Role of Graphene Oxide in Bacterial Cellulose-Gelatin Hydrogels for Wound Dressing Applications

Abstract

Biopolymer-based hydrogels have several advantages, including robust mechanical tunability, high biocompatibility, and excellent optical properties. These hydrogels can be ideal wound dressing materials and advantageous to repair and regenerate skin wounds. In this work, we prepared composite hydrogels by blending gelatin and graphene oxide-functionalized bacterial cellulose (GO-f-BC) with tetraethyl orthosilicate (TEOS). The hydrogels were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscope (AFM), and water contact angle analyses to explore functional groups and their interactions, surface morphology, and wetting behavior, respectively. The swelling, biodegradation, and water retention were tested to respond to the biofluid. Maximum swelling was exhibited by GBG-1 (0.01 mg GO amount) in all media (aqueous = 1902.83%, PBS = 1546.63%, and electrolyte = 1367.32%). All hydrogels were hemocompatible, as their hemolysis was less than 0.5%, and blood coagulation time decreased as the hydrogel concentration and GO amount increased under in vitro standard conditions. These hydrogels exhibited unusual antimicrobial activities against Gram-positive and Gram-negative bacterial strains. The cell viability and proliferation were increased with an increased GO amount, and maximum values were found for GBG-4 (0.04 mg GO amount) against fibroblast (3T3) cell lines. The mature and well-adhered cell morphology of 3T3 cells was found for all hydrogel samples. Based on all findings, these hydrogels would be a potential wound dressing skin material for wound healing applications.

Figure 1

FTIR spectrum presenting the different functional groups of the hydrogels.

Figure 2

The surface morphology of hydrogels was observed at different scales (200 μm and 70 μm) to study their morphological behavior. A) The surface morphology of oven-dried hydrogels (a–h) have micro-/macro island/flakes were observed due to different incorporated amount of GO into the polymeric matrix of hydrogels, and the hydrogels have a similarity like a natural extracellular matrix. B) The porous surface morphology of freeze-dried hydrogels (a–h) was studied to investigate different pore size. The surface morphology can be changed by changing fabrication method and the incorporated GO may impart multifunctional behavior in the hydrogels.

Figure 3

Surface roughness of the hydrogels observed by AFM analysis.

Figure 4

The wetting of hydrogels, gel fraction, and swelling have been presented to determine their behavior while interacting with biofluids. The wetting behavior was conducted to determine hydrophilic and hydrophobic behavior at room temperature (a, b), gel fraction that exhibited at room temperature (c), and swelling of the hydrogel in different media (aqueous, PBS, and NaCl media) at 37 °C (d) and (e) biodegradation of the hydrogels in PBS media at 37 °C.

Figure 5

In vitro hemocompatibility and antibacterial activities of hydrogels. (a) Hemolysis characteristics, (b) blood clotting time, and (c) antibacterial activities of hydrogels against severe skin infection-causing Gram (positive and negative) pathogens. The cell viability (d–f) of hydrogels was determined after different time intervals (d = 24, e = 48, and f = 72 h) and cell proliferation (g–i) after different time intervals (g = 24, h = 48, and i = 72 h). It was found that contact time and increased crosslinking have resulted in increased cell viability and proliferation under in vitro standard conditions. (j) Hemocompatibility procedure and (k) antibacterial mechanism.

Figure 6

Cellular behavior of fibroblast cell lines against hydrogels. (a) Cell morphology against hydrogels after different times (24, 48, and 72 h) to determine the cellular behavior. (b) Cell adherence of 3T3 cell lines over hydrogels at different times (24, 48, and 72 h) to determine the adherence behavior. It was found that increased contact time increased cell population and cell adherence under in vitro standard conditions.