Sentences with phrase «np clusters»

PNB lifetime (ns)(measure of its maximal diameter) obtained for individual gold NP clusters of similar size for the different combinations of NP types and the wavelengths of optical excitation (@optical fluence, mJ / cm2).

This mechanism works through the selective formation of NP clusters (tightly aggregated groups of 5 - 50 NPs) in specifically targeted cells and the cluster size - dependent mechanism of optical activation of such NP clusters through the generation of plasmonic nanobubbles (PNBs)[35 - 38].

This feature decreases the bubble generation threshold fluence below the threshold level for mono - NP clusters.

The results obtained (Table 1, Figures 2, 4) show the definite priority of the novel «rainbow» mechanism over the standard excitation of a single plasmon resonance: the lifetime and brightness of rainbow PNBs increased by almost one order of magnitude compared with the identical excitation of the mono - NP clusters.

For each condition, we measured the lifetime of individual PNBs that were generated around individual NP clusters under a single pulse excitation.

The size of NP clusters was quantified and compared through the amplitudes of their optical scattering images (obtained for individual NP clusters).

Endocytosis provides the selective formation of big NP clusters only in diagnosis - specific cells, while fewer NPs incidentally accumulated by non-specific cells are insufficient to form an NP cluster.

Both fluence levels were chosen to be significantly below the PNB generation thresholds for single NPs (46 mJ / cm2 @ 532 nm for NSP and 32 mJ / cm2 @ 787 nm for NRs) and slightly below the PNB generation thresholds for the mono - NP clusters of NSPs (16 mJ / cm2 @ 532 nm) and NRs (20 mJ / cm2 @ 787 nm), in order to compare the standard and rainbow mechanisms of PNB generation.

All cells were targeted with conjugates of gold nanoparticles (NPs) through an antibody - receptor - endocytosis - nanocluster mechanism that produced NP clusters.

The diagnostic effect of a PNB is associated with its brightness that is characterized through the pixel image amplitudes (Figure 2A, C, E), normalized by the pixel image amplitudes of the corresponding NP clusters as measured prior to their optical excitation and calculated as an amplification of optical scattering by the PNB relative to that by the NP cluster (Figure 4).

PNBs are generated as transient vapor bubbles around intracellular NP clusters under their exposure to short laser pulses.

A, C, E: time - resolved scattering optical images show individual transient PNBs generated around single NP clusters during exposure to the two simultaneous laser pulses (0.5 ns each, 532 nm and 787 nm): A - the mono - NP cluster of gold spheres, C - the mono - NP cluster of gold rods, E - the multi-NP cluster of the same diameter as in A and C but consisting of a mixture of gold spheres and rods; the pixel image amplitude is shown in the gray scale.

Independent control and tuning of the fluence: each excitation laser pulse provides maximal flexibility in manipulating the lifetime (i.e. size) of the rainbow PNB in a wide range of cluster size and composition, thus circumventing the problem of the heterogeneous formation and content of NP clusters in cells.

All three above features are unique to rainbow PNBs and can be especially useful during in vivo applications where the heterogeneity of NP clustering and optical propagation and scattering create challenges both for nano - and for optical technologies.

Confocal fluorescent, confocal scattering images of prostate cancer C4 - 2B (A, B) and stromal HS - 5 (D, E) cells: (A, D)- confocal fluorescent images of AlexaFluor488 conjugated to PSMA antibody, (B, E)- confocal scattering images of gold NPs clusters (shown in red on the green fluorescent background that shows cell tracker dye) and (C, F) the corresponding profiles of scattering signal amplitudes by gold NPs clusters in cells.

To compare the efficacy of the rainbow and standard mechanisms, we determined the fluence of the single laser pulse that provided the same lifetime of the PNB around a mono - NP cluster as was achieved for the rainbow PNB.

We expanded this approach into a principally new mechanism that employs the simultaneous effect of several different plasmon resonances in one NP cluster.

Not exact matches

Below we report the experimental results for a new selective mechanism of PNB generation around clusters of gold NPs, and the evaluation of the developed mechanism at cell level for the theranostics of prostate cancer cells growing amidst normal stroma.

Excitation optical wavelength and fluence: several simultaneous pulses at the wavelengths that match the plasmon resonances of the corresponding NPs in the cluster.

Initially we studied the generation of PNBs around mono - NP and multi-NP clusters in water.

This was realized through using two different types of plasmonic (gold) NPs, rods and spheres, and their clustering through collective endocytosis (Figure 1B).

However, if we irradiate this multi-NP cluster with two simultaneous pulses at two different wavelengths (matching the plasmon resonances of the NPs), their cumulative thermal effect will exceed the PNB threshold and will result in a PNB (Figure 1C).

Three types of gold NPs were used to form the multi-NP clusters: gold spheres (50 and 60 nm), rods (25x75 nm) and shells (52 nm).

The clustering of plasmonic NPs was shown to reduce the PNB generation threshold [37,38].

Optical scattering was also used for the imaging of single NPs and their clusters.

The internalization and clustering of NPs in living cells (unlike the water model studied above), involves several biological processes that not only form such clusters, but also create significant heterogeneity in their size.

Nanobubble source: clusters of different NPs, rather than clusters of NPs of one type.