Bioactivity is an important aspect that can be appropriately used to tune the cellular interactions occurring at the biomaterial-physiological interface. In this regard, we explore here the nano- or quantum-size effects of a highly dispersible nanostructured carbon present in the void space between the polymers chains (Nylon 6,6) in modulating the cellular functions when osteoblasts are seeded on biocompatible substrates. The filling-up of void space in polymer facilitates filopodia to access the extracellular matrix, enabling integrin receptors to bind to the artificial biomedical device, promoting cellular interactions. In this regard, the fundamental principles of materials processing and cellular biology were combined to elucidate the mechanism of cell-substrate interactions and the molecular machinery controlling the cell response. This is accomplished by investigating cell attachment, proliferation, and morphology, including cytomorphometry evaluation and quantitative assessment of prominent proteins, actin, vinculin, and fibronectin that are sensitive to cell-substrate interactions. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.