Biomedical Materials Science

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Dr. Michael Roach – Contributions to Science

Recently, my research laboratory team has been focused on the development of titanium oxide anodization coatings to improve osseointegration and reduce bacterial attachment.  It is now widely known that anatase and rutile crystalline titanium oxide phases exhibit photocatalytic activity and generate reactive oxygen species (ROS) when stimulated with UVA light. The generated ROS have been shown to be effective in attacking bacteria cell membranes and reducing the initial attachment.  Recent studies have suggested mixed oxides, consisting of anatase and rutile phases, provide the best photocatalytic results. Additionally, these oxides may be further modified with beneficial chemical dopants to add additional antimicrobial properties as well as stimulate osseointegration. We have recently shown aniline-doped and silver-doped mixed oxides on commercially pure titanium to significantly increase the photocatalytic ROS generation and ultimately reduce initial Staphlococcus aureus attachment. We have also shown oxides doped with combinations of phosphorus and calcium to improve the mineralization of osteoblast cells. Finally, we recently co-developed a novel laser-treatment technique in collaboration with colleagues at Auburn University to spatially pattern anatase and rutile oxides in an attempt to maximize the photocatalytic activity. The following recent publications, have stemmed from this research.

  1. Bruni CL, Johnson HA, Ali A, Parekh A, Marquart ME, Janorkar AV, Roach MD (2024). Phosphorus-and-Silver-Doped Crystalline Oxide Coatings for Titanium Implant Surfaces. Oxygen, 4(4):402-420. https://doi.org/10.3390/oxygen4040025

  2. Johnson HA, Donaho D, Ali A, Parekh A, Williamson RS, Marquart ME, Bumgardner JE, Janorkar AV, Roach MD (2024), Photocatalytic Activity and Antibacterial Properties of Mixed-Phase Oxides on Titanium Implant Alloy Substrates. Coatings, 14(5):595. 3390/coatings14050595

  3. Ali A, Polepalli L, Chowdhury S, Carr MA, Janorkar AV, Marquart ME, Griggs JA, Bumgardner JD, and Roach MD (2024). Silver-Doped Titanium Oxide Layers for Improved Photocatalytic Activity and Antibacterial Properties of Titanium Implants, J Funct Biomater, 15(6):163. https://doi.org/10.3390/jfb15060163

  4. Ali A, Chowdhury S, Janorkar AV, Marquart M, Griggs JA, Bumgardner JD, Roach MD (2023). A Novel Single-Step Anodization Approach for PANI-doping Oxide Surfaces to Improve the Photocatalytic Activity of Titanium Implants, Biomedical Materials, 18, 015010. 1088/1748-605X/aca37d

  5. Ali A, Chowdhury S, Janorkar AV, Marquart M, Griggs JA, Bumgardner JD, Roach MD, (2023). Antibacterial and Biocompatible Polyaniline-Doped Titanium Oxide layers, J Biomed Mater Res Part B, 111(5): 1100-1111, 2023. 1002/jbm.b.35217

  6. Nelson J, Jain S, Pal P, Johnson HA, Nobles KP, Janorkar AV, Williamson RS, Roach MD (2022). Anodized Titanium with Calcium and Phosphorus Surface Enhancements for Dental and Orthopedic Implant Applications, Thin Solid Films, 745, 193117. https://doi.org/10.1016/j.tsf.2022.139117

  7. Hardman C, Johnson HA, Doukas M, Pettit C, Williamson RS, Janorkar AV, Roach MD (2022), Photocatalytic, Phosphorous-Doped, Anatase Oxide Layers Applicable to Titanium Implant Alloys, Surface and Interface Analysis, 54(6):619-630. https://doi.org/10.1002/sia.7074

  8. Fathi-Hafshejani P, Johnson H, Ahmadi Z, Roach M, Shamsaei N, Mahjouri-Samani M (2021). Laser-Assisted Selective and Localized Surface Transformation of Titanium to Anatase, Rutile, and Mixed Phase Nanostructures, J Laser Appl, 33(1). https://doi.org/10.2351/7.0000316

  9. Fathi-Hafshejani P, Johnson H, Ahmadi Z, Roach M, Shamsaei N, Mahjouri-Samani M (2020). Phase-Selective and Localized TiO2 Coating on Additive and Wrought Titanium by a Direct Laser Surface Modification Approach, ACS Omega, 5(27):16744-16751. https://doi.org/10.1021/acsomega.0c01671

  10. Williamson RS, Disegi J, Marquart M, Roach M (2020). Antimicrobial Properties of Anodized Titanium Components Used in a Combination Device. Antimicrobial Combination Devices, ASTM STP 1630, 89-104. 1520/STP163020190113

Another area of my research interest has been investigating fatigue crack initiation and propagation mechanisms in metallic biomaterials.  During my doctoral research, I developed a new EBSD-based sequential scanning methodology for tracking surface damage leading up to fatigue crack initiation and early crack propagation mechanisms in two wrought austenitic steels.   This EBSD-based methodology involved scanning the same representative sections of the microstructure at specific fatigue cycle intervals in order to track the progression of surface damage.  Fatigue crack initiation sites were able to be classified into categories of slip band, grain boundary, twin boundary, or inclusion. In addition, I also employed atomic force microscopy to assess the relative amounts of dislocation pile-up occurring at slip-bands, grain boundaries, and twin boundaries on selected failed samples. These investigations revealed one of the austenitic steels to exhibit a strong preference for twin boundary crack initiation, while the other steel showed a strong preference for slip band crack initiation. As a continuation of this research, I recently co-mentored a doctoral student who applied the EBSD-based sequential scanning methodology to track fatigue crack initiation and propagation in wrought and additively-manufactured 304 grade stainless steels. In addition to the possible fatigue crack initiation categories listed above, the 304 stainless steel studies added stress-induced martensitic transformation zones. The additively-manufactured 304 steel showed different microstructural characteristics leading to improvements in the fatigue life compared to its wrought 304 steel counterpart.

We have most recently utilized the same EBSD-based scanning methodologies to investigate localized phase transformations and strain buildup deformation processes occuring within the crack process zones of modern dental zirconia. The following publications have resulted from this area of research.

  1. Lenthe W, Pang E, Roach M, Griggs J, Wright S, Nowell M (2021). Real World Application of EBSD Forward Models, Microscopy and Microanalysis (M&M), 27 (Supplement 1), 40-43. https://doi.org/10.1017/S1431927621000738

  2. Pegues JW, Roach MD, and Shamsaei N (2020). Additive Manufacturing of Fatigue Resistant Austenitic Stainless Steels by Understanding Process-Structure-Property Relationships, Mater Res Lett, 8(1):8-15. https://doi.org/10.1080/21663831.2019.1678202

  3. Pegues JW, Roach MD, and Shamsaei N (2020). Effects of Postprocess Thermal Treatments on Static and Cyclic Deformation Behavior of Additively Manufactured Austenitic Stainless Steel, JOM, 72:1355-1365. 1007/s11837-019-03983-x

  4. Pegues JW, Roach MD, Shamsaei N (2017). Influence of Microstructure on Crack Initiation and Microstructurally Small Crack Growth of an Austenitic Stainless Steel, Mater Sci & Eng, A, 707:657-667. https://doi.org/10.1016/j.msea.2017.09.081

  5. Roach MD, Wright SI (2014). Investigations of Twin Boundary Fatigue Cracking in Nickel and Nitrogen-Stabilized Cold-Worked Austenitic Stainless Steels, Mater Sci & Eng A, 607:611-620. https://doi.org/10.1016/j.msea.2014.04.059

  6. Roach MD, Wright SI, Lemons JE, Zardiackas LD (2013). An EBSD-Based Comparison of the Fatigue Crack Initiation Mechanisms of Nickel and Nitrogen-Stabilized Cold-Worked Austenitic Stainless Steels, Mater Sci & Eng, A, 586:382-391. https://doi.org/10.1016/j.msea.2013.08.027

Additionally, we actively participate in the development of new implants manufactured out of wrought and additively-manufactured metallic materials that show potential for use as biomaterials.  Many of the additively-manufactured alloys currently being suggested for implants have wrought counterparts with a long history of successful in vivo use. The need to achieve similar material properties to the wrought counterparts, has facilitated several new research collaborations based on additive manufacturing of metallic materials. As a result, I have worked with a number of collaborators in an effort to improve the properties of additively manufactured materials. We recently participated in the implant product development for a relatively new titanium alloy showing high fatigue strength and corrosion resistance while maintaining substantial ductility. This unusual combination of properties shows much promise for implant applications requiring high strengths while maintaining sufficient ductility.  Below is a list of a few of my recent publications in this research area.

  1. Roach M, Williamson RS, Pegues JW, and Shamsaei N (2020). Comparison of Stress Corrosion Cracking Susceptibility in Additively-Manufactured Ti-6Al-4V for Biomedical Applications, Structural Integrity of Additive Manufactured Parts, ASTM STP 1620:423-436. https://doi.org/10.1520/STP162020180124

  2. Pegues JW, Shamsaei N, Williamson RS and Roach MD (2019). Fatigue Life Estimation of Additive Manufactured Parts in the As-Built Surface Condition, Mater Design Process Comm, e36:1-8, https://doi.org/10.1002/mdp2.36.

  3. Li P, Warner DH, Pegues JW, Roach MD, Shamsaei N, and Phan N (2019). Towards Predicting Differences in Fatigue Performance of Laser Powder Bed Fused Ti-6Al-4V Coupons from the Same Build, Int J Fatigue, 126:284-296. https://doi.org/10.1016/j.ijfatigue.2019.05.004

  1. Li P, Warner DH, Pegues JW, Roach MD, Shamsaei N, and Phan N (2018). Investigation of the Mechanism by Which Hot Isostatic Pressing Improves the Fatigue Performance of Powder Bed Fused Ti-6Al-4V, Int J Fatigue, 120:342-352. https://doi.org/10.1016/j.ijfatigue.2018.10.015.

  1. Pegues JW, Roach MD, Williamson RS, and Shamsaei N (2018). Surface Roughness Effects on the Fatigue Strength of Additively Manufactured Ti-Al-4V, Int J Fatigue, 116:543-552. https://doi.org/10.1016/j.ijfatigue.2018.07.013

  2. Disegi J, Roach M, McMillan R, and Shultzabarger B (2017). Alpha plus beta annealed and aged Ti-15Mo alloy for high strength implant applications, J Biomed Mater Res Part B, 105(7):2010-2018. 1002/jbm.b.33679.

  3. Roach MD, Williamson RS, Thomas J, Griggs JA, and Zardiackas LD (2014). A Comparison of the Stress Corrosion Cracking Susceptibility of Commercially Pure Titanium Grade 4 in Ringer’s Solution and in Distilled Water: A Fracture Mechanics Approach”, J Biomed Mater Res Part B, 102(1):73-79. 10.1002/jbm.b.32983.