As an important glycoprotein of the lectin family, soybean agglutinin (SBA) is an anti-nutritional factor with considerable toxic and side effects and plays a significant role in tumor analysis. In ...order to achieve the sensitive detection of SBA, a sandwich-structured electrochemiluminescence (ECL) biosensor was constructed using carboxylated carbon nitride (C-g-C
3
N
4
) as luminophore and D-galactosamine (galM) as a recognition element. A glassy carbon electrode (GCE) was modified with Au nanoparticles (Au NPs) for capturing the galM via Au-N bond, and further capturing the target SBA by specific recognition between galM and SBA. In the presence of SBA, the composite C-g-C
3
N
4
-galM was immobilized onto the electrode. With the increase in the concentration of SBA, the ECL signal from C-g-C
3
N
4
increased, thus achieving a signal-on detection of SBA. The linear range of the biosensor was 1.0 ng/mL~10 μg/mL and detection limit for SBA was as low as 0.33 ng/mL. In this construction strategy, C-g-C
3
N
4
not only acted as an excellent signal probe, but also as an immobilization matrix to easily achieve a high loading of the small molecule recognition element galM. This strategy provides a simple alternative SBA detection platform.
Graphical abstract
A novel biosensor has been constructed by the electrodeposition of Au-nanoclusters (nano-Au) on poly(3-amino-5-mercapto-1,2,4-triazole) (
p-TA) film modified glassy carbon electrode (GCE) and ...employed for the simultaneous determination of dopamine (DA), ascorbic acid (AA), uric acid (UA) and nitrite (NO
2
−). NH
2 and SH groups exposed to the
p-TA layer are helpful for the electrodeposition of nano-Au. The combination of nano-Au and
p-TA endow the biosensor with large surface area, good biological compatibility, electricity and stability, high selectivity and sensitivity and flexible and controllable electrodeposition process. In the fourfold co-existence system, the linear calibration plots for AA, DA, UA and NO
2
− were obtained over the range of 2.1–50.1
μM, 0.6–340.0
μM, 1.6–110.0
μM and 15.9–277.0
μM with detection limits of 1.1
×
10
−6
M, 5.0
×
10
−8
M, 8.0
×
10
−8
M and 8.9
×
10
−7
M, respectively. In addition, the modified biosensor was applied to the determination of AA, DA, UA and NO
2
− in urine and serum samples by using standard adding method with satisfactory results.
One-dimensional Pd–Au nanowires (Pd–Au NWs) were prepared and applied to fabricate an electrochemiluminescence (ECL) biosensor for the detection of acetylcholinesterase (AChE) activity. Compared with ...single-component of Pd or Au, the bimetallic nanocomposite of Pd–Au NWs offers a larger surface area for the immobilization of enzyme, and displays superior electrocatalytic activity and efficient electron transport capacity. In the presence of AChE and choline oxidase (ChOx), acetylcholine (ATCl) is hydrolyzed by AChE to generate thiocholine, then thiocholine is catalyzed by ChOx to produce H2O2in situ, which serves as the coreactant to effectively enhance the ECL intensity in luminol-ECL system. The detection principle is based on the inhibited AChE and reactivated AChE as dual biomarkers, in which AChE was inhibited by organophosphorus (OP) agents, and then reactivated by obidoxime. Such dual biomarkers method can achieve credible evaluation for AChE activity via providing AChE activity before and after reactivation. The liner range for AChE activity detection was from 0.025UL−1 to 25KUL−1 with a low detection limit down to 0.0083UL−1.
•One-dimensional Pd–Au NWs were synthesized.•An ECL biosensor was fabricated for AChE detection based on dual biomarkers for the first time.•The method of dual biomarkers can achieve credible and accurate evaluation for AChE activity.•Pd–Au NWs and AChE–ChOx remarkably amplify the ECL response.
Novel luminescence‐functionalized metal–organic frameworks (MOFs) with superior electrogenerated chemiluminescence (ECL) properties were synthesized based on zinc ions as the central ions and ...tris(4,4′‐dicarboxylicacid‐2,2′‐bipyridyl)ruthenium(II) dichloride (Ru(dcbpy)32+) as the ligands. For potential applications, the synthesized MOFs were used to fabricate a “signal‐on” ECL immunosensor for the detection of N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP). As expected, enhanced ECL signals were obtained through a simple fabrication strategy because luminescence‐functionalized MOFs not only effectively increased the loading of Ru(dcbpy)32+, but also served as a loading platform in the ECL immunosensor. Furthermore, the proposed ECL immunosensor had a wide linear range from 5 pg mL−1 to 25 ng mL−1 and a relatively low detection limit of 1.67 pg mL−1 (signal/noise=3). The results indicated that luminescence‐functionalized MOFs provided a novel amplification strategy in the construction of ECL immunosensors and might have great prospects for application in bioanalysis.
Trap the light fantastic: Luminescence‐functionalized metal–organic frameworks (MOFs) were synthesized by using Zn2+ as the central ion and a Ru complex as the ligand. This provided a method to use a metallic complex instead of a small organic molecule as a ligand to prepare MOFs. Moreover, MOFs were applied to the construction of a sensitive electrogenerated chemiluminescence biosensor (see figure).
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•PDDA–G–MoS2 nanoflowers were firstly used for the fabrication of thrombin aptasensor.•MoS2 was adopted to enhance the surface area of graphene and accelerate the electron ...transfer.•GOD, PdNPs and hemin/G-quadruplex could amplify the electrochemical signal through synergetic catalysis.•The proposed aptasensor displayed an improved sensitivity.
In the present study, with the aggregated advantages of graphene and molybdenum disulfide (MoS2), we prepared poly(diallyldimethylammonium chloride)–graphene/molybdenum disulfide (PDDA–G–MoS2) nanocomposites with flower-like structure, large surface area and excellent conductivity. Furthermore, an advanced sandwich-type electrochemical assay for sensitive detection of thrombin (TB) was fabricated using palladium nanoparticles decorated PDDA–G–MoS2 (PdNPs/PDDA–G–MoS2) as nanocarriers, which were functionalized by hemin/G-quadruplex, glucose oxidase (GOD), and toluidine blue (Tb) as redox probes. The signal amplification strategy was achieved as follows: Firstly, the immobilized GOD could effectively catalyze the oxidation of glucose to gluconolactone, coupling with the reduction of the dissolved oxygen to H2O2. Then, both PdNPs and hemin/G-quadruplex acting as hydrogen peroxide (HRP)-mimicking enzyme could further catalyze the reduction of H2O2, resulting in significant electrochemical signal amplification. So the proposed aptasensor showed high sensitivity with a wide dynamic linear range of 0.0001 to 40nM and a relatively low detection limit of 0.062pM for TB determination. The strategy showed huge potential of application in protein detection and disease diagnosis.
Abstract Herein, a label-free electrochemiluminescence (ECL) aptasensor for highly sensitive determination of kanamycin was developed based on a novel “on-off-on” switch system. The first “switch on” ...state with remarkably high ECL intensity was obtained by the tri-layer composite films modified glassy carbon electrode towards the S2 O82− -O2 system. To be specific, the first layer was the Au nanoparticles decorated C60 nanoparticles (abbreviation as Au@nano-C60 ) as inner-layer which was prepared by the in situ generating of Au nanoparticles onto the surface of bovine serum albumin decorated nano-C60 nanoparticles. Then poly- l -histidine was first selected as a novel coreactant of S2 O82− -O2 system and it was adsorbed on the Au@nano-C60 modified electrode as inter-layer. Finally, a self-assembling layer of colloidal Au nanoparticles (AuNPs) was the outer-layer. The three layers were interaction by the Au–N covalent bond which could achieve a desirable initial amplified ECL signal. Successively, the capture probes (CPs) of the aptamer for the target of kanamycin was anchored on the resultant tri-layer composite films modified electrode. Later, the “switch off” state was made by the quenching effect of hemin/G-quadruplex DNAzymes towards S2 O82− -O2 system according to the DNA hybridization reaction of an assistant probes (APs, guanine-rich nucleic acid) with CPs which could generate a large amount of hemin/G-quadruplex DNAzymes in the presence of hemin with a simple and label-free process. As expected, the second “switch on” state was the ECL signal recovery when the target of kanamycin was present, it is attributed to that the formation of the aptamer–kanamycin complex makes the quencher of hemin/G-quadruplex DNAzymes release from the sensing interface. With the association of “on-off-on” switch system, a linear response about 9 orders of magnitude for kanamycin detection was obtained from 0.15 nM to 170 m m as well as a detection limit down to 45 pM.
A kind of biocatalyst, laccase, has been employed as a biocompatible coreactant accelerator to efficiently catalyze coreactant (dissolved O
2
) for generating high local concentration of superoxide ...radical (O
2
•−
), acquiring high-intense electrochemiluminescence (ECL) emission of ABEI (N-(aminobutyl)-N-(ethylisoluminol))/dissolved O
2
system. Furthermore, a modified strand displacement reaction with excellent amplification efficiency was constructed by replacing traditional single strand DNA to the hairpin DNA as template for triggering the immobilization of more signal probes. As a result, the biosensor for microRNA-21 determination has preeminent selectivity and favorable sensitivity with detection limit down to 80.8 aM. Significantly, the devised strategy has blazed a new path for seeking more coreaction accelerators with splendid biocompatibility thus promoting the application of ternary ECL systems in biological analysis and clinical diagnosis.
Graphical abstract
A ferrocene-switched electrochemiluminescence "off-on" sensor is proposed on the basis of target transduction and a DNA walking machine for the sensitive detection of cardiac troponin I (cTnI). The ...proposed method offers high selectivity with a low detection limit of 0.016 pg mL(-1), and provides a universal platform for detecting a wide range of targets, including other proteins and DNAs, by changing the molecular recognition elements to the corresponding antibodies, aptamers or DNA probes.
For the first time, a glucose oxidase-functionalized bioconjugate was prepared and served as a new trace label through its direct electrochemistry and electrocatalysis in a sandwich-type ...electrochemical aptasensor for ultrasensitive detection of thrombin.
In this paper, a novel covalently crosslinked perylene derivative (PTC-PEI) composed of polyethylenimine (PEI) and perylenetetracarboxylic acid (PTCA) has been first investigated for cathodic ...electrochemiluminescence (ECL) in an aqueous system with dissolved O2 as coreactant. The promising novel ECL materials of PTC-PEI exhibited admirable physical and chemical stability and high ECL intensity, which held an alternative way to construct ECL sensor with improved sensitivity. Thus, it was applied to construct a dual amplified “signal-on” mercury ion (Hg2+) sensor by the employment of nicking endonuclease (NEase)-assisted target recycling and rolling circle amplification (RCA) for signal amplification. Herein, a long G-rich sequence was generated by RCA process to capture abundant hemin on the electrode surface, and then a significantly amplified ECL signal of PTC-PEI was obtained. Based on dual signal amplification strategy, the devised sensor showed a linear range from 0.1pM to 0.1μΜ with a detection limit down to 33fM (S/N=3), and was successfully used in the direct detection of real water sample with high sensitivity and selectivity.
•A ECL system of perylene derivative utilized dissolved O2 as endogenous coreactant.•The catalysis of hemin towards dissolved O2 could enhance ECL signal effectively.•The Hg2+ sensor combined target recycling and RCA for signal amplification.
