Nonbleaching Fluorescence of Gold Nanoparticles and Its Applications in Cancer Cell Imaging

College of Chemistry and Chemical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai, 200240, PR China.
Analytical Chemistry (Impact Factor: 5.64). 08/2008; 80(15):5951-7. DOI: 10.1021/ac8005796
Source: PubMed


In this paper, we investigated the fluorescent properties of gold nanoparticles (GNPs) with several tens of nanometers by ensemble fluorescence spectrometry, fluorescence correlation spectroscopy (FCS), and fluorescence microscopy. We observed that GNPs synthesized by the citrate reduction of chloroauric acid possessed certain fluorescence, narrow full width at half-maximum (17 nm), and with an increase of particle sizes, the emission intensity showed a gradual increase while the emission wavelength remained almost constant (at 610 nm). Especially, the fluorescence of GNPs possessed the excellent behavior of antiphotobleaching under strong light illumination. Despite their low quantum yields, GNPs exhibited strong native fluorescence under relatively high excitation power. The fluorescence of GNPs could be characterized by fluorescence imaging and FCS at the single particle level. On the basis of this excellent antiphotobleaching of GNPs and easy photobleaching of cellular autofluorescence, we developed a new method for imaging of cells using GNPs as fluorescent probes. The principle of this method is that after cells stained with GNPs or GNPs bioconjugates are illuminated by strong light, the cellular autofluorescence are photobleached and the fluorescence of GNPs on cell membrane or inside cells can be collected for cell imaging. On the basis of this principle, we imaged living HeLa cells using GNPs as fluorescent probes and obtained good cell images by photobleaching of cellular autofluorescence. Furthermore, anti-EGFR/GNPs were successfully used as targeted probes for fluorescence imaging of cancer cells. Our preliminary results demonstrated that GNPs possessed excellent behaviors of antiphotobleaching and were good fluorescent probes in cell imaging. Our cellular imaging method described has potential applications in cancer diagnostics, studies, and immunoassays.

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    • "Furthermore, their surfaces can be easily biomodified for different biomedical applications (Durr et al., 2007; El-Sayed et al., 2005; Murphy et al., 2008; Sokolov et al., 2003). These properties make them ideal as imaging and sensing agents in many biomedical applications (Anker et al., 2008; He et al., 2008; Tong et al., 2009). "
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    ABSTRACT: Gold nanorods (NRs) with tunable plasmon-resonant absorption in the near-infrared region have considerable advantages over organic fluorophores as imaging agents due to their brightness and lack of photobleaching. However, the luminescence spectral properties of NRs have not been fully characterized at the single particle level due to lack of proper analytic tools. Here, we present a spectral phasor analysis method that allows investigations of NRs' spectra at single particle level showing the spectral variance and providing spatial information during imaging. The broad phasor distribution obtained by the spectral phasor analysis indicates that spectra of NRs are different from particle to particle. NRs with different spectra can be identified in images with high spectral resolution. The spectral behaviors of NRs under different imaging conditions, for example, different excitation powers and wavelengths, were revealed by our laser-scanning multiphoton microscope using a high-resolution spectrograph with imaging capability. Our results prove that the spectral phasor method is an easy and efficient tool in hyper-spectral imaging analysis to unravel subtle changes of the emission spectrum. We applied this method to study the spectral dynamics of NRs during direct optical trapping and by optothermal trapping. Interestingly, different spectral shifts were observed in both trapping phenomena. Microsc. Res. Tech., 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
    Microscopy Research and Technique 02/2015; 78(4). DOI:10.1002/jemt.22473 · 1.15 Impact Factor
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    • "Due to the poly(amino acid) coating, these nanocrystals are highly water-stable, biocompatible, and bioconjugatable with chemical and biological moieties. Meanwhile, their shape, size, optical/magnetic properties are well retained, which is highly desirable for bioapplications4647. "
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    ABSTRACT: Hydrophobic nanocrystals with various shape, size, and chemical composition were successfully functionalized by poly(amino acid) with one particle per micelle without aggregation or precipitation via a facile, general, and low-cost strategy. Via simply tuning the pH value, multifunctional nanocomposites consisting of different nanocrystals were also fabricated. Due to the poly(amino acid) coating, these nanocrystals are highly water-stable, biocompatible, and bioconjugatable with chemical and biological moieties. Meanwhile, their shape, size, optical/magnetic properties are well retained, which is highly desirable for bioapplications. This developed strategy presents a novel opportunity to apply hydrophobic nanocrystals to various biomedical fields.
    Scientific Reports 06/2013; 3:2023. DOI:10.1038/srep02023 · 5.58 Impact Factor
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    • "Focus has been directed to design strategies to visualize and monitor the accumulation of nanomaterials and release of drugs at specific sites which is essential to optimize the effectiveness of nanomaterials-based therapeutics (Chithrani et al. 2010; Alkilany et al. 2009; Murphy et al. 2008). Recently, much emphasis has been devoted to develop less labor intense, rapid methods largely based on optical techniques to look into the uptake of the particles by cells as well as delivery of drug onto target (Dasary et al. 2009; Kneipp et al. 2005; El-Sayed et al. 2005; Galanzha et al. 2009; He et al. 2008; Louit et al. 2009). Most of these faster non-invasive approaches stem from the optical properties of GNPs. "
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    ABSTRACT: This study refers an aqueous synthesis of methotrexate (MTX)-conjugated gold nanoparticles (GNPs), their interaction with HepG2 cells, and the use of Raman imaging to observe cellular internalization and drug delivery. GNPs of average size 3.5-5 nm were stabilized using the amine terminated bifunctional biocompatible copolymer and amended by conjugating MTX, an anticancer drug. The nanoparticles were released MTX at a faster rate in acidic pH and subsequently found to form aggregates. The Raman signals of cellular components were found to be enhanced by the aggregated particles enabling the mapping to visualize site-specific drug delivery. The methodology seems to have potential in optimizing the characteristics of nanodrug carriers for emptying the cargo precisely at specified sites. © Springer Science+Business Media B.V. 2012.
    Journal of Nanoparticle Research 09/2012; 14(9-9). DOI:10.1021/mp060132k; · 2.18 Impact Factor
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