Search

This paper demonstrates for the first time the use of adaptive functional nickel nanowires for switching on-demand operation of microfluidic devices. Controlled reversible magnetic positioning and orientation of these nanowires at the microchannel outlet offers modulation of the detection and separation processes, respectively. The former facilitates switching between active and passive detection states to allow the microchip to be periodically activated to perform a measurement and reset it to the passive ('off') state between measurements. Fine magnetic tuning of the separation process (postchannel broadening of the analyte zone) is achieved by reversibly modulating the nanowire orientation (i.e., detector alignment) at the channel outlet. The concept can be extended to other microchip functions and stimuli-responsive materials and holds great promise for regulating the operation of microfluidic devices in reaction to specific needs or unforeseen scenarios.

The directional microchip motion, controlled cargo manipulation and several other operational performance parameters of synthetic nanomotors within microchannel networks are discussed. These synthetic nanomachines are shown to be widely used in several integrated functional microdevices.

Adaptive nanowires are used for the on-demand protection of electrochemical sensors for trace metals. The on-demand protection capability might lead to the next-generation of smart analytical devices that recognize changes in the surrounding environment and then auto-reconfigure themselves on the basis of the results.

The magnetic and electrocatalytic properties of nickel microparticles can be exploited for magnetoswitchable control of electrochemical reactivity without the need of functionalized ferromagnetic particles. The application of nanowires for magnetic control of the electrochemical reactivity is reported and also, an attempt is made to demonstrate how one can modulate the electrocatalytic activity by orienting catalytic nanowires at different angles.

This work focuses on fabricating poly(2-aminobenzylamine)-modified screen-printed carbon electrode as an electrochemical immunosensor for the label-free detection of human immunoglobulin G. To selectively detect immunoglobulin G, the anti-immunoglobulin G antibody with high affinity to immunoglobulin G was covalently linked with the amine group of poly(2-aminobenzylamine) film-deposited screen-printed carbon electrode. The selectivity for immunoglobulin G was subsequently assured by being challenged with redox-active interferences and adventitious adsorption did not significantly interfere the analyte signal. To obviate the use of costly secondary antibody, the [Fe(CN)6]4-/3- redox probe was instead applied to measure the number of human immunoglobulin G through the immunocomplex formation that is quantitatively related to the level of the differential pulse voltammetric current. The resulting immunosensor exhibited good sensitivity with the detection limit of 0.15 ng mL−1, limit of quantitation of 0.50 ng mL−1 and the linear range from 1.0 to 50 ng mL−1. Given those striking analytical performances and the affordability arising from using cheap screen-printed carbon electrode with label-free detection, the immunosensor serves as a promising model for the next-step development of a diagnostic tool. [ABSTRACT FROM AUTHOR]

Sometimes, smaller size is not always better, and looking for nanomaterials that offer better device performance requires consideration of their properties at the first stage. In this study, the effects of the size of polyethylenimine-capped AuNPs (PEI-AuNPs) and proteins on the immunosensor performances, namely, sensitivity and limit of detection, are examined. The size-effect investigation of PEI-AuNPs involves their modification on the surface of disposable screen-printed carbon electrodes to support primary antibodies and their ability to load secondary antibodies and redox probes to perform amplification in the immunosensor. The correlation of the average size, electrochemical activities, protein size, and device property of PEI-AuNPs is investigated. The synthesized PEI-AuNPs with different average diameters ranging from 4.7 to 44.9 nm are employed for the investigation. When the sensor surface forms a sandwich architecture, the detection employs the current response of Ag + ions on the PEI-AuNPs bioconjugate, which greatly increases by increasing the protein concentration. In addition, the best electrochemical signal of PEI-AuNPs or their antibody complexes with a unique AuNPs' average size allows superior signal amplification. The effect of using different sizes of target proteins on their devices is not significantly observed. Although in general small-sized nanomaterials offer high active surface areas, which can improve the electrode surface, reactivity, and device performance, we observe that the medium size of PEI-AuNPs (16.3 nm) gives the best sensitivity and detection limit of this sensor type. Therefore, the finding is useful for considering and optimizing their sizes for tunable voltammetric properties and acquiring a superior sensor., Competing Interests: The authors declare no competing financial interest., (© 2025 The Authors. Published by American Chemical Society.)

We use a simple device architecture based on a poly(3,4-ethylendioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-coated indium tin oxide anode and a LiF/Al cathode to assess the effects of shell thickness on the properties of light-emitting diodes (LEDs) comprising CdSe/CdS core/shell nanocrystal quantum dots (NQDs) as the emitting layer. Specifically, we are interested in determining whether LEDs based on thick-shell nanocrystals, so-called "giant" NQDs, afford enhanced performance compared to their counterparts incorporating thin-shell systems. We observe significant improvements in device performance as a function of increasing shell thickness. While the turn-on voltage remains approximately constant for all shell thicknesses (from 4 to 16 CdS monolayers), external quantum efficiency and maximum luminance are found to be about one order of magnitude higher for thicker shell nanocrystals (≥13 CdS monolayers) compared to thinner shell structures (<9 CdS monolayers). The thickest-shell nanocrystals (16 monolayers of CdS) afforded an external quantum efficiency and luminance of 0.17% and 2000 Cd/m(2), respectively, with a remarkably low turn-on voltage of ~3.0 V., (© 2011 American Chemical Society)