Fig. 3.

(A–B) Biochemically measured GAG and collagen contents of TE constructs (TGF-β free and TGF-β supplemented) after 0, 14, 28, 42, and 56 days of culture. (C) Mean Raman spectra ± 1 standard deviation (SD) of native cartilage and TE constructs after varying culture durations. (D) Multivariate curve resolution (MCR) developed from native and tissue-engineered (TE) constructs (TGF-β free and TGF-β supplemented). The MCR pure components correlate well with laboratory grade water, GAG, and collagen (water R² = 0.62, GAG: R² = 0.80, and collagen: R² = 0.80) (E–F) Correlations between the Raman prediction (in arbitrary units) and biochemically measured GAG and collagen, respectively, with linear fits to the data. Raman spectroscopy showed an excellent correlation with biochemical assays for measurement of collagen (R² = 0.84) and GAG (R² = 0.86). The correlation for prediction of water content was poor (R² = 0.16) due to inherently weak signals in the range 800–1800 cm⁻¹ and is therefore not shown.