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RNA or DNA aptamers have received much attention in recent literature as therapeutic agents and chromatographic matrices, however, their use in analytical methodologies is relatively unexplored. We describe here investigations aiming to combine this promising technology with versatile liposomes in a competitive assay format. Thus, a phospholipid derivative of an unsymmetrical 1,3-disubstituted xanthine...
A sensitive method for rapid angiogenin (Ang) detection based on fluorescence resonance energy transfer (FRET) has been described. A dual-labeled probe based on high affinity aptamer for Ang was constructed. As donor and acceptor, 6-carboxyfluorescein (FAM) and 6-carboxy-tetramethylrhodamine (TMR) were labeled at 5′- and 3′-termini of the aptamer probe, respectively. The dual-labeled probe showed...
This work reports the advantages of a label free electrochemical aptasensor for the detection of lysozyme. The biorecognition platform was obtained by the adsorption of the aptamer on the surface of a carbon paste electrode (CPE) previously blocked with mouse immunoglobulin under controlled-potential conditions. The recognition event was detected from the decrease in the guanine and adenine electro-oxidation...
A label-free and highly sensitive impedimetric aptasensor based on a polyamidoamine dendrimer modified gold electrode was developed for the determination of thrombin. Amino-terminated polyamidoamine dendrimer was firstly covalently attached to the cysteine functionalized gold electrode through glutaraldehyde coupling. Subsequently, the dendrimer was activated with glutaraldehyde, and amino-modified...
Features of Au NPs-aptamer conjugates as a powerful competitive reagent to substitute antibody in enhancing surface plasmon resonance spectroscopy (SPR) signal for the detection of small molecule are explored for the first time. In order to evaluate the sensing ability of Au NPs-aptamer conjugates as a competitive reagent, a novel SPR sensor based on indirect competitive inhibition assay (ICIA) for...
We have developed a novel sensitive chemiluminescence (CL) aptasensor for the target assay as exemplified by using adenosine as a model target. In this work, we have demonstrated the signaling mechanism to make detection based on magnetic separation and 3,4,5-trimethoxyl-phenylglyoxal (TMPG), a special CL reagent as the signaling molecule, which reacts instantaneously with guanine nucleobases (G)...
In this protocol, a fluorescent aptasensor based on magnetic separation for simultaneous detection thrombin and lysozyme was proposed. Firstly, one of the anti-thrombin aptamer and the anti-lysozyme aptamer were individually immobilized onto magnetic nanoparticles, acting as the protein captor. The other anti-thrombin aptamer was labeled with rhodamine B and the anti-lysozyme aptamer was labeled with...
An aptamer-participated haprin structure was designed by employing cellular prion protein (PrP C ) as a model protein, and thus an aptamer-mediated turn-on fluorescence assay for proteins was developed in this contribution. The designed aptamer-participated haprin structure consists of three segments. Namely, an aptamer sequence located in the loop, three guanine bases at 3′-terminal, and...
A novel low-cost platform to assess biomolecular interactions was investigated using surface plasmon resonance and an aptamer-based assay for thrombin detection. Gold SPR surface functionalized with a carboxylated cross-linked BSA film (cBSA) and commercially available carboxymethylated dextran chip (CM5) were used as immobilization platforms for the thrombin binding aptamer. The high end commercial...
An aptamer-based assay for thrombin with high specificity and sensitivity was presented. In the protocol, the aptamer for thrombin was immobilized on magnetic nanoparticle, and its complementary oligonucleotide was labeled with gold nanoparticles, then the aptamer was hybridized with the complementary oligonucleotide to form the duplex structure as a probe, this probe could be used for the specific...
In this paper, we combine the advantages of aptamer, nanomaterial and antibody to design an electrochemical sandwich immunoassay for the ultrasensitive detection of human immunoglobulin E (IgE) by using methylene blue (MB) as electrochemical indicator. The sandwich structure is fabricated by using goat anti-human IgE as capturing probe. Aptamer-Au nanoparticles (NPs) conjugates are used both as a...
In this study, we have developed a simple, cost-effective, label-free fluorescence analytical assay – comprising an adenosine-binding aptamer (Apt Ado ), platelet-derived growth factor (PDGF)-binding aptamer (Apt PDGF ), gold nanoparticles (Au NPs), and the DNA-binding dye Oligreen (OG) – for the determination of adenosine. Apt Ado and Apt PDGF are for the recognition...
Fluorophore-labeled bioprobes are the key for fluorescent-labeled imaging technology. In the present work, mouse liver hepatoma cell line BNL 1ME A.7R.1 (MEAR)-specific ssDNA aptamer TLS9a was used to fabricate quantum dot-labeled aptamer bioprobe (QD-Apt), which was obtained by conjugating streptavidin-modified quantum dots (SA-QDs) with biotin-derived aptamer via the interaction between biotin and...
A novel electrochemical aptasensor for the detection of thrombin was developed on basis of the thrombin-binding aptamer (TBA) as a molecular recognition element and multi-walled carbon nanotubes (MWCNTs) as a carrier of the electrochemical capture probe. Amine-modified capture probe (12-mer) was covalently conjugated to the MWCNTs modified glassy carbon electrode (GCE). The target aptamer probe (21-mer)...
The 5nm nanosilver was prepared by the sodium borohydride procedure, using sodium citrate as a stabilizing reagent. The nanosilver particle was combined with the aptamer for K + to form aptamer–nanosilver complex that was stabile in pH 7.0 Na 2 HPO 4 –NaH 2 PO 4 buffer solutions and in the presence of high concentration of NaCl. In 85°C water bath, K + ...
In the present study, the authors report a novel sensitive method for the detection of thrombin using time-resolved fluorescence sensing platform based on two different thrombin aptamers. The thrombin 15-mer aptamer as a capture probe was covalently attached to the surface of glass slide, and the thrombin 29-mer aptamer was fluorescently labeled as a detection probe. A bifunctional europium complex...
A simple, highly sensitive, and label-free electrochemical impedance spectroscopy (EIS) aptasensor based on an anti-lysozyme-aptamer as a molecular recognition element, was developed for the detection of lysozyme. Improvement in sensitivity was achieved by utilizing gold nanoparticles (AuNPs), which were electrodeposited onto the surface of a gold electrode, as a platform for immobilization of the...
We have developed a fluorescence technique for the detection of Hg 2+ and Pb 2+ ions using polythymine (T 33 )/benzothiazolium-4-quinolinium dimer derivative (TOTO-3) and polyguanine (G 33 )/terbium ions (Tb 3+ ) conjugates, respectively. Hg 2+ ions induce T 33 to form folded structures, leading to increased fluorescence of the T 33 /TOTO-3...
A new kind of selective sorbent based on the use of aptamers and dedicated to the selective solid phase extraction was developed. Cocaine aptamer was chosen as model aptamer to demonstrate the feasibility of this material and to provide a complete evaluation of the synthesized sorbent. The effect of different parameters such as the nature of the immobilisation support (silica, agarose), the type of...
A novel competitive electrochemical cytosensor was reported by using aptamer (Apt)-quantum dots (Qdots) conjugates as a platform for tumor cell recognition and detection. The complementary DNA (cDNA), aptamer and Qdots could be assembled to the gold electrode surface. When the target cells existed, they could compete with cDNA to bind with Apt-Qdots conjugates based on the specific recognition of...
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