Enhancing of intensity of fluorescence by DEP manipulations of polyaniline-coated Al2O3 nanoparticles for immunosensing

A novel modification of low-cost Al2O3 nanoparticles (Al2O3 NPs) for antibody-protein immunosensing is proposed. The modified NPs are utilized to enhance the intensity of fluorescence in a dielectrophoretic (DEP) chip with a microelectrode array. The surface of the Al2O3 NPs is modified by ionic polyaniline (PANDB) rather than the conventional silane (3-aminopropyltrimethoxysilane) to conjugate the antibody on the outer shell. After the PANDB-Al2O3 NPs is functionalized to form probes, a DEP chip with a vertical non-uniform electric field that is produced by top and bottom electrodes condenses and immobilizes the nanoprobes on the surface of the electrodes by positive DEP force for immunosensing of the fluorescent protein. Additionally, each microelectrode array can be individually controlled with/without DEP manipulation using a computer program. Experimental results indicate that PANDB-based nanoprobes provide more rapid and sensitive immunosensing than those having undergone conventional silane modification. During immunosensing, fluorescence intensity can be doubled by the application of extra DEP force. The individual control of NPs on the microelectrode array has great potential for applications in multi-antibody arrays in a single chip for immunosensing. (C) 2013 Elsevier B.V. All rights reserved.