Quench-Shield Ratiometric Upconversion Luminescence Nanoplatform for Biosensing

Abstract

Upconversion nanoparticles (UCNPs) possess several unique features, but they suffer from surface quenching effects caused by the interaction between the UCNPs and fluorophore. Thus, the use of UCNPs for target-induced emission changes for biosensing and bioimaging has been challenging. In this work, fluorophore and UCNPs are effectively separated by a silica transition layer with a thickness of about 4 nm to diminish the surface quenching effect of the UCNPs, allowing a universal and efficient luminescence resonance energy transfer (LRET) ratiometric upconversion luminescence nanoplatform for biosensing applications. A pH-sensitive fluorescein derivative and Hg(2+)-sensitive rhodamine B were chosen as fluoroionphores to construct the LRET nanoprobes. Both showed satisfactory target-triggered ratiometric upconversion luminescence responses in both solution and live cells, indicating that this strategy may find wide applications in the design of nanoprobes for various biorelated targets.

Simultaneous Visualization and Quantitation of Multiple Steroid Hormones Based on Signal‐Amplified Biosensing with Duplex Molecular Recognition

“…Regarded as a special type of nanophosphor, UCNPs are capable of converting near‐infrared (NIR) light to shorter wavelength luminescence through the energy‐transfer process . Compared to fluorophore‐based detection, UCNP‐based measurement presents decreased light scattering and less background interference, with significant improvement in sensitivity and limits of detection . More importantly, since the upconversion luminescence of UCNPs can be tuned by varying lanthanide dopants (including Er 3+ , Tm 3+ , and Ho 3+ ), these multicolor nanophosphors can be used to design ideal luminescent nanoprobes for the simultaneous detection of multiple targets .…”

Recent Advances on Functionalized Upconversion Nanoparticles for Detection of Small Molecules and Ions in Biosystems

“…Recently, dye‐modified UCNPs can also be used as pH probes for the application in living cells. For example, different energy acceptors such as xylenol orange90 and fluorescein isothiocyanate91, 92 have been reported.…”

Lanthanide Ion Doped Upconverting Nanoparticles: Synthesis, Structure and Properties

“…However, no clear evidence for the “active” role of silica coating was presented and a simple separation of the lanthanide ions on the surface from the quenching effects of the environment is a more likely mechanism for UCL enhancement. More recently, Tan and co‐workers used SiO 2 ‐coated NaYF 4 :Tm,Yb UCNP to design ratiometric sensors based on a resonance ET of UCL to a fluorophore . The thickness of the silica coating was found to be critical to eliminate the non‐specific surface quenching, while still maintaining an efficient ET .…”

“…More recently, Tan and co‐workers used SiO 2 ‐coated NaYF 4 :Tm,Yb UCNP to design ratiometric sensors based on a resonance ET of UCL to a fluorophore . The thickness of the silica coating was found to be critical to eliminate the non‐specific surface quenching, while still maintaining an efficient ET . The silica coating also makes UCNPs dispersible in water which is useful for biological applications.…”