| Electrochemiluminescenceaptasensor is a novel device with aptamer as recognize elment and chemiluminescence reaction reagent direct or indirect assembling on the sensor interface via immobilizing methods. The quantitative detection of targets is accomplished according to the change of luminous intensity. It combines the ECL technology with high specificity and affinity of aptamer,, possessing many sperior advantages such as high sensitivity, high selectivity, low background signals and so on. The article intends to solve the shortcomings of the ECL signal probe-bipyridine ruthenium, such as water-solubility, difficult immobilization with no functional groups and so on. And develop simple, reliable, fast, high-sensitivity signal-on or signal-off ECL aptasensor for the detection of thrombin with nanomaterials as the carriers for increasing the immobilization amount of bipyridine ruthenium through the immobilized methods of adsorption, crosslink et al. The detail contents are as follows:1An amplification electrochemiluminescence aptasensor based on gold nanoparticles and cysteine for thrombin detectionAs a hot research in electrochemical and electrical analysis, molecular self-assembled monolayers possess biofilm-like characteristic and high stability. In this work, the electropolymerized L-Cys was self-assembled on the gold electrode surface in order to promote electron transfer and catalytic ECL luminous efficiency. Then, a layer of nano-Au was electrodeposited for immobilizing of thiol-thrombin binding aptamer (TBA).In this case, amino-bipyridine ruthenium (Ru-NH2) labled complementary strand was modified on the electrode surface via complementary pairing of the bases. With the amplification of L-Cys and nano-Au, the aptasensor showed strong ECL signal. However, when the quantitative analysis was carried out, the TBA on electrode surface captured thrombin and followed with the leave of Ru-NH2labled complementary strand from the electrode surface, which led to an increase in steric hindrance of electrode surface and a decrease in chemiluminescence reaction reagent bipyridine ruthenium, finally led to a reduced ECL signal. As a result, the proposed aptasensor showed a high sensitivity with the detection range from1×10-12～1.5×10-8mol/L. The detection limit was0.3pmol/L(S/N=3).24-(Dimethylamino)butyric acid@PtNPs as enhancer for solid-state electrochemiluminesc-ence aptasensor based on target-induced strand displacementA solid-state electrochemiluminescence (ECL) aptasensor based on target-induced aptamer displacemnt for highly sensitive detection of thrombin was successfully developed using4-(dimethyIamino)butyric acid (DMBA)@PtNPs labeling as enhancer. Such a special aptasensor included three main parts:ECL substrate, ECL intensity amplification and target-induced aptamer displacement. The ECL substrate was made by modifying the complex of Pt nanoparticles (PtNPs) and tris(2,2-bipyridyl) ruthenium (II)(Ru(bpy)32+)(Ru-PtNPs) onto nafion@multi-walled carbon nanotubes (nafion@MWCNTs) modified electrode surface through electrostatic adherence. Then, the double-stranded, which fromed by thrombin aptamer and DMBA@PtNPs tabled complementary thrombin aptamer (Aptamer Ⅱ), was assembled on the electrode surface with the aim of amplifing ECL signal. The introduction of target thrombin triggered the displacement of Aptamer II from the self-assembled duplex into the solution and the association of inert protein thrombin on the electrode surface, decreasing the amount of DMBA@PtNPs and increasing the electron transfer resistance of the aptasensor and thus resulting large decrease in ECL signal. With the synergistic amplification of DMBA and PtNPs to Ru(bpy)32+ECL, the aptasensor showed an enlarged ECL intensity change before and after the detection of thrombin. As a result, the change of ECL intensity has a direct relationship with the logarithm of thrombin concentration in the range of0.001-30nmol/L. The detection limit of the proposed aptasensor is0.4pmol/L, providing very broad application prospects for the field of protein detection in clinical as well as bioanalysis.3An electrochemiluminescence aptamsensor based on the quenching of ferrocene-labeled molecular beacon for thrombin detectionP-cyclodextrin (P-CD) has a tapered hollow cylindrical three-dimensional cyclic structure. Its outer body and cavity has the nature of hydrophilic and hydrophobic respectively, which makes the β-CD can be used as the host molecular to accommodate the corresponding guest molucular and change its physical and chemical properties. Take advantage of these features, we constructed an electroluminescent chemiluminescence aptasensor based on the quenching of ferrocene-labeled molecular beacon for quantitative detection of thrombin. In this work, Nafion dispersed multi-walled carbon nanotubes (CNTs/Nafion) first served as the solid carrier matrix on the electrode surface, and then the P-CD and Ru(bpy)32+complexes assembled on carrier matrix via electrostatic adsorption. Here, ferrocene (Fc) labled thrombin aptamer molecular beacon was served as the target molecule recognition probe. When the quantitative analysis was carried out, the molecular beacon recognized the target thrombin and made the open of molecular beacon, which could following led to the combination of Fc with P-CD, effectively quenched the ECL luminescence of Ru(bpy)32+. The quantitative analysis of thrombin could be accomplished according to the decrease of ECL luminous intensity. As a result, the proposed aptasensor showed a high sensitivity with the detection range from0.1×10-12～2.0×10-8mol/L. The detection limit was0.03pmol/L (S/N=3).4An ultrasensitive electrochemiluminescence aptasensor with in situ generated praline as co-reactant for amplifying the ECL of tris (2,2’-bipyridyl) rutheniumThe in situ generated co-reactant can effectively enhance the ECL intensity and thus improve the sensitivity of aptasensor. In this work, dendrimers PAMAM with substantial tertiary amino groups were used as carriers for loading Ru-PtNPs with the aim of increasing the loading amount of Ru. Then, biotin-labeled proline peptides enzyme (GDPA) were modified on the surface of Ru-PtNPs. With the bridging effect of biotin and avidin, avidin labeled thrombin aptamer was then immobilized and finally formed the second aptamer. Through sandwich reaction, we succefully fabricated an ultrasensitive thrombin electrochemiluminescence aptasenor with in situ generated praline as co-reactant of for amplifying the ECL of tris(2,2’-bipyridyl) ruthenium. Since proline is a secondary amines, it can catalytic the ECL of Ru(bpy)32+and its derivatives. When the substrate glycine-D-proline (GDP) added in electrolytic cell, the GDPA catalyticed the GDP to in situ generate praline on the electrode surface, effectively improving the intensity of the ECL. As a result, the proposed aptasensor showed a high sensitivity with the detection range from1.0×10-14～1.0×10-8mol/L. The detection limit was3.3fmol/L.53,4,9,10-Perylenetetracarboxylic dianhydride functionalized graphene sheet as labels for ultrasensitive electrochemiluminescent detection of thrombinA novel tracer,3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) functionalized graphene sheet (GS) composite (GS-TCDA), was employed to label the thrombin aptamer (TBA) to form secondary aptamer (APT II) for constructing an ultrasensitive thrombin electrochemiluminescent sandwich-type aptasensor. The GS provided large surface area for loading abundant PTCDA and TBA with good stability and biocomparibility. In addition, the GS has superior conductivity, which could effectively catalytical the ECL luminescence of peroxodisulfates (SzO82-) in the presence of PTCDA. On the basis of the considerably amplified ECL signal and sandwich format, an extremely wide range from1fmol/L to1nmol/L and an ultralow detection limit of0.33fmol/L for thrombin were obtained. Additionally, the selectivity and stability of the proposed aptasensor were also excellent, which provided great promise for detection of thrombin at ultra-trace levels during early stage of diseases. |
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