Electrospun Nanodiamond–Silk Fibroin Membranes: A Multifunctional Platform for Biosensing and Wound-Healing Applications

Abstract

Next generation wound care technology capable of diagnosing wound parameters, promoting healthy cell growth and reducing pathogenic infections noninvasively would provide patients with an improved standard of care and an accelerated wound repair mechanism. Temperature is one of the indicating biomarkers specific to chronic wounds. This work reports a hybrid, multifunctional optical material platform -nanodiamond-silk membranes as bioinspired dressings capable of temperature sensing and wound healing. The hybrid structure was fabricated through electrospinning and formed 3D sub-micron fibrous membranes with high porosity. The silk fibres are capable of compensating for the lack of extracellular matrix at the wound site, supporting the wound healing process. The negatively charged nitrogen vacancy (NV -) color centres in nanodiamonds (NDs) exhibit optically detected magnetic resonance (ODMR) properties and act as fluorescent nanoscale thermometers, capable of sensing temperature variations associated to the presence of infection or inflammation in a wound, without physically removing the dressing. Our results show that the presence of NDs in the hybrid ND-silk membranes improve the thermal stability of silk fibres. The NVcolor centres in NDs embedded in silk fibres exhibit well-retained fluorescent and ODMR properties. Using the NVcentres as fluorescent nanoscale thermometers, we achieved temperature sensing at a range of temperatures, including the biologically relevant temperature window, on cellcultured ND-silk membranes. An enhancement in the temperature sensitivity of the NVcentres was observed for the hybrid materials. The hybrid membranes were further tested in vivo in a murine wound healing model and demonstrated biocompatibility and equivalent wound closure rates as the control wounds. Additionally, the hybrid ND-silk membranes showed selective antifouling and biocidal propensity toward Gram-negative Pseudomonas aeruginosa and Escherichia coli, while no effect was observed on Gram-positive Staphylococcus aureus.

Imaging the Morphological Structure of Silk Fibroin Constructs through Fluorescence Energy Transfer and Confocal Microscopy

“…On that mats, we were able to perform a deeper morphological analysis using a mild 405 nm laser power level, allowing us to obtain resolute Z-stacks with a 1.6-µm thick confocal plane. The produced fibers might find application as an optical sensor whenever an interaction with biological tissues is required [31,36] as for example in the case of wound healing [37,38] or for visualization purposes both in vitro and in vivo [39,40]. In addition, the proposed methods could be easily coupled with other additive manufacturing techniques [41,42] to produce 3D constructs [43].…”

Silk Fibroin-Based Therapeutics for Impaired Wound Healing

“…Understanding ROS levels expedites the process of treatment and can elucidate which medications are needed and offer a prognosis for wound healing. Another SF biosensor—a membrane consisting of SF and nanodiamonds—can be implanted into wound beds for temperature monitoring; higher temperatures can indicate infection or increased inflammation [ 88 ]. These biosensors also have antibacterial properties, helping to prevent infection as well.…”

Additive Manufacturing of Biopolymers for Tissue Engineering and Regenerative Medicine: An Overview, Potential Applications, Advancements, and Trends

“…Injuries can be classed as chronic or acute injuries depending on the healing procedure. Chronic injury is predominantly tissue lesions, usually within 8 to 12 weeks, which appear to have totally resolved [156]. Acute injuries continue to occur and are still more than 12 weeks of recuperation.…”