We report the novel fabrication of a highly sensitive, selective, fast responding, and affordable amperometric glucose biosensor using exfoliated graphite nanoplatelets (xGnPs) decorated with Pt and Pd nanoparticles. Nafion was used to solublize metal-decorated graphite nanoplatelets, and a simple cast method with high content organic solvent (85 wt %) was used to prepare the biosensors. The addition of precious metal nanoparticles such as platinum (Pt) and palladium (Pd) to xGnP increased the electroactive area of the electrode and substantially decreased the overpotential in the detection of hydrogen peroxide. The Pt−xGnP glucose biosensor had a sensitivity of 61.5 ± 0.6 μA/(mM·cm2) and gave a linear response up to 20 mM. The response time and detection limit (S/N = 3) were determined to be 2 s and 1 μM, respectively. Therefore, this novel glucose biosensor based on the Pt nanoparticle coated xGnP is among the best reported to date in both sensing performance and production cost. In addition, the effects of metal nanoparticle loading and the particle size on the biosensor performance were systematically investigated.
Regular arrays of single colloidal particles on confined regions of patterned polyelectrolyte templates are fabricated based on alternating charged docking sites and neutral deposition resists on the surface. The diameter ratio between surface patterns and the colloid controls the size and spatial arrangement of the clusters. The Figure shows an optical image of up to seven‐membered clusters of colloidal beads 4.3 μm in diameter (see also cover).
The selective adsorption of two different types of particles to a patterned surface is shown for thiol‐modified gold. The far end of the alkanethiols is chemically varied and binds polymer particles with different properties—as illustrated in the Figure for charged polymer particles of different composition and size. Tuning of hydrophobicity and hydrogen bonding in this manner provides a versatile route to composite colloidal structures.
A novel and highly sensitive electroanalytical sensing nanocomposite material is reported for the development of a glucose biosensor. Exfoliated graphite nanoplatelets (xGnP) were tested to enhance the sensing capability. The xGnP has a diameter of 1 µm and a thickness of 10 nm, on average. The glucose biosensing interface was prepared by casting glucose oxidase and xGnP in a Nafion water–isopropyl-alcohol solution with a high concentrated organic solvent (85 wt%). The resulting biosensors showed rapid response time within 5 s, limits of detection of 10 µM glucose (S/N = 3), a linear detection range up to 6 mM, and high sensitivity of 14.17 µA/(mM·cm2) with an optimum glucose oxidase loading. The biosensors also showed good selectivity and long-term stability. These results indicate that xGnP can be an inexpensive alternative to carbon nanotubes for the fabrication of affordable high-performance biosensors.
For the first time, we report on methods to control and prevent polymer films from buckling. Buckled morphologies were created by thermally cycling or mechanically compressing a poly(dimethylsiloxane) substrate coated with a polyelectrolyte multilayer film. By variation of the dimensions of the surface topography relative to the buckling wavelength (e.g., pattern size is less than, equal to, and greater than the buckling wavelength), the orientation and the local morphology of the buckled films were controlled. On the basis of the information obtained, we demonstrate how to alleviate the unavoidable buckling by incorporating nanoparticles into the film. In addition, we studied the effect of the silica layer that results from oxygen plasma treatment and the critical temperature for permanent film buckling.
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