Protein adsorption on carbon nanotubes for biosensor applications
Carbon nanotubes (CNTs) were synthesized using catalyst thin films and catalyst nanoparticles in a microwave plasma chemical vapor deposition system. Biofunctionalization of CNTs were initially tested using fluorescence microscopy, where fluorescently labeled bovine serum albumin (BSA) was confirmed to physically adsorb on CNTs. The varying degree of fluorescence intensity observed on samples grown under different bias voltage conditions was thought to have occurred due to differences in nanostructure. Further biofunctionalization was carried out with glucose oxidase, and subsequent cyclic voltammetry measurements were conducted on a matrix of growth samples of differing calcination temperatures and bias voltages. Varying levels of current densities during voltage sweep were observed and further investigation via scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy revealed that total CNT surface area and the level of enzyme adsorption per CNT surface area (proportional to the number of defect sites on CNTs) are the main factors that dictate the levels of macroscopic current density. Refinement of growth conditions that yield large CNT surface areas and high levels of enzyme adsorption should lead to the development of CNTs for higher performance substrates in biosensor applications.^
Timothy S. Fisher, Purdue University.
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