Shancheng Yan

Electrochemical biosensor based on CdS nanostructure surfaces

Well-defined hexangularly faced CdS nanorod arrays have been grown directly on a conductive ITO glass via a facile one-step and non-template hydrothermal approach. Gold nanoparticles were decorated onto the nanorods to enhance the electron transfer process of electrode. Glucose oxidase (GOD) was then immobilized on the CdS through crosslinking with chitosan (CS), which resulted in a glucose biosensor with high enzyme loading and excellent sensitivity. Such a chitosan-encapsulated GOD-based biosensor revealed a relatively rapid response time of less than 50s, and an approximate linear detection range of glucose concentration, from 50 to 500 μmol L(-1) with a detection limit of 38 μmol L(-1) and an electrode sensitivity of 5.9 μA mM(-1).

Direct electrochemical analysis of glucose oxidase on a graphene aerogel/gold nanoparticle hybrid for glucose biosensing

AbstractHomogeneously distributed self-assembling graphene aerogel/gold nanoparticle (GA/GNs) hybrid materials with three-dimensional (3D) interconnected pores were fabricated through a simple hydrothermal route. A highly sensitive glucose oxidase (GOD) sensor is then developed based on the GA/GN hybrid materials. The obtained porous structure of the GA/GNs hybrid favored high-density immobilization of the enzyme and penetration of water-soluble molecules, which provided a biocompatible sensing platform for GOD immobilization. This GOD biosensor exhibits remarkable sensitivity (257.60xa0μAu2009·u2009mM−1u2009·u2009cm−2), an approximate linear detection range of glucose concentration (50xa0μmolu2009·u2009L−1 to 450xa0μmolu2009·u2009L−1), and a detection limit of 0.597xa0μmolu2009·u2009L−1. These results indicate that the in situ encapsulation of different nanomaterials into a 3D graphene aerogel framework can enable the fabrication of a series of graphene-based 3D porous materials with promising applications.n Graphical AbstractWe have demonstrated a novel glucose sensor based on porous structure of the GA/GNs hybrid, which favored high-density immobilization of the enzyme, penetration of water-soluble molecules, and providing a biocompatible sensing platform for GOD immobilization.

Scalable alignment and transfer of nanowires based on oriented polymer nanofibers

We develop a simple and scalable method based on oriented polymer nanofiber films for the parallel assembly and transfer of nanowires at high density. Nanowires dispersed in solution are aligned and selectively deposited at the central space of parallel nanochannels formed by the well-oriented nanofibers as a result of evaporation-induced flow and capillarity. A general contact printing method is used to realize the transfer of the nanowires from the donor nanofiber film to a receiver substrate. The mechanism, which involves ordered alignment of nanowires on oriented polymer nanofiber films, is also explored with an evaporation model of cylindrical droplets. The simplicity of the assembly and transfer, and the facile fabrication of large-area well-oriented nanofiber films, make the present method promising for the application of nanowires, especially for the disordered nanowires synthesized by solution chemistry.

Solution-based synthesis of SnO2 nanoparticle/CdS nanowire heterostructures

Heterostructures of SnO2 nanoparticles (NP)/CdS nanowires (NW) were successfully fabricated by a two-step chemical solution method. In the first step, CdS nanowires were synthesized by a simple solvothermal route. In the second step, SnO2 nanoparticles were grown on the surface of the CdS nanowires in a chemical solution of SnCl4·5H2O and anhydrous ethanol at 200 °C. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were adopted to characterize the as-prepared products. The possible formation mechanism of the SnO2 NP/CdS NW heterostructures has been phenomenologically discussed. The effects of reaction conditions, such as deposition reaction time, reaction temperature, and solvent were also studied.

Synthesis of silver sulfide nanowires in ethylene glycol through a sacrificial templating route

In this study, Ag2S nanowires were prepared in ethylene glycol using single-crystal silver nanowires as a sacrificial templating and choosing suitable sulfur sources for the sulfuration reaction. X-ray powder diffraction and a transmission electron microscope equipped with an energy dispersive X-ray analysis were used to characterize the products. The results indicated Ag2S nanowires with diameters of about one hundred nanometers and lengths up to several micrometers could be obtained through this method. The selected area electron diffraction pattern and high-resolution transmission electron microscope imaging indicated that the Ag2S nanowires thus formed were crystalline.

Patterning of self-assembled monolayers by phase-shifting mask and its applications in large-scale assembly of nanowires

A nonselective micropatterning method of self-assembled monolayers (SAMs) based on laser and phase-shifting mask (PSM) is demonstrated. Laser beam is spatially modulated by a PSM, and periodic SAM patterns are generated sequentially through thermal desorption. Patterned wettability is achieved with alternating hydrophilic/hydrophobic stripes on octadecyltrichlorosilane monolayers. The substrate is then used to assemble CdS semiconductor nanowires (NWs) from a solution, obtaining well-aligned NWs in one step. Our results show valuably the application potential of this technique in engineering SAMs for integration of functional devices.

Interfacial transport homogenization for nanowire ensemble photodiodes by using a tunneling insertion

Interfacial transport inhomogeneity critically degrades the performance of nanowire ensemble photodiodes. In this work, an ultrathin Al2O3 insertion is introduced to improve the photoresponse including stable response, a high on/off ratio, and a quick response ascent/descent. Homogeneous tunneling across the insertion dominantly controls the transport fluctuation originated from the inconsistent interfacial states of individual nanowires. The present work demonstrates a progressive practical application of nanowire ensemble devices.

Recognition of microRNA-binding sites in proteins from sequences using Laplacian Support Vector Machines with a hybrid feature

The recognition of microRNA (miRNA)-binding residues in proteins would further enhance our understanding of how miRNAs silence their target genes and some relevant biological processes. Due to the insufficient labeled examples, traditional methods such as SVMs could not work well on such problems. Thus, we propose a semi-supervised learning method, i.e., Laplacian Support Vector Machine (LapSVM) for recognizing miRNA-binding residues in proteins from sequences by making use of both labeled and unlabeled data in this article. A hybrid feature is put forward for coding instances which incorporates evolutionary information of the amino acid sequence and mutual interaction propensities in protein-miRNA complex structures. The results indicate that the LapSVM model receives good performance with a F1 score of 22.06±0.28% and an AUC (area under the ROC curve) value of 0.760±0.043. A web server called MBindR is built and freely available at http:// cbi.njupt.edu.cn/MBindR/MBindR.htm for academic usage.

Cell affinity of PHBV thin films evaluated by a parallel plate flow chamber

The aim of the study is to evaluate the cell affinity of Poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) thin films using a parallel plate flow chamber system. The PHBV thin films were modified by anhydrous ammonia gaseous plasma treatment. Mouse 3T3 fibroblast cells were seeded on bare and plasma modified PHBV thin films, respectively. A laminar flow enforces the cells on these films in a parallel plate flow chamber system. The percentage of initial cells remaining on the films after serials flows was used to evaluate the cell affinity of films. The results showed that, compared with control groups, ammonia plasma treatment could promote the cell affinity of PHBV films. It also indicated that the parallel plate flow chamber system can be used to evaluate the cell affinity of a material.