Sub‐10 nm Lanthanide‐Doped CaF₂ Nanoprobes for Time‐Resolved Luminescent Biodetection

Rare earth based nanostructured materials: synthesis, functionalization, properties and bioimaging and biosensing applications

“…Regarding the matrices of Ln-based luminescent materials, a wide variety of inorganic structures for both DC and UC materials have been proposed in the literature. Fluorides are used for their low phonon energy (<400 cm −1 ), which involves a low probability of NR relaxation and therefore provides improved quantum efficiency [177,178], while phosphates are interesting for their biocompatibility and biodegradability [179]. Other matrices based on vanadates [86,180], oxyfluorides [92], wolframates [181][182][183] and molybdates [184,185] are employed to enhance the global luminescent emission of the DC materials, as it will be detailed later.…”

Nanomaterial-functionalized Cellulose: Design, Characterization and Analytical Applications

“…Another commonly used fluorescent agent is 2,3-diaminophenazine which can be oxidized from o-phenylenediamine in the presence of Ag(I) or Au(II) ions 86 to create fluorescent light. Lanthanide series ions such as Tb 3+ has been utilized to generate a fluorescent response for detection of soluble uPAR (an important tumor marker) 87 or dipicolinic acid (DPA), 88 an anthrax biomarker. Fluorescent nanospheres of tris 8-hydroxyquinoline aluminum (Alq3), a complex between aluminum and three 8-hydroxyquinoline molecules have been used as fluorescent probes to detect 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (TNP) explosives through fluorescence quenching.…”

Inorganic lanthanide nanoprobes for background-free luminescent bioassays

“…For example, by utilizing the positively charged Ln 3+ ions exposed on ligand-free LiLuF 4 :Yb, Er UCNPs, we have succeeded in the avidin functionalization of the UCNPs through electrostatic interaction [62]. Likewise, Lu and coworkers [101] developed an exceptionally simple strategy for the direct synthesis of DNA-func- -Benzotriazole-N,N,N',N'-tetramethyluronium-hexafluoro-phosphate (HBTU) and N,N-diisopropylethy (DIEA) as cross-linking reagents [65,102]. Despite the validity of these methods, the functional groups are omnipresent in biological systems and cannot be labeled specifically in complex biological systems.…”

“…After biotinylation, the GdF 3 : Tb 3+ NPs were further explored as sensitive nanoprobes in a heterogeneous TRPL bioassay to detect trace amounts of avidin with a limit of detection (LOD) down to 74 pM. On the basis of similar protocol, we have recently extended the TRPL bioassay technique to other Ln 3+ -NPs like CaF 2 : Ce,Tb and to the assay of tumor markers such as carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP) and prostate-specific antigen (PSA) with LODs ranging from several to tens of pM [65].…”

“…After biotinylation, the GdF 3 : Tb 3+ NPs were further explored as sensitive nanoprobes in a heterogeneous TRPL bioassay to detect trace amounts of avidin with a limit of detection (LOD) down to 74 pM. On the basis of similar protocol, we have recently extended the TRPL bioassay technique to other Ln 3+ -NPs like CaF 2 : Ce,Tb and to the assay of tumor markers such as carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP) and prostate-specific antigen (PSA) with LODs ranging from several to tens of pM [65].Besides the application in heterogeneous TRPL bioassays, Ln 3+ -doped NPs are also regarded as excellent energy donors in homogeneous TR-FRET assays. In a typical TR-FRET process, the energy transfer from Ln 3+ -NP donor will apparently lengthen the PL lifetime of the acceptor such as organic dyes that are intrinsically short-lived, due to the slow population of the acceptor's excited-state from the long-lived Ln 3+ 's excited state [27].…”