Nanocomposites of chitosan and graphene oxide are prepared by simple self-assembly of both components in aqueous media. It is observed that graphene oxide is dispersed on a molecular scale in the chitosan matrix and some interactions occur between chitosan matrix and graphene oxide sheets. These are responsible for efficient load transfer between the nanofiller graphene and chitosan matrix. Compared with the pure chitosan, the tensile strength, and Young's modulus of the graphene-based materials are significantly improved by about 122 and 64%, respectively, with incorporation of 1 wt % graphene oxide. At the same time, the elongation at the break point increases remarkably. The experimental results indicate that graphene oxide sheets prefer to disperse well within the nanocomposites.

High-throughput screening and optimization experiments are critical to a number of fields, including chemistry and structural and molecular biology. The separation of these two steps may introduce false negatives and a time delay between initial screening and subsequent optimization. Although a hybrid method combining both steps may address these problems, miniaturization is required to minimize sample consumption. This article reports a ''hybrid'' droplet-based microfluidic approach that combines the steps of screening and optimization into one simple experiment and uses nanoliter-sized plugs to minimize sample consumption. Many distinct reagents were sequentially introduced as Ϸ140-nl plugs into a microfluidic device and combined with a substrate and a diluting buffer. Tests were conducted in Ϸ10-nl plugs containing different concentrations of a reagent. Methods were developed to form plugs of controlled concentrations, index concentrations, and incubate thousands of plugs inexpensively and without evaporation. To validate the hybrid method and demonstrate its applicability to challenging problems, crystallization of model membrane proteins and handling of solutions of detergents and viscous precipitants were demonstrated. By using 10 l of protein solution, Ϸ1,300 crystallization trials were set up within 20 min by one researcher. This method was compatible with growth, manipulation, and extraction of high-quality crystals of membrane proteins, demonstrated by obtaining high-resolution diffraction images and solving a crystal structure. This robust method requires inexpensive equipment and supplies, should be especially suitable for use in individual laboratories, and could find applications in a number of areas that require chemical, biochemical, and biological screening and optimization.droplets ͉ plugs ͉ protein structure ͉ high-throughput ͉ miniaturization T his work reports a ''hybrid'' microfluidic approach that uses nanoliter plugs to perform screening and optimization simultaneously in the same experiment. To validate this method using a challenging problem, we demonstrate its compatibility with crystallization of membrane proteins. Small-scale screening and optimization experiments are important for biological assays, chemical screening, and protein crystallization (1-3). Screening and optimization are usually carried out sequentially. In the case of protein crystallization, random sparse matrix screening initially identifies the precipitants that may lead to crystallization. Subsequent gradient optimization establishes concentrations of these precipitants that lead to diffractionquality crystals (4). Combining screening and optimization steps into a single hybrid experiment would eliminate the need to wait for the outcome of the initial screen before carrying out subsequent optimizations. Furthermore, a hybrid experiment would reduce the false negatives (5) associated with screens performed at a single concentration. The hybrid experiment could also be more conclusive, because a single batch of the s...

The synthesis of high-quality In2Se3 nanowire arrays via thermal evaporation method and the photoconductive characteristics of In2Se3 individual nanowires are first investigated. The electrical characterization of a single In2Se3 nanowire verifies an intrinsic n-type semiconductor behavior. These single-crystalline In2Se3 nanowires are then assembled in visible-light sensors which demonstrate a fast, reversible, and stable response. The high photosensitivity and quick photoresponse are attributed to the superior single-crystal quality and large surface-to-volume ratio resulting in fewer recombination barriers in nanostructures. These excellent performances clearly demonstrate the possibility of using In2Se3 nanowires in next-generation sensors and detectors for commercial, military, and space applications.