Flexible membranes of Ag-nanosheet-grafted polyamide-nanofibers as effective 3D SERS substrates

Abstract

We report on a synthetic approach to produce self-supported flexible surface-enhanced Raman scattering (SERS) active membranes consisting of polyamide (PA) nanofibers grafted with vertical Ag-nanosheets, via a combinatorial process of electrospinning PA-nanofiber membranes, assembling Au-nanoparticles on the PA-nanofibers as seeds for subsequent growth of Ag-nanosheets, and electrodepositing Ag-nanosheets on the electrospun PA-nanofibers. As a high density of Ag-nanosheets are vertically grown around each PA-nanofiber in the three-dimensional (3D) networked PA-nanofiber membranes, homogeneous nano-scaled gaps between the neighboring Ag-nanosheets are formed, leading to a high density of 3D SERS "hot spots" within the Ag-nanosheet-grafted PA-nanofiber membranes. The Ag-nanosheet-grafted PA-nanofiber membranes demonstrate high SERS activity with excellent Raman signal reproducibility for rhodamine 6G over the whole membrane. For a SERS-based trial analysis of polychlorinated biphenyls (PCBs, a kind of global environmental hazard), the 3D SERS substrate membranes are modified with mono-6-β-cychlodextrin to effectively capture PCB molecules. As a result, not only a low concentration down to 10(-6) M is reached, but also two congeners of PCBs in their mixed solution are identified, showing promising potential in SERS-based rapid detection of trace organic pollutants such as PCBs in the environment.

Nanoplasmonic Chitosan Nanofibers as Effective SERS Substrate for Detection of Small Molecules

“…2g) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 12 785 nm. The obtained value of the EF is in agreement with recently published data 21,25 . In order to verify the uniformity of the SERS signal from the developed plasmonic nanofibers, which is extremely important in terms of reproducibility, confocal Raman imaging was performed.…”

Electrospun Nanostructures for High Performance Chemiresistive and Optical Sensors

“…Electrospun optical nanomaterials have mainly been possible due to the chemical versatility of electrospinning, which allows functional NPs and small organic molecules to be incorporated and spun together with polymer solutions. Also, methods for post‐processing and surface functionalization are being developed which allow optically active NPs and molecular systems to be directly linked on the surface of fibers . Optically active NFs can be electrospun by basically three approaches: (i) embedding absorbing or luminescent chromophores or NPs, bio‐chromophores, and plasmonic metal NPs in transparent and optically inert polymers; (ii) using conjugated polymers, which can intrinsically absorb/emit light, as fiber constituents, and (iii) attaching optically active nanosystems to the polymer surface, by suitable chemical functionalization.…”

“…In other approaches, substrates for SERS are produced by decorating the surface of the electrospun NFs by metal NPs or nanosheets . Given the high localization of the field enhancement by NPs, these approaches are in principle more effective to improve Raman and SERS signals generated by analytes.…”

CNTs-anchored egg shell membrane decorated with Ag-NPs as cheap but effective SERS substrates

“…Compared with the dispersed Ag colloidal nanoparticles (NPs), delicate spatial arrangement of Ag-NPs on the 3D-frameworks may ensure better reproducibility and reliability of SERS signals, and also provide additional signal enhancement due to the newly generated "hot spots" and possible cavity resonances [7][8][9]. Thus much effort has been made on the fabrication of SERS substrates with various arrangements of Ag nanostructures on nonplasmonic 3D-frameworks with high uniformity [6][7][8][9][10][11][12][13][14][15][16][17]. However, sophisticated fabrication procedures with high cost are usually required in the previously reported studies, which are time/ energy-consuming.…”