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.

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.

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.