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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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False color two-photon images of C. elegans at 980 nm excitation with red representing the bright field and green for the phosphor emission. (Left) The worms were deprived of food over a period of 24 h, showing little or no change at (a) 0 h, (b) 4 h, and (c) 24 h. (Right) The worms were given food immediately after being fed with phosphors, showing decreasing amounts of phosphors at (d) 0 h, (e) 1 h, and (f) 2 h [22].
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f10-sensors-12-02414: False color two-photon images of C. elegans at 980 nm excitation with red representing the bright field and green for the phosphor emission. (Left) The worms were deprived of food over a period of 24 h, showing little or no change at (a) 0 h, (b) 4 h, and (c) 24 h. (Right) The worms were given food immediately after being fed with phosphors, showing decreasing amounts of phosphors at (d) 0 h, (e) 1 h, and (f) 2 h [22].

Mentions: Lim et al. [22,53] performed in vivo and scanning electron microscopy imaging of UCNs in C. elegans due to its short life cycle, rapid growth, and appropriate size to optical microscopy. In their study, C. elegans were fed with UCNs and imaged at fixed time intervals in order to track the movement of the phosphors through their digestive system. No significant change in the phosphors was monitored up to 24 h and after feeding the worms with food (Figure 10), the phosphors were secreted in under 2 h. It demonstrated that UCNs were nonbleaching, biocompatible, and nontoxic, which make them ideal candidates in the biological system.


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

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

False color two-photon images of C. elegans at 980 nm excitation with red representing the bright field and green for the phosphor emission. (Left) The worms were deprived of food over a period of 24 h, showing little or no change at (a) 0 h, (b) 4 h, and (c) 24 h. (Right) The worms were given food immediately after being fed with phosphors, showing decreasing amounts of phosphors at (d) 0 h, (e) 1 h, and (f) 2 h [22].
© Copyright Policy
Related In: Results  -  Collection

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

f10-sensors-12-02414: False color two-photon images of C. elegans at 980 nm excitation with red representing the bright field and green for the phosphor emission. (Left) The worms were deprived of food over a period of 24 h, showing little or no change at (a) 0 h, (b) 4 h, and (c) 24 h. (Right) The worms were given food immediately after being fed with phosphors, showing decreasing amounts of phosphors at (d) 0 h, (e) 1 h, and (f) 2 h [22].
Mentions: Lim et al. [22,53] performed in vivo and scanning electron microscopy imaging of UCNs in C. elegans due to its short life cycle, rapid growth, and appropriate size to optical microscopy. In their study, C. elegans were fed with UCNs and imaged at fixed time intervals in order to track the movement of the phosphors through their digestive system. No significant change in the phosphors was monitored up to 24 h and after feeding the worms with food (Figure 10), the phosphors were secreted in under 2 h. It demonstrated that UCNs were nonbleaching, biocompatible, and nontoxic, which make them ideal candidates in the biological system.

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