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Nanogap Plasmonic Structures Fabricated by Switchable Capillarya??Force Driven Selfa??Assembly for Localized Sensing of Anticancer Medicines with Microfluidic SERS
摘要： Nanogap plasmonic structures, which can strongly enhance electromagnetic fields, enable widespread applications in surface-enhanced Raman spectroscopy (SERS) sensing. Although the directed self-assembly strategy has been adopted for the fabrication of micro/nanostructures on open surfaces, fabrication of nanogap plasmonic structures on complex substrates or at designated locations still remains a grand challenge. Here, a switchable self-assembly method is developed to manufacture 3D nanogap plasmonic structures by combining supercritical drying and capillary-force driven self-assembly (CFSA) of micropillars fabricated by laser printing. The polymer pillars can stay upright during solvent development via supercritical drying, and then can form the nanogap after metal coating and subsequent CFSA. Due to the excellent flexibility of this method, diverse patterned plasmonic nanogap structures can be fabricated on planar or nonplanar substrates for SERS. The measured SERS signals of different patterned nanogaps in fluidic environment show a maximum enhancement factor ≈8 × 107. Such nanostructures in microchannels also allow localized sensing for anticancer drugs (doxorubicin). Resulting from the marriage of top-down and self-assembly techniques, this method provides a facile, effective, and controllable approach for creating nanogap enabled SERS devices in fluidic channels, and hence can advance applications in precision medicine.
关键词： anticancer drugs,doxorubicin,nanogap plasmonic structures,capillary-force driven self-assembly,surface-enhanced Raman spectroscopy,SERS,laser printing
更新于2025-09-23 15:19:57
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a??Burning Lampa??-like Robust Molecular Enrichment for Ultrasensitive Plasmonic Nanosensors
摘要： Enriching and locating target analytes into specific “hot spot” are vital for ultrasensitive molecular identification and detection using plasmonic-based techniques. Inspired by mass transportation in lamp wicks, we develop an effective enrichment strategy for highly diluted analytes, in which analytes and Au nanoparticles are transported via solution microflow under the capillarity driving force of glass fiber papers to a heated region. After evaporation, a large volume of solution contained analytes and Au nanoparticles are condensed into a very limited area, and thus, analyte molecules are effectively enriched and located into SERS hot spots. Using this enrichment strategy, the sensitivity and detection limits of SERS are remarkably improved. Detection levels of crystal violet and anthracene are down to 10-16 M and 10-10 M, respectively. This enrichment strategy is very robust and easy to implement, and it can potentially be exploited in various plasmonic-based molecular detection and identification techniques.
关键词： enrichment,ultrasensitive detection,heating evaporation,capillary force,surface enhanced Raman scattering
更新于2025-09-19 17:13:59
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Interfacial Capillarya??Forcea??Driven Selfa??Assembly of Monolayer Colloidal Crystals for Supersensitive Plasmonic Sensors
摘要： Colloidal lithography technology based on monolayer colloidal crystals (MCCs) is considered as an outstanding candidate for fabricating large-area patterned functional nanostructures and devices. Although many efforts have been devoted to achieve various novel applicatons, the quality of MCCs, a key factor for the controllability and reproducibility of the patterned nanostructures, is often overlooked. In this work, an interfacial capillary-force-driven self-assembly strategy (ICFDS) is designed to realize a high-quality and highly-ordered hexagonal monolayer MCCs array by resorting the capillary effect of the interfacial water film at substrate surface as well as controlling the zeta potential of the polystyrene particles. Compared with the conventional self-assembly method, this approach can realize the reself-assembly process on the substrate surface with few colloidal aggregates, vacancy, and crystal boundary defects. Furthermore, various typical large-scale nanostructure arrays are achieved by combining reactive ion etching, metal-assisted chemical etching, and so forth. Specifically, benefiting from the as-fabricated high-quality 2D hexagonal colloidal crystals, the surface plasmon resonance (SPR) sensors achieve an excellent refractive index sensitivity value of 3497 nm RIU?1, which is competent for detecting bovine serum albumin with an ultralow concentration of 10?8 m. This work opens a window to prepare high-quality MCCs for more potential applications.
关键词： colloidal lithography,plasmonic sensors,monoloidal colloidal self-assembly,nanostructure arrays,interfacial capillary force
更新于2025-09-16 10:30:52
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Decoupling the contributions to the enhancement of electrical conductivity in transparent silver nanowire/zinc oxide composite electrodes
摘要： Electrical properties of silver nanowire (AgNW)-based transparent electrodes have been improved without transmittance loss by forming a composite with zinc oxide (ZnO). Here, we identified the dominant effect responsible for the improvement of electrical conductivity of the transparent AgNW:ZnO composite electrodes by fabricating the AgNW:ZnO composite electrodes with different architectures and theoretically calculating the overall resistance of their equivalent circuits. Specifically, when we compared the overall resistances of the AgNW:ZnO electrodes with various architectures by experiment, the electrode with only the electrical bridge effect showed the lowest electrical resistance. In addition, while the theoretical overall resistances were comparable on changing the interconnect resistances between the silver nanowires in the equivalent circuits of all architectures, they decreased dramatically with the decreasing ZnO bridging resistance. Thus, it was concluded that the electrical bridge effect is more important than the capillary force effect which decreases the interconnect resistance between the silver nanowires for the enhancement of the electrical properties of AgNW:ZnO composite electrodes. It was also found that the AgNW:ZnO electrodes with only the electrical bridge effect showed better device performances when applied to optoelectronic devices such as organic photovoltaics.
关键词： electrical conductivity,silver nanowire,electrical bridge effect,zinc oxide,capillary force effect
更新于2025-09-09 09:28:46