Biomaterials Research

Material properties and their interactions with biological components dictate the performance of devices and drug carriers. Reliable, robust measurements and standards are needed to maximize the success of clinical outcomes. NIST initially focused on dental materials research, but the current program addresses materials challenges associated with assuring safety and performance of devices through the development of new materials, theories and models, measurement technologies, and standards. The biomaterials effort has a large research portfolio that includes tissue engineering, cell-material interactions, stabilities of protein therapeutics (drug delivery), biomineralization, smart materials, antimicrobial materials, and measurement of complex structure-property relationships of dental and biomaterials. These efforts can be broadly categorized into three areas: Dental Materials, Protein Preservation, and 3D Tissue Engineering Scaffolds. 

Dental Materials

NIST has provided leadership in national and international standards organizations, including leading and/or overseeing the development of several international documentary standards. We have developed and validated an instrument for simultaneous measurement of polymerization kinetics, reaction exotherm, and polymerization stress development for photopolymerized composites. The instrument and concepts for additional application have been granted a patent application. This instrument is under discussion for a new International Standard to measure polymerization stress. Discussion is also underway with NIDCR to use NIST developed tensometer for a large NIDCR U01 grant participants. NIST will provide expertise in experimental design and data analysis, and when appropriate, will conduct measurements.

There is a high demand for NIST Calcium Hydroxyapatite Standard Reference Materials (SRM) continues to grow with our latest supply not lasting as long as expected. NIST is in the process of completing certification and the Report of Analysis for SRM 2910b: Calcium Hydroxyapatite, a new batch of SRM. As a part of the corresponding research portfolio, the team is developing additional SRMs with more biologically relevant properties to better mimic bone and teeth. Research efforts have included directed biomineralization processes to anticipate the needs in advanced materials. This work is partially supported by the National Institute of Dental and Craniofacial Research (NIDCR/NIH) through interagency agreements to develop robust, standardized measurements for industry and academia ($7.1M over nine years).

Protein Preservation

NIST was the first to show that ns material dynamics could track protein stability in solid storage formats. We demonstrated that the same ns dynamics measured with neutron scattering could be obtained from time-dependent fluorescence experiments. Those measurements were more generally accessible, but still not amenable to use in a biopharmaceutical process lab. We are now developing a tabletop
steady-state fluorescence instrument that could easily be used in a biopharmaceutical lab, and that gives a signature of the relevant ns dynamics.

3D Tissue Engineering Scaffolds

NIST deployed four Reference Materials (RM8394 - RM8397) for how to measure the porosity of and cell proliferation on scaffolds. We invented an airbrushing technology for the rapid fabrication of fibrillar mats that may enable point-of-care spray-on 3D tissue scaffolds and wound dressings. Additionally, we developed combinatorial cassettes as high-throughput, systematic in vivo testing platforms to increase measurement confidence and reduce the number of animals needed for testing (animal welfare), and 3D image analysis methods for quantitative descriptors of cell and scaffold shape metrics. We are currently conducting the largest study of 3D stem cell morphology (1500 z-stacks of stem cells, 1 TB of data) to determine the role of cell shape on biological response. Major research findings have been published (17 peer-reviewed papers since Oct 2012), 11 invited presentations have been delivered, and one patent application was filed.