Hydrophilic–Hydrophobic Nanohybrids of AuNP-Immobilized Two-Dimensional Nanomica Platelets as Flexible Substrates for High-Efficiency and High-Selectivity Surface-Enhanced Raman Scattering Microbe Detection

Abstract

A flexible hybrid substrate was developed by affixing gold nanoparticles (AuNPs) onto the surface of two-dimensional nanomica platelets (NMPs). The substrate was successfully used in biosensors with high efficiency and high selectivity through surface-enhanced Raman scattering (SERS). By controlling the amphiphilicity of the hybrid substrate, the flexible substrate was made highly selective toward biomolecules. Four different SERS substrate systems were constructed, including intercalated mica, exfoliated NMPs, hydrophilic exfoliated NMPs, and hydrophobic exfoliated NMPs. NMPs were only 1 nm thick. AuNPs adsorbed on both sides of NMPs and thus created excellent threedimensional hot junction effects in the z-axis direction. For the detection of adenine in DNA, a satisfactory Raman enhancement factor (EF) of up to 8.9 × 10 6 was achieved with the detection limit as low as 10 −8 M. Subsequently, the AuNP/NMP hybrids were adopted to rapidly detect hydrophilic Staphylococcus hominis and hydrophobic Escherichia coli. The AuNP/PIB−POE−PIB/NMP nanohybrid was concurrently hydrophilic and hydrophobic. This amphiphilic property greatly enhanced the detection selectivity and signal intensity for hydrophilic or hydrophobic bacteria. Overall, AuNPs/PIB−POE−PIB/NMPs developed as SERS substrates enable rapid, sensitive biodetection.

Au Nanorods on Carbon-Based Nanomaterials as Nanohybrid Substrates for High-Efficiency Dynamic Surface-Enhanced Raman Scattering

“…Figure g shows that the limit of detection of the AuNRs was 10 –7 M. The sensitivity of the SERS substrate for each kind of backplane was quantified based on the enhancement factor (EF). The formula for calculating the EF value is as follows: EF = ( I SERS / N SERS ) / ( I Raman / N bulk ) …”

“…The resulting nanohybrids are used for SERS measurements. The nanohybrid materials have good optical penetration, increase the contact area with the target analyte, and generate hotspots on the z axis. − When further applied in D-SERS, this method affords fast, stable, and more strongly enhanced Raman signals. Finally, the sensitivity of the fabricated SERS substrate to Rhodamine 6G (R6G), a dye molecule with fluorescent properties and high photostability, is analyzed, where the single molecule is rapidly detected, enabling water quality and environmental monitoring …”

Triangular gold nanoplates/two-dimensional nano mica platelets with a 3D lightning-rod effect as flexible nanohybrid substrates for SERS bacterial detection

“…48 They can serve as a good carrier for stabilizing nanoparticles. 46 As we have reported recently, many noble metal nanoparticles/2D material nanohybrids have been developed as SERS substrates, and they have shown excellent sensitivity for the detection of single molecule and biomolecules. 14,26 In this study, we focused on the use of the lightning-rod effect of TAuNPs for the detection of biomolecules.…”

“…43,44 In our previous study, we used synthetic fluorinated mica to obtain nano mica nanoplatelets (NMPs) using a one-step delamination method. 45,46 The surface structure is made up of silicon–oxygen bonds, and the adsorption of microbial molecules was enhanced by the polar interactions and ionic charge on the surface. 47 Delaminated mica flakes also have a uniform shape and a high surface-area-to-volume ratio, making them excellent materials for applications requiring a small-scale high-surface interaction.…”

Flexible Hybrid Electronics Nanofiber Electrodes with Excellent Stretchability and Highly Stable Electrical Conductivity for Smart Clothing

“…Following a previous study, the polymeric dispersant PIB–POE–PIB triblock copolymer was synthesized through amination and further imidization between PIB-SA and POE-2000 (molar ratio: 2:1), as shown in Figure S4 of the Supporting Information. − PIB-SA (25.0 g, 2 mol) was dissolved in THF (200 mL) in a three-necked round-bottom flask; then, POE-2000 (19.0 g, 1 mol, dissolved in THF (152 mL) in advance) was added dropwise, and a mechanical stirrer and thermocouple were used for mixing and heating, respectively. The mixture was allowed to react at 25 °C for 3 h under constant stirring before being analyzed by Fourier transform infrared spectroscopy (FT-IR), as shown in Figure S5 of the Supporting Information.…”