Au-Ag Alloy Nanoshuttle Mediated Surface Plasmon Coupling for Enhanced Fluorescence Imaging

Abstract

Surface plasmon-coupled emission (SPCE), a novel signal enhancement technology generated by the interactions between surface plasmons and excited fluorophores in close vicinity to metallic film, has shown excellent performance in bioimaging. Variable-angle nanoplasmonic fluorescence microscopy (VANFM), based on an SPCE imaging system, can selectively modulate the imaging depth by controlling the excitation angles. In order to further improve the imaging performance, Au-Ag alloy nanoshuttles were introduced into an Au substrate to mediate the plasmonic properties. Benefiting from the strong localized plasmon effect of the modified SPCE chip, better imaging brightness, signal-to-background ratio and axial resolution for imaging of the cell membrane region were obtained, which fully displays the imaging advantages of SPCE system. Meanwhile, the imaging signal obtained from the critical angle excitation mode was also amplified, which helps to acquire a more visible image of the cell both from near- and far-field in order to comprehensively investigate the cellular interactions.

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

“…A series of highly sensitive and rapid biosensing devices have been demonstrated using the versatile SPCE technology on account of its ability to render highly directional and polarized emission with superior spectral resolution capability. − Biosensing platforms specific to disease diagnostics, monitoring the efficacy of therapy, homeland security, well-being monitoring, and environmental analysis have been demonstrated using SPCE technology. − In the recent past, novel nanoengineering protocols have been developed over the SPCE substrates to enhance the fluorescence enhancements with the primary goal of increasing the clear contrast between the target signal intensity and the associated background noise. Improving the prism coupled signal intensity would drastically increase the accuracy and reproducibility, especially for sensors displaying a high operational sensing range.…”

Review of Gold Nanoparticles in Surface Plasmon-Coupled Emission Technology: Effect of Shape, Hollow Nanostructures, Nano-Assembly, Metal–Dielectric and Heterometallic Nanohybrids

“…In this section, we discuss a few case studies where the plasmonic AuNPs are hybridized with Ag plasmonic nanomaterials in different geometries and architectures and explored in SPCE platform. An outstanding example is the investigation of AuAg alloy nanoshuttle demonstrated for imaging application by Li and co-workers using the SPCE technology [ 106 ]. On account of the hybrid plasmonic coupling between the SPPs of Au substrate and the hybrid modes of AuAg nanoalloy, augmented image brightness, better signal-to-noise ratio and axial resolution were realized.…”

“…The performance of the AuAg shuttle towards imaging application was evaluated by dyeing the whole of Hela cells using rhodamine B molecule and observing the emission from the SPCE angle [ 106 ]. The dependence of the excitation angle as well as the polarization of the light on the intensity of the emission occurring from the labelled cells is shown in Figure 8 h. The experiments were performed using the critical angle excitation mode to understand the cytoplasmic region away from the substrate, while the SPCE presented information about the membrane of the cell due to the high background rejection property of SPCE.…”

“…The dependence of the excitation angle as well as the polarization of the light on the intensity of the emission occurring from the labelled cells is shown in Figure 8 h. The experiments were performed using the critical angle excitation mode to understand the cytoplasmic region away from the substrate, while the SPCE presented information about the membrane of the cell due to the high background rejection property of SPCE. From Figure 8 i,j, one can clearly observe the effect of AuAg nanoalloys in enhancing the imaging analysis with amplified brightness and better clarity in visualization [ 106 ].…”

Biosensing Technologies: A Focus Review on Recent Advancements in Surface Plasmon Coupled Emission

“…This has assisted in the realization of 60-fold SPCE enhancements; following which, several other nano-architectures with numerous sizes, shapes and assemblies have been examined in the SPCE platform for achieving amplified SPCE enhancements [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Such synergy of fluorescence spectroscopy and applied nano-research with effective nano-engineering strategies has advanced the spectro-plasmonic modalities in the SPCE platform with newer applications and processes including, but not limited to: ultra-high sensitivity [ 41 , 42 , 43 ], CNT-assisted augmented coupling [ 44 ], cardiovascular disease and food biomarker monitoring [ 45 ], fluorescent polymer brushes for large angle studies [ 46 ], interfacial molecular beacon-related explorations [ 47 ], cavity-void plasmon coupling in nano-assemblies sustaining Bragg and Mie plasmons [ 48 ], adsorption-desorption analysis [ 49 ], lightning-rod effect [ 50 ], graphene π-plasmon hybrid coupling [ 51 , 52 , 53 , 54 ], mesoporous carbon florets for photon cascading in nanocavity [ 55 ], lower-to-higher aggregates coupling [ 56 ], magneto-plasmonics [ 57 ], PLEDs [ 58 ], simultaneous multianalyte sensing [ 59 ] and other cost-effective biosensing applications [ 60 , 61 , 62 , 63 , 64 , 65 , 66 ]. In spite of these developments, the three major long-standing limitations of the SPCE technology development have been: (i) a moderate increase in the SPCE signal intensity [ 67 , 68 , 6...…”