Abstract
We have successfully developed novel surface-enhanced Raman scattering (SERS) substrates with three-dimensional (3D) porous structures for effectively improving the sensitivity and reproducibility of SERS, which can rapidly detect small molecules (rhodamine 6G as an example). Periodical arrays of the honeycomb-like substrates were fabricated by self-assembling polyurethane-co-azetidine-2,4-dione (PU-PAZ) polymers. PU-PAZ comprising amphiphilic dendrons could stabilize the phase separation between the water droplets and polymer solution, and then organize into regular porous structures during the breath figure method. Subsequently, SERS substrates were fabricated by immobilizing gold nanoparticles (AuNPs) onto the honeycomb-like films with various 3D porous structures, controlled by the different PU-PAZ concentrations and relative humidities. Results show that surface enhancement factors of honeycomb-like substrates were 20 times higher than that of flat-film substrates (control group) due to enormous hot-spots resonance effects by the 3D porous structure, verified through Raman mapping at various positions of the z-axis. Furthermore, the particle size effects were evaluated by immobilized 12 and 67 nm of AuNPs on the honeycomb-like substrates, indicating larger AuNPs could induce more pronounced hot-spots effects. The generation of hot-spots resonance to enhance Raman intensity is strongly dependent on the diameter of AuNPs and the pore size of the honeycomb-like and 3D porous substrates for label-free and rapid SERS detection.
Highlights
Surface-enhanced Raman scattering (SERS) has recently shown tremendous potential in detecting a wide range of trace-level analytes, from single functional molecules to complex biomaterials [1,2,3,4,5,6].The SERS effect improves the intrinsic limitation of a weak Raman scattering signal when detecting a low concentration of targeting samples
Selected area diffraction (SAED) images of 12 and 67 nm Au nanoparticles were illustrated in Figure 1d, showing diffraction planes of (111), (200), (220), (311), and (222)
After calculation by the method provided by Haiss et al [59], the diameters of AuNPs are similar to those observed from dynamic light scattering (DLS) and Transmission electron microscope (TEM)
Summary
Surface-enhanced Raman scattering (SERS) has recently shown tremendous potential in detecting a wide range of trace-level analytes, from single functional molecules to complex biomaterials [1,2,3,4,5,6].The SERS effect improves the intrinsic limitation of a weak Raman scattering signal when detecting a low concentration of targeting samples. Surface-enhanced Raman scattering (SERS) has recently shown tremendous potential in detecting a wide range of trace-level analytes, from single functional molecules to complex biomaterials [1,2,3,4,5,6]. The Raman spectrum is a collection of inelastic scattering photons from measured molecules, which provides specific vibrational fingerprints of chemical structures. These small quantities of scattered photons are difficult to detect. Polymers 2017, 9, 93 amplified when absorbing the compound on roughed silver substrates, and initiated the Raman detection of this SERS phenomenon. SERS has been widely applied in identifying chemical molecules, biological materials, as well as environmental/water pollutants in a facile manner [4,11,12,13,14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
