Electrostatic forces on the surface of metals as measured by atomic force microscopy

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Medical Device Engineering

Background:

• Electrostatic forces are crucial for interactions between biological components and surfaces.
• Intravascular prostheses, like stents, possess surface charges that can affect blood interactions and vascular healing.
• Understanding these surface properties is vital for developing better medical devices.

Purpose of the Study:

• To measure and compare the electrostatic surface forces of different metals used in intravascular prostheses.
• To investigate the effect of surface treatments on the electrostatic properties of metallic biomaterials.
• To evaluate the utility of atomic force microscopy (AFM) in characterizing biomaterial surfaces for medical applications.

Main Methods:

• Utilized atomic force microscopy (AFM) to measure surface electrostatic forces.
• Conducted measurements in a low saline aqueous medium at physiological pH.
• Analyzed four different metals, including gold, 316L stainless steel, and electropolished Nitinol, with and without heat oxidation.

Main Results:

• Gold and 316L stainless steel exhibited similar, significantly higher net electronegative surface charges compared to electropolished Nitinol.
• Heat oxidation of Nitinol increased its surface electronegativity and promoted a more homogeneous charge distribution.
• AFM provided quantitative data on surface charge, differentiating between the tested metallic materials.

Conclusions:

• Electrostatic surface properties of metallic biomaterials significantly influence interactions with blood components.
• AFM is a valuable tool for characterizing the electrostatic nature of biomaterial surfaces.
• Surface modification, such as heat oxidation, can be used to optimize the surface charge of intravascular prostheses for improved vascular healing.