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Compliance mismatch of commercially available artificial grafts, where the artificial graft and the native vessel are subject to different radial expansions, is a major issue that results in graft occlusion after implantation. A human artery possesses a nonlinear mechanical response to pulsatile pressure due to its nonlinear viscoelastic nature, which is difficult to replicate in artificial graft fabrication. Here, we fabricated nanocomposites with nonlinear mechanical responses for potential application as the load-bearing layer of vascular grafts, based on a poly(dimethylsiloxane) (PDMS)-casted nanofibrous film. The nanofibers consisted of a core-sheath structure with a PDMS elastomer reinforced with poly(methyl methacrylate) (PMMA) nanofibers as the sheath and thermoplastic polyurethane (TPU) elastomer as the core. The surface morphology and chemical composition together with the crystalline structure of the nanocomposites were characterized, and dynamic mechanical analysis was performed to select the graft with the most suitable properties as the load-bearing layer of a small-diameter vascular graft. The presence of the stiff polymer PMMA and elastic polymer TPU in the PMMA/PDMS/TPU combination resulted in a delayed dissipation of energy after exposure to a force corresponding to 180 mm Hg. Casting the PDMS/PMMA/TPU nanofibrous mat into a nanocomposite film improved the ultimate tensile strength of PDMS without compromising its elasticity. The compliance values of the nanocomposites were also found to be a close match to those of the greater saphenous vein, demonstrating a great potential of the nanocomposites as the load-bearing layer in a biostable vascular graft.

Owing to several key attributes, diamond is an attractive candidate material for neural interfacing electrodes. The emergence of additive-manufacturing (AM) of diamond-based materials has addressed multiple challenges associated with the fabrication of diamond electrodes using the conventional chemical vapor deposition (CVD) approach. Unlike the CVD approach, AM methods have enabled the deposition of three-dimensional diamond-based material at room temperature. This work demonstrates the feasibility of using laser metal deposition to fabricate diamond-titanium hybrid electrodes for neuronal interfacing. In addition to exhibiting a high electrochemical capacitance of 1.1 mF cm -2 and a low electrochemical impedance of 1 kΩ cm 2 at 1 kHz in physiological saline, these electrodes exhibit a high degree of biocompatibility assessed in vitro using cortical neurons. Furthermore, surface characterization methods show the presence of an oxygen-rich mixed-phase diamond-titanium surface along the grain boundaries. Overall, we demonstrated that our unique approach facilitates printing biocompatible titanium-diamond site-specific coating-free conductive hybrid surfaces using AM, which paves the way to printing customized electrodes and interfacing implantable medical devices.

Magnesium hydroxide (Mg(OH) 2 ) is hailed as a cheap and biocompatible material with antimicrobial potential; however, research aimed at instilling additional properties and functionality to this material is scarce. In this work, we synthesized novel, fluorescent magnesium hydroxide nanosheets (Mg(OH) 2 -NS) with a morphology that closely resembles that of graphene oxide. These multifunctional nanosheets were employed as a potent antimicrobial agent against several medically relevant bacterial and fungal species, particularly on solid surfaces. Their strong fluorescence signature correlates to their hydroxide makeup and can therefore be used to assess their degradation and functional antimicrobial capacity. Furthermore, their pH-responsive change in fluorescence can potentially act as a pH probe for wound acidification, which is characteristic of healthy wound healing. These fluorescent antimicrobial nanosheets were stably integrated into biocompatible electrospun fibers and agarose gels to add functionality to the material. This reinforces the suitability of the material to be used as antimicrobial bandages and gels. The biocompatibility of the Mg(OH) 2 -NS for topical medical applications was supported by its noncytotoxic action on human keratinocyte (HaCaT) cells.

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 accelerated wound repair. Temperature is one of the indicating biomarkers specific to chronic wounds. This work reports a hybrid, multifunctional optical material platform-nanodiamond (ND)-silk membranes as biopolymer dressings capable of temperature sensing and promoting wound healing. The hybrid structure was fabricated through electrospinning, and 3D submicron fibrous membranes with high porosity were formed. Silk fibers are capable of compensating for the lack of an extracellular matrix at the wound site, supporting the wound-healing process. Negatively charged nitrogen vacancy (NV - ) color centers in NDs exhibit optically detected magnetic resonance (ODMR) and act as nanoscale thermometers. This can be exploited to sense temperature variations associated with 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 improves the thermal stability of silk fibers. NV - color centers in NDs embedded in silk fibers exhibit well-retained fluorescence and ODMR. Using the NV - centers as fluorescent nanoscale thermometers, we achieved temperature sensing in 25-50 °C, including the biologically relevant temperature window, for cell-grown ND-silk membranes. An enhancement (∼1.5× on average) in the temperature sensitivity of the NV - centers 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 exhibited selective antifouling and biocidal propensity toward Gram-negative Pseudomonas aeruginosa and Escherichia coli , while no effect was observed on Gram-positive Staphylococcus aureus .