Smartphone-Based Attomolar Cyanide Ion Sensing Using Au-Graphene Oxide Cryosoret Nanoassembly and Benzoxazolium-Based Fluorophore in a Surface Plasmon-Coupled Enhanced Fluorescence Interface

Abstract

Photoplasmonic platforms are being demonstrated as excellent means for bridging nanochemistry and biosensing approaches at advanced interfaces, thereby augmenting the sensitivity and quantification of the desired analytes. Although resonantly coupled electromagnetic waves at the surface plasmon-coupled emission (SPCE) interface are investigated with myriad nanomaterials in order to boost the detection limits, rhodamine moieties are ubiquitously used as SPCE reporter molecules in spite of their well-known limitations. In order to overcome this constraint, in this work, a benzoxazolium-based fluorescent molecule, (E)-2-(4-(dimethylamino)­styryl)-3-methylbenzo­[d]­oxazol-3-ium iodide (DSBO), was synthesized to selectively detect the cyanide (CN–) ions in water samples. To this end, the sensitivity of the fabricated SPCE substrates is tested in spacer, cavity, and extended cavity nanointerfaces to rationalize the configurational robustness. The performance of the sensor is further improved with the careful engineering of gold (Au)-graphene oxide (GO) cryosoret nanoassemblies fabricated via an adiabatic cooling technology. The unique dequenching (turn-on) of the quenched (turn-off) fluorescent signal is demonstrated with the hybridized metal-π plasmon synergistic coupling in the nanovoids and nanocavities assisting delocalized Bragg and localized Mie plasmons. The spectro-plasmonic analysis yielded highly directional, polarized (>95%), and enhanced emission attributes with an attomolar limit of detection of 10 aM of CN– ions with high linearity (R 2 = 0.996) and excellent reliability, in addition to an exceptional correlation with the theoretically obtained TFclac simulations. The CN– ion sensing is experimentally validated with the smartphone-based cost-effective SPCE detection technology to render the device amenable to resource-limited settings. We believe that the unique fluorophore–cryosoret nanoassemblage presented here encourages development of frugal, unconventional, and highly desirable strategies for the selective quantitation of environmentally and physiologically relevant analytes at trace concentrations for use in point-of-care diagnostics.

DNA-Condensed Plasmonic Supraballs Transparent to Molecules

“…Considering the structural and functional uniqueness of such a new class of DNA-condensed AuNP supraballs, various application possibilities could exist. The existence of rich and tunable hotspots in the plasmonic supraballs along with their excellent colloidal and chemical stabilities promises their use as “homogeneous” SERS and fluorescence substrates workable in harsh environments. − The molecular permeability and nanoporosity of the metallic structures would be especially attractive to catalytic functions . The 5 nm AuNPs constituting the supraballs are intriguing since small AuNPs show fast hot-electron thermalization, making them attractive for photothermal applications. , The DNA matrices featuring alterable metal ions and nucleobases can be explored for their biological effects toward nanomedical pursuits .…”

A novel fluorescence–electrochemiluminescence dual-mode sensing platform for high-precision BRAF gene detection

“…Additionally, AuNPs serve as an effective immobilization platform for thiolated P-DNA, with their strong thiol affinity ensuring firm P-DNA adsorption for precise molecular recognition and signal transmission. 23–26 Their excellent biocompatibility and chemical stability further make AuNPs ideal for biosensor and analytical chemistry applications.…”

Unlocking the potential of perovskite-based nanomaterials for revolutionary smartphone-based sensor applications

“…5,13–16 The success of these sophisticated sensors is fundamentally dependent on the innovative materials from which they are constructed. 17–19 A variety of nanomaterials have demonstrated potential in this arena: graphene, with its extraordinary electrical conductivity and surface area; 20–22 gold-based nanomaterials, 23–26 revered for their distinctive plasmonic properties; and polymer dots, 27,28 quantum dots, 29,30 which may integrate seamlessly with existing semiconductor frameworks. Yet, within this innovative spectrum, Perovskite-based nanomaterials offer unmatched benefits for the evolution of smartphone-integrated sensors.…”