Yb3+,Er3+,Eu3+-codoped YVO4 material for bioimaging with dual mode excitation

Fluorescence Optosensing of Triclosan by Upconversion Nanoparticles with Potassium Permanganate

It is greatly significant to develop a simple and rapid sensing method for triclosan (TCS) because it is a widely used and a chronically toxic compound that adversely affects biological organisms and human health. This paper presents the design and development of a novel simple optosensor that uses carboxylic group-functionalized NaYF₄:Yb³⁺/Er³⁺ upconversion nanoparticles (UCNPs) coated with potassium permanganate (KMnO₄). The sensor enables the rapid, non-autofluorescence, sensitive, and selective detection of TCS based on the "turn off-on fluorescence" technique through fluorescence resonance energy transfer. Under an near-infrared radiation excitation (980 nm), the "turn-off fluorescence" process involves the transfer of fluorescence resonance energy between the UCNPs and KMnO₄, whereas the "turn-on fluorescence" process occurs when KMnO₄ is reduced in the presence of TCS. TCS was detected by recovering the green emission of UCNPs. Under optimized conditions, the resulting sensor offered an excellent response to TCS with 0.2 μM of a limit of detection. The developed sensor showed higher selectivity to TCS than other phenolic compounds. Moreover, the analytical performance of the proposed probe was practically demonstrated to successfully monitor trace levels of TCS in samples of tap water and personal care products. The developed simple and sensitive method may offer a new approach for determining TCS in environmental applications.

Design and structural investigations of Yb3+ substituted β-Ca3(PO4)2 contrast agents for bimodal NIR luminescence and X-ray CT imaging

The quest for the development of bone substitutes with contrast agents for diagnostic imaging subsists to distinguish synthetic bone from native human tissue. To this aim, ytterbium (Yb³⁺) substitutions in β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP) as contrast agents has been developed to differentiate implant materials thereby, facilitating as host for bimodal imaging application by means of NIR luminescence and X-ray computed tomography techniques. A facile aqueous chemical precipitation route with the aid of surfactant is used for the synthesis of Yb³⁺ substitutions in β-Ca₃(PO₄)₂. The characterization results affirms the ability of β-Ca₃(PO₄)₂ to host 4.36 mol% of Yb³⁺ while the excess Yb³⁺ crystallizes as YbPO₄. The structure refinement results favour the occupancy of Yb³⁺ at the Ca²⁺(5) site of β-Ca₃(PO₄)₂. The absorption and photoluminescence spectra in the near infrared region with emission intensity ~1024 nm in the second biological window correspond to ²F_5/2 → ²F_7/2 transitions of Yb³⁺. The designed Yb³⁺ substituted β-Ca₃(PO₄)₂ does not exhibit any toxicity in human osteosarcoma cell lines and delivers an excellent in vitro CT contrast ability allied by the enhanced signal intensity and high X-ray absorption coefficient.