Carbon nanotubes (CNTs) are remarkable solid-state nanomaterials due to their unique electrical and mechanical properties. The electronic properties of nanotubes combined with biological molecules such as proteins could make miniature devices for biological sensing applications. In this paper, the noncovalent interaction of single-wall CNTs with antibodies is presented for its potential applications for detecting overexpressed cell surface receptors in breast cancer cells. The degree of binding of antibodies on CNTs was found to be more than 80% for an extended sampling area by confocal microscopy. The key to achieve such high degree of functionalization is due to the separation of CNTs using surfactants that leads to a high surface area,to volume ratio and higher number of active sites for charge transfer that enhance binding. This paper also presents tuning of electronic transport properties of CNTs by monoclonal antibodies that are specific to insulin-like growth factor 1 receptor in breast cancer.