Does 2D correlation Raman spectroscopy distinguish polymer nanomaterials due to the nanoaddition?

Polymer nanocomposites obtain many new functional properties by adding appropriate nanoparticles, making them more suitable for applications in tissue engineering. The subjects of the presented research are nanocomposites composed of poly(ε-caprolactone) (PCL) matrix and carbon nanofibers as nanoadditions. Each of the tested materials contained a different type of fibrous nanoparticles: first, carbon nanofibers in the initial state (CNFs), and the second, carbon nanofibers after oxidative functionalization (CNFs-f). Both materials, PCL/CNFs and PCL/CNFs-f, were confirmed to be characterized by high bioactivity, and at the same time induced osteoblast proliferation. The aim of this work was to resolve the details of the complex relations between osteoblast-like U-2 OS cells and material, that denote the nanoaddition specificity. The 2D Raman correlation spectroscopy technique revealed that in both of the composites the key component of their interactions with the cells was the carbonous domains of the materials. In the PCL/CNFs the G-mode of the CNFs correlate asynchronously with Amide I of the U-2 OS cells, whereas, the D1-band is mostly engaged into interaction with the side chain amino acids in the case of the PCL/CNFs-f nanocomposite.