Figure 4.

Nanofibers as flexible SERS substrates. (a) AgNPs on PI nanofabric: A schematic diagram showing the preparation of the sample for SERS characterization, SERS spectra of the solid p-ATP powder, and the 1.0 × 10⁻⁴ M p-ATP dropped on the surface of the Ag@PI nanofabric (5 μL on 9 mm²) with different diameters of Ag nanoparticles (24.4 nm, 34.3 nm, and 51.8 nm), and SERS signal reproducibility of the p-ATP on the Ag@PI nanofabric with 34.3 nm Ag nanoparticles recorded on different randomly selected spots. Reproduced from [106] Copyright (2020), with permission from Elsevier. (b) Branched AuNPs on PS-P4VP nanofiber: uniform distribution of well-dispersed branched AuNP arrays, which allow for significantly higher SERS response than spherical AuNPs, and schematic representation of the fabrication procedure with application in the direct measure of the internal pH of cells and external pH gradients in cell culture environments. Adapted with permission from [107] Copyright (2020) American Chemical Society.