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ABSTRACT: It is highly desirable to obtain functional cells with specific olfactory receptors (ORs) for the development of cell-based biosensors towards odorant detection. In this study, we explored the feasibility of bioengineered primary olfactory sensory neurons (OSNs) as sensing elements of biomimetic olfactory-based biosensors, in which light addressable potentiometric sensor (LAPS) was used to monitor bioengineered OSNs membrane potential responses to odorant molecules. An olfactory receptor of C. elegances, ODR-10, as a model receptor, was expressed on the plasma membrane of OSNs by transient transfection. The response profile of bioengineered OSNs to odorant molecules was investigated by analyzing extracellular potential firings features in frequency and time domains. The results indicated that bioengineered OSNs can specifically respond to diacetyl, the natural ligand of ODR-10. In addition, bioengineered OSNs showed different temporal firing patterns in responding to different concentrations of diacetyl. All the results demonstrate that bioengineered OSNs are useful and promising to serve as novel sensing elements of biosensors for specific odorant molecule detection. It is suggested that bioengineering techniques could provide novel approaches for preparing sensitive elements as well as promoting the development of practical applicable olfactory-based biosensors.
Biosensors & bioelectronics 09/2012; · 5.43 Impact Factor
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ABSTRACT: Adenosine triphosphate (ATP) is considered as the key neurotransmitter in taste buds for taste signal transmission and processing. Measurements of ATP secreted from single taste receptor cell (TRC) with high sensitivity and specificity are essential for investigating mechanisms underlying taste cell-to-cell communications. In this study, we presented an aptamer-based biosensor for the detection of ATP locally secreted from single TRC. ATP sensitive DNA aptamer was used as recognition element and its DNA competitor was served as signal transduction element that was covalently immobilized on the surface of light addressable potentiometric sensor (LAPS). Due to the light addressable capability of LAPS, local ATP secretion from single TRC can be detected by monitoring the working potential shifts of LAPS. The results show this biosensor can detect ATP with high sensitivity and specificity. It is demonstrated this biosensor can effectively detect the local ATP secretion from single TRC responding to tastant mixture. This biosensor could provide a promising new tool for the research of taste cell-to-cell communications as well as for the detection of local ATP secretion from other types of ATP secreting individual cells.
Biomedical Microdevices 09/2012; · 3.03 Impact Factor
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ABSTRACT: The immobilization efficiency of molecular detectors is of great importance with regard to the performances of biosensors such as the sensitivity, stability, and reproducibility. This paper presents a biomimetic olfactory receptor-based biosensor with better performances by improving the immobilization efficiency of molecular detectors for odorant sensing. A mixed self-assembled monolayers (SAMs) functionalized with specific olfactory receptors (ODR-10) was constructed on the sensitive area of surface acoustic wave (SAW) chip. The immobilization of ODR-10 was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The responses of this biosensor to various odorants were recorded by monitoring the resonance frequency shifts of SAW, which is correlated to the mass loading on its sensitive area. All the results demonstrate this biosensor can specifically respond to the natural ligand of ODR-10, diacetyl, with high sensitivity and stability. The sensitivity is 4 kHz/ng, which is 2× higher than that of previous work. The detection limit is 1.2×10(-11) mM. The major advances on immobilization efficiency of molecular detectors presented in this work could substantially promote and accelerate the researches and applications of olfactory receptor-based biosensors with different transducers, such as quartz crystal microbalance (QCM), surface plasma resonance (SPR), and field effect transistors (FET).
Biosensors & bioelectronics 01/2012; 31(1):44-8. · 5.43 Impact Factor
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ABSTRACT: Olfactory receptors, which are responsible for sensing odor molecules, form the largest G protein-coupled receptor (GPCR) family in mammalian animals. These proteins play an important role in the detection of chemical signals and signal transduction to the brain. Currently, only a limited number of olfactory receptors have been characterized, which is mainly due to the lack of sensitive and efficient tools for performing functional assays of these receptors. This paper describes a novel surface acoustic wave (SAW)-based biosensor for highly sensitive functional assays of olfactory receptors. An olfactory receptor of Caenorhabditis elegans, ODR-10, was expressed on the plasma membrane of human breast cancer MCF-7 cells, which was used as a model system for this study. For specific odorant response assays, the membrane fraction of MCF-7 cells containing ODR-10 was extracted and integrated with our SAW sensors. The response of ODR-10 to various odorants was monitored by recording the resonance frequency shifts of SAWs applied to the sensor. Our results show that heterologously expressed ODR-10 receptors can specifically respond to diacetyl, its natural ligand. Dose-dependent responses were obtained by performing measurements using various concentrations of diacetyl. The sensitivity of this biosensor is 2kHz/ng and can detect concentrations as low as 10(-10)mM, which is 10× lower than what has previously been reported. This biosensor can be used to characterize odorant response profiles of olfactory receptors and provide information rich data for functional assays of olfactory receptors. In addition to providing a greater understanding of the biological mechanisms of GPCRs, such data holds great potential in many other fields such as food industry, biomedicine, and environmental protection.
Biochemical and Biophysical Research Communications 02/2011; 407(1):18-22. · 2.48 Impact Factor
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ABSTRACT: Olfaction is a very important sensation for all animals. Recently great progress has been made in the research of olfactory
transduction. Especially the novel finding of the gene superfamily encoding olfactory receptors has led to rapid advances
in olfactory transduction. These advances also promoted the research of biomimetic olfactory-based biosensors and some obvious
achievements have been obtained due to their potential commercial prospects and promising industrial applications. This paper
briefly introduces the biological basis of olfaction, summarizes the progress of olfactory signal transduction in the olfactory
neuron, the olfactory bulb and the olfactory cortex, outlines the latest developments and applications of biomimetic olfactory-based
biosensors. Finally, the olfactory biosensor based on light addressable potentiometric sensor (LAPS) is addressed in detail
based on our recent work and the research trends of olfactory biosensors in future are discussed.
Chinese Science Bulletin 06/2007; 52(14):1886-1896. · 1.32 Impact Factor
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ABSTRACT: In this paper, we aimed to study the role of mannose receptor (MR) in oligochitosan induced RAW264.7 (a murine macrophage cell line) activation. Oligochitosan, which has 3-10 saccharide (N-acetyl-glucosamine or glucosamine) residues, was prepared by enzymatic hydrolysis of chitosan using cellulase. Fluorophore 2-aminoacridone was conjugated to oligochitosan to observe cellular events of oligochitosan-RAW264.7 interaction under Confocal Laser Microscopy. RT-PCR was performed to assess the level of tumor necrosis factor-alpha (TNF-alpha) secretion. Free cytosolic Ca(2+) was measured using the fluorescent Ca(2+) indicator Fluo3/AM. We found that MR was the major receptor responsible for oligochitosan uptake. MR was also engaged in oligochitosan induced TNF-alpha enhancement and [Ca(2+)](in) flux and may serve as a signaling receptor in oligochitosan-induced activation of macrophage function.
International Immunopharmacology 10/2005; 5(10):1533-42. · 2.38 Impact Factor
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ABSTRACT: Oligochitosan, which has greater than 3 but less than 10 saccharide (N-acetylglucosamine or glucosamine) residues, is obtained by either chemical or enzymatic hydrolysis of chitosan. In this work, we demonstrated that oligochitosan had an in vitro stimulatory effect on the release of tumor necrosis factor-alpha and interleukin-1 beta in macrophages. Moreover, we observed that oligochitosan could be uptaken by macrophages through confocal laser microscopy. Scatchard analysis of internalization of 2-aminoacridone-oligochitosan in macrophages indicated its internalization was mediated by a specific receptor on macrophage membrane with a Kd of 2.1 x 10(-5) M. Competition studies showed that mannose could inhibit oligochitosan internalization, while lipopolysaccharide and beta-glucan could not do it. Inhibition of mannose-BSA, fucose-BSA, and N-acetylglucosamine-BSA on oligochitosan internalization further suggests that oligochitosan internalization is mediated by a macrophage lectin receptor like with mannose specificity.
Biochemical and Biophysical Research Communications 05/2004; 317(2):414-20. · 2.48 Impact Factor
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ABSTRACT: Oligochitosan, having an average molecular weight of 1000 Da and a degree of N-acetylation below 15%, can be obtained by either chemical or enzymic hydrolysis of chitosan. The present investigation demonstrated that oligochitosan can significantly increase the activity of inducible nitric oxide synthase (iNOS) and induce the synthesis of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) in macrophages. Moreover, nuclear factor-kappaB (NF-kappaB) protein levels in nuclear extract are increased in response to oligochitosan. Blocking NF-kappaB with specific inhibitor results in decreased levels of NO and TNF-alpha. These results indicate that NF-kappaB plays a potential role in the induction of NO and TNF-alpha by oligochitosan in macrophages.
International Immunopharmacology 03/2004; 4(2):193-200. · 2.38 Impact Factor
