Noncovalent Functionalization of Carbon Nanomaterials as a Scaffold for Tissue Engineering

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Qasem, Sahar
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جامعة النجاح الوطنية
Tissue engineering is one of the hot topics in recent research that needs especial requirements that depends on the developed scaffold to achieve a successful tissue growth. Various progress was achieved to develop the adequate biomaterials that provide a good scaffold with the optimum porosity, mechanical and electrical properties. In the recent years, considerable attention has been given to carbon nanomaterials and collagen composite materials and their applications in the field of tissue engineering. However, carbon nanomaterials suffer from low water solubility which hampered their utilization. Therefore, we aimed to functionalize carbon nanomaterials non-covalently with pyrene moiety and using an appropriate hydrophilic linker -a derivative of polyethylene glycol- to disperse the carbon nanostructures in water. This non-covalent functionalization will preserve the electronic properties of the carbon nanostructure to be as a suitable scaffold for tissue engineering. These functionalized carbon nanomaterials were characterized by transmission electron microscopy (TEM). TEM images exhibited good dispersibility of the functionalized carbon nanomaterials with a diameter range of (5-15) nm for f-CNTs and (0.6-0.8) μm for f-graphene. Also, the successful π-π stacking between the pyrene moieties and the carbon nanostructures was confirmed by absorption spectra. Moreover, thermogravimetric analysis (TGA) was used to quantify the amount of functionalization of the used carbon nanomaterials which is in the range of (17-29) %. Finally, zeta potential analysis was used obtaining in all cases around -20 mV that indicates the formation of a stable suspension. 3T3 cells-based engineered connective tissues (ECTs) were generated with different concentrations of carbon nanomaterials. Developed tissues showed a significant enhancement in the electrical conductivity that was mostly kind-dependent. While in ECTs containing primary skin fibroblasts showed lower electrical conductivity. 3T3 cells viability was confirmed by MTS assay and the data demonstrated that the concentrations 0.025% of CNTs and 0.005% of graphene derivatives reduced the cell viability between around (10-30) %. These concentrations were found to be enough to significantly enhance the electrical conductivity of the tissues. All tested tissues significantly decreased the tissue fibrosis relative to the control tissues except the 0.020% graphene-Py-COOH which exhibited a degree of fibrosis that was similar to that of the control ECT. The thickness of collagen fibers in all conditions were similar to that of the control except the 0.005% graphene-Py-COOH which exhibited a statistically significant reduction. All developed ECTs exhibited statistically significantly decrease in matrix porosity relative to the control. While in ECTs containing primary skin fibroblasts all ECTs of CNTs and graphene loadings did not exhibit any statistically significant change on collagen fiber thickness relative to the control. Taken together with the conductivity data it can be assumed that the porosity of the ECT does not correlate with the conductivity of the tissues