SERS labels for quantitative assays: application to the quantification of gold nanoparticles uptaken by macrophage cells

Amendola, Vincenzo; Meneghetti, Moreno; Fiameni, S.; Polizzi, Stefano; Fracasso, Giulio; Boscaini, Anita; Colombatti, Marco

doi:10.1039/c0ay00660b

Cited by 28 publications

(25 citation statements)

References 57 publications

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“…No traces of the Raman reporters were detected by UV–visible spectroscopy in the final SERS label solutions. This finding suggests that less than 100–200 molecules are adsorbed for each AuNP in all of our SERS labels, as previously reported 42. Some representative TEM images for the labels are displayed in Figure 1a, showing that they predominantly consist of isolated AuNPs and small AuNP dimers made of two nanoparticles of different size.…”

Section: Resultssupporting

confidence: 81%

Exploring How to Increase the Brightness of Surface‐Enhanced Raman Spectroscopy Nanolabels: The Effect of the Raman‐Active Molecules and of the Label Size

Amendola

Meneghetti

2011

Adv Funct Materials

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Due to the surface-enhanced Raman scattering (SERS) effect, SERS labels based on noble-metal nanoparticles loaded with Raman-active molecules are good candidates for ultrasensitive multiplexed assays and in vitro/in vivo imaging. However, understanding how to maximize the brightness of such labels is of paramount importance for their widespread application. The effective differential Raman scattering cross-section (dσR/dΩ) of SERS labels made of pegylated gold nanoparticles loaded with various Raman active molecules (Raman reporters) is studied. It is found that proper choice of the Raman reporter and of nanoparticle size can enhance the dσR/dΩ by several orders of magnitude. The experimental results are understood by considering the molecular cross-section for resonant Raman scattering and the local electromagnetic enhancement factor (GSERS) in the nearby of gold nanoparticles. These results are useful to guide the design of SERS labels with improved performances and to provide a reference for the comparison of the absolute value of the dσR/dΩ of SERS labels based on metal nanoparticles

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Section: Resultssupporting

confidence: 81%

Exploring How to Increase the Brightness of Surface‐Enhanced Raman Spectroscopy Nanolabels: The Effect of the Raman‐Active Molecules and of the Label Size

Amendola

Meneghetti

2011

Adv Funct Materials

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“…In the present case, we exploited the surface chemistry of the alloy nanoparticles to add stealth properties by conjugation with thiolated polyethylene glycol (PEG) . In addition, bright SERS signals require stable anchoring of Raman active dyes in the electromagnetic hot spots at the junction between two plasmonic nanoparticles, hence we also exploited Au‐S bonding for loading nanoalloys with a di‐thiolated sulforhodamine 101 (DTSR) . In our synthetic procedure, the addition of DTSR and PEG to the Au‐Fe alloy dispersion takes place simultaneously, yielding small nanoparticle aggregates with overall size of 30‐60 nm (Figure b and Figure S2 in S.I.).…”

Section: Resultsmentioning

confidence: 99%

Magneto‐Plasmonic Au‐Fe Alloy Nanoparticles Designed for Multimodal SERS‐MRI‐CT Imaging

Amendola

Scaramuzza

Litti

et al. 2014

Small

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Diagnostic approaches based on multimodal imaging are needed for accurate selection of the therapeutic regimens in several diseases, although the dose of administered contrast drugs must be reduced to minimize side effects. Therefore, large efforts are deployed in the development of multimodal contrast agents (MCAs) that permit the complementary visualization of the same diseased area with different sensitivity and different spatial resolution by applying multiple diagnostic techniques. Ideally, MCAs should also allow imaging of diseased tissues with high spatial resolution during surgical interventions. Here a new system based on multifunctional Au-Fe alloy nanoparticles designed to satisfy the main requirements of an ideal MCA is reported and their biocompatibility and imaging capability are described. The MCAs show easy and versatile surface conjugation with thiolated molecules, magnetic resonance imaging (MRI) and computed X-ray tomography (CT) signals for anatomical and physiological information (i.e., diagnostic and prognostic imaging), large Raman signals amplified by surface enhanced Raman scattering (SERS) for high sensitivity and high resolution intrasurgical imaging, biocompatibility, exploitability for in vivo use and capability of selective accumulation in tumors by enhanced permeability and retention effect. Taken together, these results show that Au-Fe nanoalloys are excellent candidates as multimodal MRI-CT-SERS imaging agents.

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“…Pure modeling and simulation is a deliberate choice of ours as direct experimental studies currently are not able to isolate and eliminate the influence of nanoparticle administration (i.e., pipetting) and nanoparticle detection. Most methods developed for detecting and quantifying nanoparticles are based on chemical elementary analysis [e.g., ICP techniques, optical spectroscopy (e.g., absorption, fluorescence, and vibrational spectroscopy) , magnetic properties of the nanoparticle itself (e.g., superconducting quantum interference technique), a molecular probe associated to the NPs, or neutron activation (e.g., radiolabeling techniques)] . Beside the current challenge of establishing a simple, highly reproducible, controllable, and last but not least easily accessible dose‐delivery process, all these methods are not based on direct, primary measurable quantities (i.e., number of particles, overall mass, overall surface area) but on secondary quantities, such as the fluorescence from molecules associated to the nanoparticles, vibrational, emission or absorption spectra of NPs themselves, molecular probes attached, or the ratio of radioactive isotopes to stable isotopes in NPs.…”

Section: Introductionmentioning

confidence: 99%

Nanoparticle Polydispersity Can Strongly Affect In Vitro Dose

Rodríguez‐Lorenzo

Rothen‐Rutishauser

Petri‐Fink

et al. 2014

Part & Part Syst Charact

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When nanomaterials meet the biological world, the cellular interaction of nanoparticles is routinely assessed in in vitro systems. Establishing doseresponse relationships requires that the dose of nanoparticles delivered to the cell is accurate and precise. Nanoparticles as such or coated with high molecular-weight compounds are rarely uniform and the infl uence of heterogeneity, including polydispersity both in size and mass density, on the delivered dose is never studied before. Furthermore, a probabilistic term describing particle adherence to cells is introduced and the importance is discussed. By tracing the movement of discrete particles via modeling, it is found that the infl uence of heterogeneity cannot be neglected when the average particle size promotes settling over diffusion. However, the infl uence of polydispersity on the delivered cellular dose is less critical for particulate systems whose mean size promotes diffusion. The infl uence of a non-instantaneous particle association to the cell is negligible for particles whose motion is dominated by settling, but it is relevant for small particles whose motion is governed by diffusion.at least three elementary processes that are relevant for in vitro dose: (i) delivery of NPs to the cell, (ii) adherence to the cell membrane, and (iii) internalization. Any of these processes can be a rate-limiting factor. Awareness concerning the peculiarities of NP transport in fl uids and the relevance to liquid-based in vitro assays is on the rise, as shown by the steadily increasing number of research papers adopting the concept of particokinetics proposed by Teeguarden et al. [ 20,25 ] for interpreting dose-response curves. The concept of particokinetics, describing uniform particles, [ 20,25 ] challenges the still-reigning paradigm that the dose to which adherent cells are exposed to at the bottom of the cell-culture dish is proportional to the concentration of NPs in the suspension. However, the concentration of NPs in suspension defi nes only the administered dose, and the above paradigm is strictly valid only when all NPs in the suspension have completely settled, in which case the delivered dose is equal to the administered dose. The ultimate fate of NPs in a fl uid is eventually dictated by its mass density, i.e., NPs will settle if their mass density is greater than that of the fl uid. The impact of NP size and mass density on transport has been known for a long time [26][27][28][29] : in general, sedimentation is dominant for large NPs of "higher" mass density, while diffusion dominates the transport for small NPs of "lower" mass density. The kinetics of a particle is quantifi ed by the diffusion coeffi cient (the Stokes-Einstein equation and the settling velocity, Stokes' law). [ 26 ] Depending on (i) the hydrodynamic radius of the NPs, (ii) the mass density difference between the particle and the fl uid, (iii) the concentration of NPs in the colloidal suspension, (iv) the total volume of the colloidal suspension administrated to the cell culture, and (v...

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SERS labels for quantitative assays: application to the quantification of gold nanoparticles uptaken by macrophage cells

Cited by 28 publications

References 57 publications

Exploring How to Increase the Brightness of Surface‐Enhanced Raman Spectroscopy Nanolabels: The Effect of the Raman‐Active Molecules and of the Label Size

Exploring How to Increase the Brightness of Surface‐Enhanced Raman Spectroscopy Nanolabels: The Effect of the Raman‐Active Molecules and of the Label Size

Magneto‐Plasmonic Au‐Fe Alloy Nanoparticles Designed for Multimodal SERS‐MRI‐CT Imaging

Nanoparticle Polydispersity Can Strongly Affect In Vitro Dose

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