Hierarchical assembly in PLA-PEO-PLA hydrogels with crystalline domains and effect of block stereochemistry

Xuechen Yin; David R.O. Hewitt; Alyssa N. Preston; Luke A. Heroux; Michael M. Agamalian; Suan P. Quah; Bingqian Zheng; Andrew J. Smith; Scott T. Laughlin; Robert B. Grubbs; Surita R. Bhatia

doi:10.1016/j.colsurfb.2019.04.031

Hierarchical assembly in PLA-PEO-PLA hydrogels with crystalline domains and effect of block stereochemistry

Xuechen Yin, David R.O. Hewitt, Alyssa N. Preston, Luke A. Heroux, Michael M. Agamalian, Suan P. Quah, Bingqian Zheng, Andrew J. Smith, Scott T. Laughlin, Robert B. Grubbs, Surita R. Bhatia

Research output: Contribution to journal › Article › peer-review

6 Scopus citations

Abstract

Understanding the development of microstructure (e.g., structures with length scales roughly 0.5–500 μm)in hydrogels is crucial for their use in several biomedical applications. We utilize ultra-small-angle neutron scattering (USANS)and confocal microscopy to explore microstructure of poly(lactide)-poly(ethylene oxide)-poly(lactide)(PLA-PEO-PLA)triblock copolymer hydrogels with varying L/D-lactide ratio. We have previously found that these polymers self-assemble on the nanoscale into micelles. Here, we observe large-scale structures with diverse morphologies, including highly porous self-similar networks with characteristic sizes spanning approximately 120 nm–200 μm. These structural features give rise to power-law scattering indicative of fractal structures in USANS. Mass fractal and surface fractal structures are found for gels with L/D ratios of 80/20 and 50/50, respectively. Confocal microscopy shows microscale water-filled channels and pores that are more clearly evident in gels with a higher fraction of L-lactide in the PLA block as compared to the 50/50 hydrogels. Tuning block stereochemistry may provide a means of controlling the self-assembly and structural evolution at both the nanoscale and microscale, impacting application of these materials in tissue engineering and drug delivery.

Original language	English
Pages (from-to)	102-109
Number of pages	8
Journal	Colloids and Surfaces B: Biointerfaces
Volume	180
DOIs	https://doi.org/10.1016/j.colsurfb.2019.04.031
State	Published - Aug 1 2019
Externally published	Yes

Funding

The authors gratefully acknowledge financial support from NSF awards CBET-1335787 and CHE-1358959, ACS PRF grant 55729-ND9, NIH T32GM092714 training grant support of A.N.P. a Turner Dissertation Fellowship for D.R.O.H, and a Department of Education GAANN Fellowship (Award P200A160163)for S.P.Q. and B.Z. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The authors thank Dr. Christopher Stanley at ORNL for assistance with SANS experiments. The sponsors had no role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.

Funders	Funder number
National Sleep Foundation	CBET-1335787, CHE-1358959
American Chemical Society Petroleum Research Fund	NIH T32GM092714, 55729-ND9

Keywords

Hydrogel
Microstructure
PLGA
PLLA
Porous
Scaffold
Stereochemistry
USANS

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10.1016/j.colsurfb.2019.04.031

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Yin, X., Hewitt, D. R. O., Preston, A. N., Heroux, L. A., Agamalian, M. M., Quah, S. P., Zheng, B., Smith, A. J., Laughlin, S. T., Grubbs, R. B., & Bhatia, S. R. (2019). Hierarchical assembly in PLA-PEO-PLA hydrogels with crystalline domains and effect of block stereochemistry. Colloids and Surfaces B: Biointerfaces, 180, 102-109. https://doi.org/10.1016/j.colsurfb.2019.04.031

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abstract = "Understanding the development of microstructure (e.g., structures with length scales roughly 0.5–500 μm)in hydrogels is crucial for their use in several biomedical applications. We utilize ultra-small-angle neutron scattering (USANS)and confocal microscopy to explore microstructure of poly(lactide)-poly(ethylene oxide)-poly(lactide)(PLA-PEO-PLA)triblock copolymer hydrogels with varying L/D-lactide ratio. We have previously found that these polymers self-assemble on the nanoscale into micelles. Here, we observe large-scale structures with diverse morphologies, including highly porous self-similar networks with characteristic sizes spanning approximately 120 nm–200 μm. These structural features give rise to power-law scattering indicative of fractal structures in USANS. Mass fractal and surface fractal structures are found for gels with L/D ratios of 80/20 and 50/50, respectively. Confocal microscopy shows microscale water-filled channels and pores that are more clearly evident in gels with a higher fraction of L-lactide in the PLA block as compared to the 50/50 hydrogels. Tuning block stereochemistry may provide a means of controlling the self-assembly and structural evolution at both the nanoscale and microscale, impacting application of these materials in tissue engineering and drug delivery.",

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AU - Yin, Xuechen

AU - Hewitt, David R.O.

AU - Preston, Alyssa N.

AU - Heroux, Luke A.

AU - Agamalian, Michael M.

AU - Quah, Suan P.

AU - Zheng, Bingqian

AU - Smith, Andrew J.

AU - Laughlin, Scott T.

AU - Grubbs, Robert B.

AU - Bhatia, Surita R.

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AB - Understanding the development of microstructure (e.g., structures with length scales roughly 0.5–500 μm)in hydrogels is crucial for their use in several biomedical applications. We utilize ultra-small-angle neutron scattering (USANS)and confocal microscopy to explore microstructure of poly(lactide)-poly(ethylene oxide)-poly(lactide)(PLA-PEO-PLA)triblock copolymer hydrogels with varying L/D-lactide ratio. We have previously found that these polymers self-assemble on the nanoscale into micelles. Here, we observe large-scale structures with diverse morphologies, including highly porous self-similar networks with characteristic sizes spanning approximately 120 nm–200 μm. These structural features give rise to power-law scattering indicative of fractal structures in USANS. Mass fractal and surface fractal structures are found for gels with L/D ratios of 80/20 and 50/50, respectively. Confocal microscopy shows microscale water-filled channels and pores that are more clearly evident in gels with a higher fraction of L-lactide in the PLA block as compared to the 50/50 hydrogels. Tuning block stereochemistry may provide a means of controlling the self-assembly and structural evolution at both the nanoscale and microscale, impacting application of these materials in tissue engineering and drug delivery.

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KW - PLLA

KW - Porous

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ER -

Hierarchical assembly in PLA-PEO-PLA hydrogels with crystalline domains and effect of block stereochemistry

Abstract

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Keywords

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