Sircol collagen standard

Neocartilage samples were removed from the outer and inner regions of the ceramic for histological examination from both OC Assembly groups. Samples from the outer region were taken from the outer circumferential periphery of the neocartilage, no more than 3 mm away from the edge (Fig. 1). Samples from the inner region were taken from the exact middle of the neocartilage. All samples were weighed to obtain wet weights WW, lyophilized for 3 days, and weighed again to obtain dry weights. Samples were then digested with 125 µg/mL papain (Sigma), 5 mM N-acetyl-L-cysteine (Sigma), and 5 mM EDTA (Acros Organics) in phosphate buffer overnight at 60 °C. Sulfated GAG content was measured using the Blyscan GAG Assay kit (Biocolor). DNA content was measured with a Picogreen assay. Total collagen content was determined by measuring hydroxyproline content using a modified chloramine-T colorimetric assay^{54 (link)}. A standard curve was generated using a Sircol collagen standard (Biocolor). GAG and collagen content were normalized to wet weight, dry weight, and DNA content. All biochemical measurements were performed on distinct samples.