Countercation Engineering of Graphene-Oxide Nanosheets for Imparting a Thermoresponsive Ability

Polylactic-Co-Glycolic Acid/Alginate/Neem Oil-Reduced Graphene Oxide as a pH-Sensitive Nanocarrier for Hesperidin Drug Delivery: Antimicrobial and Acute Otitis Media Assessments

Background/Objectives: Hesperidin (HSP) is a potent phytochemical antioxidant and anti-inflammatory agent that protects against otitis media. However, due to its low solubility and bioavailability, a suitable delivery method is needed to overcome these problems. A hydrogel is a promising nanocarrier for controlled drug delivery in response to external stimuli, such as pH variations. Methods: Graphene oxide (GO)-based nanocarriers that encapsulate hesperidin (HSP) were further coated with a polylactic-co-glycolic acid/alginate (PLGA-Alg) hydrogel before being integrated into a green neem oil (N.O.) double emulsion to produce a synergistic effect and then characterized by different assays. Results: The nanocarriers exhibited a substantial particle size (168 ± 0.32 nm), with high encapsulation (89.86 ± 0.23%) and a zeta potential of 37 ± 0.43 mV. In vitro release studies conducted over 96 h indicated a sustained HSP release of 82% at pH 5.4 and 65% at pH 7.4. The GO-HSP-loaded neem oil double emulsion formulation exhibits substantial antibacterial activity, as evidenced by inhibition zones of 39 ± 0.02 mm against Staphylococcus epidermidis, and considerable antifungal activity against Candida albicans, with an inhibition zone of 43 ± 0.13 mm, along with biofilm inhibition activity. The formulation demonstrated antioxidant activity (5.21 µg/mL) and increased cell viability (90-95%) while maintaining low cytotoxicity in HSE-2 cells. A histopathological analysis confirmed that treatment with the nanocarriers reduced the levels of pro-inflammatory cytokines (IL-1β, TNF-α, TLR4, IL-6) and raised the levels of antioxidant markers (Nrf-2, SOD) in an in vivo rat model of otitis media. Conclusions: GO-based nanocarriers integrated into a neem oil double emulsion and coated with PLGA-Alg hydrogel deliver hesperidin with sustained release and enhanced antibacterial, antifungal, and antioxidant properties. This formulation may be used to treat otitis media and other oxidative stress diseases.

Enhancing Photothermal Therapy for Antibiofilm Wound Healing: Insights from Graphene Oxide-Cranberry Nanosheet Loaded Hydrogel in vitro, in silico, and in vivo Evaluation

Background

Diabetic foot ulcers present a formidable challenge due to colonization by biofilm-forming microorganisms, heightened oxidative stress, and continuous wound maceration caused by excessive exudation.

Methods

To address these issues, we developed a robust, stretchable, electro-conductive, self-healing, antioxidant, and antibiofilm hydrogel. This hydrogel was synthesized through the crosslinking of polyvinyl alcohol (PVA) and chitosan (CH) with boric acid. To enhance its antimicrobial efficacy, graphene oxide (GO), produced via electrochemical exfoliation in a zinc ion-based electrolyte medium, was incorporated. For optimal antibiofilm performance, GO was functionalized with cranberry (CR) phenolic extracts, forming a graphene oxide-cranberry nanohybrid (GO-CR).

Results

The incorporation of GO-CR into the hydrogel significantly improved its stretchability (280% for PVA/CH/GO-CR compared to 200% for PVA/CH). Additionally, the hydrogel demonstrated efficient photothermal conversion under near-infrared (NIR) light, enabling dynamic exudate removal, which is expected to minimize retained exudate between the wound and the dressing, reducing the risk of wound maceration. The hydrogel effectively reduced levels of lipopolysaccharide (LPS)-induced skin inflammation markers, significantly lowering the expression of NLRP3, TNF-α, IL-6, and IL-1β by 39.2%, 31.9%, 41%, and 52.3%, respectively. Histopathological and immunohistochemical analyses further confirmed reduced inflammation and enhanced wound healing.

Conclusion

The PVA/CH/GO-CR hydrogel exhibits multifunctional properties that enhance wound healing ulcers. Its superior mechanical, antibacterial, and anti-inflammatory properties and ability to promote angiogenesis make it a promising candidate for effective wound management in diabetic patients.

Size-Dependent Magnetic Responsiveness of a Photonic Crystal of Graphene Oxide Nanosheets

A magnetically responsive photonic crystal of colloidal nanosheets can exhibit a controllable structural color, offering diverse potential applications. In this study, we systematically investigated how the lateral sizes of graphene oxide (GO) nanosheets affect their magnetic responsiveness in a photonic system. Contrary to the prediction that larger lateral sizes of nanosheets would be more responsive to an applied magnetic field based on the magnetic energy of anisotropic materials, we discovered that GO nanosheets with larger lateral sizes in the photonic system scarcely responded to a 12 T magnetic field. The lack of magnetic response may be due to the strongly restricted rotational motion of GO nanosheets by mutual electrostatic forces. In contrast, GO nanosheets with medium lateral sizes readily responded to the 12 T magnetic field, forming a uniaxially oriented structure that resulted in a vivid structural color. However, smaller GO nanosheets displayed a less vivid structural color, possibly because of less structural ordering of GO nanosheets. Finally, we found that the photonic crystal of GO nanosheets with optimized lateral sizes responded effectively to the 12 T magnetic field across various GO concentrations, resulting in a vivid and tunable structural color.

A magnetically responsive photonic crystal of graphene oxide nanosheets

Magnetically responsive photonic crystals of colloidal nanosheets hold great promise for various applications. Here, we systematically investigated the magnetically responsive behavior of a photonic crystal consisting of graphene oxide (GO) nanosheets and water. After applying a 12 T magnetic field perpendicular and parallel to the observation direction, the photonic crystal exhibited a more vivid structural color and no structural color, respectively, based on the magnetic orientation of GO nanosheets. The reflection wavelength can be modulated by varying the GO concentration, and the peak intensity can be basically enhanced by increasing both the time and strength of the magnetic application. To improve color quality, we developed a novel approach of alternately applying a magnetic field to two orthogonal directions, instead of using a rotating magnetic field. Finally, we achieved color switching by changing the direction of applied magnetic fields.