Fluorescent Nanodiamonds Embedded in Poly-ε-Caprolactone Fibers as Biomedical Scaffolds

Fluorescent nanodiamonds (fNDs) are emerging as important tools for imaging and sensing in biology, which enable the optical detection, for example, of temperature and magnetic fields at the nanoscale. At the same time, their unique physicochemical properties allow fNDs to drastically improve the properties of nanocomposites. Here, we report the integration of fNDs into electrospun poly-ε-caprolactone (PCL) fibers and the use of the resulting hybrid material as a nontoxic and multifunctional bioscaffold. We investigate the morphology, size distribution, optical properties, wettability, and biocompatibility of PCL fibers containing 0.2 and 0.4 wt % fNDs and demonstrate the quantum sensing capability of the nanocomposite via optically detected magnetic resonance measurements of the nitrogen-vacancy center in fNDs. We find that the use of ethanol as a cosolvent improves the dispersion of fNDs into PCL fibers and reduces the occurrence of fiber defects. We demonstrate that the PCL/fND scaffold is not cytotoxic for mesenchymal stem cells and even promotes cell adhesion and cell proliferation up to 21 days because of an increase in wettability compared to pure PCL fibers. Our results highlight the immense potential of PCL/fND nanocomposites as smart bioscaffolds for advanced biomedical applications such as tissue engineering, biosensing, and theranostics.