Novel One-pot Fabrication of Lab-on-a-Bubble@Ag Substrate without Coupling-agent for Surface Enhanced Raman Scattering

Abstract

Through in-situ reduction of silver nitrate without using any coupling-agent, a substrate for surface-enhanced Raman scattering (SERS) was prepared by coating silver on hollow buoyant silica microspheres as a lab on a bubble (LoB). The silver coated LoBs (LoBs@Ag) floated on surface of a solution could provide a very convenient platform for the detection of target molecules in the solution. The LoBs@Ag substrate not only immobilized well-distributed Ag nanoparticles on the surface LoBs, but excluded the interference of coupling agents. This yielded high-resolution SERS spectra with excellent reproducibility. The adsorption of crystal violet (CV) on the LoBs@Ag substrate was investigated by means of SERS combined with density functional theory (DFT) calculations. The LoBs@Ag substrate exhibited a remarkable Raman enhancement effect for CV with an enhancement factor of 6.9 × 108 and wide adaptability from dye, pesticide to bio-molecules. On the basis of this substrate, a simple and sensitive SERS method was proposed for the determination of trace organic pollutants or bio-molecules.

Surface-enhanced Raman scattering (SERS)-active substrates from silver plated-porous silicon for detection of crystal violet

“…The assignments of Raman bands of CV are listed in Table 1. The vibrational spectra for both SERS and normal Raman are well-matched with recently reported works [18,22].…”

“…AgNPs/meso-PSi 10 This result is consistent with the recently reported work of CV adsorption using hollow buoyant silica microspheres coated Ag substrates [22]. Of particular interest is the observation of a new, reasonable peak at 218 cm −1 in the SERS spectrum (Fig.…”

“…The estimated EF locates within the range of average reported values for immobilized metallic nanoparticles on solid supports (10 4 -10 7 ), even though larger EFs of 10 10 are sometimes claimed [28]. The SERS performance of the present PSi/Ag substrate towards the detection of CV in comparison to previously reported substrates is summarized in Table 2 [18,22,[29][30][31][32][33][34][35][36][37].…”

“…Based on the above observations and according to the surface selection rule [39], the enhancement in both in-plane and out-of-plane stretching modes indicates that the aromatic rings of dye molecule are tilted with respect to the PSi/Ag substrate. Table 2 Performance comparison of various SERS substrates towards the detection of CV (where n/a, not applicable) [18,22,[29][30][31][32][33][34][35][36][37].…”

Acetylcholinesterase-functionalized two-dimensional photonic crystals for the detection of organophosphates

“…Therefore, intensive attention is focused on the determination of Dipterex and other organophosphates with efficient methods, such as uorescent sensors, 1,2 chromogenic recognition, 3 quartzcrystal-microbalance (QCM) 4,5 and surface enhanced Raman spectroscopy (SERS). 6,7 However, a potential drawback of the above methods is the requirement of instruments with high cost and large sample volumes during the monitoring of target analytes, which can cause inconvenience in the eld detection.…”