Control of surface profile in periodic nanostructures produced with ultrashort pulsed laser

Abstract

Pure Titanium (Ti) and its alloys are the most used biomaterials. However, they have insufficient bioactivity. Therefore, it is required to add new function to Ti and Ti alloys. One method to add new function is the creation of periodic nanostructures on the biomaterial surfaces, which can control cell spreading. Ultrashort pulsed laser is one of the useful tools to create periodic nanostructures. Previous study revealed that the nanostructures with the period of 590 nm could be formed on the Ti surface by using the ultrashort pulsed laser with the wavelength of 775 nm. Cells tests indicated that cell spreading occurred along the grooves of the nanostructures. However, all cells could not be controlled on the nanostructures with the periods of 590 nm, and it was considered that surface profiles of the nanostructures with the period of 590 nm were insufficient to control cell spreading. Therefore, controlling surface profiles of the nanostructures is required to promote controlling cell spreading, and surface profiles on the nanostructures were experimentally investigated by changing laser parameters, such as pulse duration, laser fluence, shot number and laser wavelength.In the first experiments, periods are varied with laser wavelength and influence of periods on cell spreading is investigated. In the second experiments, control of surface profiles is tried by changing the pulse durations. Periodic nanostructures were created on Ti plate for three laser wavelengths of 775, 388 and 258 nm. The periods increased with laser wavelengths. Cell tests showed periods of approximately 300 and 600 nm were useful for controlling cell spreading. On the other hand, aspect ratio of the nanostructures increased with pulse duration. These results suggest that surface profile of the nanostructures are controlled with pulse duration.Pure Titanium (Ti) and its alloys are the most used biomaterials. However, they have insufficient bioactivity. Therefore, it is required to add new function to Ti and Ti alloys. One method to add new function is the creation of periodic nanostructures on the biomaterial surfaces, which can control cell spreading. Ultrashort pulsed laser is one of the useful tools to create periodic nanostructures. Previous study revealed that the nanostructures with the period of 590 nm could be formed on the Ti surface by using the ultrashort pulsed laser with the wavelength of 775 nm. Cells tests indicated that cell spreading occurred along the grooves of the nanostructures. However, all cells could not be controlled on the nanostructures with the periods of 590 nm, and it was considered that surface profiles of the nanostructures with the period of 590 nm were insufficient to control cell spreading. Therefore, controlling surface profiles of the nanostructures is required to promote controlling cell spreading, and surf...