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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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Schematic diagram of photon avalanche.
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f2-sensors-12-02414: Schematic diagram of photon avalanche.

Mentions: PA process is a more complex process, which can be characterized by three distinct nonlinear behaviors: transmission, emission, and rise time on the pump power intensity with generally the existence of a critical pump threshold. Take a four-energy system as an example (Figure 2), in which E0, E1 and E2, and E represents ground state, intermediate states, and upper excited states, respectively.


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

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

Schematic diagram of photon avalanche.
© Copyright Policy
Related In: Results  -  Collection

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

f2-sensors-12-02414: Schematic diagram of photon avalanche.
Mentions: PA process is a more complex process, which can be characterized by three distinct nonlinear behaviors: transmission, emission, and rise time on the pump power intensity with generally the existence of a critical pump threshold. Take a four-energy system as an example (Figure 2), in which E0, E1 and E2, and E represents ground state, intermediate states, and upper excited states, respectively.

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