Statement of Purpose: Developing nanocomposite scaffolds embedded with electrically conductive nanomaterials have been at the center of attention for engineering functional cardiac tissues [1-2]. Previous work in this regard have shown that the incorporation of conductive nanomaterials within the matrix of scaffold led to significantly enhanced maturation and electrical excitability. The enhanced tissue functionalities are attributed to the increased electrical conductivity and mechanical stiffness as well as the induced nano-scale topographies of nanocomposite scaffolds. Despite the significance, what is missing in the literature is whether the sole presence of nanomaterials, regardless of their electrical conductivity, could promote electrical and contractile functionalities among cardiomyocytes (CMs). To address this knowledge gap, in this work, we developed four different classes of nanocomposite scaffolds, embedded with conductive gold nanorods (GNRs) and non-conductive silica nanoparticles (SNPs), to dissect the role of scaffold stiffness and nano-scale topography, from its electrical conductivity, on maturation and excitability of the engineered cardiac tissues.