Abstract
The use of SERS for real-world bioanalytical applications represents a concrete opportunity, which, however, is being largely delayed by the inadequacy of existing substrates used to collect SERS spectra. In particular, the main bottleneck is their poor usability, as in the case of unsupported noble metal colloidal nanoparticles or because of the need for complex or highly specialized fabrication procedures, especially in view of a large-scale commercial diffusion. In this work, we introduce a graphene paper-supported plasmonic substrate for biodetection as obtained by a simple and rapid aerosol deposition patterning of silver nanowires. This substrate is compatible with the analysis of small (2 μL) analyte drops, providing stable SERS signals at sub-millimolar concentration and a detection limit down to the nanogram level in the case of hemoglobin. The presence of a graphene underlayer assures an even surface distribution of SERS hotspots with improved stability of the SERS signal, the collection of well-resolved and intense SERS spectra, and an ultra-flat and photostable SERS background in comparison with other popular disposable supports.
Highlights
Two-dimensional plasmonic substrates were rapidly obtained by a nebulizing jet of a proper amount of AgNWs colloidal solution toward a 2 × 2 cm2 piece of thin graphene paper (G-paper) (Figure 1)
The system included the possibility to impart a custom spacing of the graphene target to tune the covered airbrushed area, which was optimally set at 1 cm
Two-dimensional p substrates were rapidly obtained by a nebulizing jet of a proper amount of colloidal solution toward a 2 × 2 cm2 piece of thin graphene paper (G-paper)
Summary
We recently introduced a disposable SERS substrate in the form of a spotted membrane of silver nanowires (AgNWs), as obtained by a combined bottom-up/top-down scheme based on the flow-through method, plus laser patterning for rapid label-free analysis of small volumes of biological species [12]. This system provided a successful detection of proteins with different molecular weights, hydrodynamic radius, and secondary structures [14] and was tested in the chemostructural discrimination between toxic and nontoxic amyloid beta forms of Alzheimer’s disease [15]
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