Integral Algorithms to Evaluate TiO₂ and N-TiO₂ Thin Films' Cytocompatibility.

Area of Science:

• Biomaterials Science
• Surface Engineering
• Cell Biology

Background:

• Nitinol stents require improved cytocompatibility for endothelial cell interaction.
• Existing methods for assessing titanium oxide (TiO₂) and oxynitride (N-TiO₂) coatings lack standardization, hindering result comparison.

Purpose of the Study:

• Develop an integral cytocompatibility index (ICI) and a decision tree algorithm (DTA).
• Establish a standardized model for evaluating EA.hy926 cell interaction with TiO₂ and N-TiO₂ coatings.
• Identify the optimal cytocompatible coating for nitinol stents.

Main Methods:

• Magnetron sputtering with varied N₂:O₂ ratios and bias voltages to create TiO₂ and N-TiO₂ coatings.
• Surface morphology analysis using scanning electron microscopy (SEM) and Raman spectroscopy.
• Cytocompatibility assessment including cytotoxicity, adhesion, viability, and nitric oxide (NO) production.

Main Results:

• The integral cytocompatibility index (ICI) and decision tree algorithm (DTA) were successfully developed.
• Optimal cytocompatibility was achieved with a sample sputtered at U_bias = 0 V and an N₂:O₂ ratio of 2:1, favoring the rutile crystalline phase.
• The DTA provided detailed insights into cytocompatibility influenced by sputtering parameters, surface morphology, and crystalline phase.

Conclusions:

• The developed ICI and DTA offer a standardized approach to assess and compare the cytocompatibility of TiO₂ and N-TiO₂ coatings.
• Mathematical models were established to correlate cytocompatibility with physical characteristics of the coatings.
• The study identified specific sputtering conditions yielding superior cytocompatible coatings for nitinol stents.