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Nanoclay–polymer shear-thinning composites are designed for a broad range of biomedical applications, including tissue engineering, drug delivery, and additive biomanufacturing. Despite the advances in clay–polymer injectable nanocomposites, colloidal properties of layered silicates are not fully considered in evaluating the in vitro performance of shear-thinning biomaterials (STBs). Here, as a model system, we investigate the effect of ions on the rheological properties and injectability of nanoclay–gelatin hydrogels to understand their behavior when prepared in physiological media. In particular, we study the effect of sodium chloride (NaCl) and calcium chloride (CaCl 2 ), common salts in phosphate buffered saline (PBS) and cell culture media ( e.g. , Dulbecco's Modified Eagle's Medium, DMEM), on the structural organization of nanoclay (LAPONITE® XLG-XR, a hydrous lithium magnesium sodium silicate)-polymer composites, responsible for the shear-thinning properties and injectability of STBs. We show that the formation of nanoclay–polymer aggregates due to the ion-induced shrinkage of the diffuse double layer and eventually the liquid–solid phase separation decrease the resistance of STB against elastic deformation, decreasing the yield stress. Accordingly, the stress corresponding to the onset of structural breakdown (yield zone) is regulated by the ion type and concentration. These results are independent of the STB composition and can directly be translated into the physiological conditions. The exfoliated nanoclay undergoes visually undetectable aggregation upon mixing with gelatin in physiological media, resulting in heterogeneous hydrogels that phase separate under stress. This work provides fundamental insights into nanoclay–polymer interactions in physiological environments, paving the way for designing clay-based injectable biomaterials.
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2D Nanoclay for Biomedical Applications: Regenerative Medicine, Therapeutic Delivery, and Additive Manufacturing
Abstract Clay nanomaterials are an emerging class of 2D biomaterials of interest due to their atomically thin layered structure, charged characteristics, and well‐defined composition. Synthetic nanoclays are plate‐like polyions composed of simple or complex salts of silicic acids with a heterogeneous charge distribution and patchy interactions. Due to their biocompatible characteristics, unique shape, high surface‐to‐volume ratio, and charge, nanoclays are investigated for various biomedical applications. Here, a critical overview of the physical, chemical, and physiological interactions of nanoclay with biological moieties, including cells, proteins, and polymers, is provided. The state‐of‐the‐art biomedical applications of 2D nanoclay in regenerative medicine, therapeutic delivery, and additive manufacturing are reviewed. In addition, recent developments that are shaping this emerging field are discussed and promising new research directions for 2D nanoclay‐based biomaterials are identified.
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- Award ID(s):
- 1705852
- PAR ID:
- 10461467
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 31
- Issue:
- 23
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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