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Conducting Polymer-Based Nanomaterials for Tissue Engineering
Published in Ram K. Gupta, Conducting Polymers, 2022
Murugan Prasathkumar, Chenthamara Dhrisya, Salim Anisha, Robert Becky, Subramaniam Sadhasivam
The polymer scaffolds are fabricated into nerve guidance conduits (NGCs) to treat peripheral nerve injury. Nerve conduits are biomaterial-based nerve guiding channels that are sutured to the proximal and distal terminals of the severed nerve, facilitating the regrowth of axons. A promising PPy-based conductive nerve conduit has shown the higher expression of neurotrophic factors when the neural progenitor stem cells are cultured in vitro. Likewise, improved myelination and axon regeneration was observed in the in vivo examination. Such functional cues represent improved peripheral nerve regeneration and enhanced functional recovery. Another study involved the fabrication of PPy/PLGA fiber-based nerve conduits on peripheral nerve generation has established a higher proliferation rate and PC12 cell attachment. The in vivo efficacy of the scaffold was assessed in the sciatic nerve transected rats and the PPy/PLGA conductive conduits had stimulated increased nerve outgrowth and extension and higher recovery of sciatic-injured nerves. It is explained that the electrical cues directed the regulated cell proliferation and neurite extension [40].
Developments in 4D-printing: a review on current smart materials, technologies, and applications
Published in International Journal of Smart and Nano Materials, 2019
Zhizhou Zhang, Kahraman G. Demir, Grace X. Gu
Nerve guidance conduits (NGCs) are tubular devices that facilitate nerve regeneration and must meet physical, chemical and biological requirements that allow for tissue formation. Using a naturally derived, photo-crosslinking monomer (soybean oil epoxidized acrylate, SOEA), Miao et al. 4D-printed (using stereolithography) an NGC that served multiple desired functions for nerve tissue regeneration (Figure 4(f)). The shape memory property of the NGC allows for easy readjustments (through thermal stimulation) to be made during implantation. Additionally, the shape memory property provides axial tension necessary for guiding regrowth. Graphene was used to further enhance other critical properties of the NGC [52]. Miao et al. also 4D-printed a biomedical scaffold (Figure 4(g)) with SOEA. The scaffold possesses excellent shape changing properties and has excellent attachment and proliferation of human mesenchymal stem cells when compared to the traditional polyethylene glycol diacrylate scaffolds [91].
Electrospun natural polymer and its composite nanofibrous scaffolds for nerve tissue engineering
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Fangwen Zha, Wei Chen, Lifeng Zhang, Demei Yu
Electrospun nanofiber is a new class of promising scaffolds to support nerve regeneration used in peripheral nerve injuries repair. The development of artificial nerve guidance conduits (NGCs), which can potentially overcome the limitations associated with nerve autografts and allografts, is essential to neural tissue engineering. Nanofibers scaffolds NGCs with high porosity and large surface area could closely mimic the hierarchical structure of natural ECM. Bioactive molecules functionalized nanofibers could affect the nerve cell behavior. Moreover, electrospun nanofibers can be readily aligned into uniaxial arrays with anisotropic properties which was an effective method to direct and enhance neurite outgrowth [19]. Properties of nanofibers such as fiber components [24], fiber diameter and size [129, 152], and fiber orientation have influence on cell activities and morphologies. For neural tissue engineering, topographies of micro- and nano- fibrous scaffolds, especially fiber orientation, play a critical role in neurite outgrowth and cell migration. The influences of fiber orientation on neural cell growth, extension and differentiation are studied extensively. An established contact guidance theory illustrates that a cell has the maximum probability of migrating in preferred directions which are associated with chemical, structural and/or mechanical properties of the substrate. From the perspective of nerve cells, one possible explanation is that the polymerization rate of neurofilaments and the signaling between axons are enhanced on aligned nanofibers. The mechanisms of how nerve cell senses the aligned nanofibers and extends parallel neurites along the nanofibers are inconclusive. Deeper mechanism awaits further investigation.