made site specific, their drug release must be predictable. As hydrogels sit in a water based medium, (such as lung fluid), they swell and release their contents due to a difference in osmotic pressure [3] This swelling, combined with the enzymatic degradation, releases the drug into the body. By using a peptide conjugated poly(ethylene glycol) (PEG) diacrylate and tuning the composition of the hydrogel, the degradation rate and thereby drug release rates of the particles can be controlled. PEG Peptide was synthesized by reacting Acr PEG SVA with the Gly Pro Gln Gly Ile Phe Gly Gln Lys protein sequence in a basic (pH = 8.0) bicarbonate buffer for 4 hours, dialyzed versus deionized water, then freeze dried. The microgel particles were created by first mixing the desired weight percent of polymer in deionized water, then incubating overnight at 37 deg C. At the same time, 50 mg of 2,2 dimethoxy 2 phenylacetophenone (DMPA), a photocrosslinker was mixed with 10 mL of silicone oil under agitation for 24 hours until fully dissolved. Next, the two mixtures were combined and vortexed at high speed to create an emulsion. This emulsion was then poured into a petri dish and placed under UV light for 30 minutes to allow crosslinking. Finally, the particles were rinsed of any silicone oil and freeze dried. [1] Particles were imaged dry in a Scanning Electron Microscope (SEM). Then, a small amount of particles were mixed with 0.5 mL of DIW and placed in a well plate. This process was repeated for each concentration with an equal amount of cell culture. After 24 hours, the swollen particles were imaged using an optical microscope. The diameters of 50 particles were then measured and averaged using ImageJ. The swell ratio was computed by performing the following calculation. where D swollen is the diameter of the swollen particle, and D dry is the diameter of the freeze dried particle [4 ] From the study conducted, the hypothesis was proved true when dealing with particles in water. Particles were formed from the hydrogel, and as the polymer concentration increased, the swollen particle diameter decreased compared to the original. To extrapolate the findings, as water allowed the hydrogel can escape. However, in cell culture media, the hypothesis was proved false. This phenomenon could occur for a number of reasons. First, the cell culture media contains more than just water it contains a variety of other substances, including proteins found in the body. These substances could interact with the polymer mesh, causing it to collapse rather than swell. This would lead a higher concentration of polymer to collapse smaller, which is what is seen. Either way, however, the amount of drug can be predicted, measured, and controlled. It is clear from Figure 6 that as the concentration of polymer increases, the swell ratio of particles swollen in water decreases. However, the exact opposite trend follows for the cell culture media as polymer concentrations increase, the swell ratio also increases. [1] E. Secret, K. E. Crannell S.J. Kelly, M. Villancio Wolter sensitive hydrogel microparticles J. Mater. Chem. B, vol 3, pp. 5629 5634, Jun 2015. Fluorogenic Methods Mol Biol Vol 151, pp. 495 518, Mar 2015. [3] T. R. Hoare, D. S. Kohane Polymer vol. 49, no. 8, pp. 1993 2007. April 2008. [4] Standard Test Methods for Determination of Gel Content and Swell Ratio of Crosslinked Ethylene Plastics, ASTM D2765 16, 14 Oct 2016. Matriz metalloproteinases: What do they not do? Biochimica et Biophysica Acta Vol 1803, no. 1, pp. 39 54, Jan 2010. [6] Martin TA, Ye L, Sanders AJ, et al. Cancer Invasion and Metastasis: Molecular and Cellular Perspective. In: Madame Curie Bioscience Database [Internet]. Austin (TX): Landes Bioscience; 2000 2013. Available from: https://www.ncbi.nlm.nih.gov/books/NBK164700/ [ 7] M. W. Ndinguri Based Selective Inhibitors of Matrix Metalloproteinase Mediated Molecules Vol 17, no. 12, pp 14230 14248, Nov 2012. Dr. Jennifer Andrew, Principal Investigator Amanda Uhl Graduate Research Assistant Braden Li, Undergraduate Research Assistant Hypothesis Hydrogel particles are essentially an interwoven, water containing mesh of cross linked polymers molecules [3] In addition to water, other substances (i.e. drugs for delivery) can be added while manufacturing the particles. As the particles sit in water, more water molecules enter the mesh, increasing the distance between polymer chains and causing the drug to be released. Physically, this means that the particle increases in size By increasing the initial polymer concentration, the difference between the dry particle size and the swollen particle size should be smaller. This is because there are is more interconnected polymer per unit area, which will prevent as many water molecules from filling the space between chains In the case of our particles, the drug loaded inside the particles is dexamethasone. Because of this, the swelling ratio should be a good indication of how much drug will be released. By measuring this, the amount of drug that is released can be predicted, making the drug safer to prescribe and deliver to patients Future Work The potential this drug has to help cure lung disease is found not only in its controlled release of drug, but also in its selectivity. As evinced by much research [5] [6] and their metastic nature, cancerous cells tend to overexpress matrix metalloproteinases (MMPs), which are a type of enzyme that help to break down the tissue in the body. This aids their abnormal growth. To attack these bodily tissues, MMPs target specific protein sequences [7] In the case of lung cancer, MMP 1 (which attacks collagen fibers) especially is overexpressed. By incorporating the Gly Pro Gln Gly Ile Phe Gly Gln Lys protein sequence into the drug coating, only the cells overexpressing MMP 1 will degrade the hydrogel network and receive the encapsulated drug. [2] Future work will include using MMP 1 to degrade microparticles made of different polymeric weight concentrations, then studying their weight change to see how much drug is released Swollen mesh, with water molecules inside As formed mesh Microparticle Figure 1 Magnified mesh of a microparticle When the mesh is soaked in water, the mesh swells and expands. vs Figure 2 Difference between a high polymer concentration mesh versus a low polymer concentration mesh. Dry Water Cell Culture 40 wt % PEG Peptide 50 wt % PEG Peptide 60 wt % PEG Peptide 200 m 200 m 200 m 200 m 200 m Figure 4 : Size and Swell Ratio Calculations Dry Swollen in Water Swollen in Cell Culture Media Avg Size ( ) Avg Size ( ) Swell Ratio Avg Size ( ) Swell Ratio 40 wt % 9.09 3.2 33.53 5.9 3.69 0.5 18.66 3.6 2.05 0.5 50 wt % 14.48 6.1 31.93 2.7 2.20 0.5 32.07 10.6 2.21 0.8 60 wt % 9.42 3.6 20.23 3.9 2.15 0.6 24.53 12.2 2.60 0.9 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 40 wt % 50 wt % 60 wt % Swell Ratio Figure 5 Water Cell Culture 0 0.5 1 1.5 2 2.5 3 3.5 4 40 wt % 50 wt % 60 wt % Swell Ratio Figure 6 Effect of Hydrogel Concentration on Swell Ratio