Transferrable SERS Barcodes

Abstract

The demand for encoded surfaces has increased significantly over the past decade driven by the rapid digitalization of the world. Surface‐enhanced Raman scattering (SERS) offers unique capabilities in generation of encoded surfaces. The challenge is the limited versatility of SERS‐based encoding systems in terms of the applicable surfaces. This study addresses this challenge by using a temporary tattoo approach together with simplified fabrication of SERS‐active patterns by ink‐jet printing of a particle‐free reactive silver ink. Plasmonic silver nanostructures form on the tattoo paper upon ink‐jet printing and a brief thermal annealing. The SERS activity is sufficient to detect taggant molecules of rhodamine 6G, methylene blue, and rhodamine B with a nanomolar level sensitivity. Raman‐active taggants can be incorporated into the ink, for drop‐on‐demand patterning of multiple molecules in 1D and 2D barcode geometries. The SERS barcodes can be effectively transferred to a range of different substrates retaining high plasmonic activity and geometric integrity. The presented approach decouples the SERS‐active pattern preparation from the final substrate and greatly improves the versatility of the barcodes.

Disintegration and Machine-Learning-Assisted Identification of Bacteria on Antimicrobial and Plasmonic Ag–CuxO Nanostructures

“…The XRD analysis also confirms the existence of metallic Ag 0 via peaks located at 38, 44, 65, 77, and 82°, corresponding to planes (111), (200), (220), (311), and (222) of the fcc (face-centered cubic) crystal structure (JCPDS, file nos. 04-0783), respectively . Besides these, peaks originating from the paper (cellulose and CaCO 3 ) substrate also show up in the XRD (elemental analysis of the untreated paper is shown in Figure S4).…”

“…For this purpose, we first characterized the SERS activity of the nanostructured surface using R6G as a probe molecule and studied the detection limit, enhancement factor, repeatability, and analyte concentration-SERS intensity relationship. As shown in Figure 4, the characteristic peaks of R6G 36,44 be collected on the untreated paper surface, even at a very high concentration (Figure S8A). The composite nanostructure showed a high level of SERS activity with an AEF of 5.1 × 10 6 (Figure S8B), which is comparable to other studies.…”

“…32 The XRD analysis also confirms the existence of metallic Ag 0 via respectively. 36 Besides these, peaks originating from the paper (cellulose and CaCO 3 ) substrate also show up in the XRD (elemental analysis of the untreated paper is shown in Figure S4). Concerning bactericidal activity, the Ag−Cu x O nanostructures killed almost all bacteria, while bacteria on untreated surfaces increased by approximately ∼200 times after only 24 h (Table S4).…”

Machine Learning-Assisted Pesticide Detection on a Flexible Surface-Enhanced Raman Scattering Substrate Prepared by Silver Nanoparticles

“…With respect to the amount of materials used, at least 3 mL of the C. libani extract (Figure b) has to be used to obtain reasonable SERS signals for the in-plane C–C–C stretch, out-of-plane C–H bend, and the aromatic C–C stretch vibrational peaks of R6G at 614, 773, and 1364–1649 cm –1 , respectively . When only 1 mL of the C.…”

“…With respect to the amount of materials used, at least 3 mL of the C. libani extract (Figure 3b) has to be used to obtain reasonable SERS signals for the in-plane C−C−C stretch, out-of-plane C−H bend, and the aromatic C−C stretch vibrational peaks of R6G at 614, 773, and 1364−1649 cm −1 , respectively. 60 When only 1 mL of the C. libani extract is used to reduce AgNO 3 , no characteristic SERS signal of R6G is detected on the paper surface, implying that no Ag NPs are grown. Interestingly, when an extra amount of the reducing agent is used (5 mL of the C. libani extract), the SERS signal decreases.…”