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Functional Nucleic Acid Sensors

DNA-Mediated Homogeneous Binding Assays for Nucleic Acids and Proteins

An abasic site called dSpacer has been introduced into duplex regions of the 8−17 DNAzyme and adenosine aptamer for label-free fluorescent detection of Pb2+ and adenosine, respectively. The dSpacer can bind an extrinsic fluorescent compound, 2-amino-5,6,7-trimethyl-1,8-naphthyridine (ATMND), and quench its fluorescence. Addition of Pb2+ enables the DNAzyme to cleave its substrate and release ATMND from DNA duplex, recovering the fluorescence of ATMND. Similarly, the presence of adenosine induces structural switching of the aptamer, resulting in the release of ATMND from the DNA duplex and a subsequent fluorescence enhancement. Under optimized conditions, this label-free method exhibits detection limits of 4 nM for Pb2+ and 3.4 μM for adenosine, which are even lower than those of the corresponding labeled-DNAzyme and aptamer sensors. These low detection limits have been obtained without compromising any of the selectivity of the sensors. Finally, the dynamic range of the adenosine sensor has been tuned by ...

Abasic Site-Containing DNAzyme and Aptamer for Label-Free Fluorescent Detection of Pb2+ and Adenosine with High Sensitivity, Selectivity, and Tunable Dynamic Range

Recent advances in nanotechnology have enabled the development of nanoscale sensors that outperform conventional biosensors. This review summarizes the nanoscale biosensors that use aptamers as molecular recognition elements. The advantages of aptamers over antibodies as sensors are highlighted. These advantages are especially apparent with electrical sensors such as electrochemical sensors or those using field-effect transistors.

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Aptamers as molecular recognition elements for electrical nanobiosensors.

Nanobiotechnologies for Proteins, Nucleic Acids, Small Molecules, and Ions Juwen Shen, Yuebin Li,†,§,⊥ Haoshuang Gu, Fan Xia,*,† and Xiaolei Zuo*,‡ †Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China ‡Division of Physical Biology and Bioimaging Center, Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Science, Shanghai 201800, China Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physical and Electronic Sciences, Hubei University, Wuhan 430062, China Key Laboratory of Systems Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China

Recent Development of Sandwich Assay Based on the Nanobiotechnologies for Proteins, Nucleic Acids, Small Molecules, and Ions

Aptamers are nucleic acids selected for binding target molecules of interest with high affinity and selectivity. They have seen increasing application in protein detection due to many of their advantages over traditional protein probes such as antibodies. Aptamers' robust yet flexible functional structures and relatively small sizes have allowed us to develop several strategies for sensitive protein detection in real time and in homogeneous solutions while posing minimum effects on the biological activities of the proteins. Quantitative protein analyses were done using aptamers labeled with a fluorophore and a quencher based on fluorescence resonance energy transfer (FRET), or using aptamers labeled with only one fluorophore based on fluorescence anisotropy. Real world biological samples were tested for the presence of target proteins. We believe that aptamers hold great potential for high throughput protein analysis in areas such as disease diagnosis and functional proteomics.

Weihong Tan

Papers

Molecular Beacon Aptamers for Protein Monitoring in Real-Time and in Homogeneous Solutions