Measuring contact angles on hydrophilic porous scaffolds by implementing a novel raised platform approach: A technical note

Abstract

Contact angle (CA) analysis is a widely employed technique to assess the surface properties of solid samples, including in tissue engineering research where scaffolds are typically designed to be both porous and hydrophilic to enable cell and tissue infiltration. Paradoxically, the types of scaffolds that possess the most optimal hydrophilic surface properties for cell attachment are the most challenging surfaces to attain accurate CA measurements. Here, we propose the use of a small 3D printed platform to elevate samples above the CA measurement substrate and demonstrate reproducible and accurate CA measurements on a range of popular polymer scaffolds that had undergone 5 min plasma treatment to instigate hydrophilicity. Using four polycaprolactone or high-density polyethylene scaffolds with porosity ranging from 35.8%–93.1%, 0° CAs were reproducibly observed by measuring the CA while the scaffolds were elevated on the 3D printed platform, compared to the highly variable false-positive results when measuring the scaffolds while directly sitting on measurement substrates of various materials. This versatile, low-cost modification to CA hardware overcomes the challenges associated with measuring the surface properties of porous, hydrophilic scaffolds and provides a simple tool for tissue engineering researchers to perform CA measurements for any biomaterial scaffolds to ascertain hydrophilicity which is used to infer the suitability of scaffold surfaces for cell attachment.