Development of carbon nanotube-based bioelectronic sensors using receptor proteins and peptides for to water and food quality assessment and disease diagnosis

Abstract

Bioelectronic sensors that combine biomolecules as primary recognition elements and electronics as signal transducers have been extensively developed.1, 2 Biologically-inspired technologies for detection of target molecules increased the functionality of sensors with the nature system. Nanomaterial-based electronic devices rapidly amplify biological signals and convert into intuitive forms.3, 4, 5 Furthermore, many parts of living organisms are operated by action potentials so that they can be applied to the sensing mechanism of biolectronic sensors. Recently, various nanomaterials, such as carbon nanotube (CNT), graphene, nanoparticle, nanofiber, nanowire and nanofilm have been used in the fabrication of the bioelectronic sensors. Such nanomaterials were functionalized with biomolecules, such as DNA, protein, peptide, and cell for the specific binding. Advantages of using bioelectronic sensors are low manufacturing cost, small size, fast response, high sensitivity and selectivity. The objective of this research is to develop a CNT-based bioelectronic sensor using receptor proteins and peptides for various applications. Receptors receive external stimuli from out of the cell membrane and activate signal transduction pathways.6 The Receptors play important functions in the human body such as sensory transduction, cellular communication, neural transmission and hormonal signaling.7 In this study, receptor proteins were produced in forms of cell-derived nanovesicles, purified proteins and synthetic peptides. Their biological signals were monitored by The CNT-based transducers and applied to environmental monitoring, disease diagnosis and food quality assessment. For the deorphanization of olfactory receptors, artificial olfactory cells were constructed using heterologous reporter gene systems.8 Specific receptors were screened for detection of potential biomarkers and evaluation of cell surface expression was performed. The cell-derived nanovesicles were constructed for the scalable signal transduction to the CNTs.9 A CNT-based field-effect transistor (FET) was fabricated via the conventional photolithography process.10 CNT channels were functionalized with nanovecsicles and the electrical properties of the CNT-FET were also maintained after the immobilization of nanovesicles. The nanovesicle-based bioelectronic sensor detected target biomarkers with high sensitivity and selectivity. The bioelectronic sensor using receptors presented simple rapid analytical methods for water quality monitoring and diabetes diagnosis. Developing a multiplexed platform and miniaturizing sensing device is necessary for practical applications of bioelectronic sensors. Four kinds of receptor proteins were expressed in Escherichia coli, purified and refolded with the detergent micelle methods. The proteins were immobilized onto the multi-type CNT channels which designed for simultaneous detection of the target molecules. A current monitoring device was customized for the multi-channel CNT-FET and operated by a laptop computer. Complex pattern recognitions of various molecules were available without any interference from non-target molecules. The simple portable bioelectronic device was suitable for efficient assessment of food quality and is expected to be used as a rapid on-site sensing platform. Receptor protein-derived peptides were synthesized based on the sequence of ligand binding sites and applied to the development of the bioelectronic sensor. The peptides do not require cell membrane-like environments so that they were easily stored.11 Furthermore, The synthesized peptides could directly immobilized onto the CNTs using the pi-pi interaction by simple modifications with additional phenylalanine residues.12, 13 The peptide-based bioelectronic sensor detected a serum biomarker of nerumyelitis optica with high specificity. Furthermore, the sensitivity was much higher so that the early-phase detection was available. In this research, bioelectronic sensor using carbon nanotubes and various types of receptors such as nanovesicles, proteins and peptides were developed for simple and rapid detection of the biomarkers. The developed sensors applied for the environmental monitoring, disease diagnosis and food quality assessment.