Synthesis of Au@Ag core-shell nanostructures with a poly(3,4-dihydroxy-L-phenylalanine) interlayer for surface-enhanced Raman scattering imaging of epithelial cells

Abstract

Poly(3,4-dihydroxy-L-phenylalanine) (polyDOPA) is a stable and biocompatible reducing agent. A versatile strategy is described here for the synthesis of core-shell Au@Ag nanostructures containing a polyDOPA interlayer. The latter provides abundant sites for deposition of nanocomposites, to immobilize molecules and to grow shells. The Au@polyDOPA@Ag nanoparticles are shown to generate strong and stable surface-enhanced Raman spectroscopy (SERS) signals compared to bare AuNPs and bare AgNPs. Folic acid was then immobilized on Au@polyDOPA@Ag nanoparticles and then applied to SERS imaging of human lung adenocarcinoma cell line A549 by the specific recognition of the folic acid receptor. The folic acid-conjugated SERS tags were promising to be nanoplatforms for imaging of cancer cells. Graphical abstract An Au@Ag core-shell nanostructures SERS nanotag with a polyDOPA interlayer was fabricated and then applied to SERS imaging of epithelial cells. (DOPA: 3,4-Dihydroxy-[-phenylalanine]; FA: folic acid; 4-MBA: 4-mercaptobenzoic acid).

Gold–Silver Bimetallic Alloy Nanoparticles in a Covalent Organic Framework for Real-Time Monitoring of Hydrogen Peroxide from Live Cells

“…04-0783) (curve b). ,, The XRD patterns of AuNPs-COF 2θ peaks at 19.92, 24.12, 38.17, 44.67, 64.62, and 77.72° correspond to (001), (202), (111), (200), (220), and (311) for AuNPs-COF. − , The obtained peaks at 38.37° (111), 44.67° (200), 64.72° (220), and 77.72° (311) are characteristic peaks of AuNPs and also highly crystalline in behavior (JCPDS No. 04-0784). , Finally, the Au-AgNPs-COF showed notable 2θ peaks at 19.77° (001), 24.07° (202), 38.17° (111), 44.22° (200), 64.22° (220), and 77.47° (311), which are characteristics of the bimetallic nanocomponents (curve c). , In the absence of two different 2θ values in the bimetallic composite, nanoparticles are clearly reveal that the system has an alloy nature. Figure S8 (SI SI.5) describes the detailed thermal properties of the COF and its nanocomposites.…”

“…04-0784). 17,25 Finally, the Au-AgNPs-COF showed notable 2θ peaks at 19.77°(001), 24.07°(202), 38.17°(111), 44.22°( 200), 64.22°(220), and 77.47°(311), which are characteristics of the bimetallic nanocomponents (curve c). 41,42 In the absence of two different 2θ values in the bimetallic composite, nanoparticles are clearly reveal that the system has an alloy nature.…”

“…To develop electrically conductive COFs, carbon nanotubes (CNTs), graphene oxide (GO), metal oxides (MOx), polymer films (PFs), and metal nanoparticles (MNPs) can be potentially used. − Among them, metal nanoparticles have received huge significant attention because of their remarkable properties, including optical, electrical, thermal, biocompatibility, and high active surface area. ,,, Bimetallic nanoparticles (BMNPs) have many advantages over monometallic nanoparticles due to their synergic and alloy effects that together offer enhanced electrocatalytic properties. , Bimetallic NPs can be intertwined through core–shell, intermetallic, clusters, and alloy structures (ASs) . The ASs and core–shell (CS) designs have recently received more attention. , The morphology of bimetallic alloy and core–shell nanoparticles depends on the molar ratio composition, metal selection/reducing agent, solvent, and contact time .…”

Rapid and sensitive analysis of trace β-blockers by magnetic solid-phase extraction coupled with Fourier transform ion cyclotron resonance mass spectrometry

“…The catechol in polyDOPA films is easily oxidized to quinone, inducing a localized reduction of metal ions [ 35 , 38 ]. Simultaneously, a polyDOPA film is spontaneously deposited outside the structure, acting as a protective layer to prevent the oxidation of the generated Ag [ 34 ]. Therefore, DOPA was the reductant and stabilizer for the formation of AgNPs during the reaction process, and polyDOPA@Ag-MNPs were synthesized in situ.…”

“…Wen et al. [ 34 ] prepared Au@polyDOPA@Ag nanoparticles to form a surface-enhanced Raman spectroscopy tag for imaging in the human lung adenocarcinoma cell line A549. A one-step in situ reduction process has been reported for the preparation of Ag@DOPA@Hg nanostructures to detect Hg 2+ using a colorimetric method [ 35 ].…”