To improve the metal-enhanced fluorescence (MEF) effect of nanogolds (AuNPs) and accurately detect specific DNA sequences via DNA hybridization, novel hybrid magnetic nanoparticles/nanogold clusters (HMNCs) were designed based on finite-difference time-domain simulation results and prepared by using Fe3O4 and nanogolds. The nanogolds outside the HMNC were then conjugated with thiol-terminated DNA molecules, thus DNA modified-HMNCs (DNA-HMNCs) were obtained. The size distributions of these nanostructures were measured by a Malvern size analyzer, and their morphology was observed via transmission electron microscopy (TEM). The ultraviolet (UV)-visible (vis) absorption spectra of the samples were recorded with a UV-2600 spectrophotometer. Fluorescence spectra and the MEF effect were recorded using a spectrophotofluorometer, and lifetimes were determined using a time-correlated single photon counting apparatus. The prepared HMNCs were stable in aqueous solutions and had an average diameter of 87 ± 3.2 nm, with six to eight AuNPs around a single Fe3O4 nanoparticle. Fluorescein isothiocyanate (FITC) tagged DNA-HMNC conjugates exhibited a significant MEF effect and could accurately detect specific DNA sequences after DNA hybridization. This result indicates their various potential applications in sensors and biomedical fields.
Nanomaterials
(NMs) inevitably adsorb proteins in blood and form
“protein corona” upon intravenous administration as
drug carriers, potentially changing the biological properties and
intended functions. Inspired by anti-adhesion properties of natural
proteins, herein, we employed the one-bead one-compound (OBOC) combinatorial
peptide library method to screen anti-adhesion peptides (AAPs) against
proteins. The library beads displaying random peptides were screened
with three fluorescent-labeled plasma proteins. The nonfluorescence
beads, presumed to have anti-adhesion property against the proteins,
were isolated for sequence determination. These identified AAPs were
coated on gold nanorods (GNRs), enabling significant extension of
the blood circulating half-life of these GNRs in mice to 37.8 h, much
longer than that (26.6 h) of PEG-coated GNRs. In addition, such AAP
coating was found to alter the biodistribution profile of GNRs in
mice. The bioinspired screening strategy and resulting peptides show
great potential for enhancing the delivery efficiency and targeting
ability of NMs.
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