ACS Nano最新文献

While traditional Pt-based catalysts suffer from inadequate selectivity and stability in electrocatalytic ethylene glycol oxidation reactions, we present a general and scalable synthesis strategy, fabricating a broad multimetallic Pt-based alloy nanowires (NWs) library from binary to quinary. Among these, the PtAgCuRhRu NWs exhibit exceptional performance, with a mass activity ∼8 times higher than that of Pt/C and a Faradaic efficiency for glycolic acid (GA) reaching 93.49%. In the membrane electrode assembly electrolyzer, the catalyst maintained its activity over 140 h with 99% GA selectivity. In situ experimental and theoretical calculations reveal oxygenophilic Rh and Ru promote *OH adsorption, facilitating the conversion of *COCH₂OH to GA and the oxidative removal of CO_ads, enhancing activity and stability. Additionally, the high energy barrier for C-C bond cleavage suppresses undesired decomposition due to the introduction of Ag and Cu, leading to superior GA selectivity.

Digital immunoassays enable highly sensitive detection of biomolecules, offering absolute quantification rather than relying on bulk signal intensity. We adapt a digital immunoassay scheme for a nanopore sensor, a versatile platform for single-molecule counting. Current nanopore sensors have demonstrated great progress when counting nucleic acids but struggle with proteins due to variability in translocation behavior and limited recognition strategies. While recent advancements have highlighted the promise of nanopore platforms for protein studies, precise quantification remains a challenge. Here, building on previous work, we present a nanopore-based digital immunoassay that employs gold nanoparticle-mediated molecular amplification with a single-molecule readout. This approach translates protein recognition into quantifiable DNA, enabling a precise digital assay. This assay employs a DNA NanoLock probe combined with a paramagnetic bead-based immunocapture, where the target proteins trigger a structural transformation of the NanoLock, converting their presence into a binary DNA-based signal. By incorporating AuNPs carrying hundreds of DNA proxy reporters, we effectively amplify the detectable signal by 2 orders of magnitude, significantly improving sensitivity. We validate the performance of this system by detecting the glial fibrillary acidic protein, a biomarker for traumatic brain injury and neurodegenerative diseases, in plasma samples and demonstrate high femtomolar-level sensitivity (∼40 pg/mL). Using the NanoLock probe, we further mitigate previous challenges, with reduced assay times (hours) and extended dynamic range (3-log). The self-calibrating nature of this digital approach offers robust, reproducible measurements across different nanopores, eliminating interdevice variability.

Precise control of light-matter interactions is a cornerstone of next-generation technologies, from ultrasensitive biosensing and single-molecule tracking to the development of adaptive metamaterials. While small, symmetric nanostructures are well-understood, micrometer-scale plasmonic Janus particles (pJPs), comprising dielectric cores with thin metallic caps, exhibit complex optical properties due to their asymmetric structure. Despite widespread applications in active matter research, their orientation-dependent scattering properties remain largely unexplored. We introduce Fourier plane tomographic spectroscopy for simultaneous four-dimensional characterization of scattering from individual micrometer-scale particles across wavelength, incident angle, and scattering angle. Combining measurements with finite-element simulations, we identify discrete spectral markers in visible and near-infrared regions that evolve predictably with cap orientation. Spherical-harmonics decomposition reveals that these markers arise from three distinct multipolar modes up to fifth order: axial-propagating transverse-electric, transverse-propagating transverse-electric, and transverse-propagating axial-electric, with retardation-induced splitting. We observe progressive red-shifts and line width narrowing of higher-order resonances, demonstrating curvature's influence on mode dispersion. Orientation-specific scattering patterns exhibit polarization-dependent features enabling optical tracking of particle rotation. Beyond pJPs, this methodology establishes a general framework for characterizing asymmetric nanostructures of diverse material combinations and geometries, offering a toolkit for designing orientation-responsive nanoantennas, reconfigurable metasurfaces, active colloidal systems with tailored light-matter interactions, and high-precision optical tracking of particle rotation.