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This work describes a novel electrochemiluminescence aptasensor for highly sensitive detection of platelet-derived growth factor BB (PDGF-BB) using aptamer functionalized CdS quantum dots–polyamidoamine as probe (CdS QDs–PAMAM–Apt). CdS QDs–PAMAM nanocomposites were synthesized by one-pot synthesis in methanol. The prepared nanocomposites were linked with the NH 2 –aptamer 2 (Apt2) of PDGF-BB to form the CdS QDs–PAMAM–Apt2 probe by glutaraldehyde as coupling reagent. For constructing the aptasensor, MWCNTs–chitosan composites and NH 2 –aptamer 1 (Apt1) with the same base sequence as Apt2 were immobilized on the electrode by the self-assembled method to recognize the target protein PDGF-BB. In the presence of PDGF-BB, the structure of sandwiched format was formed between the Apt1 and the CdS QDs–PAMAM–Apt2 probe, thereby resulting in a proportional increase of ECL emission. Thanks to the efficient and stable ECL emission of CdS QDs–PAMAM dendrimer and the advantage of MWCNTs for accelerating the electron transfer, the highly sensitive detection of PDGF-BB with a detection limit of 0.13 pM was achieved. The linear range is from 0.5 pM to 1 nM. The present protocol was applied to the analysis of PDGF-BB in human serum samples. The recoveries of PDGF-BB in human serum samples are 87.2–113% and RSD values are less than 3.6%. [ABSTRACT FROM AUTHOR]

In this paper, a sandwich-type electrochemiluminescent (ECL) immunosensor for detection of microcystin-leucine-arginine (MCLR) based on gold nanoparticles (GNPs) and CdS quantum dots (QDs) was constructed. Transmission electron microscope image (TEM), photoluminescence spectra, ultraviolet-visible absorption spectra were used to characterize the CdS QDs. The fabrication processes of the immunosensor were characterized via electrochemical impedance spectra (EIS). A strong and stable ECL signal was emitted through the electron-transfer reaction between the electron-injected CdS QDs and reduced products of S 2 O 8 2− in phosphate buffered solution (PBS, pH 7.4) containing of 0.1 M K 2 S 2 O 8 and 0.1 M KCl. Under the optimum conditions, the ECL immunosensor possesses a wide linear response to MCLR that ranges from 0.01 to 50 μg/L, with a low detection limit of 0.0028 μg/L. Moreover, selectivity, stability, and reproducibility of the proposed immunosensor were acceptable. [ABSTRACT FROM AUTHOR]

A sandwich-type luminol electrochemiluminescence (ECL) aptasensor for highly sensitive and selective detection of platelet-derived growth factor BB (PDGF-BB) is fabricated. For this proposed ECL aptasensor, a multilayered AuNPs-electrochemically reduced graphene (AuNPs-EG) nanocomposite film was formed on the GCE surface as the base of the aptasensor through a co-electrodeposition method. The AuNPs-EG composites possess high conductivity to promote the electron transfer at the electrode interface and good biocompatibility and large surface area to capture large amounts of primary aptamer (Apt1), thus amplifying the detection response. Moreover, glucose oxidase (GOD) functionalized AuNPs labeled secondary aptamer (GOD–Apt2–AuNPs) was designed as the signal probe for the sandwiched aptasensor. Enhanced sensitivity was obtained by in situ generation of H 2 O 2 from reaction between GOD and glucose and the excellent catalytic behavior of AuNPs to the ECL of the luminol–H 2 O 2 system. Under the optimal conditions, the as-prepared ECL aptasensor exhibited excellent analytical property for the detection of PDGF-BB in the range from 1.0×10 –13 to 5.0×10 −10 mol L −1 with a detection limit of 1.7×10 –14 mol L −1 ( S / N =3). The application of the present protocol was demonstrated by analyzing PDGF-BB in human serum and human urine samples with the recoveries from 85.0% to 110%. [ABSTRACT FROM AUTHOR]

A novel label-free electrochemiluminescence (ECL) aptasensor for sensitive and selective detection of thrombin was constructed using Ru(bpy)3 2+ functionalized dopamine-melanin colloidal nanospheres (Dpa-melanin CNSs) and gold nanoparticles (AuNPs) as signal-amplifying tags. Dpa-melanin CNSs were synthesized by a simple chemical route. A large amount of Ru(bpy)3 2+ was coated over the Dpa-melanin CNSs with large surface area using Nafion as a bridge to form the Ru(bpy)3 2+/Nafion/Dpa-melanin CNSs composite which was considered as a sensing platform. AuNPs were introduced to the platform for immobilization of aptamer and further amplification of signal. A label-free ECL aptasensor for thrombin detection was subsequently fabricated by assembling aptamer on AuNPs/Ru(bpy)3 2+/Nafion/Dpa-melanin CNSs modified electrode. Greatly enhanced sensitivity is achieved based on the dual signal amplification strategy. The high sensitive detection of thrombin could be realized and the detection limit of thrombin was down to 2.2×10−13 M with a linear range from 1.0×10−12 to 1.0×10−9 M. The aptasensor was applied to the thrombin analysis of human plasma samples with recoveries of 86.0-97.7%. [ABSTRACT FROM AUTHOR]

The advancement of highly sensitive electrochemiluminescence (ECL) biosensors has garnered escalating interest over time. Owing to the distinctive physicochemical attributes, the signal amplification strategy facilitated by functional nanomaterials has achieved notable milestones. Single-atom catalysts (SACs), featuring atomically dispersed metal active sites, have garnered significant attention. SACs offer unprecedented control over active sites and surface structures at the atomic level. However, to fully harness their potential, ongoing efforts focus on strategies to enhance the catalytic performance of SACs, profoundly influencing both the sensitivity and selectivity of SACs-based sensing platforms. In this study, we focused on the synthesis and application of Fe-Co-PNC dual-atom catalysts (DACs) with the incorporation of phosphorus, aiming to enhance catalytic efficiency, particularly in the context of the oxygen reduction reaction (ORR) correlated cathodic luminol ECL. The synergistic effects arising from the combination of Fe and Co in DACs were explored by ECL emission. Comparative studies with Fe-PNC SACs highlighted the superior catalytic performance of Fe-Co-PNC DACs. The ECL sensing platform exhibited excellent sensitivity, which provided a fast detection of Trolox with a wide linear range (0.1 μM–1.0 mM) and a low detection limit (LOD) of 0.03 μM. The platform demonstrated remarkable reproducibility and long-term stability, showcasing its potential for practical biosensing applications. This study introduced the novel concept of Fe-Co-PNC DACs. The demonstrated synergistic effects and enhanced catalytic efficiency of DACs offer new avenues for the rational design of advanced catalysts. The successful application in the sensitive detection of Trolox emphasizes their potential significance in biosensing. It not only expands our understanding of SACs but also opens doors for the development of efficient and stable catalysts with broader applications. Schematic illustration of dual-atom catalysts boosted luminol cathodic electrochemiluminescence. [Display omitted] • Fe-Co-PNC dual-atom catalysts (DACs) with heteroatom doping were synthesized for the catalysis of cathodic luminol ECL. • The precise control of single-atom catalysts at atomic level provided new opportunities for the ECL amplification. • The synergistic effects of combining Fe and Co in DACs were explored, revealing their superior catalytic performance. • The ECL sensing platform provided a fast detection of Trolox with a low detection limit (LOD) of 0.03 μM. • The platform demonstrated remarkable reproducibility and long-term stability, showcasing its potential for bioanalysis. [ABSTRACT FROM AUTHOR]

A novel electrochemiluminescence (ECL) aptasensor based on CdS–MoS 2 nanocomposites was designed for detection of immunoglobulin E (IgE). The flowerlike CdS–MoS 2 composites were synthesized through a simple one-pot hydrothermal method. The CdS–MoS 2 composites were immobilized on glassy carbon electrode surface as ECL emitter attached a complementary ssDNA (NH 2 –ssDNA) of IgE. IgE aptamer (T-Apt) with DNAzyme–AuNPs can hybridize with NH 2 –ssDNA to form dsDNA. The DNAzyme with horseradish peroxidase-like activity could electrocatalyze the reduction of H 2 O 2 , the coreactant of CdS–MoS 2 ECL emission, leading to an obvious ECL quenching. In the presence of IgE, IgE conjugated with DNAzyme–AuNPs–T-Apt and thereafter the conjugations released, which decreased the consumption of H 2 O 2 by DNAzyme–AuNPs, produced an increased ECL signal. The changed ECL intensity is proportional to concentration of IgE in the range of 0.001–10.0 nM with the detection limit of 0.34 pM ( S / N = 3). The prepared aptasensor has been applied to determination of IgE in human serum samples. The recoveries of IgE in human serum samples are between 83.0% and 108% with the RSD values no more than 3.8%. The developed sensor with CdS–MoS 2 composites and DNAzyme features high sensitivity, good selectivity and wide linear range, suggesting the potential applications in biochemical analysis. [ABSTRACT FROM AUTHOR]

A label-free and ultrasensitive electrochemiluminescence (ECL) aptasensor was constructed for the detection of thrombin. Molybdenum sulfide–graphene nanocomposites with good conductivity and large surface area were immobilized on glassy carbon electrode (GCE), and then Nafion was fixed to chemosorb the Ru(bpy) 3 2+ used as luminescence agent. Subsequently, gold nanoparticles (AuNPs) were modified on the electrode to immobilize the thiol-modified thrombin aptamer for fabrication of the thrombin aptasensor. The proposed ECL aptasensor produced the ultrasensitive detection of thrombin with a low detection limit of 3.6 × 10 −15 M ( S / N = 3) and over a wide target concentration range from 1.0 × 10 −14 to 5.0 × 10 −9 M . The aptasensor has been successfully applied in the determination of thrombin in human plasma samples of both traumatic and non-traumatic injury patients, indicating its promise in biochemical analysis. The recoveries of thrombin in human plasma samples are between 88.6% and 105.0%, and the RSD values are no more than 3.7%. The results demonstrate that this aptasensor has excellent sensitivity, selectivity and stability. [ABSTRACT FROM AUTHOR]

A novel, simple, and versatile electrochemiluminescence (ECL) sensing platform for Pb(II) ions was developed based on DNAzyme with peroxidase-like activity to catalyze the reduction of hydrogen peroxide. Poly (diallyldimethylammonium chloride) (PDDA) with positive charge was adsorbed onto the surface of graphene oxide (GO) and then CdS quantum dots (QDs) with negative charge were enriched to the surface of GO by electrostatic interaction between CdS QDs and PDDA to prepare a composite (denoted as P-GO@QDs) which was immobilized on the surface of a glassy carbon electrode (GCE). When hydrogen peroxide was used as coreactant CdS QDs can produce ECL signal. G-rich DNA strand, i . e . T30695, can combine with Pb (II) ions to form a stable parallel G-quadruplex. The G-quadruplex can further combine with hemin to form DNAzyme which have catalysis towards the reduction of hydrogen peroxide causing the decrease of ECL signal. Amino-modified T30695 was attached to P-GO@QDs composite by the reaction between the amino group of T30695 and carboxyl group of CdS QDs. The ECL signal of the biosensor was linearly dependent on the logarithm of Pb(II) concentration from 1.0 × 10 − 14 to 1.0 × 10 − 11 M with a detection limit of 9 fM. An excellent performance of ECL biosensor indicated that it is promising for Pb(II) detection in real samples. [ABSTRACT FROM AUTHOR]

A novel competitive electrochemiluminescence (ECL) aptasensor based on CdSe/ZnS quantum dots (QDs) functionalized MoS 2 modified electrode was developed for sensitive immunoglobulin E (IgE) detection using horseradish peroxidase (HRP) catalyzed biocatalytic precipitation (BCP) for signal quenching. MoS 2 was introduced to load QDs using PDDA as a bridge to form the MoS 2 -QDs composites which were employed as matrix for the immobilization of the complementary DNA (cDNA) of IgE aptamer, then HRP functionalized gold nanoparticles (AuNPs) labeled aptamer (aptamer-AuNPs-HRP) was designed as the signal probe for the aptasensor, the presence of HRP would stimulate the BCP onto the electrode surface for its insulating effect on ECL signal, thereby impairing the ECL emission. In the presence of IgE, the signal probe would capture IgE to form conjugation, released from the electrode accompanying decrease of HRP and increase of ECL intensity. Improved sensitivity is achieved through using the signal probe. This fabricated aptasensor displays a liner range from 0.5 pM to 0.5 nM with a detection limit of 0.18 pM ( S/N = 3). Moreover, eight human sera samples were analyzed with recoveries of 85.0–107.5%. The present strategy provides a promising method for the future development of ECL aptasensor for advanced biochemical analysis. [ABSTRACT FROM AUTHOR]