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Biological Targeting of Plasmonic Nanoparticles Improves Cellular Imaging via the Enhanced Scattering in the Aggregates Formed.

Aioub M, Kang B, Mackey MA, El-Sayed MA - J Phys Chem Lett (2014)

Bottom Line: Nuclear-targeted AuNPs showed the greatest scattering due to the formation of denser nanoparticle clusters (i.e., increased localization).We also obtained a dynamic profile of AuNP localization in living cells, indicating that nuclear localization is directly related to the number of nuclear-targeting peptides on the AuNP surface.Increased localization led to increased plasmonic field coupling, resulting in significantly higher scattering intensity.

View Article: PubMed Central - PubMed

Affiliation: Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.

ABSTRACT
Gold nanoparticles (AuNPs) demonstrate great promise in biomedical applications due to their plasmonically enhanced imaging properties. When in close proximity, AuNPs plasmonic fields couple together, increasing their scattering cross-section due to the formation of hot spots, improving their imaging utility. In the present study, we modified the AuNPs surface with different peptides to target the nucleus and/or the cell as a whole, resulting in similar cellular uptake but different scattering intensities. Nuclear-targeted AuNPs showed the greatest scattering due to the formation of denser nanoparticle clusters (i.e., increased localization). We also obtained a dynamic profile of AuNP localization in living cells, indicating that nuclear localization is directly related to the number of nuclear-targeting peptides on the AuNP surface. Increased localization led to increased plasmonic field coupling, resulting in significantly higher scattering intensity. Thus, biochemical targeting of plasmonic nanoparticles to subcellular components is expected to lead to more resolved imaging of cellular processes.

No MeSH data available.


Related in: MedlinePlus

Dynamics of scattered light intensityfor bands of (A) small AuNPclusters at 641 nm and (B) large AuNP clusters at 745 nm. Localizationhalf-times of small AuNP clusters were calculated to be 6.4 h forRGD-AuNPs (black, R2 = 0.995), 5.4 h forRGD1/NLS1-AuNPs (red, R2 = 0.997), and 2.7 h for RGD1/NLS10-AuNPs(blue, R2 = 0.979). Localization half-timesof large AuNP clusters were calculated to be 8.1 h for RGD-AuNPs (black,R2 = 0.989), 7.4 h for RGD1/NLS1-AuNPs(red, R2 = 0.996), and 3.3 h for RGD1/NLS10-AuNPs (blue, R2 = 0.996).
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fig4: Dynamics of scattered light intensityfor bands of (A) small AuNPclusters at 641 nm and (B) large AuNP clusters at 745 nm. Localizationhalf-times of small AuNP clusters were calculated to be 6.4 h forRGD-AuNPs (black, R2 = 0.995), 5.4 h forRGD1/NLS1-AuNPs (red, R2 = 0.997), and 2.7 h for RGD1/NLS10-AuNPs(blue, R2 = 0.979). Localization half-timesof large AuNP clusters were calculated to be 8.1 h for RGD-AuNPs (black,R2 = 0.989), 7.4 h for RGD1/NLS1-AuNPs(red, R2 = 0.996), and 3.3 h for RGD1/NLS10-AuNPs (blue, R2 = 0.996).

Mentions: AuNP Localization Dynamics. The overallscatteringspectrum shown in Figure 3 not only describesthe total amount of light scattered by the different AuNPs in cellsover time, but it can also provide a detailed dynamic profile of AuNPaggregation and localization. This subcellular localization resultsin the formation of AuNP clusters with smaller interparticle separations,leading to stronger coupling of their plasmonic fields and therefore,large red-shifted plasmon peaks. Thus, the total scattering spectrumobtained was fit to multiple Gaussians, allowing its deconvolutioninto three components: (1) AuNP monomers indicated by the plasmonband at 538 nm, (2) small AuNP clusters (with higher local concentrationsof AuNPs, relative to AuNP monomers, which do not have interactingplasmonic fields), having a plasmon band at 641 nm, and (3) largerclusters of AuNPs (with the highest local AuNP concentration, indicatingeven greater coupling between the plasmonic fields of AuNPs in closeproximity) give scattering at the longest wavelength of the 745 nmplasmon band (all are denoted with the dashed lines in Figure 2). Although the spectrum for each different AuNPcontains these three components, the bands vary significantly basedon the AuNP surface modification, indicating varying degrees of localization(i.e., different local concentrations of AuNPs within cells). In orderto compare these bands for the different surface modified AuNPs andobtain detailed information on their degree of localization, the small(641 nm) and large (745 nm) AuNP cluster bands were integrated togive their total scattering intensities, as shown in Figure 4A,B, respectively. From these integrated scatteringintensities, we again calculated a scattering half-time (see Supporting Information) for each different surfacemodified AuNP tested, to give a measure of how quickly the differentAuNPs with different surface biochemical capping become localized.


Biological Targeting of Plasmonic Nanoparticles Improves Cellular Imaging via the Enhanced Scattering in the Aggregates Formed.

Aioub M, Kang B, Mackey MA, El-Sayed MA - J Phys Chem Lett (2014)

Dynamics of scattered light intensityfor bands of (A) small AuNPclusters at 641 nm and (B) large AuNP clusters at 745 nm. Localizationhalf-times of small AuNP clusters were calculated to be 6.4 h forRGD-AuNPs (black, R2 = 0.995), 5.4 h forRGD1/NLS1-AuNPs (red, R2 = 0.997), and 2.7 h for RGD1/NLS10-AuNPs(blue, R2 = 0.979). Localization half-timesof large AuNP clusters were calculated to be 8.1 h for RGD-AuNPs (black,R2 = 0.989), 7.4 h for RGD1/NLS1-AuNPs(red, R2 = 0.996), and 3.3 h for RGD1/NLS10-AuNPs (blue, R2 = 0.996).
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fig4: Dynamics of scattered light intensityfor bands of (A) small AuNPclusters at 641 nm and (B) large AuNP clusters at 745 nm. Localizationhalf-times of small AuNP clusters were calculated to be 6.4 h forRGD-AuNPs (black, R2 = 0.995), 5.4 h forRGD1/NLS1-AuNPs (red, R2 = 0.997), and 2.7 h for RGD1/NLS10-AuNPs(blue, R2 = 0.979). Localization half-timesof large AuNP clusters were calculated to be 8.1 h for RGD-AuNPs (black,R2 = 0.989), 7.4 h for RGD1/NLS1-AuNPs(red, R2 = 0.996), and 3.3 h for RGD1/NLS10-AuNPs (blue, R2 = 0.996).
Mentions: AuNP Localization Dynamics. The overallscatteringspectrum shown in Figure 3 not only describesthe total amount of light scattered by the different AuNPs in cellsover time, but it can also provide a detailed dynamic profile of AuNPaggregation and localization. This subcellular localization resultsin the formation of AuNP clusters with smaller interparticle separations,leading to stronger coupling of their plasmonic fields and therefore,large red-shifted plasmon peaks. Thus, the total scattering spectrumobtained was fit to multiple Gaussians, allowing its deconvolutioninto three components: (1) AuNP monomers indicated by the plasmonband at 538 nm, (2) small AuNP clusters (with higher local concentrationsof AuNPs, relative to AuNP monomers, which do not have interactingplasmonic fields), having a plasmon band at 641 nm, and (3) largerclusters of AuNPs (with the highest local AuNP concentration, indicatingeven greater coupling between the plasmonic fields of AuNPs in closeproximity) give scattering at the longest wavelength of the 745 nmplasmon band (all are denoted with the dashed lines in Figure 2). Although the spectrum for each different AuNPcontains these three components, the bands vary significantly basedon the AuNP surface modification, indicating varying degrees of localization(i.e., different local concentrations of AuNPs within cells). In orderto compare these bands for the different surface modified AuNPs andobtain detailed information on their degree of localization, the small(641 nm) and large (745 nm) AuNP cluster bands were integrated togive their total scattering intensities, as shown in Figure 4A,B, respectively. From these integrated scatteringintensities, we again calculated a scattering half-time (see Supporting Information) for each different surfacemodified AuNP tested, to give a measure of how quickly the differentAuNPs with different surface biochemical capping become localized.

Bottom Line: Nuclear-targeted AuNPs showed the greatest scattering due to the formation of denser nanoparticle clusters (i.e., increased localization).We also obtained a dynamic profile of AuNP localization in living cells, indicating that nuclear localization is directly related to the number of nuclear-targeting peptides on the AuNP surface.Increased localization led to increased plasmonic field coupling, resulting in significantly higher scattering intensity.

View Article: PubMed Central - PubMed

Affiliation: Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.

ABSTRACT
Gold nanoparticles (AuNPs) demonstrate great promise in biomedical applications due to their plasmonically enhanced imaging properties. When in close proximity, AuNPs plasmonic fields couple together, increasing their scattering cross-section due to the formation of hot spots, improving their imaging utility. In the present study, we modified the AuNPs surface with different peptides to target the nucleus and/or the cell as a whole, resulting in similar cellular uptake but different scattering intensities. Nuclear-targeted AuNPs showed the greatest scattering due to the formation of denser nanoparticle clusters (i.e., increased localization). We also obtained a dynamic profile of AuNP localization in living cells, indicating that nuclear localization is directly related to the number of nuclear-targeting peptides on the AuNP surface. Increased localization led to increased plasmonic field coupling, resulting in significantly higher scattering intensity. Thus, biochemical targeting of plasmonic nanoparticles to subcellular components is expected to lead to more resolved imaging of cellular processes.

No MeSH data available.


Related in: MedlinePlus