Label-free multimodal profiling of collagen-matrix mineralization during nucleus pulposus osteogenesis to guide bioactive scaffold design for spinal fusion cell therapy.

Here, we established a label-free, multimodal framework integrating Raman spectroscopy, two-dimensional correlation spectroscopy (2D-COS), X-ray diffraction (x-ray diffraction), and nanoindentation to longitudinally track the in vitro osteogenesis of human nucleus pulposus cells from degenerated discs (Pfirrmann grades III-V).

Raman analysis identified key spectral markers, with the phosphate-to-phenylalanine ratio progressively increasing from day 14 to 28 to track mineral integration.