Single-step generation of fluorophore-encapsulated gold nanoparticle core–shell materials

Abstract

We report a simple route to produce fluorophore-encapsulated gold nanoparticles (AuNPs) in a single step under aqueous conditions using the fluorophore 1-pyrenemethylamine (PMA). Different amounts of PMA were used and the resulting core-shell gold nanoparticles were analyzed using UV-visible absorption spectroscopy, fluorescence spectroscopy, and transmission and scanning electron microscopy. Electron microscopy analysis shows nanoparticles consisting of a gold nanoparticle core which is encapsulated with a lower contrast shell. In the UV-visible spectra, we observed a significant red shift (37 nm) of the localized surface plasmon resonance (LSPR) absorption maximum (lambda(max)) compared to citrate-stabilized AuNPs of a similar size. We attribute the prominent LSPR wavelength shift for PMA-AuNP conjugates to the increase in the local dielectric environment near the gold nanoparticles due to the shell formation. This simple, aqueous-based synthesis is a new approach to the production of fluorophore-encapsulated AuNPs that could be applicable in biological sensing systems and photonic device fabrication.

Controlled spontaneous generation of gold nanoparticles assisted by dual reducing and capping agents

“…Notably, addition of a large excess of honey, compared with Au(III), inverted the ratio of nanotriangles and nanospheres. Recently, a fluorophore-substituted amine 1-pyrenemethylamine acted as a strong coating agent for Au-NPs following an auto-reduction pathway based on the electrostatic interaction of the amine with the gold salt followed by a reduction process promoted by the protonated amine [99]. The authors clearly showed that the shell around the metal core of the particles was composed of unpolymerized 1-pyrenemethylamines.…”

Construction of a Porphyrin-Based Nanohybrid as an Analogue of Chlorophyll Protein Complexes and Its Light-Harvesting Behavior Research

“…29 The C 1s core level peak (Figure 3C) appearing at 285.2 eV is probably generated from the CNTs carbon (CC) at 284.6 eV, low levels of oxidized eV. 24,29,32 Therefore, XPS data suggests that an Au@THPP/ CNTs/AP composite combined by covalent linkage and Au@ THPP is surely attached on CNTs. Above all, Au@THPP/ CNTs/AP/ITO was accurately prepared, namely, a model has been successfully constructed by a chemical method.…”

“…The interaction of the nanohybrid can be revealed by examining Au 4f photoelectron spectra (Figure B). The binding energies of the Au 4f peak core level are all at 83.9 and 88.0 eV, which is the gold 4f 7/2 (83.9 eV) and 4f 5/2 (88.0 eV), − respectively. The line in 90.8 eV is probably the signal of gold oxide .…”

“…The N 1s spectrum from the AP-modified ITO and porphyrin molecules may be present as free molecules and as part of the shell structure and can be separated into two peaks with binding energies at 399.9 and 401.2 eV (Figure D), possibly attributed to the amino groups (−NH 2 ) and azo groups (NN) . The C 1s core level peak (Figure C) appearing at 285.2 eV is probably generated from the CNTs carbon (CC) at 284.6 eV, low levels of oxidized carbon species at 285.5 eV, the ether carbon species (C–O–C) at 286.2 eV, porphyrin carbon species i.e., amide carbon species at 287.2 eV, and the carboxylic acid carbon species at 288.5 eV. ,, Therefore, XPS data suggests that an Au@THPP/CNTs/AP composite combined by covalent linkage and Au@THPP is surely attached on CNTs. Above all, Au@THPP/CNTs/AP/ITO was accurately prepared, namely, a model has been successfully constructed by a chemical method.…”

“…The size of AuNPs is measured to be 40 nm, and the thickness of Au@THPP and vesicle structure aggregated by THPP are about 20 nm. There are a few possible reasons accounting for the formation of vesicle structure, resulting from high temperature and ethanol reduction in this reaction. , In order to further investigate formation of the core–shell structure, both Au@THPP and THPP were also analyzed by FT-IR (Figure S5, Supporting Information).…”