Taotao Yang

A label-free electrochemical immunosensor for carcinoembryonic antigen detection on a graphene platform doped with poly(3,4-ethylenedioxythiophene)/Au nanoparticles

In this work, a two-step method was developed for the fabrication of a graphene sensing platform doped with poly(3,4-ethylenedioxythiophene)/Au nanoparticles (AuNPs/PEDOT/GR). PEDOT nanorods grown on graphene oxide nanosheets (PEDOT/GO) were firstly synthesized by liquid–liquid interfacial polymerization, followed by the chemical reduction of HAuCl4 by NaBH4. During the reduction process, GO doped in the PEDOT was also reduced to a more conductive form of GR. The obtained AuNPs/PEDOT/GR showed excellent conductivity and large surface area. Thus, a simple and sensitive label-free immunosensor based on AuNPs/PEDOT/GR nanocomposite has been proposed to detect carcinoembryonic antigen (CEA) by measuring the change of electrochemical response before and after the immunoreaction. Under the optimized conditions, the linear range of the proposed immunosensor is estimated to be from 0.0004 to 40 ng mL−1 (R2 = 0.9969) and the detection limit is estimated to be 0.1 pg mL−1 at a signal-to-noise ratio of 3. Moreover, the immunosensor was examined for use in the determination of CEA in real human serum samples with satisfactory results.

Facile one-pot preparation of Pd–Au/PEDOT/graphene nanocomposites and their high electrochemical sensing performance for caffeic acid detection

In this study, bimetallic Pd–Au/PEDOT/graphene (Pd–Au/PEDOT/rGO) nanocomposites were facilely prepared in an aqueous medium by a one-pot method. In addition to the Pd–Au/PEDOT nanoparticles, dendritic bimetallic Pd–Au nanoclusters were also obtained in the composites, which were verified by transmission electron microscopy and element analysis mapping characterization. The morphology of the nanocomposites was greatly influenced by the molar ratio of the added metal salt precursors. X-ray photoelectron spectroscopy and X-ray diffraction analyses indicated the presence of synergism and electron exchange between the Pd–Au bimetallic nanostructures, which play an important role in the enhancement of the electrocatalytic activity of the composite toward the oxidation of caffeic acid (CA). Under optimized conditions, the Pd–Au/PEDOT/rGO modified glassy carbon electrode showed a wide linear range of 0.001–55 μM and a low detection limit of 0.37 nM (S/N = 3) for CA detection. These results provide valuable insight on the development of novel modified electrodes based on bimetallic graphene nanocomposites for high performance electrochemical sensors.

A universal strategy for the facile synthesis of a sandwich-structured Pt–graphene–Pt nanocomposite for salbutamol sensing

In this work, a sandwich-structured Pt–graphene–Pt (P–Gr–P) nanocomposite has been prepared by a two-step method including (i) a chemical and (ii) an electrochemical reduction process. The P–graphene oxide–P (P–GO–P) nanocomposite was firstly synthesized by an in situ growth method, during which platinum nanoparticles (PtNPs) grew on both sides of GO. In the second step, P–GO–P was coated onto a glass carbon electrode (GCE). In this process, GO in the P–GO–P nanocomposite was reduced to a more conductive form of graphene (Gr). The obtained sandwich-structured P–Gr–P can effectively separate the individual layers of Gr sheets from each other, prevent the agglomeration of Gr sheets and improve the conductivity of the Gr film. In addition, the electrocatalytic properties of the as-prepared P–Gr–P nanocomposite towards the oxidation of salbutamol (SAL) were investigated. Results revealed that the sandwich-structured P–Gr–P nanocomposite with higher electrochemically active surface area showed better electrocatalytic activity toward SAL oxidation than PtNPs–Gr prepared by using the one-step electrochemical co-deposition method. On the basis of the excellent electrochemical activity of the P–Gr–P nanocomposite, a highly sensitive electrochemical platform was developed for the rapid detection of SAL. The present work provides an interesting strategy to prepare a Gr-based nanocomposite for electrochemical sensors.