An Ultrasensitive Electrochemiluminescence Immunoassay for Carbohydrate Antigen 19-9 in Serum Based on Antibody Labeled Fe3O4 Nanoparticles as Capture Probes and Graphene/CdTe Quantum Dot Bionanoconjugates as Signal Amplifiers

Abstract

The CdTe quantum dots (QDs), graphene nanocomposite (CdTe-G) and dextran–Fe3O4 magnetic nanoparticles have been synthesized for developing an ultrasensitive electrochemiluminescence (ECL) immunoassay for Carcinoembryonic antigen 19-9 (CA 19-9) in serums. Firstly, the capture probes (CA 19-9 Ab1/Fe3O4) for enriching CA 19-9 were synthesized by immobilizing the CA 19-9’s first antibody (CA 19-9 Ab1) on magnetic nanoparticles (dextran-Fe3O4). Secondly, the signal probes (CA 19-9 Ab2/CdTe-G), which can emit an ECL signal, were formed by attaching the secondary CA 19-9 antibody (CA 19-9 Ab2) to the surface of the CdTe-G. Thirdly, the above two probes were used for conjugating with a serial of CA 19-9 concentrations. Graphene can immobilize dozens of CdTe QDs on their surface, which can emit stronger ECL intensity than CdTe QDs. Based on the amplified signal, ultrasensitive antigen detection can be realized. Under the optimal conditions, the ECL signal depended linearly on the logarithm of CA 19-9 concentration from 0.005 to 100 pg/mL, and the detection limit was 0.002 pg/mL. Finally, five samples of human serum were tested, and the results were compared with a time-resolved fluorescence assay (TRFA). The novel immunoassay provides a stable, specific and highly sensitive immunoassay protocol for tumor marker detection at very low levels, which can be applied in early diagnosis of tumor.

Nanoparticle-Based Immunochemical Biosensors and Assays: Recent Advances and Challenges

“…The authors used a comparable approach with CdSe for the assay of the CEA; the remarkably low LOD was 0.1 fg/mL, which corresponds to few (7) molecules of the CEA in 20 μL of sample, thus approaching the single-molecule detection capabilities . For CdTe-based QDs, significantly enhanced ECL was obtained after deposition of these QDs onto graphene sheets . The multicolor sensing could also be achieved with common band-pass filters and PMT detectors .…”

“…209 For CdTe-based QDs, significantly enhanced ECL was obtained after deposition of these QDs onto graphene sheets. 210 The multicolor sensing could also be achieved with common bandpass filters and PMT detectors. 211 The graphene-modified glassy carbon was linked to two different capture antibodies (anti-AFP and anti-CEA) in the sandwich format; the biotinylated secondary Ab's were labeled with different streptavidin−QD conjugates.…”

Immunosensor for Pancreatic Cancer Based on Electrospun Nanofibers Coated with Carbon Nanotubes or Gold Nanoparticles

“…The extensive list of nanomaterials that can be utilized in immunosensors includes graphene, 18 − 21 carbon nanotubes (CNTs), 22 − 26 carbon nanoballs, metallic nanoparticles, 26 and nanostructures derived from natural resources, for example, chitosan, 27 and electrospun polymer nanofibers. 28 , 29 Such nanomaterials are normally used with a twofold purpose.…”

“…The extensive list of nanomaterials that can be utilized in immunosensors includes graphene, − carbon nanotubes (CNTs), − carbon nanoballs, metallic nanoparticles, and nanostructures derived from natural resources, for example, chitosan, and electrospun polymer nanofibers. , Such nanomaterials are normally used with a twofold purpose. On one hand, they serve as a matrix for immobilizing the biomolecules, but they can also be exploited to enhance the sensitivity by increasing the measured signal.…”

Filmes nanoestruturados aplicados em biossensores para detecção precoce de câncer de pâncreas

“…sensibilidade dos biossensores A, B e E foi estimada através da mudança da capacitância, relativa à interação de antígenos CA 19-9 com a camada ativa (anticorpos) adsorvida à superfície dos filmes. Na Figura 32, curvas de calibração em estágio inicial(GAN et al, 2013). Mas a característica mais importante é o valor de referência estar contido na faixa de detecção do sensor, já que as concentrações de CA 19-9 abaixo de 37 U/mL também podem indicar lesões MUA: o primeiro processo ocorre em baixas concentrações de antígeno, havendo mudança significativa apenas a partir de 16 U/mL.…”