Department of Biomedical Engineering Posters and Presentations

Title

In Vitro Hydrodynamic Investigation of Polyvinyl Alcohol Scaffolds for Drug Delivery

Document Type

Poster

Keywords

Tissue Engineering, Biofluid Dynamics, Fluid Dynamics

Publication Date

4-2017

Abstract

In the field of tissue engineering, rapidly-prototyped polymer scaffolds are being researched for allografting and in vivo, ultra-fast drug release applications [1]. Degradation of these scaffolds must match patient recovery time. General degradation of polymers occurs in two stages: polymeric matrix swelling and structural failure [2]. Accordingly, the objective of this study is to monitor the degradation, diffusion, and transport of polyvinyl alcohol (PVA) scaffolds in an alkaline medium. The diffusion coefficient of diluted PVA was measured using a Polson cell apparatus and UV spectrophotometer [3]. A Beer’s Law calibration curve was found using known concentrations of dilute PVA and their absorption at 275 nm wavelength light. The base concentrations were then inserted into the bottom section of the Polson Cell while deionized (DI) water was inserted into the top as the solvent. The Polson Cell-sections were aligned for certain time durations and then offset. The absorption at 275 nm wavelength light of the solution from the top section was found. The diffused concentrations were determined using the absorbance values and the Beer’s Law calibration curve. Using these diffused concentrations, the diffusion coefficient for a base concentration of 50 mg/mL was found to be 0.6096 × 10-5 cm^2/s (± 4.3e-06 at ~ 25 °C), analytically. The dynamic degradation was studied in a lab-scale, curved artery-based flow loop system with steady and unsteady flow conditions for PVA scaffold geometries of 20%, 40%, and 60% infill. The unsteady flow rate was modeled with a carotid artery-based pulsatile flow rate waveform. Two microelectromechanical systems-based (MEMS) were used to measure the pressure differential across the scaffold in the flow loop and the degradation of the PVA-scaffolds was monitored. All experiments were performed at room temperature (~ 25 °C ± 1 °C) with deionized (DI) water as the working fluid and pre-wetted scaffolds to ensure homogeneity. The results have tremendous potential to impact our understanding of drug-release and transport in clinically-relevant scenarios.

References

[1] D. W. Hutmacher, and S. Cool, "Concepts of scaffold-based tissue engineering – the rationale to use solid free-form fabrication techniques." J. Cell. Mol. Med. Vol 11.4, pp 654-669, 2007.

[2] Y. Fu, and W. J. Kao, "Drug release kinetics and transport mechanisms of nondegradable and degradable polymeric delivery systems." Expert Opin Drug Deliv. Vol 7.4, pp 429-444, 2010.

[3] A. Polson, "A new method for measuring diffusion constants of biologically active substances." Nature Vol 154 pp 823, Dec. 1944.

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Open Access

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Comments

To be presented at GW Research Days 2017.

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In Vitro Hydrodynamic Investigation of Polyvinyl Alcohol Scaffolds for Drug Delivery

In the field of tissue engineering, rapidly-prototyped polymer scaffolds are being researched for allografting and in vivo, ultra-fast drug release applications [1]. Degradation of these scaffolds must match patient recovery time. General degradation of polymers occurs in two stages: polymeric matrix swelling and structural failure [2]. Accordingly, the objective of this study is to monitor the degradation, diffusion, and transport of polyvinyl alcohol (PVA) scaffolds in an alkaline medium. The diffusion coefficient of diluted PVA was measured using a Polson cell apparatus and UV spectrophotometer [3]. A Beer’s Law calibration curve was found using known concentrations of dilute PVA and their absorption at 275 nm wavelength light. The base concentrations were then inserted into the bottom section of the Polson Cell while deionized (DI) water was inserted into the top as the solvent. The Polson Cell-sections were aligned for certain time durations and then offset. The absorption at 275 nm wavelength light of the solution from the top section was found. The diffused concentrations were determined using the absorbance values and the Beer’s Law calibration curve. Using these diffused concentrations, the diffusion coefficient for a base concentration of 50 mg/mL was found to be 0.6096 × 10-5 cm^2/s (± 4.3e-06 at ~ 25 °C), analytically. The dynamic degradation was studied in a lab-scale, curved artery-based flow loop system with steady and unsteady flow conditions for PVA scaffold geometries of 20%, 40%, and 60% infill. The unsteady flow rate was modeled with a carotid artery-based pulsatile flow rate waveform. Two microelectromechanical systems-based (MEMS) were used to measure the pressure differential across the scaffold in the flow loop and the degradation of the PVA-scaffolds was monitored. All experiments were performed at room temperature (~ 25 °C ± 1 °C) with deionized (DI) water as the working fluid and pre-wetted scaffolds to ensure homogeneity. The results have tremendous potential to impact our understanding of drug-release and transport in clinically-relevant scenarios.

References

[1] D. W. Hutmacher, and S. Cool, "Concepts of scaffold-based tissue engineering – the rationale to use solid free-form fabrication techniques." J. Cell. Mol. Med. Vol 11.4, pp 654-669, 2007.

[2] Y. Fu, and W. J. Kao, "Drug release kinetics and transport mechanisms of nondegradable and degradable polymeric delivery systems." Expert Opin Drug Deliv. Vol 7.4, pp 429-444, 2010.

[3] A. Polson, "A new method for measuring diffusion constants of biologically active substances." Nature Vol 154 pp 823, Dec. 1944.