Due to the rapid developing biomaterials market, techniques to quickly assess how in vitro results translate to in vivo results are needed. To this end, a non-fouling interpenetrating polymer network (IPN) of p(AAm-co-EG/AAc) was developed on polystyrene for high throughput applications and assay development to test the correlation between short-term cell substratum adhesion strength and matrix mineralization of rat calvarial osteoblasts (RCOs). The surfaces were fully characterized using XPS, water contact angle measurements, density measurements (fluorescence technique), cell culture, and a centrifugal adhesion assay to quantify the adhesive nature of the peptide-modified IPNs towards osteogenic cells. The ligand density (T) was controllable from ~ 1 to 18 pmol/cm² by modulating peptide input concentration (0.02 to 20 pM). Five different RGD peptides based on the sequence of rat bone sialoprotein (BSP) [Ac-CGGNGEPRGDTYRAY-NH2 (1-RGD), Ac-CGGEPRGDTYRA-NH2 (s2-RGD), Ac-CGGPRGDT-NH2 (s-RGD), Ac-CGEPRGDTY-NH2, and cyclic(CGEPRGDTY)] were examined at five ligand densities (1, 5.5, 12.5, 16.5, and 18 pmol/cm²) on IPN modified PS. Additionally, the heparin-binding domain (AcCGGFHRRIKA-NH2)) from BSP was examined on both homogeneous and as a cofactor to 1-RGD on mixed peptide surfaces. The heparin binding peptide (FHRRIKA) showed no propensity to enhance matrix mineralization or promote adhesion to IPN modified surfaces in vitro. Modulating peptide size (15,12, or 8 amino acids), conformation (cyclic vs. linear), and density (1, 5.5,12.5,16.5, and 18 pmol/cm²), significantly altered the short-term cell-substratum detachment strength (< 20 min) resulting in values ranging from ~0 to ~1600 g (0 to ~7.7×10⁻³ dyne/cell). Reducing the peptide length and hence the number of BSP characteristic amino acids flanking the RGD cell-binding domain resulted in surfaces less adhesive to RCOs presumably through a change in binding-domain conformation. IPN surfaces with peptide densities < 1 pmol/cm² supported significantly less adhesion, proliferation, and matrix mineralization (Von Kossa staining) compared to higher density surfaces (> 5.5 pmol/cm²) suggesting a ligand density threshold effect. Surfaces that supported similar initial (20 hr) cell attachment (1-RGD, c-RGD, s2-RGD, and lc-RGD; > 5.5 pmol/cm²) and thus similar numbers of osteoprogenitors, supported similar matrix mineralization.