Biomaterials have become integral in modern medicine, facilitating advancements in tissue engineering, drug delivery, and medical device design. These materials often come into direct contact with biological systems, making their surface properties a critical factor in their performance. One such surface property that significantly impacts biomaterial functionality is wettability. In this blog post, we will explore the concept of wettability, its importance in biomaterials, and how it can be manipulated to improve biocompatibility and overall performance.
Wettability refers to the ability of a liquid to spread across the surface of a solid material. This phenomenon is governed by the balance between adhesive forces (attractive forces between the liquid and solid) and cohesive forces (forces within the liquid). The contact angle, which is the angle formed between the liquid's interface and the solid surface, is a key parameter used to assess wettability.
Contact angles can be categorized into three primary regimes:
Hydrophilic: Materials with low contact angles (typically less than 90 degrees) are considered hydrophilic. They have a high affinity for water, causing liquids to spread easily across their surfaces.
Hydrophobic: Materials with high contact angles (typically greater than 90 degrees) are considered hydrophobic. They repel water and other polar liquids, causing droplets to bead up and roll off their surfaces.
Superhydrophobic and Superhydrophilic: Materials with extremely high or extremely low contact angles, respectively, are referred to as superhydrophobic or superhydrophilic. These surfaces exhibit extraordinary wetting properties.
Importance of Wettability in Biomaterials
Wettability plays a crucial role in the performance of biomaterials for several reasons:
Biocompatibility: Biomaterials used in medical applications must interact harmoniously with biological systems. Controlling wettability allows for better cell adhesion, minimizing inflammation and adverse reactions when biomaterials are implanted or used in contact with biological fluids.
Drug Delivery: Wettability influences the release of drugs from biomaterial-based carriers. Tailoring the surface properties can control drug release rates and enhance therapeutic outcomes.
Increase performance: By making surfaces hydrophilic or hydrophobic, depending on the particular use of the biomaterial, can be advantageous. For example, coating a urinary catheter with hydrophilic coating improves the lubricity for increased patient comfort.
Controlling Wettability in Biomaterials
Manipulating the wettability of biomaterials can be achieved through various techniques and surface modifications:
Chemical Modification: Surface treatments, such as plasma treatment, chemical coatings, or grafting of functional groups, can alter the material's surface chemistry and wettability.
Topographical Changes: Creating micro or nanostructures on the material's surface can influence wettability. Superhydrophobic surfaces often feature hierarchical structures that trap air pockets, preventing liquid contact.
Biomimicry: Drawing inspiration from nature, biomaterials can be designed to mimic the lotus leaf's superhydrophobicity or the adhesive properties of gecko feet, enabling tailored wetting behaviors.
Coating Technologies: Applying thin films or coatings with specific wettability properties can modify biomaterial surfaces without altering their bulk properties.
Wettability is a fundamental property that profoundly affects the performance and biocompatibility of biomaterials used in various medical applications. By carefully manipulating the surface properties of these materials, researchers and engineers can enhance their wetting behaviors, enabling better integration with biological systems, controlled drug release, and improved long-term performance. The continued exploration of wettability in biomaterials promises to unlock new possibilities in the field of medical science and technology.
Susanna is an Application Scientist at Biolin Scientific. In her PhD thesis, she developed fabrication methods for a new type of inorganic-organic polymers. Microfabricated polymer chips were utilized as tool for biomolecule separation in analytical chemistry.