Wettability is a critical property of materials, especially in the biomedical field, where it significantly influences the interaction between materials and biological entities such as proteins, cells, and bacteria. This blog post highlights the importance of wettability measurements in biomedical applications, exploring various methods and their implications.
Introduction to Wettability
Wettability refers to how a liquid interacts with a solid surface, which can be quantified by measuring the contact angle formed at the interface. This property is crucial in biomedical applications as it affects protein adsorption, cell adhesion, blood coagulation, and bacterial colonization.
Importance of Wettability in Biomedical Applications
In the biomedical field, the surface properties of materials are often modified to enhance biocompatibility. This can be achieved either by altering the bulk material or by applying a coating. For instance, hydrophilic coatings are used to improve the interaction of medical devices with biological tissues. Wettability measurements help in evaluating these modifications to ensure they meet the desired biocompatibility standards.
Methods of Measuring Wettability
- Sessile Drop Method: This is the most common technique where a droplet of liquid is placed on the material surface, and the contact angle is measured using an optical tensiometer. This method is straightforward and cost-effective, making it ideal for initial assessments.
- Captive Bubble Method: Used primarily for highly hydrophilic surfaces, this method involves placing an air bubble on an inverted sample submerged in water. It helps prevent dehydration of the sample and provides accurate measurements for materials like contact lenses and hydrogels.
- Picoliter Drop Method: For very small surface areas, picoliter-sized droplets are used. This method is particularly useful for measuring the wettability of catheters and other small biomedical devices.
- Wilhelmy Plate Method: This technique involves immersing a sample in a liquid and measuring the force exerted on the sample. It is useful for studying thin fibers and adsorption phenomena.
Dynamic Contact Angles and Hysteresis
Static contact angle measurements provide a snapshot of wettability, but dynamic measurements offer more detailed insights. Dynamic contact angles, including advancing and receding angles, help in understanding the behavior of liquids on surfaces under different conditions. This is particularly important for developing advanced materials like superhydrophobic surfaces used in blood-repellent medical devices.
Surface Free Energy
Surface free energy (SFE) is another critical parameter derived from contact angle measurements. It provides a comprehensive understanding of surface chemistry and its interaction with biological entities. Higher SFE generally correlates with better cell adhesion, which is crucial for implants and other biomedical devices.
Conclusion
Wettability measurements are indispensable in the development and evaluation of biomedical materials. By understanding and controlling wettability, researchers can design materials that interact optimally with biological systems, enhancing the performance and safety of medical devices.
For more detailed information on wettability measurement techniques and their applications in biomedical research, download the white paper below.
