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Thiolated Cyanines Appended to Partially Pegylated Gold Nanoparticles for Fluorescence Quenching of Two-Channel Photothermal Inks. | LitMetric

AI Article Synopsis

  • - The study presents a new nanoink created from gold nanoparticles (AuNP) with two photothermally responsive absorption bands, one from AuNP and another from two specific Cy dyes that quench fluorescence due to their proximity to the gold surface.
  • - To create stable nanosystems, AuNPs were partially pegylated to avoid precipitation and then combined with the Cy dyes, resulting in stable AuNP@Cy/PEG hybrids that function in water and alcohol mixtures.
  • - Upon laser irradiation, these nanoinks show separate thermal responses based on the wavelengths used, enhancing their potential for use in photothermal anticounterfeit applications by complicating attempts to duplicate temperature responses.

Article Abstract

Following a new approach, we prepared a nanoink with two separate photothermally responsive absorption bands. One is the localized surface plasmon resonance (LSPR) absorption of gold nanoparticles (AuNP, d=17 nm), the second is the absorption band of two cyanine (Cy) dyes, Cy7-C6 or Cy7-C11, grafted to the AuNP surface through thiolated bridges of different lengths: the close proximity to the Au surface induces full quenching of the Cy fluorescence, resulting in thermal relaxation on irradiation. Attempts to full coat AuNP with the lipophilic Cy7-C6 and Cy7-C11 lead to precipitation from aqueous solutions. We thus prepared AuNP with partial pegylation (30, 50, or 70 %), using a long chain thiol-terminated PEG bearing a -COOH function. Addition until saturation of either Cy7-C6 or Cy7-C11 to the partially pegylated AuNP gave the AuNP@Cy/PEG hybrids (X=30, 50, 70) that are stable in water and in the water/alcohol mixtures used to prepare the nanoinks. Further overcoating of AuNP@Cy7-C6/PEG with PAH (polyallylamine hydrochloride) avoids LSPR hybridization in the dry nanoink printouts, that present two separate bands. When irradiated with laser sources near their absorption maxima, the printouts of the AuNP@Cy7-C6/PEG@PAH nanoink respond on two channels, giving different temperature increases depending on the irradiation wavelengths. This enhances the potentiality of use of these nanoinks for photothermal anticounterfait printouts, making more difficult to reproduce the correct ΔT vs λ output.

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Source
http://dx.doi.org/10.1002/chem.202400777DOI Listing

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