Material Dynamics

Contact

David Saylor, Ph.D.

Summary

The goal of this program is to support the regulation of medical devices by advancing our knowledge of the internal dynamics of device materials that dictate their biocompatibility and stability. The research combines experimental measurements and multi-scale computational models to address the many regulatory issues governed by transport and degradation processes, such as corrosion and metal ion release, leaching of additives or manufacturing residuals in polymeric materials, hydrolytic and oxidative degradation, barrier properties, and drug delivery. Because these issues are ubiquitous in device applications, this research impacts a wide range of medical device areas. The current areas of focus include: 1) potential patient exposure to additives and impurities in polymeric device materials, 2) leaching and biokinetics of nickel released from device alloys, 3) degradation of polymeric components in cardiac implants (both intended and unintended), and 4) drug and infusion pump compatibility. These projects are conducted in active collaboration with several researchers both within the FDA and at other government and academic institutions and industry organizations.  

All-atom molecular dynamics simulation of a tetracycline molecule diffusing through poly(styrene-b-isobutylene-b-styrene) (SIBS) polymer.

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Multi-scale model of patient exposure to nickel released from nitinol (NiTi) cardiovascular devices. The model captures nickel transport at a hierarchy of length scales.

The tools and information derived through this research directly impact the regulation of medical devices. Validated multi-scale mass transport models developed by our group are used in regulatory decision-making and can reduce the testing needed to establish the safety and effectiveness of devices during pre-market evaluation. In addition, our efforts to elucidate and quantify potential degradation mechanisms and unintended interactions inform not only pre-market evaluations, but also potential post-market actions.

Current funding sources

• FDA Critical Path Initiative
• National Science Foundation (NSF) FDA Scholar In Residence
• Medical Countermeasures Initiative
• Office of Women’s Health  

External collaborators

• National Institute of Standards and Technology
• National Center for Toxicological Research
• University of Wisconsin–Milwaukee 
• University of Maryland
• University of Michigan

Personnel

Vaishnavi Chandrasekar, Ph.D.
David Saylor, Ph.D.
David Simon, Ph.D.
Eric Sussman, Ph.D.
Paul Turner, Ph.D.

Resource facilities

• TA Instruments HP-TGA Sorption Analyzer
• Q-Sense Quartz Crystal Microbalance System
• TA Instruments ARG2 Rheometer
• TA Instruments RSA3 Dynamic Mechanical Analyzer
• TA Instruments Q200 Differential Scanning Calorimeter
• TA Instruments Q500 Thermogravimetric Analyzer
• Waters Alliance V2000 Gel Permeation Chromatography system
• ThermoFisher Liquid Chromatography Mass Spectrometer
• Agilent Gas Chromatography Mass Spectrometer
• Sotax USP4
• Varian USP7
• Nicolet Fourier Transform InfraRed Spectrometer
• White Oak NanoCORE Facility
• Biovia/Accelrys Materials Studio 

Public domain software

• Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)
• Trilinos
• FiPy: A Finite Volume PDE Solver Using Python 

Relevant standards & guidance

• Draft Guidance - Coronary Drug-Eluting Stents-Nonclinical and Clinical Studies
• Cardiovascular implants and extracorporeal systems -- Vascular device-drug combination products
• Standard Guide for Testing Absorbable Stents
• Infusion Pumps Total Product Life Cycle - Guidance for Industry and FDA Staff
• ISO 10993: Biological evaluation of medical devices
• Reporting of Computational Modeling Studies in Medical Device Submissions - Draft Guidance for Industry and Food and Drug Administration Staff
• Select Updates for Non-Clinical Engineering Tests and Recommended Labeling for Intravascular Stents and Associated Delivery Systems
• ISO/TS 17137: Cardiovascular implants and extracorporeal systems – Cardiovascular absorbable implants

 Selected Peer-Review Publications

• Predicting patient exposure to nickel released from cardiovascular devices using multi-scale modeling, Acta Biomaterialia. (2018) 1–11. doi:10.1016/j.actbio.2018.01.024.
• V. Chandrasekar, , et al., Conservative Exposure Predictions for Rapid Risk Assessment of Phase-Separated Additives in Medical Device Polymers, Annals of Biomedical Engineering. 46 (2018) 14–24. doi:10.1007/s10439-017-1931-4.
• V. Chandrasekar, , et al., Improving risk assessment of color additives in medical device polymers, J. Biomed. Mater. Res. 106 (2018) 310–319. doi:10.1002/jbm.b.33845.
• Y. Xu, et al, Polymer degradation and drug delivery in PLGA-based drug-polymer applications: A review of experiments and theories, J. Biomed. Mater. Res. 105 (2017) 1692–1716. doi:10.1002/jbm.b.33648.
• S. Nagaraja, et al, Current practices in corrosion, surface characterization, and nickel leach testing of cardiovascular metallic implants, J. Biomed. Mater. Res. 105 (2017) 1330–1341. doi:10.1002/jbm.b.33630.
• DM Saylor, et al, “A biokinetic model for nickel released from cardiovascular devices,” Regulatory Toxicology and Pharmacology 80, 1 (2016).
• DM Saylor, et al “Communication: Relationship between solute localization and diffusion in a dynamically constrained polymer system,” J. Chem. Phys. 145, 031106 (2016).
• DM Saylor, et al, “Diffuse interface methods for modeling drug-eluting stent coatings,” Annals of biomedical engineering 44 (2), 548-559 (2016).