Upconversion nanoparticles for sensitive and in-depth detection of Cu2+ ions

Abstract

Detection of Cu(2+) ions and study of their subcellular distribution in physiological processes are of considerable significance because of their potential environmental and biological applications. Some fluorescence based sensors have been developed for selective detection of Cu(2+) ions, based on organic fluorescent probes that specifically bind to Cu(2+) ions. However, these sensors are not suitable for detection in biological samples due to the short penetration depth of UV/visible light used to excite the fluorescent probes. The use of near-infrared (NIR) light can afford penetration depths of an order of magnitude greater than that of visible light, however, a material that can convert NIR light to visible light is required. A facile method has been developed for in-depth detection of Cu(2+) ions based on fluorescence upconversion. A mesoporous silica shell is coated on upconversion nanoparticles (UCNPs) and a Cu(2+) ion sensitive fluorescent probe, rhodamine B hydrazide, is incorporated into the mesoporous silica. Upon excitation by a NIR light, the UCNPs emit visible light to excite the Cu(2+)-sensitive fluorescent probe. Because of the unique optical properties of UCNPs and their ability to convert NIR light to visible light, this is a feasible method for sensitive and in-depth detection of Cu(2+) ions in a complex biological or environmental sample due to the low autofluorescence and the high penetration depth of NIR light.

Upconversion Nanoparticle-Based Nanocomposites

“…In this method, CTAB not only acts as a capping and phase-transfer agent, but also as the template for the formation of mesoporous structures in the silica sol-gel reaction. This outstanding work provides a new opportunity to directly coat diverse hydrophobic nanoparticles possessing different compositions, shapes, and sizes with mesoporous silica shells [51,52]. Enlightened by these studies, Lin's group and Shi's group have independently reported the synthesis of uniform and monodisperse UCNPs@mSiO 2 nanocomposites using a one-step sol-gel process [44,45,53,54].…”

Upconversion nanoprobes for efficiently in vitro imaging reactive oxygen species and in vivo diagnosing rheumatoid arthritis

“…In particular, it is extremely important to note that the single NIR laser used to excite UCNPs does not co-excite dyes that absorb in the UV/visible regions. In this respect, UCNPs are promising energy donors for LRET based ratiometric nanoprobes which provide built-in correction for environmental effects and permit signal rationing [38,39]. All these favorable advantages make UCNPs particularly attractive for biolabeling and biosensing [40e47].…”

Electrochemically assisted flexible lanthanide upconversion luminescence sensing of heavy metal contamination with high sensitivity and selectivity

“…Numerous reports have revealed the good sensitivity and selectivity of UCL sensors towards various metal ions such as Zn 2+ , 8 Cu 2+ , [14][15][16] Hg 2+ , 17 and Pb 2+ ions. 18 Most strategies were established based on the luminescence resonance energy transfer (LRET) phenomenon, by which metal-responsive dyes played important roles in quenching UCL for ratiometric luminescence sensing while promoting the selectivity.…”

“…-chelating molecules. [14][15][16] Hence, the E-chem technique can help establish a versatile, simple, rapid and sensitive UCL sensor. Apart from being developed as an optical sensor, the CFC-UCNP probe is also promising for UCL/E-chem dual modal sensing because the sensitivity of the E-chem sensing mode is comparable to the UCL sensing at 0.3 V.…”