Measuring wettability of biosurfaces at the microscale

Methods Mol Biol. 2012;811:163-77. doi: 10.1007/978-1-61779-388-2_11.

Abstract

Determining the contact angle of a liquid on a solid surface is a simple method to assess the surface wettability. The most common method to measure the contact angle of a liquid consists of capturing the profile of a sessile drop of a few microliters on the surface using an optical system. Currently, this is a widely used technique to analyze wettability both in researched materials and in products of multiple technological fields. However, the drop dispensed by a traditional macroscopic contact angle meter is too big to assess the wettability properties of individual topographical features and/or chemical patterns at the micro/nanoscale. Recently, contact angle meters that can discharge drops that are microscopic, with volumes in the range of 1 × 10(-3) to 10(-5) μL have been developed. The novel microscopic contact angle meter uses a pneumatic injection system to discharge the drop of the liquid through a capillary of a few micrometers of internal diameter and a high-resolution ultrafast digital camera. We have tested different biosurfaces - microimprinted polymers for biosensors, calcium-phosphate cements with different topographical microfeatures, orthodontic wires - and assessed the potential applicability in the field in comparison with the conventional macroscopic contact angle meters. This protocol describes the basic tasks needed to test wettability on biosurfaces with a microscopic contact angle meter. The focus of the protocol is on the challenging methodological steps and those that differentiate the use of this equipment to the use of a traditional macroscopic contact angle meter.

MeSH terms

  • Biosensing Techniques
  • Biotechnology / instrumentation
  • Biotechnology / methods*
  • Calcium Phosphates / chemistry
  • Chemistry Techniques, Analytical / instrumentation
  • Chemistry Techniques, Analytical / methods*
  • Orthodontic Wires
  • Polymers / chemistry
  • Regenerative Medicine / instrumentation
  • Regenerative Medicine / methods*
  • Wettability*

Substances

  • Calcium Phosphates
  • Polymers