Patterned Polymer Nanofibers Based Biosensors
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Patterned Polymer Nanofibers Based Biosensors Timothy O. Mertz1, Vindhya Kunduru2, Prabir K. Patra3, Krishna Vattipalli1, and Shalini Prasad1 1 Department of Electrical Engineering and Computer Science, Wichita State University, Wichita, KS 67260, U.S.A. 2 Biomedical Engineering Department, North Carolina State University, Raleigh, North Carolina 27694, U.S.A. 3 Department of Mechanical Engineering, School of Engineering, University of Bridgeport, Bridgeport, Connecticut 06604, U.S.A. ABSTRACT “Label-free” biomolecule sensors for detection of inflammatory cardiovascular biomarker associated with vulnerable coronary vascular plaque were designed and fabricated using micro and nano-textured polystyrene structures that functioned as sensing elements coupled with electronic measurement equipment. We demonstrated that scaling down the surface texturing from the micro to the nanoscale enhances the amplitude of the measured signal strength. We believe that the nanoscale fiber morphology provides size matched spaces for trapping and immobilizing the protein biomolecules resulting in enhanced detection and signal strength. We selected polystyrene as the model system and demonstrated the detection of human serum Creactive protein (hs-CRP). We employed these findings in designing a platform “lab-on-a-chip” protein sensor. Comparative studies were performed on two different polystyrene textured surfaces: a polystyrene microsphere mat, and an electrospun polystyrene nanofiber matrix. INTRODUCTION Polystyrene is the most commonly used material in a solid phase immunoassay since it offers a biocompatible, non-porous and hydrophobic surface. Protein immobilization can take place via passive hydrophobic adsorption to polystyrene surfaces by means of non covalent bonding [3]. The method of adsorption occurs primarily through van-der-waals attraction between the hydrophobic areas of the adsorbed ligands and the polymer surface [3]. Polystyrene microbeads and nanofibers were employed as solid supports for protein immobilization in this study. In the first scheme – A uniform layer of polystyrene microspheres functioned as the interfacial solid support for antibody immobilization. Polystyrene microbeads offer ample surface area, and are easily used to conduct biofunctionalization procedures [3]. Reports suggest that polystyrene microbeads can be employed as carriers for the nanoscale proteins, enabling protein detection in immunosensor applications [1]. However, polystyrene nanofibers further improve detection by enhancement of the measured signal strength, due to the greater surface area to volume ratio than microbeads. This increases the immobilization locations for protein biomolecules, which improves signal transduction along the nanotextured surface [4]. The multiscale immunosensors presented here, follow a hierarchical transduction scheme where the primary signals are released by electrochemical reactions occurring at the nanoscale interface due to antibody-antigen binding. Signal is passed to the underlying microelectrode platform
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