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Upconversion nanomaterials: synthesis, mechanism, and applications in sensing.

Chen J, Zhao JX - Sensors (Basel) (2012)

Bottom Line: Over the past decade, high-quality rare earth-doped upconversion nanoparticles have been successfully synthesized with the rapid development of nanotechnology and are becoming more prominent in biological sciences.The synthesis methods are usually phase-based processes, such as thermal decomposition, hydrothermal reaction, and ionic liquids-based synthesis.In this review, the synthesis of upconversion nanoparticles and the mechanisms of upconversion process will be discussed, followed by their applications in different areas, especially in the biological field for biosensing.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of North Dakota, Grand Forks, ND 58202, USA. jiao.chen@my.und.edu

ABSTRACT
Upconversion is an optical process that involves the conversion of lower-energy photons into higher-energy photons. It has been extensively studied since mid-1960s and widely applied in optical devices. Over the past decade, high-quality rare earth-doped upconversion nanoparticles have been successfully synthesized with the rapid development of nanotechnology and are becoming more prominent in biological sciences. The synthesis methods are usually phase-based processes, such as thermal decomposition, hydrothermal reaction, and ionic liquids-based synthesis. The main difference between upconversion nanoparticles and other nanomaterials is that they can emit visible light under near infrared irradiation. The near infrared irradiation leads to low autofluorescence, less scattering and absorption, and deep penetration in biological samples. In this review, the synthesis of upconversion nanoparticles and the mechanisms of upconversion process will be discussed, followed by their applications in different areas, especially in the biological field for biosensing.

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Related in: MedlinePlus

Time-dependent in vivo upconversion luminescence imaging of subcutaneous U87MG tumor (left hind leg, indicated by short arrows and MCF-7 tumor (right hind leg, indicated by long arrows) borne by athymic nude mice after intravenous injection of UCN-RGD over a 24 h period. (H) The in vivo signal-to-noise ratio (SNR) calculation. Region of interest (ROI)1, specific uptake; ROI 2, nonspecific uptake; ROI 3, background. SNR = (IROI 1 – IROI 3)/(IROI 2 – I ROI 3) [23].
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f11-sensors-12-02414: Time-dependent in vivo upconversion luminescence imaging of subcutaneous U87MG tumor (left hind leg, indicated by short arrows and MCF-7 tumor (right hind leg, indicated by long arrows) borne by athymic nude mice after intravenous injection of UCN-RGD over a 24 h period. (H) The in vivo signal-to-noise ratio (SNR) calculation. Region of interest (ROI)1, specific uptake; ROI 2, nonspecific uptake; ROI 3, background. SNR = (IROI 1 – IROI 3)/(IROI 2 – I ROI 3) [23].

Mentions: Since Chatterjee et al. [55] first studied the in vivo imaging of UCNs in small mammals which showed much higher fluorescence compared to QDs, it has made significant progress and attracted great interest. In Li’s group [4], they found a high relaxivity of 5.60 s−1 (mM)−1 of UCNs, and the UCNs were successfully applied as contrast agents form magnetic resonance imaging (MRI) in vivo. The concept of upconversion and magnetic resonance dual-modality imaging in vivo of whole-body animals using UCNs with magnetic resonance properties has showed great promise to serve as a platform technology for the next-generation of probes for bioimaging in vivo. Fluorescence targeted imaging in vivo has proven very useful in tumor recognition and drug delivery. Xiong et al. [23] developed a high contrast upconversion imaging protocol based on UCNs as luminescent labels for targeted imaging of tumors both in in vivo and in vitro. No autofluorescence signal observed in imaging even at high penetration depth (∼600 μm) and the signal-to-noise ratio could be reached ∼24 between the tumor and the background, which cannot be obtained in single-photon or two-photon fluorescence imaging (Figure 11). Their study may open up a new perspective for cell recognition and targeted imaging-guided cancer diagnosis.


Upconversion nanomaterials: synthesis, mechanism, and applications in sensing.

Chen J, Zhao JX - Sensors (Basel) (2012)

Time-dependent in vivo upconversion luminescence imaging of subcutaneous U87MG tumor (left hind leg, indicated by short arrows and MCF-7 tumor (right hind leg, indicated by long arrows) borne by athymic nude mice after intravenous injection of UCN-RGD over a 24 h period. (H) The in vivo signal-to-noise ratio (SNR) calculation. Region of interest (ROI)1, specific uptake; ROI 2, nonspecific uptake; ROI 3, background. SNR = (IROI 1 – IROI 3)/(IROI 2 – I ROI 3) [23].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376553&req=5

f11-sensors-12-02414: Time-dependent in vivo upconversion luminescence imaging of subcutaneous U87MG tumor (left hind leg, indicated by short arrows and MCF-7 tumor (right hind leg, indicated by long arrows) borne by athymic nude mice after intravenous injection of UCN-RGD over a 24 h period. (H) The in vivo signal-to-noise ratio (SNR) calculation. Region of interest (ROI)1, specific uptake; ROI 2, nonspecific uptake; ROI 3, background. SNR = (IROI 1 – IROI 3)/(IROI 2 – I ROI 3) [23].
Mentions: Since Chatterjee et al. [55] first studied the in vivo imaging of UCNs in small mammals which showed much higher fluorescence compared to QDs, it has made significant progress and attracted great interest. In Li’s group [4], they found a high relaxivity of 5.60 s−1 (mM)−1 of UCNs, and the UCNs were successfully applied as contrast agents form magnetic resonance imaging (MRI) in vivo. The concept of upconversion and magnetic resonance dual-modality imaging in vivo of whole-body animals using UCNs with magnetic resonance properties has showed great promise to serve as a platform technology for the next-generation of probes for bioimaging in vivo. Fluorescence targeted imaging in vivo has proven very useful in tumor recognition and drug delivery. Xiong et al. [23] developed a high contrast upconversion imaging protocol based on UCNs as luminescent labels for targeted imaging of tumors both in in vivo and in vitro. No autofluorescence signal observed in imaging even at high penetration depth (∼600 μm) and the signal-to-noise ratio could be reached ∼24 between the tumor and the background, which cannot be obtained in single-photon or two-photon fluorescence imaging (Figure 11). Their study may open up a new perspective for cell recognition and targeted imaging-guided cancer diagnosis.

Bottom Line: Over the past decade, high-quality rare earth-doped upconversion nanoparticles have been successfully synthesized with the rapid development of nanotechnology and are becoming more prominent in biological sciences.The synthesis methods are usually phase-based processes, such as thermal decomposition, hydrothermal reaction, and ionic liquids-based synthesis.In this review, the synthesis of upconversion nanoparticles and the mechanisms of upconversion process will be discussed, followed by their applications in different areas, especially in the biological field for biosensing.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of North Dakota, Grand Forks, ND 58202, USA. jiao.chen@my.und.edu

ABSTRACT
Upconversion is an optical process that involves the conversion of lower-energy photons into higher-energy photons. It has been extensively studied since mid-1960s and widely applied in optical devices. Over the past decade, high-quality rare earth-doped upconversion nanoparticles have been successfully synthesized with the rapid development of nanotechnology and are becoming more prominent in biological sciences. The synthesis methods are usually phase-based processes, such as thermal decomposition, hydrothermal reaction, and ionic liquids-based synthesis. The main difference between upconversion nanoparticles and other nanomaterials is that they can emit visible light under near infrared irradiation. The near infrared irradiation leads to low autofluorescence, less scattering and absorption, and deep penetration in biological samples. In this review, the synthesis of upconversion nanoparticles and the mechanisms of upconversion process will be discussed, followed by their applications in different areas, especially in the biological field for biosensing.

Show MeSH
Related in: MedlinePlus