Yanhu Wang

A three-dimensional origami-based immuno-biofuel cell for self-powered, low-cost, and sensitive point-of-care testing.

A three-dimensional microfluidic origami glucose-air immuno-biofuel cell has been successfully demonstrated for the first time to implement self-powered, sensitive, and low-cost sandwich immunoassay for cancer markers based on the signal amplifications of a porous Au-paper electrode and Au nanoparticles attached to carbon nanotubes.

Facile and sensitive paper-based chemiluminescence DNA biosensor using carbon dots dotted nanoporous gold signal amplification label

A facile and sensitive chemiluminescence (CL) protocol for the detection of DNA on low-cost paper analytical device using simple, rapid wax-screen-printing method was developed by combining simply covalent modification and signal amplification in this work. The DNA sensor was prepared with N,N′-disuccinimidyl carbonate (DSC) to capture DNA by covalently immobilizing on μPADs, and carbon dots (C-dots) dotted nanoporous gold (C-dots@NPG) was employed for signal amplification label. After the sandwich-type DNA hybridization reaction, C-dots@NPG labeled signal DNA was captured on the DNA biosensor. In the presence of potassium permanganate, the radiative recombination of oxidant injected holes and electrons generated oxidant induced CL reaction of the C-dots@NPG and produced the CL signals. Under optimal conditions, the application of this paper-based DNA sensor was successfully performed with a linear range of 10−18 to 10−14 M and with a detection limit of 8.56 × 10−19 M for target DNA. The newly designed strategy not only provides a simple DSC modified platform to improve the immobilization of capture DNA or antibody, but also offers a high-efficiency C-dots@NPG signal amplification label to enhance the sensitivity, and thus will be a promising potential in public health and environmental monitoring.

Graphene functionalized porous Au-paper based electrochemiluminescence device for detection of DNA using luminescent silver nanoparticles coated calcium carbonate/carboxymethyl chitosan hybrid microspheres as labels

In the paper, a simple and sensitive electrochemiluminescence (ECL) DNA sensor based on graphene-modified porous Au-paper working electrode (GR/Au-PWE) and calcium carbonate/carboxymethyl chitosan (CaCO3/CMC) hybrid microspheres @ luminescent silver nanoparticles (AgNPs) composites was developed. The GR/Au-PWE with excellent conductivity was successfully prepared for the immobilization of capture probe. The CaCO3/CMC hybrid microspheres were prepared by the precipitation of calcium carbonate in an aqueous solution containing CMC. The AgNPs was synthesized by thermal reduction of silver ions in glycine matrix, taking advantage of the solid-state matrix to control the nucleation and migration of reduced silver atoms. The CaCO3/CMC@AgNPs composites exhibited 3.6 times higher ECL intensity than the pure AgNPs-labeled reporter DNA. Taking advantage of dual-amplification effects, the paper-based DNA sensor could detect the target DNA quantitatively, in the range of 4.0×10(-17)-5.0×10(-11) M, with a limit of detection as low as 8.5×10(-18) M, and perform excellent selectivity. The simple, low-cost, sensitive device could be easily applied for point-of-care testing, public health and environmental monitoring in remote regions, developing or developed countries.

Visible photoelectrochemical sensing platform by in situ generated CdS quantum dots decorated branched-TiO2 nanorods equipped with Prussian blue electrochromic display

In this study, based on in situ generation of CdS quantum dots (QDs) on the surface of branched TiO2 (B-TiO2) nanorods, an solar innovative photoelectrochemical (PEC) sensing platform was constructed for real-time, and sensitive detection of cellular H2S. Specifically, B-TiO2 nanorods arrays consisting of TiO2 nanorods directly grown on fluorine-doped tin oxide (FTO) further using TiCl3 mediated surface treatment of TiO2 nanorods are designed and fabricated as a new type of photoelectrode. CdS quantum dots (QDs) was formed on the surface of B-TiO2 nanorods arrays through the reaction between Cd2+ and S2-. And a significant enhancement in the photocurrent was obtained that ascribed to the formation of CdS-B-TiO2 heterostructures, thus leading to sensitive PEC recording of the H2S level in buffer and cellular environments. By using Prussian blue (PB) a electrochromic material to capture the photoelectron generated from the photoelectrode, a new visual system was proposed due to the formation of Prussian white (PW), which could be used to visualize the quantum photoelectric effect. This novel PEC sensing platform not only achieved satisfied analysis results toward S2-, but also showed excellent sensitivity, selectivity, low cost, and portable features. The strategy through the in situ generation of semiconductor nanoparticles on the surface of wide band-gap semiconductor paves the way for the improvements of PEC analytical performance. Meanwhile, the quantitative read-out electrochromic display paves a facile avenue and initiates new opportunities for creation of cheap, miniaturization sensors for other relevant analytes.

Self-powered competitive immunosensor driven by biofuel cell based on hollow-channel paper analytical devices.

A mediator-less and compartment-less glucose/O2 enzymatic biofuel cell (BFC) was introduced into microfluidic paper-based analytical devices (μ-PADs) that relies on flow in hollow channels with silver nanoparticles/graphene modified paper electrode as the anodic and cathodic substrate, to implement self-powered sensitive carcinoembryonic antigen (CEA) detection. Glucose dehydrogenase (GDH)-gold nanoparticles bioconjugate modified with CEA acted as a biocatalyst for enhancing glucose oxidation in the bioanode, as well as the transducing enzyme for signaling magnification. Similarly, nanoporous PtNi/bilirubin oxidase (BOD) acted as a biocatalyst for enhancing O2 reduction in the biocathode. With an increase in the concentration of CEA, the amount of CEA-Au-GDH bioconjugate on bioanode decreases, thus leading to the lower output of the as-prepared BFC. This proposed BFC-based self-powered immunosensor for CEA possessed largely increased linear detection range from 1 pg mL(-1) to 0.5 μg mL(-)(1) with a detection limit of 0.7 pg mL(-)(1). The proposed BFC-based self-powered immunosensor shows high sensitivity, stability, and reproducibility and can become a promising platform for other protein detection.

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.

A disposable paper-based electrochemiluminescence device for ultrasensitive monitoring of CEA based on Ru(bpy)32+@Au nanocages

In this work, an electrochemiluminescence (ECL) immunoassay integrated with the proposed 3D microfluidic origami device for the sensitive detection of carcinoembryonic antigen (CEA) was developed based on Ag nanospheres modified paper working electrode (Ag-PWE) as the sensor platform and Au nanocages functionalized tris-(bipyridine)-ruthenium(II) (Ru(bpy)32+) as the ECL signal amplification label. The novel Ag-PWE with excellent conductivity was constructed through the growth of an Ag nanosphere layer on the surfaces of cellulose fibers and served to provide a good pathway for electron transfer and enhance the amount of captured antibody (Ab1). Au nanocages, which possessed a hollow structure, were first used to construct the ECL immunosensor as a signal amplification carrier. Both the inner and outer surfaces of the Au nanocages can adsorb Ru(bpy)32+, therefore the signal can be amplified as much as possible. In addition, this as-prepared 3D microfluidic origami ECL immunodevice had the advantages of high sensitivity, acceptable precision and reasonable accuracy. On the basis of the considerably amplified ECL signal and sandwich-type format, the as-proposed immunodevice successfully fulfilled the highly sensitive detection of CEA with a linear range of 0.001–50 ng mL−1 and a detection limit of 0.0007 ng mL−1. The resulting 3D microfluidic origami ECL immunodevice exhibited great promise in the point-of-care diagnostics application of clinical screening of tumor markers.

Visible-light driven biofuel cell based on hierarchically branched titanium dioxide nanorods photoanode for tumor marker detection

In this work, a novel sensing platform based on visible light driven biofuel cell (BFC) has been facilely designed for sensitive detection of prostate-specific antigen (PSA) with the photo-response bioanode, realizing the dual route energy conversion of light energy and chemical energy to electricity. The hierarchical branched TiO2 nanorods (B-TiO2 NRs) decorated with CdS quantum dots (QDs) act as the substrate to confine glucose dehydrogenase (GDH) for the visible light driven glucose oxidation at the bioanode. Three dimensional flowers like hierarchical carbon/gold nanoparticles/bilirubin oxidase (3D FCM/AuNPs/BOD) bioconjugate served as biocatalyst for O2 reduction at the biocathode. With an increase in the concentration of PSA, the amount of BOD labels on biocathode increases, thus leading to the higher current output of the as-proposed visible light driven BFC. Based on this, this sensing platform provide great performance in sensitivity and specificity, increasing linear detection range from 0.3pgmL(-1) to 7μgmL(-1) with a detection limit of 0.1pgmL(-1). Most importantly, our new sensing strategy provided a simple and inexpensive sensing platform for tumor markers detection, suggesting its wide potential applications for clinical diagnostics.

Platelike WO3 sensitized with CdS quantum dots heterostructures for photoelectrochemical dynamic sensing of H2O2 based on enzymatic etching.

A platelike tungsten trioxide (WO3) sensitized with CdS quantum dots (QDs) heterojunction is developed for solar-driven, real-time, and selective photoelectrochemical (PEC) sensing of H2O2 in the living cells. The structure is synthesized by hydrothermally growing platelike WO3 on fluorine doped tin oxide (FTO) and subsequently sensitized with CdS QDs. The as-prepared WO3-CdS QDs heterojunction achieve significant photocurrent enhancement, which is remarkably beneficial for light absorption and charge carrier separation. Based on the enzymatic etching of CdS QDs enables the activation of quenching the charge transfer efficiency, thus leading to sensitive PEC recording of H2O2 level in buffer and cellular environments. The results indicated that the proposed method will pave the way for the development of excellent PEC sensing platform with the quantum dot sensitization. This study could also provide a new train of thought on designing of self-operating photoanode in PEC sensing, promoting the application of semiconductor nanomaterials in photoelectrochemistry.

A chemiluminescence excited photoelectrochemistry aptamer-device equipped with a tin dioxide quantum dot/reduced graphene oxide nanocomposite modified porous Au-paper electrode

In this work, a paper-based chemiluminescence excited photoelectrochemical aptamer device (PPECD) was developed for adenosine triphosphate (ATP) measurement based on a porous Au-paper electrode modified with a tin dioxide quantum dot/reduced graphene oxide nanocomposite (SnO2 QD/RGO) integrated with an all-solid-state paper supercapacitor (PSC) amplifier and a digital multi-meter (DMM). The Au-paper electrode was constructed through the growth of a gold nanoparticle (AuNP) layer on the back of the paper working electrode to improve the electron conduction. Fe3O4@AuNP nanocomposites were used as labels of luminol, glucose oxidase (GOx) and signal aptamer which greatly enhanced the chemiluminescence emission and provided a simple magnetic separation approach to attain interference-free measurement for real detection. GOx was used for the oxidation of glucose to produce H2O2 which was not only used as the co-reactant in the CL system, but also as the electron donors to suppress the corrosion of SnO2 QDs under illumination as well as to facilitate the generation of stable photocurrent. A PSC was constructed and integrated into a PPECD as an effective electrical energy storage unit to collect and store the photocurrents. The stored electrical energy could be released instantaneously through a low cost, portable, and simple DMM to obtain an amplified current for the quantification of ATP.