Electrochemical Immunodevice Research Articles

A 3D electrochemical immunodevice based on an Au paper electrode and using Au nanoflowers for amplification

A highly sensitive electrochemical immunosensor combined with a 3D origami device for detection of cancer antigen was developed based on a novel Au nanoparticle-modified paper working electrode.

A 3D electrochemical immunodevice based on a porous Pt-paper electrode and metal ion functionalized flower-like Au nanoparticles.

A 3D microfluidic paper-based electrochemical immunodevice (μ-PEID) for simultaneous sensitive detection of two tumor biomarkers was fabricated. A nanoporous Pt particle modified paper working electrode (NPPt-PWE) was used as the matrix and metal ions loaded on the l-cysteine capped flower-like Au nanoparticles (Au-Cys) were used as a signal amplification label. The NPPt-PWE was constructed through the growth of a NPPt layer on the back of the paper working electrode to improve electron conduction. Besides, the prepared flower-like Au-Cys could significantly enhance the amount of loaded metal ions and played an important role in connecting the signal antibodies. The metal ion labels could be detected directly through differential pulse voltammetry without metal pre-concentration, and the distinct voltammetric peaks had a close relationship with each sandwich-type immunoreaction. Therefore, a novel 3D μ-PEID for simultaneously detecting carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) with wider linear ranges was developed. The linear range was from 0.004 to 200 ng mL-1 and the limits of detection for AFP and CEA were 1.0 pg mL-1 and 1.3 pg mL-1 (S/N = 3), respectively. The good stability, reproducibility, and accuracy of the μ-PEID indicate that it has great potential application in clinical diagnostics.

A 3D origami electrochemical immunodevice based on a Au@Pd alloy nanoparticle-paper electrode for the detection of carcinoembryonic antigen.

Herein, a novel 3D microfluidic paper-based electrochemical (EC) immunodevice (μ-PEI) for sensitive detection of carcinoembryonic antigen (CEA) was developed. Au@Pt core-shell nanoparticles (NPs), with high conductivity, large surface area, and synergistic electronic effects, were not only used as carriers of secondary antibodies, methylene blue (MB) redox probes and glucose oxidase but also catalyzed the EC reaction of MB, thus amplifying the EC signal of MB in the presence of glucose. In addition, using a novel Au@Pd alloy NP modified porous paper working electrode as the biosensor platform could not only enhance the surface area to immobilize antibodies but also catalyze the reduction of hydrogen peroxide, which further amplified the detection response. On the basis of the considerably amplified EC signal and the sandwich-type format, the EC immunosensor has a sensitive response to CEA in a linear range of 1.0 pg mL-1-100 ng mL-1 with a detection limit of 0.4 pg mL-1. Additionally, this 3D μ-PEI showed satisfactory reproducibility, selectivity and stability.

3D origami electrochemical immunodevice for sensitive point-of-care testing based on dual-signal amplification strategy

A dual signal amplification immunosensing strategy that offers high sensitivity and specificity for the detection of low-abundance biomarkers was designed on a 3D origami electrochemical device. High sensitivity was achieved by using novel Au nanorods modified paper working electrode (AuNRs-PWE) as sensor platform and metal ion-coated Au/bovine serum albumin (Au/BSA) nanospheres as tracing tags. High specificity was further obtained by the simultaneous measurement of two cancer markers on AuNRs-PWE surface using different metal ion-coated Au/BSA tracers. The metal ions could be detected directly through differential pulse voltammetry (DPV) without metal preconcentration, and the distinct voltammetric peaks had a close relationship with each sandwich-type immunoreaction. The position and size of the peaks reflected the identity and level of the corresponding antigen. Integrating the dual-signal amplification strategy, a novel 3D origami electrochemical immunodevice for simultaneous detecting carcinoembryonic antigen (CEA) and cancer antigen 125 (CA125) with linear ranges of over 4 orders of magnitude with detection limits down to 0.08pgmL−1 and 0.06mUmL−1 was successfully developed. This strategy exhibits high sensitivity and specificity with excellent performance in real human serum assay. The AuNRs-PWE and the designed tracer on this immunodevice provided a new platform for low-cost, high-throughput and multiplex immunoassay and point-of-care testing in remote regions, developing or developed countries.

Sensitive origami dual-analyte electrochemical immunodevice based on polyaniline/Au-paper electrode and multi-labeled 3D graphene sheets

In this work, a sensitive microfluidic origami electrochemical immunodevice (denoted as μ-OECI in this work) has been developed, based on polyaniline-Au nanoparticles (AuNPs) modified paper working electrode (PANI/Au-PWE) as sensor platform and different redox substrates as tracers. Au-PWE was fabricated through the growth of an AuNPs layer on the surfaces of cellulose fibers in the PWE. Through electropolymerization of aniline in an Au-PWE, the effective surface area and the sensitivity of the PANI/Au-PWE were enhanced remarkably. 3D graphene sheets (GS) with high surface-to-volume reaction and good in-plane conductivity were used as matrices to immobilize the redox probes and antibodies. Each biorecognition event yielded a distinct voltammetric peak, whose position and size reflected the identity and level of the corresponding antigen. The large amount of redox probes on the 3D GS greatly amplified the detection signals, and the good biocompatibility of PANI/Au-PWE retained good stability for the sandwich-type immunoassay. Using carcinoembryonic antigen and α-fetoprotein as model analytes, the simultaneous multiplex immunoassay showed linear ranges of over 4 orders of magnitude with the detection limits down to 0.5 and 0.8 pg·mL−1, respectively. This facile biosensing μ-OECI exhibited high sensitivity and specificity, and it was applied in point-of-care testing of other cancer markers for remote regions and developing countries.

A paper-based microfluidic electrochemical immunodevice integrated with amplification-by-polymerization for the ultrasensitive multiplexed detection of cancer biomarkers

A novel signal amplification strategy for ultrasensitive multiplexed detection of cancer biomarkers using a paper-based microfluidic electrochemical immunodevice is described. Specifically, a controlled radical polymerization reaction is triggered after the capture of target molecules on the immunodevice surface. Growth of long chain polymeric materials provides numerous sites for subsequent horseradish peroxidase (HRP) coupling, which in turn significantly enhances electrochemical signal output. The signal was further amplified through the use of graphene to modify the immunodevice surface to accelerate the electron transfer. Activators generated electron transfer for atom transfer radical polymerization (AGET ATRP) was used in this study for its high efficiency in polymer grafting and better tolerance toward oxygen in air. Glycidyl methacrylate (GMA) was examined to provide excess epoxy groups for HRP coupling. In the electrochemical immunodevice, eight carbon working electrodes, as well as their conductive pads, were screen-printed on a piece of square paper, and the same Ag/AgCl reference and carbon counter electrodes were shared with another piece of square paper via stacking. Using the HRP-O-phenylenediamine-H2O2 electrochemical detection system, four cancer biomarkers: carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), cancer antigen 125 (CA125), and carbohydrate antigen 153 (CA153) were detected. A limit of detection of 0.01, 0.01, 0.05 and 0.05ngmL−1 was demonstrated, respectively. The results show that the proposed strategy offers great promises in providing a sensitive and cost-effective solution for biosensing applications.

Paper-Based Microfluidic Electrochemical Immunodevice Integrated with Nanobioprobes onto Graphene Film for Ultrasensitive Multiplexed Detection of Cancer Biomarkers

To the best of our knowledge, this was the first report on the integration of a signal amplification strategy into a microfluidic paper-based electrochemical immunodevice for the multiplexed measurement of cancer biomarkers. Signal amplification was achieved through the use of graphene to modify the immunodevice surface to accelerate the electron transfer and the use of silica nanoparticles as a tracing tag to label the signal antibodies. Accurate, rapid, simple, and inexpensive point-of-care electrochemical immunoassays were demonstrated using a photoresist-patterned microfluidic paper-based analytical device (μPAD). Using the horseradish peroxidase (HRP)-O-phenylenediamine-H2O2 electrochemical detection system, the potential clinical applicability of this immunodevice was demonstrated through its ability to identify four candidate cancer biomarkers in serum samples from cancer patients. The novel signal-amplified strategy proposed in this report greatly enhanced the sensitivity of the detection of cancer biomarkers. In addition, the electrochemical immunodevice exhibited good stability, reproducibility, and accuracy and thus had potential applications in clinical diagnostics.

Development of a 3D origami multiplex electrochemical immunodevice using a nanoporous silver-paper electrode and metal ion functionalized nanoporous gold–chitosan

A simple and sensitive 3D microfluidic origami multiplex electrochemical immunodevice was developed for the first time using a novel nanoporous silver modified paper working electrode as a sensor platform and different metal ion functionalized nanoporous gold-chitosan as a tracer.

Paper-based three-dimensional electrochemical immunodevice based on multi-walled carbon nanotubes functionalized paper for sensitive point-of-care testing

In this study, electrochemical immunoassay was introduced into the recently proposed microfluidic paper-based analytical device (μPADs). To improve the performance of electrochemical immunoassay on μPAD for point-of-care testing (POCT), a novel wax-patterned microfluidic paper-based three-dimensional electrochemical device (3D-μPED) was demonstrated based on the multi-walled carbon nanotubes (MWCNTs) modified μPAD. Using typical HRP- O-Phenylenediamine-H 2O 2 electrochemical system, a sandwich immunoassay on this 3D-μPED for sensitive diagnosis of two tumor markers simultaneously in real clinical serum samples was developed with a linear range of 0.001–75.0 U mL −1 for cancer antigen 125 and 0.05–50.0 ng mL −1 for carcinoembryonic antigen. In addition, this 3D-μPED can be easily integrated and combined with the recently emerging paper electronics to further develop simple, sensitive, low-cost, disposable and portable μPAD for POCT, public health and environmental monitoring in remote regions, developing or developed countries.