Self-Healing 3D Liquid Freestanding Plasmonic Nanoparticle Membrane for Reproducible Surface-Enhanced Raman Spectroscopy Sensing

Abstract

Poor reproducibility has long been one of the major limitations for quantitative surface-enhanced Raman scattering (SERS) analysis. Historically, plasmonic nanoparticles (NPs) have been assembled onto a certain solid support to address this limitation. Here, in this work, we report a highly reproducible and self-healing liquid SERS platform based on a three-dimensional liquid freestanding membrane. Briefly, the plasmonic NP suspension is mixed with an analyte and then transferred into the perforated mold to form an FSM, which not only improves signal reproducibility but also enables on-demand analysis. The FSM was characterized in situ with a confocal laser scanning microscope and small-angle X-ray scattering. It was found that even with the most common, wet chemistry-prepared nonuniform silver NPs (Ag NPs), the relative standard deviation (RSD) of a large-area (3.5 mm2) SERS mapping was only 8.80%. The RSDs of the 2500 point-mappings of FSMs formed with Au or Ag NPs of different shapes and sizes were all below 10%. Various samples were quantitatively analyzed with the FSM method and compared with high-performance liquid chromatography/UV–vis. Statistical analysis revealed no significant difference. It is worth mentioning that this general-purpose method with low cost is extremely simple, which may pave the way for universal SERS quantitative analysis on-demand at the point-of-use.

Free-Standing Membrane Liquid-State Platform for SERS-Based Determination of Norfloxacin in Environmental Samples

“…It is incredibly critical to be able to reproduce the Raman signal of the measured substance stably for the use of SERS as a routine analytical tool [28]. We suspect that the FSM platform can form a uniform and stable liquid film due to the high concentration of nanoparticles after inspissation, the Brownian motion of the particles and the fluidity of the liquid, which could be found in literature [13]. To verify the repeatability of the FSM platform, we evaluated 10 FSM platforms in Fig.…”

“…The Ag NPs, the bimetallic NPs and the Au NPs were prepared according to the previous literature [13,14]. The characterization of UV − Vis and SEM can be seen in Fig.…”

“…In this work, we discovered a new FSM SERS substrate, which can directly place a concentrated bimetallic NPs suspension on a hydrophobic surface, and then use a special metal film orifice plate to form FSM. This method has high repeatability and good sensitivity [13]. The application of FSM SERS substrate in the quantitative detection of NOR in running water and river water was also explored, which showed the method having great potential in the detection of drug residues for real environmental samples.…”

Boosting bacteria differentiation efficiency with multidimensional surface‐enhanced Raman scattering: the example of Bacillus cereus

“…The construction of the FLM platform could be completed in short period of time. [35,36] Briefly, 20 μl of the concentrated SERS NPs suspension was mixed with the same volume of bacterial lysate before being subjected to vortexing for 20 s. Then, 25 μl of the mixed sample solution was placed onto polytetrafluoroethylene (PTFE) tape to form droplets. Finally, a customized mould was used to form the FLM to acquire the SERS spectra.…”

Probing Dynamic Features of Phagosome Maturation in Macrophage using Au@MnOx@SiO2 Nanoparticles as pH‐Sensitive Plasmonic Nanoprobes

“…Thanks to the localized surface plasmonic resonance effect, versatile plasmonic nanoprobes with elegant optical properties have been developed for biosensing and bioimaging in past decades. [13] In this work, we proposed the multilayered Au@MnO x @SiO 2 nanoparticles as pH-sensitive plasmonic nanoprobes for monitoring the dynamic acidification features of individual phagosomes in macrophage under darkfield microscopy. The gold nanoparticle core within the plasmonic nanoprobe plays a role of signal reporter, the MnO x shell and the outmost SiO 2 act as the sensing layer and the protecting layer, respectively.…”