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Riccardi C, Pérez de Carvasal K, Platella C, Meyer A, Smietana M, Morvan F, Montesarchio D. Probing naphthalene diimide and 3-hydroxypropylphosphate as end-conjugating moieties for improved thrombin binding aptamers: Structural and biological effects. Bioorg Chem 2023; 141:106917. [PMID: 37865055 DOI: 10.1016/j.bioorg.2023.106917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 09/27/2023] [Accepted: 10/09/2023] [Indexed: 10/23/2023]
Abstract
The limitations associated with the in vivo use of the thrombin binding aptamer (TBA or TBA15) have dramatically stimulated the search of suitable chemically modified analogues in order to discover effective and reversible inhibitors of thrombin activity. In this context, we previously proposed cyclic and pseudo-cyclic TBA analogues with improved stability that proved to be more active than the parent aptamer. Herein, we have investigated a novel library of TBA derivatives carrying naphthalene diimide (NDI) moieties at the 3'- or 5'-end. In a subset of the investigated oligonucleotides, additional 3-hydroxypropylphosphate (HPP) groups were introduced at one or both ends of the TBA sequence. Evaluation of the G-quadruplex thermal stability, serum nuclease resistance and in vitro anticoagulant activity of the new TBA analogues allowed rationalizing the effect of these appendages on the activity of the aptamer on the basis of their relative position. Notably, most of the different TBA analogues tested were more potent thrombin inhibitors than unmodified TBA. Particularly, the analogue carrying an NDI group at the 5'-end and an HPP group at the 3'-end, named N-TBA-p, exhibited enhanced G-quadruplex thermal stability (ΔTm + 14° C) and ca. 10-fold improved nuclease resistance in serum compared to the native aptamer. N-TBA-p also induced prolonged and dose-dependent clotting times, showing a ca. 11-fold higher anticoagulant activity compared to unmodified TBA, as determined by spectroscopic methods. Overall, N-TBA-p proved to be in vitro a more efficient thrombin inhibitor than all the best ones previously investigated in our group. Its interesting features, associated with its easy preparation, make it a very promising candidate for future in vivo studies.
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Affiliation(s)
- Claudia Riccardi
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy
| | - Kévan Pérez de Carvasal
- Institut des Biomolécules Max Mousseron, Université de Montpellier, CNRS, ENSCM, 34095 Montpellier, France
| | - Chiara Platella
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy
| | - Albert Meyer
- Institut des Biomolécules Max Mousseron, Université de Montpellier, CNRS, ENSCM, 34095 Montpellier, France
| | - Michael Smietana
- Institut des Biomolécules Max Mousseron, Université de Montpellier, CNRS, ENSCM, 34095 Montpellier, France
| | - François Morvan
- Institut des Biomolécules Max Mousseron, Université de Montpellier, CNRS, ENSCM, 34095 Montpellier, France.
| | - Daniela Montesarchio
- Department of Chemical Sciences, University of Naples Federico II, 80126 Naples, Italy.
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Riccardi C, Meyer A, Vasseur JJ, Russo Krauss I, Paduano L, Morvan F, Montesarchio D. Fine-tuning the properties of the thrombin binding aptamer through cyclization: Effect of the 5'-3' connecting linker on the aptamer stability and anticoagulant activity. Bioorg Chem 2019; 94:103379. [PMID: 31699393 DOI: 10.1016/j.bioorg.2019.103379] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/21/2019] [Accepted: 10/21/2019] [Indexed: 12/14/2022]
Abstract
A small library of cyclic TBA analogues (named cycTBA I-IV), obtained by covalently connecting its 5'- and 3'-ends with flexible linkers, has been synthesized with the aim of improving its chemical and enzymatic stability, as well as its anticoagulant properties. Two chemical procedures have been exploited to achieve the desired cyclization, based on the oxime ligation method (providing cycTBA I and II) or on Cu(I)-assisted azide-alkyne cycloaddition (CuAAC) protocols (for cycTBA III and IV), leading to analogues containing circularizing linkers with different chemical nature and length, overall spanning from 22 to 48 atoms. The resulting cyclic TBAs have been characterized using a variety of biophysical methods (UV, CD, gel electrophoresis, SE-HPLC analyses) and then tested for their serum resistance and anticoagulant activity under in vitro experiments. A fine-tuning of the length and flexibility of the linker allowed identifying a cyclic analogue, cycTBA II, with improved anticoagulant activity, associated with a dramatically stabilized G-quadruplex structure (ΔTm = +17 °C) and a 6.6-fold higher enzymatic resistance in serum compared to unmodified TBA.
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Affiliation(s)
- Claudia Riccardi
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, I-80126 Napoli, Italy
| | - Albert Meyer
- Institut des Biomolécules Max Mousseron, Université de Montpellier, CNRS, ENSCM, Montpellier, France
| | - Jean-Jacques Vasseur
- Institut des Biomolécules Max Mousseron, Université de Montpellier, CNRS, ENSCM, Montpellier, France
| | - Irene Russo Krauss
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, I-80126 Napoli, Italy; CSGI - Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase, Via della Lastruccia 3, I-50019 Sesto Fiorentino (Fi), Italy
| | - Luigi Paduano
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, I-80126 Napoli, Italy; CSGI - Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase, Via della Lastruccia 3, I-50019 Sesto Fiorentino (Fi), Italy
| | - François Morvan
- Institut des Biomolécules Max Mousseron, Université de Montpellier, CNRS, ENSCM, Montpellier, France.
| | - Daniela Montesarchio
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 21, I-80126 Napoli, Italy.
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Yang P, Wang X, Gu Z, Li H, Chen DDY, Yang X. Evaluation of the binding of natural products with thrombin binding aptamer G-quadruplex using electrospray ionization mass spectrometry and spectroscopic methods. Talanta 2019; 200:424-431. [PMID: 31036205 DOI: 10.1016/j.talanta.2019.03.080] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/20/2019] [Accepted: 03/20/2019] [Indexed: 01/02/2023]
Abstract
A 15-mer thrombin-binding aptamer (TBA) was discovered with specificity for thrombin. It forms a unique G-quadruplex (G4), which is postulated to be the molecular basis for its binding specificity. Many analytical methods make use of affinity binding between the thrombin and TBA as they form a very stable complex. We develop a strategy to stabilize TBA/G4's structure by introducing G4-interactive molecules, which may enhance its ability to recognize the target. Herein, a fast screening ESI-MS assay was employed to determine potential binding of natural products molecules with the TBA/G4 complex. The experimental results showed that four investigated natural alkaloids had apparent binding affinities. One of them, jatrorrhizine (L1), has been shown to bind strongly to the TBA/G4 mainly in 1:2 M ratio. Once the working conditions were established, the interaction of the jatrorrhizine with the TBA/G4 was explored using a combination of ESI-MS and spectroscopic techniques. Ligand-induced effects on TBA/G4 structure and its stability were examined by means of circular dichroism (CD). Jatrorrhizine inducing the G4 formation seems also to be the more effective in terms of thermal stabilization under the experimental conditions used. Both results of UV and fluorescence experiments undoubtedly showed a good binding affinity with the binding constant around 105 L mol-1. The stacking interactions of jatrorrhizine with the G-tetrads in TBA/G4 were further confirmed by competition experiment. ESI-MS was carried out to determine the coexistence of 1:1 and 1:2 complexes in TBA/G4-L1 system, and showed a dynamical shift from 1:1 to 1:2 complex in minutes.
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Affiliation(s)
- Pengfei Yang
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China
| | - Xinyi Wang
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China
| | - Zhenggui Gu
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China
| | - Huihui Li
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China.
| | - David D Y Chen
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada V6T 1Z1.
| | - Xiaodi Yang
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, PR China.
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Pal S, Paul S. Conformational deviation of Thrombin binding G-quadruplex aptamer (TBA) in presence of divalent cation Sr 2+: A classical molecular dynamics simulation study. Int J Biol Macromol 2018; 121:350-363. [PMID: 30308284 DOI: 10.1016/j.ijbiomac.2018.09.102] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 08/27/2018] [Accepted: 09/17/2018] [Indexed: 11/28/2022]
Abstract
Thrombin binding TBA-G-quadruplex aptamer (TBA) plays a major role in blood coagulation cascade. The 15-mer TBA sequence tends to form four-stranded TBA-G-quadruplex structure. In this research work, a series of explicit solvent classical MD simulations of the TBA is carried out using different salt (SrCl2) concentrations (0, 50, 100 and 200 mM). Here we have also testified the effect of salt concentration of divalent cation Sr2+ on the conformational change of quadruplex DNA. The structural deviations, fluctuations, torsional angles and the affinity of the ion are explored at different salt concentrations. It is found that the conformation of TBA-G-quadruplex at 0 mM and 50 mM salt concentrations, is very much different than the other salt concentrations (100 mM and 200 mM). Also observed are as follows: (i) no exchange of Sr2+ ion between inside and outside of the channel, (ii) an enhancement in the Sr2+ ion density around the phosphate region of the loop residues as salt concentration increases and (iii) the stacking of T3 and T4 residues of loop-1 that appears up to 50 mM concentration, vanishes as the salt concentration is increased further.
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Affiliation(s)
- Saikat Pal
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam 781039, India.
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Awachat R, Wagh AA, Aher M, Fernandes M, Kumar VA. Favorable 2'-substitution in the loop region of a thrombin-binding DNA aptamer. Bioorg Med Chem Lett 2018; 28:1765-1768. [PMID: 29678465 DOI: 10.1016/j.bmcl.2018.04.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 04/06/2018] [Accepted: 04/11/2018] [Indexed: 11/19/2022]
Abstract
Simple 2'-OMe-chemical modification in the loop region of the 15mer G-rich DNA sequence GGTTGGTGTGGTTGG is reported. The G-quadruplex structure of this thrombin-binding aptamer (TBA), is stabilized by single modifications (T → 2'-OMe-U), depending on the position of the modification. The structural stability also renders significantly increased inhibition of thrombin-induced fibrin polymerization, a process closely associated with blood-clotting.
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Affiliation(s)
- Ragini Awachat
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Homi Bhabha Road, Pashan, Pune 411008, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune 411008, India
| | - Atish A Wagh
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Homi Bhabha Road, Pashan, Pune 411008, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune 411008, India
| | - Manisha Aher
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Homi Bhabha Road, Pashan, Pune 411008, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune 411008, India
| | - Moneesha Fernandes
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Homi Bhabha Road, Pashan, Pune 411008, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune 411008, India.
| | - Vaijayanti A Kumar
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Homi Bhabha Road, Pashan, Pune 411008, India; Academy of Scientific and Innovative Research (AcSIR), CSIR-NCL Campus, Pune 411008, India.
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Yang X, Zhu Y, Wang C, Guan Z, Zhang L, Yang Z. Alkylation of phosphorothioated thrombin binding aptamers improves the selectivity of inhibition of tumor cell proliferation upon anticoagulation. Biochim Biophys Acta Gen Subj 2017; 1861:1864-9. [PMID: 28389332 DOI: 10.1016/j.bbagen.2017.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/14/2017] [Accepted: 04/02/2017] [Indexed: 12/23/2022]
Abstract
BACKGROUND Recently, aptamers have been extensively researched for therapy and diagnostic applications. Thrombin-binding aptamer is a 15nt deoxyribonucleic acid screened by SELEX, it can specifically bind to thrombin and inhibit blood coagulation. Since it is also endowed with excellent antitumor activity, the intrinsic anticoagulation advantage converted to a main potential side effect for its further application in antiproliferative therapy. METHODS Site-specific alkylation was conducted through nucleophilic reaction of phosphorothioated TBAs using bromide reagents. Circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR) measurements were used to evaluate anticoagulation activity, and a CCK-8 assay was used to determine cell proliferation activity. RESULTS The CD spectra of the modified TBAs were weakened, and their affinity for thrombin was dramatically reduced, as reflected by the KD values. On the other hand, their inhibition of A549 cells was retained. CONCLUSIONS Incorporation of different alkyls apparently disrupted the binding of TBA to thrombin while maintaining the antitumor activity. GENERAL SIGNIFICANCE A new modification strategy was established for the use of TBA as a more selective antitumor agent.
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Aviñó A, Mazzini S, Fàbrega C, Peñalver P, Gargallo R, Morales JC, Eritja R. The effect of l-thymidine, acyclic thymine and 8-bromoguanine on the stability of model G-quadruplex structures. Biochim Biophys Acta Gen Subj 2017; 1861:1205-12. [PMID: 27705754 DOI: 10.1016/j.bbagen.2016.09.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 12/13/2022]
Abstract
BACKGROUND Guanine-rich oligonucleotides are capable of forming tetrahelical structures known as G-quadruplexes with interesting biological properties. We have investigated the effects of site-specific substitution in the loops and in the tetrads model G-quadruplexes using thymine glycol nucleic acid (GNA) units, l-thymidine and 8-Br-2'-deoxyguanosine. METHODS Modified oligonucleotides were chemically synthesized and spectroscopic techniques were used to determine the relative stability of the modified G-quadruplex. The double 8-BrdG-modified quadruplexes were further characterized by Nuclear Magnetic Resonance. Binding to thrombin of selected quadruplex was analyzed by gel electrophoresis retention assay. RESULTS The most interesting results were found with a 8-bromoG substitution that had the larger stabilization of the quadruplex. NMR studies indicate a tight relationship between the loops and the tetrads to accommodate 8-bromoG modifications within the TBA. CONCLUSIONS The substitutions of loop positions with GNA T affect the TBA stability except for single modification in T7 position. Single l-thymidine substitutions produced destabilization of TBA. Larger changes on quadruplex stability are observed with the use of 8-bromoG finding a single substitution with the highest thermal stabilization found in thrombin binding aptamers modified at the guanine residues and having good affinity for thrombin. Double 8-BrdG modification in anti positions of different tetrads produce a conformational flip from syn to anti conformation of 8-Br-dG to favor loop-tetrad interaction and preserve the overall TBA stability. GENERAL SIGNIFICANCE Modified guanine-rich oligonucleotides are valuable tools for the search for G-quadruplex structures with higher thermal stability and may provide compounds with interesting protein-nucleic acid binding properties. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
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Deng L, Du Y, Xu JJ, Chen HY. An off-on-off electrochemiluminescence approach for ultrasensitive detection of thrombin. Biosens Bioelectron 2014; 59:58-63. [PMID: 24699694 DOI: 10.1016/j.bios.2014.03.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 02/18/2014] [Accepted: 03/06/2014] [Indexed: 02/08/2023]
Abstract
This work demonstrates an aptasensor for ultrasensitive electrochemiluminescence (ECL) detection of thrombin based on an "off-on-off" approach. The system is composed of an Eu(3+)-doped CdS nanocrystals (CdS:Eu NCs) film on glassy carbon electrode (GCE) as ECL emitter. Then gold nanoparticles (AuNPs) labeled hairpin-DNA probe (ssDNA1) containing thrombin-binding aptamer (TBA) sequence was linked on the NCs film, which led to ECL quenching (off) as a result of Förster-resonance energy transfer (FRET) between the CdS:Eu NC film and the proximal AuNPs. Upon the occurrence of hybridization with its complementary DNA (ssDNA2), an ECL enhancement (on) occurred owing to the interactions of the excited CdS:Eu NCs with ECL-induced surface plasmon resonance (SPR) in AuNPs at large separation. Thrombin could induce ssDNA1 forming a G-quadruplex and cause the AuNPs to be close to CdS:Eu NCs film again, which resulted in an enhanced ECL quenching (off). This "off-on-off" system showed a maximum 7.4-fold change of ECL intensity due to the configuration transformation of ssDNA1 and provides great sensitivity for detection of thrombin in a wide detection range from 50 aM to 1 pM.
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Affiliation(s)
- Li Deng
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Ying Du
- Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080, China
| | - Jing-Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
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Zhang D, Yin L, Meng Z, Yu A, Guo L, Wang H. A sensitive fluorescence anisotropy method for detection of lead (II) ion by a G-quadruplex-inducible DNA aptamer. Anal Chim Acta 2014; 812:161-7. [PMID: 24491777 DOI: 10.1016/j.aca.2013.12.029] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 12/10/2013] [Accepted: 12/24/2013] [Indexed: 12/27/2022]
Abstract
Sensitive and selective detection of Pb(2+) is of great importance to both human health and environmental protection. Here we propose a novel fluorescence anisotropy (FA) approach for sensing Pb(2+) in homogeneous solution by a G-rich thrombin binding aptamer (TBA). The TBA labeled with 6-carboxytetramethylrhodamine (TMR) at the seventh thymine nucleotide was used as a fluorescent probe for signaling Pb(2+). It was found that the aptamer probe had a high FA in the absence of Pb(2+). This is because the rotation of TMR is restricted by intramolecular interaction with the adjacent guanine bases, which results in photoinduced electron transfer (PET). When the aptamer probe binds to Pb(2+) to form G-quadruplex, the intramolecular interaction should be eliminated, resulting in faster rotation of the fluorophore TMR in solution. Therefore, FA of aptamer probe is expected to decrease significantly upon binding to Pb(2+). Indeed, we observed a decrease in FA of aptamer probe upon Pb(2+) binding. Circular dichroism, fluorescence spectra, and fluorescence lifetime measurement were used to verify the reliability and reasonability of the sensing mechanism. By monitoring the FA change of the aptamer probe, we were able to real-time detect binding between the TBA probe and Pb(2+). Moreover, the aptamer probe was exploited as a recognition element for quantification of Pb(2+) in homogeneous solution. The change in FA showed a linear response to Pb(2+) from 10 nM to 2.0 μM, with 1.0 nM limit of detection. In addition, this sensing system exhibited good selectivity for Pb(2+) over other metal ions. The method is simple, quick and inherits the advantages of aptamer and FA.
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Affiliation(s)
- Dapeng Zhang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China
| | - Lei Yin
- School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081, PR China
| | - Zihui Meng
- School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing, 100081, PR China
| | - Anchi Yu
- Department of Chemistry, Renmin University of China, Beijing, 100872, PR China
| | - Lianghong Guo
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China
| | - Hailin Wang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China.
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De Rache A, Doneux T, Kejnovská I, Buess-Herman C. On the interaction between [Ru(NH3)6]3+ and the G-quadruplex forming thrombin binding aptamer sequence. J Inorg Biochem 2013; 126:84-90. [PMID: 23787142 DOI: 10.1016/j.jinorgbio.2013.05.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 05/23/2013] [Accepted: 05/24/2013] [Indexed: 11/25/2022]
Abstract
The interaction between the thrombin binding aptamer (TBA), a G-quadruplex forming DNA sequence, and the electroactive hexaammineruthenium(III) cation has been studied by electrochemical methods and circular dichroism spectroscopy. When TBA is immobilised on a gold surface in a typical aptasensor configuration, the [Ru(NH3)6](3+) cation can be bound to the electrode surface through its interaction with the TBA sequence. This interaction is strong enough to enable the ruthenium complex to remain at the surface when the electrode is immersed in an electrolyte free of [Ru(NH3)6](3+), meaning that the complex does not diffuse back into the solution. A stoichiometry of 2 [Ru(NH3)6](3+) per TBA strand has been determined, indicating that the interaction differs from the conventional, non-specific electrostatic charge compensation, for which a 5 to 1 ratio would be expected between the triply charged cation and the 15 bases sequence. It is shown that this interaction takes place not only at the surface, but also when both TBA and hexaammineruthenium(III) are dissolved in solution. Under such conditions, a similar stoichiometry of 2 [Ru(NH3)6](3+) per TBA strand has been evidenced by two independent methods, namely circular dichroism spectroscopy and differential pulse voltammetry.
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Affiliation(s)
- Aurore De Rache
- Chimie Analytique et Chimie des Interfaces, Faculté des Sciences, Université Libre de Bruxelles, CP 255, Boulevard du Triomphe 2, B-1050 Bruxelles, Belgium
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