Qingkun Kong

Paper-based electrochemiluminescence origami cyto-device for multiple cancer cells detection using porous AuPd alloy as catalytically promoted nanolabels

The detection of cancer cells is important and fundamental for cancer diagnosis and therapy, which has attracted considerable interest recently. Although traditional cyto-sensors have been widely explored due to their high sensitivity and selectivity, it is still a challenge to develop a low-cost, portable, disposable, fast, and easy-to-use cancer cell detection method for applying in the field of cancer diagnosis and therapy. Herein, to address these challenges, we developed a microfluidic paper-based electrochemiluminescence origami cyto-device (μ-PECLOC), in which aptamers modified 3D macroporous Au-paper electrodes were employed as the working electrodes and efficient platforms for the specific cancer cells capture. Owing to the effective disproportionation of hydrogen peroxide and specific recognition of mannose on cell surface, concanavalin-A conjugated porous AuPd alloy nanoparticles were introduced into this μ-PECLOC as the catalytically promoted nanolabels for peroxydisulfate ECL system. Under the optimal conditions, the proposed μ-PECLOC exhibited excellent analytical performance with good stability, reproducibility, and accuracy, towards the cyto-sensing of four types of cancer cells indicating the potential applications to facilitate effective and multiple early cancer diagnosis and clinical treatment.

Cyto-sensing in electrochemical lab-on-paper cyto-device for in-situ evaluation of multi-glycan expressions on cancer cells

A novel electrochemical lab-on-paper cyto-device (ELPCD) was fabricated to demonstrate sensitive and specific cancer cell detection as well as in-situ monitoring of multi-glycans on living cancer cells. In this ELPCD, aptamers modified three-dimensional macroporous Au-paper electrode (Au-PE) was employed as the working electrode for specific and efficient cancer cell capture. Using a sandwich format, sensitive and reproducible cell detection was achieved in this ELPCD on the basis of the electrochemical signal amplification of the Au-PE and the horseradish peroxidase-lectin electrochemical probe. The ELPCD displayed excellent analytical performance for the detection of four K562 cells with a wide linear calibration range from 550 to 2.0×10(7) cells mL(-1). Then, this ELPCD was successfully applied to determine cell-surface multi-glycans in parallel and in-situ monitor multi-glycans expression on living cells in response to drug treatment through in-electrode 3D cell culture. The proposed method provides promising application in decipherment of the glycomic codes as well as clinical diagnosis and treatment in early process of cancer.

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 0.08 pg mL(-1) and 0.06 mU mL(-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.

Hand-drawn&written pen-on-paper electrochemiluminescence immunodevice powered by rechargeable battery for low-cost point-of-care testing.

In this paper, a pen-on-paper electrochemiluminescence (PoP-ECL) device was entirely hand drawn and written in commercially available crayon and pencil in turn for the first time, and a constant potential-triggered sandwich-type immunosensor was introduced into the PoP-ECL device to form a low-cost ECL immunodevice proof. Each PoP-ECL device contained a hydrophilic paper channel and two PoP electrodes, and the PoP-ECL device was produced as follows: crayon was firstly used to draw hydrophobic regions on pure cellulose paper to create the hydrophilic paper channels followed with a baking treatment, and then a 6B-type black pencil with low resistivity was applied for precision writing, as the PoP electrodes, across the hydrophilic paper channel. For further point-of-care testing, a portable, low-cost rechargeable battery was employed as the power source to provide constant potential to the PoP electrodes to trigger the ECL. Using Carbohydrate antigen 199 as model analyte, this PoP-ECL immunodevice showed a good linear response range from 0.01-200 U mL(-1) with a detection limit of 0.0055 U mL(-1), a high sensitivity and stability. The proposed PoP-ECL immunodevice could be used in point-of-care testing of other tumor markers for remote regions and developing countries.

CuO-induced signal amplification strategy for multiplexed photoelectrochemical immunosensing using CdS sensitized ZnO nanotubes arrays as photoactive material and AuPd alloy nanoparticles as electron sink

In this work, multiplexed photoelectrochemical (PEC) immunoassays are introduced into an indium tin oxide (ITO) device. Firstly, the ITO device is fabricated using a simple acid etch treatment method. Secondly, AuPd alloy nanoparticles are electro-deposited on ITO working electrodes as electron sink to construct the immunosensor platform. After that, ZnO nanotubes (ZNTs) arrays are synthesized via chemical etching of ZnO nanorods that are grown on AuPd surface by electrochemical deposition method. Subsequently, CdS is electro-deposited on ZNTs arrays and used as photoactive material. Then, CuO nanoseeds are labeled with signal antibodies and firstly used as PEC signal amplification label. The introduction of CuO brings signal amplification because of the conduction band (CB) of both CuO and ZnO are lower than that of CdS, CuO will compete the photo-induced electrons in CB of CdS with ZnO, leading to the decrease of the photocurrent intensity. Using cancer antigen 125, prostate specific antigen and α-fetoprotein as model analytes, the proposed immunoassay exhibits excellent precision and sensitivity. Meanwhile, this work provides a promising, addressable and simple strategy for the multi-detection of tumor markers.

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.

Self‐Powered and Sensitive DNA Detection in a Three‐Dimensional Origami‐Based Biofuel Cell Based on a Porous Pt‐Paper Cathode

In this work, a mediator-less and compartment-less glucose/air enzymatic biofuel cell (BFC) was introduced into microfluidic paper-based analytical devices (μ-PADs) with gold nanoparticles (AuNPs) and platinum nanoparticles (PtNPs)-modified paper electrode as the anodic and cathodic substrate, respectively, to implement self-powered, sensitive, low-cost and simple DNA detection. As a further development of the analytical equipment, an all-solid-state paper supercapacitor (PS) was designed and integrated into the BFC for current amplification, and a terminal digital multi-meter detector (DMM) was introduced for the current detection. A highly sensitive DNA sensor was fabricated by covalently immobilizing the capture DNA in the AuNPs-modified anode. The nanoporous gold conjugated with bienzymes, glucose oxidase and horseradish peroxidase, which were used as electrochemical labels. The electrons generated at the anode flow through an external circuit to the PtNPs-modified cathode that catalyzed the reduction of oxygen with the participation of protons. In addition, the generated current could be collected and stored by the PS. After that, the PS was automatically shorted under the control of a switch to output an instantaneously amplified current, which could be sensitively detected by the terminal DMM. At the optimal conditions, the paper-based analytical platform can detect DNA at the femtomole level. This approach also shows excellent specificity toward single nucleotide mismatches.

Ultrasensitive detection of lead ion sensor based on gold nanodendrites modified electrode and electrochemiluminescent quenching of quantum dots by electrocatalytic silver/zinc oxide coupled structures

A signal-off electrochemiluminescence (ECL) DNA sensor based on gold nanodendrites (Au NDs) modified indium tin oxide (ITO) electrode for the detection of lead ion (Pb(2+)) was developed. Well-defined Au NDs were prepared on ITO electrode using low-potential synthesis, assisted by ethylenediamine. Based on Pb(2+)-specific deoxyribozyme, the silver/zinc oxide (Ag/ZnO) with coupled structure, prepared by one-pot method, was close to the surface of the electrode to catalyze the reduction of part of H2O2, the coreactant for cathodic ECL emission, leading to a decrease of ECL intensity. In addition, taking advantage of the larger surface area to capture a large amount of capture probe as well as excellent conductivity of Au NDs, the sensor could detect Pb(2+) quantitatively in a wider range, and performed excellent selectivity. Furthermore, such simple and sensitive DNA sensor was successfully applied for the detection of Pb(2+) in lake water and human serum samples, respectively.

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.

Chemiluminescence excited paper-based photoelectrochemical competitive immunosensing based on porous ZnO spheres and CdS nanorods

A chemiluminescence excited photoelectrochemical (PEC) competitive immunosensor for sensitive and specific detection of the prostate specific antigen (PSA) is firstly developed by combining a microfluidic paper-based device. Firstly, porous ZnO spheres with large surface area and good biocompatibility are attached onto the Au nanoparticle modified paper working electrode, which serve as an effective matrix for antigens. CdS nanorods (NRs) are selected as the photoactive materials due to their excellent fast and long distance electron transport capability, which allow the binding of the horseradish peroxidase-labeled signal antibody onto CdS NRs (CdS NR-Ab-HRP). After a competitive immunoassay format, the CdS NR-Ab-HRP labels are captured onto the electrode surface. The chemiluminescent excitation is produced from the oxidation of luminol by H2O2 in the presence of HRP. The more antigens in solution can bind to CdS NR-Ab-HRP the less CdS NR-Ab-HRP can bind to antigens immobilized on the electrode, which result in the decrease of chemiluminescence emission and light absorption, leading to the decrease of photocurrent intensity. The PEC response from CdS NR-Ab-HRP successfully fulfilled the sensitive detection of PSA in the linear range from 0.005 to 150 ng mL-1 with a detection limit of 2.3 pg mL-1. The proposed immunosensor shows excellent analytical performance with high reproducibility and stability, and can become a promising platform for other protein detection.