Fabrication and Characterization of a Stretchable Sodium Alginate Hydrogel Patch Combined with Silicon Nitride and Metalized Halloysite Nanotubes to Develop a Chronic Wound Healing Treatment

Abstract

The human body is known as a responsive healing machine, but sometimes, broken bones do not heal, especially if a bacterial infection is present. The present study describes the fabrication and characterization of a nanocomposite hydrogel patch incorporated with silicon nitride and magnesium oxide (MgO) deposited on the halloysite nanotube (HNT) surface using a facile and inexpensive electrodeposition coating process. Scanning electron microscopy (SEM) was used to observe the surface morphology of the MgO/HNT surface coating and the nanocomposite patch. Material characterization, including SEM, contact angle, pore size analysis, and tensile properties, was performed to determine the composite's structure and material properties. E. coli and S. aureus bacterial cultures were used to test the antimicrobial properties. Cellular response to MgO/HNTs was studied using mouse embryonic fibroblasts. The nanocomposite hydrogel patch was discovered to possess inherent properties when tested against bacterial cultures, and it was found to enhance fibroblast cell migration and proliferation. The nanocomposite hydrogel patch also showed sustained drug release. Materials involved in the fabrication helped in the swelling properties by which the nanocomposite hydrogel patch has approximately 400% of its initial weight discovered during the swelling test.

Keywords: antimicrobial properties; halloysite nanotube; hydrogels; nanocomposite; silicon nitride.

Figure 1

Digital Microscope Images of Surface Morphology of (A) Wet Nanocomposite Hydrogels with magnification of ×80.0 (B) Dry Nanocomposite Hydrogels with magnification of ×150.0.

Figure 1

Digital Microscope Images of Surface Morphology of (A) Wet Nanocomposite Hydrogels with magnification of ×80.0 (B) Dry Nanocomposite Hydrogels with magnification of ×150.0.

Figure 2

SEM Images of Surface Morphology of Nanocomposite Hydrogels.

Figure 3

Picture of (A) Si₃N₄MgHNT and (B) Si₃N₄ Hydrogel Patch.

Figure 4

Average Pore Radius (Å) of all nanocomposite hydrogels, Measured by NOVA 2200e Surface Area and Pore Analyzer. Error Bars are Standard Deviations, where n = 3.

Figure 5

Weight change (%) of all Nanocomposite Hydrogels. Error Bars are Standard Deviations where n = 3.

Figure 6

Image of Nanocomposite Hydrogels’ Contact Angle. CA left and CA right refer to the contact angles measured at the left and right sides of the SBF droplet placed on the hydrogel. These values help in evaluating the symmetry of the droplet and the uniformity of the surface. For instance, a symmetric droplet (CA left ≈ CA right) suggests a homogenous and level surface while an asymmetric droplet (CA left ≠ CA right) might indicate surface roughness, or inclination of the hydrogel.

Figure 7

Nanocomposite Hydrogels Contact Angle Measurement. Error Bars are Standard Deviations where n = 3.

Figure 8

Tensile Test of (A) Na-alginate Hydrogel, (B) Na-alginate/Si₃N₄ Hydrogel, (C) Na-alginate/MgHNT Hydrogel (D) Na-alginate/Si₃N₄MgHNT Hydrogel. The red arrow points to the breaking point at which the material fractures, while the green arrow points to the elasticity behavior of the hydrogel.

Figure 9

Images of Cytotoxicity Test (Livedead Assay) with Mouse Embryonic Fibroblast Cell of Nanocomposite Hydrogels. Live Cells in Green (Left Image) and Dead Cells in Red or Black Indicate no Dead Cell (Right Image) for day 1, 3, 5, and 7; Na = sodium alginate, SN = Na-alginate/Si₃N₄, Mg = Na-alginate/MgHNT, SM = Na-alginate/Si₃N₄MgHNT. Scale bar is 350 µm.

Figure 10

Graph of Nanocomposite Hydrogels Showing Quantitative Cell Count Value Calculated (Live Cells/Total Cell Count). Error Bars are Standard Deviations, where n = 3.

Figure 11

Proliferation Assay for Nanocomposite Hydrogels after Exposure to Mouse Embryonic Fibroblast Cells for 7 days. The Blue Line Signifies Control Cells. Error Bars are Standard Deviations, where n = 3.

Figure 12

Images of Mechanical Wound Assay (Scratch Assay) with Mouse Embryonic Fibroblast Cell of Nanocomposite Hydrogels for 0 h, 6 h, 12 h, and 18 h. Control Cells are without the Nanocomposites. The numbers in blue are the distance of the wound created in which cells are required to cover. Images were taken with a magnification of 10× set at PH1 condenser and 35 mm focal length.

Figure 13

Scratch Assay Quantification of Nanocomposite Hydrogels. Error Bars are Standard Deviations where n = 3.

Figure 14

Graphical Representation of Cell Migration Assay of Nanocomposite Hydrogels with Mouse Embryonic Fibroblast Cells. Error Bars are Standard Deviations, where n = 3.

Figure 15

Images of β-Galactosidase Test with Mouse Embryonic Fibroblast Cell of Nanocomposite Hydrogels. Control Cells are without the Nanocomposites.

Figure 16

Graphical Representation of % SA-β-Gal Positive Stained Cells of Nanocomposite Hydrogels with Mouse Embryonic Fibroblast Cells. Error Bars are Standard Deviations where n = 3.

Figure 17

In Vitro Cumulative Release of Gentamicin from Nanocomposite Hydrogels to PBS Buffer Solution at 37 °C.

Figure 18

Bacteria Inhibition after 48 h Against E. coli. Optical Density was taken at 630 nm wavelength. Error Bars are Standard Deviations, where n = 3.

Figure 19

Bacteria Inhibition after 48 h against S. aureus. Optical Density was taken at 630 nm wavelength. Error Bars are Standard Deviations, where n = 3.

Figure 20

Schematic Illustrating Hydrogels Fabrication and Required Tests. (Figure Created through BioRender.com).

Figure 21

Experimental Setup for Tensile Test.