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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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Different shapes of RE fluoride nano-/microcrystals by hydrothermal method [37–39].
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f7-sensors-12-02414: Different shapes of RE fluoride nano-/microcrystals by hydrothermal method [37–39].

Mentions: Hydrothermal synthesis is a typical solution-based approach, which is usually employed under high temperatures and pressures [5,31,35,36]. Unlike the thermal decomposition method, which can only use an organic compound as a solvent, hydrothermal synthesis can occur in a water-based system and at a lower reaction temperature (160–220 °C) in a relatively environmentally friendly approach. It is an effective and convenient process in preparing inorganic materials with diverse controllable morphologies and architectures. For example, various shapes of hexagonal NaYF4 crystals, such as prism, disk, tube, rod, and octadecahedral shapes were synthesized by applying this method [37,38]. Recently, in Lin’s group, the mechanism of synthesizing different shapes of RE fluoride nano-/microcrystals was systematically investigated [33]. It was reported that the organic additive trisodium citrate, the fluoride source, and pH value have great effects on the shapes (Figure 7).


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

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

Different shapes of RE fluoride nano-/microcrystals by hydrothermal method [37–39].
© Copyright Policy
Related In: Results  -  Collection

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

f7-sensors-12-02414: Different shapes of RE fluoride nano-/microcrystals by hydrothermal method [37–39].
Mentions: Hydrothermal synthesis is a typical solution-based approach, which is usually employed under high temperatures and pressures [5,31,35,36]. Unlike the thermal decomposition method, which can only use an organic compound as a solvent, hydrothermal synthesis can occur in a water-based system and at a lower reaction temperature (160–220 °C) in a relatively environmentally friendly approach. It is an effective and convenient process in preparing inorganic materials with diverse controllable morphologies and architectures. For example, various shapes of hexagonal NaYF4 crystals, such as prism, disk, tube, rod, and octadecahedral shapes were synthesized by applying this method [37,38]. Recently, in Lin’s group, the mechanism of synthesizing different shapes of RE fluoride nano-/microcrystals was systematically investigated [33]. It was reported that the organic additive trisodium citrate, the fluoride source, and pH value have great effects on the shapes (Figure 7).

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