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Subwavelength imaging through ion-beam-induced upconversion.

Mi Z, Zhang Y, Vanga SK, Chen CB, Tan HQ, Watt F, Liu X, Bettiol AA - Nat Commun (2015)

Bottom Line: Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique.We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals.This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.

ABSTRACT
The combination of an optical microscope and a luminescent probe plays a pivotal role in biological imaging because it allows for probing subcellular structures. However, the optical resolutions are largely constrained by Abbe's diffraction limit, and the common dye probes often suffer from photobleaching. Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique. We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals. This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

No MeSH data available.


Related in: MedlinePlus

Luminescence imaging of NaYF4:Yb/Tm (60/2 mol%) nanorods.(a) Ionoluminescence image of the as-synthesized nanorods through α-particle excitation. (b) High-magnification ionoluminescence image of a single nanorod as marked in a. (c) The corresponding line-scanning profile extracted from the intensity counting at the region marked in b along the arrow, indicating an imaging resolution of about 28 nm. (d) Photoluminescence image of the same sample taken by using 980 nm laser excitation. (e) High-magnification photoluminescence image of the same nanorod as shown in b. (f) The corresponding line-scanning profile from the image shown in e showing a diffraction-limited resolution of 253 nm associated with conventional upconversion microscopes. (g) Ionoluminescence intensity profile as a function of the accumulated dosage of helium ions showing the considerable iono-bleaching resistance of the nanorods. The inserted images, taken at different time intervals (11, 33 and 66 min), indicate that the emission brightness of the nanorods remains essentially unaltered over time. Scale bars, 500 nm. The error bar represents the standard deviation of luminescence counts obtained from a single nanorod in two separate measurements.
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f3: Luminescence imaging of NaYF4:Yb/Tm (60/2 mol%) nanorods.(a) Ionoluminescence image of the as-synthesized nanorods through α-particle excitation. (b) High-magnification ionoluminescence image of a single nanorod as marked in a. (c) The corresponding line-scanning profile extracted from the intensity counting at the region marked in b along the arrow, indicating an imaging resolution of about 28 nm. (d) Photoluminescence image of the same sample taken by using 980 nm laser excitation. (e) High-magnification photoluminescence image of the same nanorod as shown in b. (f) The corresponding line-scanning profile from the image shown in e showing a diffraction-limited resolution of 253 nm associated with conventional upconversion microscopes. (g) Ionoluminescence intensity profile as a function of the accumulated dosage of helium ions showing the considerable iono-bleaching resistance of the nanorods. The inserted images, taken at different time intervals (11, 33 and 66 min), indicate that the emission brightness of the nanorods remains essentially unaltered over time. Scale bars, 500 nm. The error bar represents the standard deviation of luminescence counts obtained from a single nanorod in two separate measurements.

Mentions: High-resolution imaging can be achieved through α-beam irradiation of lanthanide-doped nanomaterials because the spot size of α-beam can be readily focused down to sub-30 nm (refs 28, 29). Considering that the spectral-response range of the photodetector used falls within the visible spectrum, we have adopted Yb3+/Tm3+ (60/2 mol%) as the optimal combination for maximal visible emission (Fig. 2d and Supplementary Fig. 6). Images of the NaYF4:Yb/Tm (60/2 mol%) nanorods were recorded in a 512 × 512 pixel array at a count rate of around 15,000 helium ions per second by detecting the α-particle-induced luminescence (Fig. 3a,b). To ascertain the spatial resolution of the ionoluminescence image, a representative line-scanning profile of an individual nanorod was collected and presented in Fig. 3c. By fitting the profile using a modified Gaussian model31, the imaging resolution of the α-particle-based ionoluminescence technique was determined to be 28 nm as defined by full-width at half maximum. By comparison, conventional optical microscopies equipped with a 980-nm diode laser showed a resolution limit of ∼253 nm (Fig. 3d–f and Supplementary Fig. 8). It should be noted that the effect of iono-bleaching, typically associated with the reduction in emission intensity in dye- or quantum dot-based systems3233, does not pose a constraint to lanthanide-doped nanomaterials (Fig. 3g and Supplementary Figs 9 and 10).


Subwavelength imaging through ion-beam-induced upconversion.

Mi Z, Zhang Y, Vanga SK, Chen CB, Tan HQ, Watt F, Liu X, Bettiol AA - Nat Commun (2015)

Luminescence imaging of NaYF4:Yb/Tm (60/2 mol%) nanorods.(a) Ionoluminescence image of the as-synthesized nanorods through α-particle excitation. (b) High-magnification ionoluminescence image of a single nanorod as marked in a. (c) The corresponding line-scanning profile extracted from the intensity counting at the region marked in b along the arrow, indicating an imaging resolution of about 28 nm. (d) Photoluminescence image of the same sample taken by using 980 nm laser excitation. (e) High-magnification photoluminescence image of the same nanorod as shown in b. (f) The corresponding line-scanning profile from the image shown in e showing a diffraction-limited resolution of 253 nm associated with conventional upconversion microscopes. (g) Ionoluminescence intensity profile as a function of the accumulated dosage of helium ions showing the considerable iono-bleaching resistance of the nanorods. The inserted images, taken at different time intervals (11, 33 and 66 min), indicate that the emission brightness of the nanorods remains essentially unaltered over time. Scale bars, 500 nm. The error bar represents the standard deviation of luminescence counts obtained from a single nanorod in two separate measurements.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660043&req=5

f3: Luminescence imaging of NaYF4:Yb/Tm (60/2 mol%) nanorods.(a) Ionoluminescence image of the as-synthesized nanorods through α-particle excitation. (b) High-magnification ionoluminescence image of a single nanorod as marked in a. (c) The corresponding line-scanning profile extracted from the intensity counting at the region marked in b along the arrow, indicating an imaging resolution of about 28 nm. (d) Photoluminescence image of the same sample taken by using 980 nm laser excitation. (e) High-magnification photoluminescence image of the same nanorod as shown in b. (f) The corresponding line-scanning profile from the image shown in e showing a diffraction-limited resolution of 253 nm associated with conventional upconversion microscopes. (g) Ionoluminescence intensity profile as a function of the accumulated dosage of helium ions showing the considerable iono-bleaching resistance of the nanorods. The inserted images, taken at different time intervals (11, 33 and 66 min), indicate that the emission brightness of the nanorods remains essentially unaltered over time. Scale bars, 500 nm. The error bar represents the standard deviation of luminescence counts obtained from a single nanorod in two separate measurements.
Mentions: High-resolution imaging can be achieved through α-beam irradiation of lanthanide-doped nanomaterials because the spot size of α-beam can be readily focused down to sub-30 nm (refs 28, 29). Considering that the spectral-response range of the photodetector used falls within the visible spectrum, we have adopted Yb3+/Tm3+ (60/2 mol%) as the optimal combination for maximal visible emission (Fig. 2d and Supplementary Fig. 6). Images of the NaYF4:Yb/Tm (60/2 mol%) nanorods were recorded in a 512 × 512 pixel array at a count rate of around 15,000 helium ions per second by detecting the α-particle-induced luminescence (Fig. 3a,b). To ascertain the spatial resolution of the ionoluminescence image, a representative line-scanning profile of an individual nanorod was collected and presented in Fig. 3c. By fitting the profile using a modified Gaussian model31, the imaging resolution of the α-particle-based ionoluminescence technique was determined to be 28 nm as defined by full-width at half maximum. By comparison, conventional optical microscopies equipped with a 980-nm diode laser showed a resolution limit of ∼253 nm (Fig. 3d–f and Supplementary Fig. 8). It should be noted that the effect of iono-bleaching, typically associated with the reduction in emission intensity in dye- or quantum dot-based systems3233, does not pose a constraint to lanthanide-doped nanomaterials (Fig. 3g and Supplementary Figs 9 and 10).

Bottom Line: Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique.We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals.This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.

ABSTRACT
The combination of an optical microscope and a luminescent probe plays a pivotal role in biological imaging because it allows for probing subcellular structures. However, the optical resolutions are largely constrained by Abbe's diffraction limit, and the common dye probes often suffer from photobleaching. Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique. We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals. This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.

No MeSH data available.


Related in: MedlinePlus