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Kohlberger M, Gadermaier G. SELEX: Critical factors and optimization strategies for successful aptamer selection. Biotechnol Appl Biochem 2022; 69:1771-1792. [PMID: 34427974 PMCID: PMC9788027 DOI: 10.1002/bab.2244] [Citation(s) in RCA: 72] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 08/22/2021] [Indexed: 12/30/2022]
Abstract
Within the last decade, the application range of aptamers in biochemistry and medicine has expanded rapidly. More than just a replacement for antibodies, these intrinsically structured RNA- or DNA-oligonucleotides show great potential for utilization in diagnostics, specific drug delivery, and treatment of certain medical conditions. However, what is analyzed less frequently is the process of aptamer identification known as systematic evolution of ligands by exponential enrichment (SELEX) and the functional mechanisms that lie at its core. SELEX involves numerous singular processes, each of which contributes to the success or failure of aptamer generation. In this review, critical steps during aptamer selection are discussed in-depth, and specific problems are presented along with potential solutions. The discussed aspects include the size and molecule type of the selected target, the nature and stringency of the selection process, the amplification step with its possible PCR bias, the efficient regeneration of RNA or single-stranded DNA, and the different sequencing procedures and screening assays currently available. Finally, useful quality control steps and their role within SELEX are presented. By understanding the mechanisms through which aptamer selection is influenced, the design of more efficient SELEX procedures leading to a higher success rate in aptamer identification is enabled.
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Affiliation(s)
- Michael Kohlberger
- Department of BiosciencesParis Lodron University SalzburgSalzburgAustria,Christian Doppler Laboratory for Biosimilar CharacterizationParis Lodron University SalzburgSalzburgAustria
| | - Gabriele Gadermaier
- Department of BiosciencesParis Lodron University SalzburgSalzburgAustria,Christian Doppler Laboratory for Biosimilar CharacterizationParis Lodron University SalzburgSalzburgAustria
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2
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Aptamer-modified biosensors to visualize neurotransmitter flux. J Neurosci Methods 2022; 365:109386. [PMID: 34653500 DOI: 10.1016/j.jneumeth.2021.109386] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/23/2021] [Accepted: 10/07/2021] [Indexed: 12/14/2022]
Abstract
Chemical biosensors with the capacity to continuously monitor various neurotransmitter dynamics can be powerful tools to understand complex signaling pathways in the brain. However, in vivo detection of neurochemicals is challenging for many reasons such as the rapid release and clearance of neurotransmitters in the extracellular space, or the low target analyte concentrations in a sea of interfering biomolecules. Biosensing platforms with adequate spatiotemporal resolution coupled to specific and selective receptors termed aptamers, demonstrate high potential to tackle such challenges. Herein, we review existing literature in this field. We first discuss nanoparticle-based systems, which have a simple in vitro implementation and easily interpretable results. We then examine methods employing near-infrared detection for deeper tissue imaging, hence easier translation to in vivo implementation. We conclude by reviewing live cell imaging of neurotransmitter release via aptamer-modified platforms. For each of these sensors, we discuss the associated challenges for translation to real-time in vivo neurochemical imaging. Realization of in vivo biosensors for neurotransmitters will drive future development of early prevention strategies, treatments, and therapeutics for psychiatric and neurodegenerative diseases.
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3
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Zhao C, Cheung KM, Huang IW, Yang H, Nakatsuka N, Liu W, Cao Y, Man T, Weiss PS, Monbouquette HG, Andrews AM. Implantable aptamer-field-effect transistor neuroprobes for in vivo neurotransmitter monitoring. SCIENCE ADVANCES 2021; 7:eabj7422. [PMID: 34818033 PMCID: PMC8612678 DOI: 10.1126/sciadv.abj7422] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
While tools for monitoring in vivo electrophysiology have been extensively developed, neurochemical recording technologies remain limited. Nevertheless, chemical communication via neurotransmitters plays central roles in brain information processing. We developed implantable aptamer–field-effect transistor (FET) neuroprobes for monitoring neurotransmitters. Neuroprobes were fabricated using high-throughput microelectromechanical system (MEMS) technologies, where 150 probes with shanks of either 150- or 50-μm widths and thicknesses were fabricated on 4-inch Si wafers. Nanoscale FETs with ultrathin (~3 to 4 nm) In2O3 semiconductor films were prepared using sol-gel processing. The In2O3 surfaces were coupled with synthetic oligonucleotide receptors (aptamers) to recognize and to detect the neurotransmitter serotonin. Aptamer-FET neuroprobes enabled femtomolar serotonin detection limits in brain tissue with minimal biofouling. Stimulated serotonin release was detected in vivo. This study opens opportunities for integrated neural activity recordings at high spatiotemporal resolution by combining these aptamer-FET sensors with other types of Si-based implantable probes to advance our understanding of brain function.
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Affiliation(s)
- Chuanzhen Zhao
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kevin M. Cheung
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - I-Wen Huang
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Hongyan Yang
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, Hatos Center for Neuropharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Nako Nakatsuka
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Wenfei Liu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yan Cao
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Tianxing Man
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Paul S. Weiss
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Harold G. Monbouquette
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Anne M. Andrews
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, Hatos Center for Neuropharmacology, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Corresponding author.
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4
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Zeng S, Wang S, Xie X, Yang SH, Fan JH, Nie Z, Huang Y, Wang HH. Live-Cell Imaging of Neurotransmitter Release with a Cell-Surface-Anchored DNA-Nanoprism Fluorescent Sensor. Anal Chem 2020; 92:15194-15201. [PMID: 33136382 DOI: 10.1021/acs.analchem.0c03764] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Neurotransmitters are essential chemical mediators for neuronal communication in variable neuromodulations. However, the progress of neuroscience is hampered by the shortage of suitable sensors to track neurotransmitters with high spatial and temporal resolution. Here, we introduce a self-assembled DNA-nanoprism fluorescent probe capable of nongenetically engineering the cell surface for ultrasensitive imaging of the neurotransmitter release at a single live-cell level. The DNA-nanoprism structure conjugated with three cholesterol tails enables the probe to rapidly and stably anchor on the cell surface within 10 min. The in situ detection of neurotransmitters is achieved by equipping the DNA-nanoprism with an aptamer-based "turn-on" fluorescent sensory module for the transmitter of interest. In a proof-of-concept study, we directly visualized the transient dopamine (DA) release on the cell surface with selective responsivity and high spatiotemporal precision and further explored the dynamic correlation between DA release and calcium influx triggered by high K+. This study provides a robust and sensitive tool for cell-surface-targeted imaging of neuromodulations, which might open up a new avenue to improve the understanding of neurochemistry and advance neuroscience research.
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Affiliation(s)
- Shu Zeng
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Shuo Wang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Xuan Xie
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Si-Hui Yang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Jia-Hui Fan
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Zhou Nie
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Yan Huang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Hong-Hui Wang
- College of Biology, Hunan University, Changsha 410082, P. R. China
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6
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Abstract
Nucleic acid aptamers have tremendous potential as molecular recognition elements in biomedical targeting, analytical arrays, and self-signaling sensors. However, practical limitations and inefficiencies in the process of selecting novel aptamers (SELEX) have hampered widespread adoption of aptamer technologies. Many factors have recently contributed to more effective aptamer screening, but no influence has done more to increase the efficiency, scale, and automation of aptamer selection than that of new microfluidic SELEX techniques. This review introduces aptamers as a powerful chemical and biological tool, briefly highlights traditional SELEX techniques and their limitations, covers in detail the recent advancements in microfluidic methods of aptamer selection and characterization, and suggests possible future directions of the field.
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Affiliation(s)
- Sean K Dembowski
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA.
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7
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Röthlisberger P, Gasse C, Hollenstein M. Nucleic Acid Aptamers: Emerging Applications in Medical Imaging, Nanotechnology, Neurosciences, and Drug Delivery. Int J Mol Sci 2017; 18:E2430. [PMID: 29144411 PMCID: PMC5713398 DOI: 10.3390/ijms18112430] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 11/08/2017] [Accepted: 11/09/2017] [Indexed: 12/25/2022] Open
Abstract
Recent progresses in organic chemistry and molecular biology have allowed the emergence of numerous new applications of nucleic acids that markedly deviate from their natural functions. Particularly, DNA and RNA molecules-coined aptamers-can be brought to bind to specific targets with high affinity and selectivity. While aptamers are mainly applied as biosensors, diagnostic agents, tools in proteomics and biotechnology, and as targeted therapeutics, these chemical antibodies slowly begin to be used in other fields. Herein, we review recent progress on the use of aptamers in the construction of smart DNA origami objects and MRI and PET imaging agents. We also describe advances in the use of aptamers in the field of neurosciences (with a particular emphasis on the treatment of neurodegenerative diseases) and as drug delivery systems. Lastly, the use of chemical modifications, modified nucleoside triphosphate particularly, to enhance the binding and stability of aptamers is highlighted.
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Affiliation(s)
- Pascal Röthlisberger
- Institut Pasteur, Department of Structural Biology and Chemistry, Laboratory for Bioorganic Chemistry of Nucleic Acids, CNRS UMR3523, 28, rue du Docteur Roux, 75724 Paris CEDEX 15, France.
| | - Cécile Gasse
- Institute of Systems & Synthetic Biology, Xenome Team, 5 rue Henri Desbruères Genopole Campus 1, University of Evry, F-91030 Evry, France.
| | - Marcel Hollenstein
- Institut Pasteur, Department of Structural Biology and Chemistry, Laboratory for Bioorganic Chemistry of Nucleic Acids, CNRS UMR3523, 28, rue du Docteur Roux, 75724 Paris CEDEX 15, France.
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8
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Pfeiffer F, Mayer G. Selection and Biosensor Application of Aptamers for Small Molecules. Front Chem 2016; 4:25. [PMID: 27379229 PMCID: PMC4908669 DOI: 10.3389/fchem.2016.00025] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 05/30/2016] [Indexed: 12/12/2022] Open
Abstract
Small molecules play a major role in the human body and as drugs, toxins, and chemicals. Tools to detect and quantify them are therefore in high demand. This review will give an overview about aptamers interacting with small molecules and their selection. We discuss the current state of the field, including advantages as well as problems associated with their use and possible solutions to tackle these. We then discuss different kinds of small molecule aptamer-based sensors described in literature and their applications, ranging from detecting drinking water contaminations to RNA imaging.
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Affiliation(s)
- Franziska Pfeiffer
- Department of Chemical Biology, Life and Medical Sciences Institute, University of Bonn Bonn, Germany
| | - Günter Mayer
- Department of Chemical Biology, Life and Medical Sciences Institute, University of Bonn Bonn, Germany
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9
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Nübel C, Appel B, Hospach I, Mai M, Krasteva N, Nelles G, Petruschka L, Müller S. Challenges and Opportunities in the Development of Aptamers for TNFα. Appl Biochem Biotechnol 2016; 179:398-414. [PMID: 26922730 DOI: 10.1007/s12010-016-2002-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 01/27/2016] [Indexed: 11/24/2022]
Abstract
RNA aptamers for tumor necrosis factor-alpha (TNFα), for which functionality was demonstrated in L929 cells, show only little affinity for the protein in vitro. Detailed investigation of the aptamer-protein interaction by surface plasmon resonance and quartz crystal microbalance analysis revealed that affinity is not the only crucial parameter for efficacy and functionality of those aptamers. Instead, the sensitive equilibrium of the monomeric and homotrimeric form of soluble TNFα decides on aptamer binding. Our results show that the field of application and the source of TNFα have to be carefully defined before selection of aptamer sequences.
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Affiliation(s)
- Claudia Nübel
- Institut für Biochemie, Ernst-Moritz-Arndt Universität Greifswald, Greifswald, Germany
| | - Bettina Appel
- Institut für Biochemie, Ernst-Moritz-Arndt Universität Greifswald, Greifswald, Germany
| | - Ingeborg Hospach
- Materials Science Laboratory, Sony Deutschland GmbH, Stuttgart, Germany.,Institute of Electronics and Sensor Materials, Technical University Freiberg, Freiberg, Germany
| | - Michaela Mai
- Materials Science Laboratory, Sony Deutschland GmbH, Stuttgart, Germany
| | - Nadejda Krasteva
- Materials Science Laboratory, Sony Deutschland GmbH, Stuttgart, Germany
| | - Gabriele Nelles
- Materials Science Laboratory, Sony Deutschland GmbH, Stuttgart, Germany
| | - Lothar Petruschka
- Interfakultäres Institut für Genetik und funktionelle Genomforschung, Ernst-Moritz-Arndt Universität Greifswald, Greifswald, Germany
| | - Sabine Müller
- Institut für Biochemie, Ernst-Moritz-Arndt Universität Greifswald, Greifswald, Germany.
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10
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Bauer M, Macdonald J, Henri J, Duan W, Shigdar S. The Application of Aptamers for Immunohistochemistry. Nucleic Acid Ther 2016; 26:120-6. [PMID: 26862683 DOI: 10.1089/nat.2015.0569] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Immunohistochemistry has helped to make surgical pathology the "gold" standard for tumor diagnosis. However, given the numerous problems associated with the use of antibodies for the staining of cellular markers in paraffin-embedded tissues, there is a requirement for novel agents that have the advantages of antibodies, but with few of the disadvantages. Aptamers, which are chemical antibodies, are highly specific and sensitive, like their protein counterparts, but display few of the disadvantages. These molecules represent a unique reagent that has the potential to revolutionize the field of histopathological diagnostics. In this study, we present a review of some of the aptamers that have been validated for use in diagnoses and suggest some of the advantages to using these molecules in the future.
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Affiliation(s)
- Michelle Bauer
- 1 School of Medicine, Deakin University , Geelong, Victoria, Australia
| | - Joanna Macdonald
- 1 School of Medicine, Deakin University , Geelong, Victoria, Australia
| | - Justin Henri
- 1 School of Medicine, Deakin University , Geelong, Victoria, Australia
| | - Wei Duan
- 1 School of Medicine, Deakin University , Geelong, Victoria, Australia
- 2 Centre for Molecular and Medical Research, Deakin University , Geelong, Victoria, Australia
| | - Sarah Shigdar
- 1 School of Medicine, Deakin University , Geelong, Victoria, Australia
- 2 Centre for Molecular and Medical Research, Deakin University , Geelong, Victoria, Australia
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11
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McConnell EM, Holahan MR, DeRosa MC. Aptamers as promising molecular recognition elements for diagnostics and therapeutics in the central nervous system. Nucleic Acid Ther 2015; 24:388-404. [PMID: 25296265 DOI: 10.1089/nat.2014.0492] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Oligonucleotide aptamers are short, synthetic, single-stranded DNA or RNA able to recognize and bind to a multitude of targets ranging from small molecules to cells. Aptamers have emerged as valuable tools for fundamental research, clinical diagnosis, and therapy. Due to their small size, strong target affinity, lack of immunogenicity, and ease of chemical modification, aptamers are an attractive alternative to other molecular recognition elements, such as antibodies. Although it is a challenging environment, the central nervous system and related molecular targets present an exciting potential area for aptamer research. Aptamers hold promise for targeted drug delivery, diagnostics, and therapeutics. Here we review recent advances in aptamer research for neurotransmitter and neurotoxin targets, demyelinating disease and spinal cord injury, cerebrovascular disorders, pathologies related to protein aggregation (Alzheimer's, Parkinson's, and prions), brain cancer (glioblastomas and gliomas), and regulation of receptor function. Challenges and limitations posed by the blood brain barrier are described. Future perspectives for the application of aptamers to the central nervous system are also discussed.
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Affiliation(s)
- Erin M McConnell
- 1 Department of Chemistry, Carleton University , Ottawa, Ontario, Canada
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12
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Malhotra S, Pandey AK, Rajput YS, Sharma R. Selection of aptamers for aflatoxin M1 and their characterization. J Mol Recognit 2015; 27:493-500. [PMID: 24984866 DOI: 10.1002/jmr.2370] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/22/2014] [Accepted: 03/03/2014] [Indexed: 11/07/2022]
Abstract
In the present work, aptamers against aflatoxin M1 and aflatoxin B1 were generated and tested for creating proof of principle of recognition of aflatoxin M1 by generated aptamers. The aptamers were selected through the process referred as systematic evolution of ligands by exponential enrichment. A total of 41 different aptamer (36 aptamers for aflatoxin M1 and 5 for aflatoxin B1) sequences were obtained. The determination of dissociation constant (Kd ) values revealed that aptamers generated against aflatoxin M1 exhibited Kd values in the range of 35-1515 nM. Selected aptamers were grouped on the basis of the presence of common motifs or G-quadruplex. We find it interesting that one aptamer with no conserved motif or G-quadruplex had lowest Kd value (Kd = 35 nM). This structural motif is very distinct from motifs present in other aptamers. The Kd values of selected aptamers for aflatoxin B1 were in the range of 96-221 nM. One aptamer from each group was further tested for its ability to be used in aptasensor. The aptamer recognized aflatoxin M1 as indicated by color change (red to purple or blue) of aptamer-coated gold nanoparticles in the presence of 250-500 nM aflatoxin M1. The aptamers can be used in developing methods for detection/estimation/separation of aflatoxin or antidote for aflatoxin toxicity.
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Affiliation(s)
- S Malhotra
- Animal Biochemistry Division, National Dairy Research Institute, Karnal, India
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13
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Wang CI, Periasamy AP, Chang HT. Photoluminescent C-dots@RGO Probe for Sensitive and Selective Detection of Acetylcholine. Anal Chem 2013; 85:3263-70. [DOI: 10.1021/ac303613d] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Chen-I Wang
- Department
of Chemistry, National Taiwan University, Taipei, Taiwan
| | | | - Huan-Tsung Chang
- Department
of Chemistry, National Taiwan University, Taipei, Taiwan
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Barahona F, Bardliving CL, Phifer A, Bruno JG, Batt CA. An Aptasensor Based on Polymer-Gold Nanoparticle Composite Microspheres for the Detection of Malathion Using Surface-Enhanced Raman Spectroscopy. Ind Biotechnol (New Rochelle N Y) 2013. [DOI: 10.1089/ind.2012.0029] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | | | | | - John G. Bruno
- Operational Technologies Corporation, San Antonio, TX
| | - Carl A. Batt
- Department of Food Science, Cornell University, Ithaca, NY
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15
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Ruigrok VJB, van Duijn E, Barendregt A, Dyer K, Tainer JA, Stoltenburg R, Strehlitz B, Levisson M, Smidt H, van der Oost J. Kinetic and stoichiometric characterisation of streptavidin-binding aptamers. Chembiochem 2012; 13:829-36. [PMID: 22416028 DOI: 10.1002/cbic.201100774] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Indexed: 01/06/2023]
Abstract
Aptamers are oligonucleotide ligands that are selected for high-affinity binding to molecular targets. Only limited knowledge relating to relations between structural and kinetic properties that define aptamer-target interactions is available. To this end, streptavidin-binding aptamers were isolated and characterised by distinct analytical techniques. Binding kinetics of five broadly similar aptamers were determined by surface plasmon resonance (SPR); affinities ranged from 35-375 nM with large differences in association and dissociation rates. Native mass spectrometry showed that streptavidin can accommodate up to two aptamer units. In a 3D model of one aptamer, conserved regions are exposed, strongly suggesting that they directly interact with the biotin-binding pockets of streptavidin. Mutational studies confirmed both conserved regions to be crucial for binding. An important result is the observation that the most abundant aptamer in our selections is not the tightest binder, emphasising the importance of having insight into the kinetics of complex formation. To find the tightest binder it might be better to perform fewer selection rounds and to focus on post-selection characterisation, through the use of complementary approaches as described in this study.
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Affiliation(s)
- Vincent J B Ruigrok
- Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands.
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Abstract
Antibodies are the most successful affinity tools used today, in both fundamental and applied research (diagnostics, purification and therapeutics). Nonetheless, antibodies do have their limitations, including high production costs and low stability. Alternative affinity tools based on nucleic acids (aptamers), polypeptides (engineered binding proteins) and inorganic matrices (molecular imprinted polymers) have received considerable attention. A major advantage of these alternatives concerns the efficient (microbial) production and in vitro selection procedures. The latter approach allows for the high-throughput optimization of aptamers and engineered binding proteins, e.g. aiming at enhanced chemical and physical stability. This has resulted in a rapid development of the fields of nucleic acid- and protein-based affinity tools and, although they are certainly not as widely used as antibodies, the number of their applications has steadily increased in recent years. In the present review, we compare the properties of the more conventional antibodies with these innovative affinity tools. Recent advances of affinity tool developments are described, both in a medical setting (e.g. diagnostics, therapeutics and drug delivery) and in several niche areas for which antibodies appear to be less attractive. Furthermore, an outlook is provided on anticipated future developments.
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Aptamer–biotin–streptavidin–C1q complexes can trigger the classical complement pathway to kill cancer cells. In Vitro Cell Dev Biol Anim 2011; 46:107-13. [PMID: 19915929 DOI: 10.1007/s11626-009-9257-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Accepted: 10/22/2009] [Indexed: 01/11/2023]
Abstract
Nucleic acid aptamers are regarded as rivals for antibodies and as such are being investigated for their therapeutic potential. In the present work, it is shown that two different high-affinity DNA aptamers developed previously by Ferreira et al. against MUC1 antigen (designated MUC1-5TR-1 and MUC1-S1.3/S2.2) on MCF7 breast cancer cells can be linked to the first component of complement (C1q) via a biotin–streptavidin system and induce significant killing of MCF7 cells in vitro. Cell viability was assessed by Trypan blue uptake and absorbance at 590 nm of stained cells following buffer washes and lysis in 1% SDS. While the killing effect is demonstrable versus various controls, dependent on aptamer dose, and reproducible, it appears to kill maximally about half of treated MCF7 cells. Possible reasons for the marginal killing effect include antigenic shedding in vitro and membrane-bound complement regulatory proteins (mCRPs) on the cell surface such as CD46, CD55, and CD59 which act to inhibit complement-mediated lysis of cells. Future in vitro research could benefit from application of mCRP-specific aptamers in combination with anti-MUC1 aptamers to overcome surface protective mechanisms while attacking the plasma membrane of MCF7 cells or other MUC1-expressing cancer cells. However, in vivo such a combination could have deleterious effects on normal MUC1-expressing cells as well.
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Bruno JG, Carrillo MP, Phillips T, Edge A. Serum inverts and improves the fluorescence response of an aptamer beacon to various vitamin D analytes. LUMINESCENCE 2011; 27:51-8. [PMID: 21710586 DOI: 10.1002/bio.1324] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2011] [Revised: 05/04/2011] [Accepted: 05/04/2011] [Indexed: 11/06/2022]
Abstract
A dominant aptamer loop structure from a library of nearly 100 candidate aptamer sequences developed against immobilized 25-hydroxyvitamin D(3) (calcidiol) was converted into a 5'-TYE 665 and 3'-Iowa black-labelled aptamer beacon. The aptamer beacon exhibited a mild 'lights on' reaction in buffer as a function of increasing concentrations of several vitamin D analogues and metabolites, with a limit of detection of approximately 200 ng/mL, and was not specific for any particular congener. In 10% or 50% human serum, the same aptamer beacon inverted its fluorescence behaviour to become a more intense 'lights off' reaction with an improved limit of detection in the range 4-16 ng/mL. We hypothesized that this drastic change in fluorescence behaviour was due to the presence of creatinine and urea in serum, which might destabilize the quenched beacon, causing an increase in fluorescence followed by decreasing fluorescence as a function of vitamin D concentrations that may bind and quench increasingly greater fractions of the denatured beacons. However, the results of several control experiments in the presence of physiological or greater concentrations of creatinine and urea, alone or combined in buffer, failed to produce the beacon fluorescence inversion. Other possible mechanistic hypotheses are also discussed.
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Affiliation(s)
- John G Bruno
- Operational Technologies Corporation, San Antonio, TX, 78229, USA.
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Kang HRJ, Chan Kang K, Newby JG, Lee JH. Fieldable flow injection analysis system with chemiluminescence detection capable of quantifying. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2011; 3:374-379. [PMID: 32938039 DOI: 10.1039/c0ay00440e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We developed a highly sensitive biosensor for quantifying acetylcholine (ACh) using flow injection analysis system with 1,1'-oxalyldiimidazole chemiluminescence (ODI-CL) detection designed based on the principle of liquid core waveguide. ACh in Tris-HCl (pH 8.5) was incubated with the mixture of 1.0 U/ml acetylcholinesterase, 0.5 U/ml choline oxidase, 0.04 U/ml horseradish peroxidase, and 1.0 μM Amplex Red in PBS (pH 7.4) for 15 min at room temperature. The concentration of resorufin formed from the consecutive enzyme reactions was proportional to the concentration of ACh in analytical sample. The dynamic range of linear calibration curve (y = 12444x + 11617, R2 = 0.998) for the quantification of ACh using the biosensor with ODI CL detection was 0.7∼11.3 μM. The limit of detection (LOD = background noise + 3σ) of the biosensor was as low as 0.14 μM. Based on the results of recovery test and linearity study, finally, we confirmed that FIA system with ODI CL detection is accurate, precise, and reproducible.
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Affiliation(s)
- Hui Rak J Kang
- Newton North High School, Newtonville, MA 02460, USA
- Luminescent MD, LLC, Hagerstown, MD 21742, USA.
| | - Kam Chan Kang
- Luminescent MD, LLC, Hagerstown, MD 21742, USA.
- Brookline High School, 115 Greenough St., Brookline, MA 02445, USA
| | - John G Newby
- Department of Pathology, Washington County Hospital, Hagerstown, MD 21740, USA
| | - Ji Hoon Lee
- Luminescent MD, LLC, Hagerstown, MD 21742, USA.
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A novel screening method for competitive FRET-aptamers applied to E. coli assay development. J Fluoresc 2010; 20:1211-23. [PMID: 20443050 DOI: 10.1007/s10895-010-0670-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 04/26/2010] [Indexed: 10/19/2022]
Abstract
A novel high-throughput screening method is described in which a family of DNA aptamers selected against E. coli outer membrane proteins (OMPs) is subjected to PCR in the presence of fluorophore-dUTP conjugates using Deep Vent® exo- polymerase. The fluorophore-doped aptamers and their complementary strands are then heated to render them single-stranded and screened in filter well microtiter plates for fluorescence resonance energy transfer (FRET) assay potential. Using this system, a superior competitive FRET-aptamer designated EcO 4R was identified and the location of its putative binding pocket was determined by individually testing FRET potential in each of the secondary loop structures. By labeling the binding pocket with Alexa Fluor (AF) 647 and binding the aptamer to heavily Black Hole Quencher-3 (BHQ-3)-labeled E. coli bacteria, detection of as few as 30 live unlabeled E. coli per ml was achieved in a competitive displacement FRET assay format. The far red fluorescence emission enables detection in largely blue-green autofluorescent matrices. In addition, the competitive transfer of AF 647-EcO-4R aptamer to unlabeled E. coli cells after a 15 min equilibration period was verified by fluorescence microscopy. The present study also demonstrated that high aptamer affinity is not well correlated with competitive FRET potential.
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Bruno JG, Carrillo MP, Cadieux CL, Lenz DE, Cerasoli DM, Phillips T. DNA aptamers developed against a soman derivative cross-react with the methylphosphonic acid core but not with flanking hydrophobic groups. J Mol Recognit 2009; 22:197-204. [PMID: 19051203 DOI: 10.1002/jmr.932] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Twelve rounds of systematic evolution of ligands by exponential enrichment (SELEX) were conducted against a magnetic bead conjugate of the para-aminophenylpinacolylmethylphosphonate (PAPMP) derivative of the organophosphorus (OP) nerve agent soman (GD). The goal was to develop DNA aptamers that could scavenge GD in vivo, thereby reducing or eliminating the toxic effects of this dangerous compound. Aptamers were sequenced and screened in peroxidase-based colorimetric plate assays after rounds 8 and 12 of SELEX. The aptamer candidate sequences exhibiting the highest affinity for the GD derivative from round 8 also reappeared in several clones from round 12. Each of the highest affinity PAPMP-binding aptamers also bound methylphosphonic acid (MPA). In addition, the aptamer with the highest overall affinity for PAPMP carried a sequence motif (TTTAGT) thought to bind MPA based on previously published data (J. Fluoresc 18: 867-876, 2008). This sequence motif was found in several other relatively high affinity PAPMP aptamer candidates as well. In studies with the nerve agent GD, pre-incubation of a large molar excess of aptamer candidates failed to protect human butyrylcholinesterase (BuChE) from inhibition. With the aid of three-dimensional molecular modeling of the GD derivative it appears that a hydrophilic cleft sandwiched between the pinacolyl group and the p-aminophenyl ring might channel nucleotide interactions to the phosphonate portion of the immobilized GD derivative. However, bona fide GD free in solution may be repulsed by the negative phosphate backbone of aptamers and rotate its phosphonate and fluorine moieties away from the aptamer to avoid being bound. Future attempts to develop aptamers to GD might benefit from immobilizing the pinacolyl group of bona fide GD to enhance exposure of the phosphonate and fluorine to the random DNA library.
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Affiliation(s)
- John G Bruno
- Operational Technologies Corporation, 4100 NW Loop 410, Suite 230, San Antonio, TX 78229-4253, USA.
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Reinemann C, Stoltenburg R, Strehlitz B. Investigations on the specificity of DNA aptamers binding to ethanolamine. Anal Chem 2009; 81:3973-8. [PMID: 19361229 DOI: 10.1021/ac900305y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In our previous work, we selected aptamers binding to ethanolamine, one of the smallest molecular aptamer targets so far (Mann, D., Reinemann, C., Stoltenburg, R. and Strehlitz, B. Biochem. Biophys. Res. Commun. 2005, 338, 1928-1934). Two representatives of these aptamers (EA#14.3 and EA#9.4) were analyzed regarding their specificity. Ethanolamine is a very small organic molecule (M(w) = 61.08) with biological, medical, and industrial relevance. Its small size represented a challenge for aptamer development, as ethanolamine only consists of a short carbon chain (2C) and two functional groups (amino and hydroxyl group). Related organic molecules, ethanolamine derivatives, and some amino acids were tested to act as potential binding partners for these aptamers. In this way we were able to determine the exact binding domain within the target. The results revealed that both aptamers bind to various molecules, which contain a freely accessible ethyl- or methylamine group. In contrast to the amino group (in a primary, secondary, or tertiary amine) the hydroxyl group was not necessary for the aptamer binding. The aptamers were not able to bind to negatively charged organic molecules, despite containing an ethyl- or methylamine group, nor did they bind to molecules with quaternary amines. The selected ethanolamine binding aptamers are useful for the detection of molecules containing accessible ethyl- or methylamine groups; they can be used as linker elements to immobilize a target molecule of interest on a surface or to purify targets from complex samples.
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Affiliation(s)
- Christine Reinemann
- UFZ-Helmholtz Centre for Environmental Research, Permoserstrasse 15, D-04318 Leipzig, Germany
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Bruno JG, Phillips T, Carrillo MP, Crowell R. Plastic-adherent DNA aptamer-magnetic bead and quantum dot sandwich assay for Campylobacter detection. J Fluoresc 2008; 19:427-35. [PMID: 19052851 DOI: 10.1007/s10895-008-0429-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2008] [Accepted: 10/14/2008] [Indexed: 10/21/2022]
Abstract
DNA aptamers were developed against MgCl(2)-extracted surface proteins from Campylobacter jejuni. The two highest affinity aptamers were selected for use in a magnetic bead (MB) and red quantum dot (QD)-based sandwich assay scheme. The assay was evaluated using both heat-killed and live C. jejuni and exhibits detection limits as low as an average of 2.5 colony forming unit (cfu) equivalents in buffer and 10-250 cfu in various food matrices. The assay exhibits low cross-reactivity with bacterial species outside the Campylobacter genus, but exhibits substantial cross-reactivity with C. coli and C. lari. The assay was evaluated with a spectrofluorometer and a commercially available handheld fluorometer, which yielded comparable detection limits and ranges. Remarkably, the sandwich assay components adhere to the inside face of polystyrene cuvettes even in food matrices near neutral pH, thereby enabling a rapid homogeneous assay, because fluorescence is concentrated to a small, thin planar area and background fluorescence from the bulk solution is minimized. The plastic cuvette-adherent technology coupled to a sensitive handheld fluorometer may enable rapid (15-20 min), portable detection of foodborne pathogens from "farm-to-fork" by obviating the slow enrichment culture phase used by other food safety tests.
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Affiliation(s)
- John G Bruno
- Operational Technologies Corporation, 4100 NW Loop 410, Suite 230, San Antonio, TX, 78229, USA.
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