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Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session D

Poster I17 - Polyethylene Glycol Surface Modification of Electrospun PDMS Fibers

Friday, October 25, 2024
3:30 PM - 4:30 PM EST
Location: Exhibit Hall E, F & G

Introduction:  PDMS is a widely used elastomeric material known for its flexibility and biocompatibility, making it suitable for various biomedical and engineering applications [1]. Though PDMS is hydrophobic in nature, with the use of PEG, a hydrophilic polymer, this challenge may be addressed by imparting improved hydrophilicity versatility to the material [2]. This surface modification technique holds promise in advancing the performance of PDMS in its use as a biocompatible substance.

Materials and

Methods:  Sylgard 184 silicone elastomer kit (PDMS) was purchased from Ellsworth Adhesives (Germantown, WI). Dimethylsiloxane (60-70% Ethylene Oxide) Block Copolymer (PEG BCP) MW 600, 20 cSt was purchased from Gelest (Morrisville, PA). Polyvinylpyrrolidone (PVP) and Tetrahydrofuran (THF) were purchased from ThermoFisher Scientific (Waltham, MA). Paraffin wax pencils purchased from Fashionwu. PDMS fibers were created using the MSK-NFES-3 benchtop electrospinning unit. PVP and PDMS-PEG solutions were placed into 15.65 mL syringes and fed through PTFE tubing. To form the coaxial structure, a 21-gauge and 14-gauge needle were used for core and sheath respectively. After fiber deposition, fiber mats were cured at 100 ⁰C for 24 hours; then the PVP sheath was removed by soaking fiber mats in ethanol for 20 minutes. PDMS-PEG was investigated with 10:1 and 30:1 elastomeric base to cure ratios of PDMS. PEG BCP was added to PDMS mixtures in weight percentages of 1% and 2% with added THF in weight percentages of 10%, 15%, and 20%.

Results, Conclusions, and Discussions: PEG BCP reportedly enhances the Si-O group in PDMS, resulting in a more hydrophilic surface due to an increase in a silicon oxide rich layer; this explains the decrease in WCA with increasing PEG (Figure 1A). When observing the effects of WCA with PEG BCP on PDMS fiber mats with 2% PEG and 20% THF having a hydrophilic WCA of 51.26 ± 29.77⁰. With the fabrication process incorporating PEG BCP into uncured PDMS, the longevity of the WCA for pure PDMS fibers over seven days ranged from 131⁰–135⁰, for 1% PDMS-PEG, the WCA ranged from 43⁰–116⁰, and for 2% PDMS-PEG the WCA ranged from 22⁰–75⁰ (Figure 1B). PDMS-PEG fiber mats have similar adhesion loads to commercially available wound dressings [3]. Through Van der Waals forces, PDMS-PEG can be seen adhering to the skin. Likewise, the PDMS-PEG fiber mat, maintains contact with the stratum corneum under stretching, twisting, and compression motions of the skin. A sample developed with the use of paraffin wax-printing techniques to create a design on the surface of a PDMS-PEG fiber mat, append the fiber mat with fluidic channels through which water-soluble liquids can flow, allowing for an additional application for PDMS-PEG fiber mats as microfluidic devices (Figure 1D). Figure 1C shows a one-way ANOVA test to evaluate the significance of differences between PEG BCP percentages and pure PDMS, revealing statistical differences between groups. The Tukey post-hoc test assessed the statistical significance of the PDMS-PEG fiber mats compared to the pure PDMS. The 1% PEG 15% THF and 2% PEG 20% THF fiber mats compared to pure PDMS fiber mats showed statistical significance with a p-value of 0.02 and 0.04 (p < 0.05), respectively. However, the 2% PEG 15% THF fiber mat compared to pure PDMS fiber mats showed statistical significance with a p-value of 0.002 (p < 0.01). PDMS is a highly flexible and biocompatible elastomeric material. However, its inherent hydrophobic nature poses challenges. By incorporating PEG, these challenges can be mitigated, enhancing the hydrophilicity and overall versatility of PDMS.

Acknowledgements (Optional):