Effects Induced by the Temperature and Chemical Environment on the Fluorescence of Water-Soluble Gold Nanoparticles Functionalized with a Perylene-Derivative Dye

Abstract

We developed a fluorescent molecular probe based on gold nanoparticles functionalized with N,N'-bis(2-(1-piperazino)ethyl)-3,4,9,10-perylenetetracarboxylic acid diimide dihydrochloride, and these probes exhibit potential for applications in microscopic thermometry. The intensity of fluorescence was affected by changes in temperature. Chemical environments, such as different buffers with the same pH, also resulted in different fluorescence intensities. Due to the fluorescence intensity changes exhibited by modified gold nanoparticles, these materials are promising candidates for future technologies involving microscopic temperature measurements.

Keywords: gold nanoparticles; gold nanorods; perylene-derivative dye; temperature-dependent fluorescence.

Figure 1

Fluorescence spectra of PZPER (50 μM, λ_ex = 450 nm) in water at 25, 50, 60, 70, 75, and 80 °C.

Figure 2

(a) Fluorescence spectra of PZPER (50 μM, λex = 450 nm) in water and buffers (10 mM, pH 7.4) at 25 and 80 °C, (b) fluorescence spectra of PZPER (50 μM, λex = 450 nm) in water and MOPS buffer (1 mM and 10 mM, pH 7.4) at 25 and 80 °C.

Figure 3

(a) Fluorescence spectra of PZPER (50 μM, λ_ex = 450 nm) in water and MOPS buffer (1 mM, pH 5.35 and 7.4) at 25 and 80 °C, (b) fluorescence spectra of PZPER (50 μM, λ_ex = 450 nm) in MOPS buffer (1 mM, pH 5.35) at variable temperatures (25 (black), 50 (red), 60 (green), 70 (purple), 75 (orange), and 80 (violet) °C.

Figure 4

Fluorescence spectra of PZPER (50 μM, λ_ex = 450 nm) in MOPS buffer (1 mM, pH 5.35) at 25 (1 cycle (green), 2 cycle (blue), 3 cycle (black)) and 80 °C (1 cycle (red), 2 cycle (orange), 3 cycle (purple)) (three cycles).

Figure 5

Synthesis of AuNPs functionalized with PZPER.

Figure 6

UV–Vis (a) and fluorescence (b) spectra of functionalized AuNPs (red, λ_ex = 450 nm) and PZPER (black, 50 μM) in water at 23 °C.

Figure 7

(a) DLS measurement of functionalized AuNPs, (b) TEM image of functionalized AuNPs.

Figure 8

(a) Fluorescence spectra of AuNPs (1 × 10¹² NP/mL) functionalized with PZPER (λ_ex = 532 nm) in MOPS buffer (1 mM, pH 5.35) at variable temperatures, (b) the correlation between the temperature and fluorescence of AuNPs functionalized with PZPER.

Figure 9

Fluorescence spectra of AuNPs (1 × 10¹² NP/mL) functionalized with PZPER (λ_ex = 532 nm) in MOPS buffer (1 mM, pH 5.35) at 25 (1 cycle (black), 2 cycle (green), 3 cycle (blue)) and 50 °C (1 cycle (orange), 2 cycle (purple), 3 cycle (red)) (three cycles).

Figure 10

(a) UV–Vis spectrum of AuNRs functionalized with PZPER, (b) TEM image of AuNRs functionalized with PZPER.

Figure 11

Fluorescence spectra of AuNRs (16.9 × 10¹⁴ NR/mL) functionalized with HSPEG3,000COOH (black), PZPER (0.85 μM) (red), and a mixture of AuNRs (16.9 × 10¹⁴ NR/mL) and PZPER (0.85 μM) (blue) (λ_ex = 532 nm) in MOPS buffer (1 mM, pH 5.35) at 25 °C.