Search

Nanocomposites consisting of upconversion nanoparticles (UCPs) and plasmonic materials have been widely explored for bio-imaging and cancer photothermal therapy (PTT). However, several challenges, including incomprehensible efficiency of energy transfer processes and optimization of the conditions for plasmon-induced photothermal effects, still exist. In this study, we fabricated NaYF4:Yb3+/Er3+ nanoparticles (NPs) conjugated with gold nanomaterials (Au NMs), such as Au NPs and gold nanorods (Au NRs). NaYF4:Yb3+/Er3+ NPs were used as photoconverters, which could emit green and red light under excitation of a 980 nm laser; Au NPs and Au NRs were also prepared and used as heat producers. The silica shell was further coated around UCPs to improve biocompatibility and as a bridge linking UCPs and the Au NMs. Most importantly, the thickness of the silica shell was tuned precisely to investigate the effective distance of the plasmonic field for heat induction. Energy transfer was confirmed by the declining UCL photoluminescence and emission decay time after connecting to the Au NMs. Moreover, a simulative model was built using the finite element method to assess the differences in heat generation between UCP@SiO2-NPs and UCP@SiO2-NRs. The surfaces of the hybrid nanocomposites were modified with folic acid to improve the specific targeting to cancer cells. The performance of the modified hybrid nanocomposites in PTT for OECM-1 oral cancer cells was evaluated. [ABSTRACT FROM AUTHOR]

Single-composition (or single-phase) phosphors have been proposed as a new strategy to overcome the concerns of emission reabsorption and different degradation rates of the three primary phosphors for light-emitting diode (LED) applications. A series of Ce3+, Sm3+ and Tb3+ co-doped NaSrBO3 phosphors were synthesized via a high temperature solid-state reaction. Upon near ultraviolet (NUV) excitation, tunable emission from violet to white in the visible region was realized in NaSrBO3:Ce3+,Sm3+,Tb3+ phosphors by controlling the dopant concentrations. Particularly, highly efficient white-light emission with a quantum yield as high as 48.2% was achieved. The energy transfer mechanism between Ce3+ and Sm3+ ions in NaSrBO3 was found to be predominantly of dipole–dipole nature. Moreover, the thermal quenching effect on the photoluminescence of NaSrBO3:Ce3+,Sm3+,Tb3+ was comprehensively surveyed over the range of 300–600 K, showing a good thermal stability for LED applications. By integrating this single-composition white-emitting NaSrBO3:Ce3+,Sm3+,Tb3+ phosphor with a 360 nm NUV chip, we fabricated a high-performance white LED (WLED), which exhibited an excellent color rendering index Ra of 80.1 and a correlated color temperature of 6731 K with CIE coordinates of (0.311, 0.314). These findings demonstrate that the proposed single-composition white-emitting NaSrBO3:Ce3+,Sm3+,Tb3+ phosphors can serve as promising phosphors for NUV-excited WLEDs. [ABSTRACT FROM AUTHOR]

Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great promise in bioapplications. Exploring new host materials to realize efficient upconversion luminescence (UCL) output is a goal of general concern. Herein, we develop a unique strategy for the synthesis of novel LiLuF4:Ln3+ core/shell UCNPs with typically high absolute upconversion quantum yields of 5.0 % and 7.6 % for Er3+ and Tm3+, respectively. Based on our customized UCL biodetection system, we demonstrate for the first time the application of LiLuF4:Ln3+ core/shell UCNPs as sensitive UCL bioprobes for the detection of an important disease marker β subunit of human chorionic gonadotropin (β-hCG) with a detection limit of 3.8 ng mL−1, which is comparable to the β-hCG level in the serum of normal humans. Furthermore, we use these UCNPs in proof-of-concept computed tomography imaging and UCL imaging of cancer cells, thus revealing the great potential of LiLuF4:Ln3+ UCNPs as efficient nano-bioprobes in disease diagnosis. [ABSTRACT FROM AUTHOR]

Eine zusätzliche Na ‐ Dotierung ermöglichte die Synthese von hochemissiven, weniger als 10 nm kleinen CaF2:Ln3+ ‐ Nanopartikeln, die empfindliche Sonden für den Nachweis von löslichem uPAR (einem wichtigen Tumormarker) durch zeitaufgelösten Fluoreszenzenergietransfer sind (siehe Bild; FITC=Fluoresceinisothiocyanat). Die Nanosonden konnten außerdem für die uPAR ‐ vermittelte Bildgebung von Krebszellen genutzt werden. [ABSTRACT FROM AUTHOR]

Hochauflösende Photolumineszenzspektroskopie mit Eu3+ als Struktursonde offenbarte einen universalen Gittersymmetriebruch in Lanthanoid ‐ dotierten fehlgeordneten Kristallen. Die spektrale Gittersymmetrie für Eu3+ sinkt von Oh nach Cs (oder C2) in α ‐ NaYF4 und von C3h nach Cs in β ‐ NaYF4. Die Ergebnisse wurden durch Kristallfeldrechnungen bestätigt. [ABSTRACT FROM AUTHOR]

• A new family of NIR-II semiconductor nano-bioprobes based on CuInSe2 QDs is proposed. • The excitation band of these CuInSe2 QDs spans from ultraviolet to NIR regions. • A record-high absolute NIR-II photoluminescence quantum yield (21.8%) for CuInSe2@ZnS QDs is achieved. • These CuInSe2@ZnS nanoprobes are employed for autofluorescence-free bioassay of circulating tumor cells spiked in whole blood samples with the limit of detection down to 12 cell/well of a 96-well plate. • The CuInSe2@ZnS nanoprobes are exploited for real-time tumor-targeted bioimaging in live mice with a signal-to-noise ratio of 5.8. Biosensing of circulating tumor cells (CTCs) is of vital significance in cancer theranostics. Thus, the development of highly efficient luminescent nano-bioprobes is imperative to meet the growing demand of CTCs-related clinical diagnosis and biomedical research. Herein, we exquisitely manipulate the stoichiometry of Se/In to synthesize CuInSe 2 (CISe) quantum dots (QDs) with near-infrared (NIR) emission peak tunable from 920 to 1224 nm. Meanwhile, the excitation band of these CISe QDs spans from ultraviolet to NIR regions, which is highly desired for various bioapplications. Through surface coating of thin ZnS shell, an absolute NIR-II photoluminescence quantum yield of 21.8% can be achieve, which is the highest among Pb/Cd-free QDs reported so far. By virtue of their intense NIR-II emission, we demonstrate the application of CISe nanoprobes for autofluorescence-free bioassay of CTCs (e.g. , human breast cancer MCF-7 cells) spiked in whole blood samples, with the limit of detection down to 12 cell/well of a 96-well plate. Furthermore, the CISe@ZnS nanoprobes are exploited for tumor-targeted bioimaging in live mice with a signal-to-noise ratio of 5.8. These findings reveal the great potentials of the novel NIR-II luminescent CuInSe 2 nanoprobes in the field of cancer diagnosis and imaging-guided surgery. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive nanoagents, which simultaneously satisfy normal tissue clearance and tumor‐specific responsive treatment, are highly attractive for precise cancer theranostics. Herein, we develop a unique template‐induced self‐assembly strategy for the exquisitely controlled synthesis of self‐assembled lanthanide (Ln3+) nucleotide nanoparticles (LNNPs) with amorphous structure and tunable size from sub‐5 nm to 105 nm. By virtue of the low‐temperature (10 K) and high‐resolution spectroscopy, the local site symmetry of Ln3+ in LNNPs is unraveled for the first time. The proposed LNNPs are further demonstrated to possess the ability for highly efficient loading and tumor‐microenvironment‐responsive release of doxorubicin. Particularly, sub‐5 nm LNNPs not only exhibit excellent biocompatibility and predominant renal‐clearance performance, but also enable efficient tumor retention. These findings reveal the great potential of LNNPs as a new generation of therapeutic platform to overcome the dilemma between efficient therapy and long‐term toxicity of nanoagents for future clinical applications. [ABSTRACT FROM AUTHOR]

Nd3+‐doped near‐infrared (NIR) luminescent nanocrystals (NCs) have shown great promise in various bioapplications. A fundamental understanding of the electronic structures of Nd3+ in NCs is of vital importance for discovering novel Nd3+‐activated luminescent nanoprobes and exploring their new applications. Herein, the electronic structures of Nd3+ in LiLuF4 NCs are unraveled by means of low‐temperature and high‐resolution optical spectroscopy. The photoactive site symmetry of Nd3+ in LiLuF4 NCs and its crystal‐field (CF) transition lines in the NIR region of interest are identified. By taking advantage of the well‐resolved and sharp CF transition lines of Nd3+, the application of LiLuF4:Nd3+ NCs as sensitive NIR‐to‐NIR luminescent nanoprobes for ratiometric detection of cryogenic temperature with a linear range of 77–275 K is demonstrated. These findings reveal the great potential of LiLuF4:Nd3+ NCs in temperature sensing and also lay a foundation for future design of efficient Nd3+‐based luminescent nanoprobes. [ABSTRACT FROM AUTHOR]

In dieser Replik entgegnen die Autoren der Zuschrift „Breakdown of Crystallographic Site Symmetry in Lanthanide ‐ Doped NaYF4 Crystals“ dem Kommentar von Karbowiak et al., welche die Kristallfeldanalyse des Eu3+ ‐ Ions in ungeordnetem NaYF4 kritisierten. Die Autoren stellen klar, dass die Kritik auf mehreren Missverständnissen beruht. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new class of NIR-LED photostimulated luminescence (PSL) nanoprobes based on SrS:Eu2+,Dy3+@SrS NCs is proposed. • The stimulation band of these SrS:Eu2+,Dy3+@SrS NCs spans from 700 to 1400 nm. • A PSL duration time longer than 2 h is achieved upon 808-nm LED stimulation. • These SrS:Eu2+,Dy3+@SrS nanoprobes are exploited for tumor-targeted imaging in zebrafish. Near-infrared (NIR) photostimulated luminescence (PSL) nanocrystals (NCs) exhibit deep penetrability and low autofluorescence, recently evoking extensive interest for their application in biosensing. Nevertheless, most of the NIR PSL NCs encounter substantial constraints in biomedicine applications, primarily stemming from the necessity of high-power diode laser stimulation or their larger particle size. Herein, we design a new class of NIR light-emitting diode (LED) PSL NCs based on SrS:Eu2+ NCs, which were coated with SrS shell to improve their stability and photoluminescence (PL) intensity. The trap depth and density of the NCs were further tailored through thermal annealing and Dy3+ co-doping, resulting in efficient NIR PSL with a duration time longer than 2 h by stimulation with an NIR LED in a broad region within 700–1400 nm. Benefiting from their excellent NIR PSL, we showcased the potential of SrS:Eu2+,Dy3+@SrS NCs as sensitive nanoprobes for tumor-targeted imaging in zebrafish with a signal-to-noise ratio of 18.9. These findings demonstrate the significant promise of the proposed SrS:Eu2+,Dy3+@SrS nanoprobes for in vivo bioimaging, which may pave the way for the development of effective NIR PSL nanoprobes for diverse bioapplications in the future. [ABSTRACT FROM AUTHOR]

Cypate-sensitized lanthanide upconversion nanoprobes with NIR dual-excitation have been developed for ratiometric detection of ATP in living cells and zebrafish larvae. The involved interfacial interactions and underlying energy transfer pathway were deeply explored. [Display omitted] • ATP-responsive dual NIR-excitation ratiometric nanoprobes were constructed. • The interfacial interactions and underlying photophysics in the nanoprobes were explored. • The nanoprobes were applied for the quantification of the ATP level in living cells. • The nanoprobes provided accurate monitoring of the in-vivo ATP fluctuation. As energy currency of life, adenosine triphosphate (ATP) is highly dynamic in living organisms. It is crucial yet challenging to probe intracellular or in-vivo ATP precisely without destruction of the living biological systems. Herein, we have designed novel ATP-responsive ratiometric nanoprobes by employing upconversion nanoparticles (UCNPs) with cypate as antennas. Nuclear magnetic resonance spectroscopy was used to analyze the interfacial interactions among lanthanide nanocrystal, cypate and adenosine phosphates, disclosing the origin of detection specificity. ATP induced interruption of energy transfer pathway in cypate-sensitized UCNPs was further investigated by femtosecond transient absorption and time-resolved photoluminescence spectroscopy. The nanoprobes with dual near-infrared (NIR)-excited ratiometric UCL were successfully applied for quantification of ATP level in living cells under vegetatively growing, starving, and glycolysis-inhibiting states, respectively. Furthermore, the increase of available energy by feeding for zebrafish larvae was confirmed through monitoring the in-vivo ATP variation with the nanoprobes. Such nanoprobes showed great potential in ATP-associated biological research and clinical applications. These findings may gain deep insights into the surface science and photophysics in dye-lanthanide nanocomposites, and open new avenues for the design and bioapplications of lanthanide nanoprobes. [ABSTRACT FROM AUTHOR]

Understanding the origin of temperature‐dependent bandgap in inorganic lead‐halide perovskites is essential and important for their applications in photovoltaics and optoelectronics. Herein, it is found that the temperature dependence of bandgap in CsPbBr3 perovskites is variable with material dimensionality. In contrast to the monotonous redshift ordinarily observed in bulk‐like CsPbBr3 nanocrystals (NCs), the bandgap of 2D CsPbBr3 nanoplatelets (NPLs) exhibits an initial blueshift then redshift trend with decreasing temperature (290–10 K). The Bose–Einstein two‐oscillator modeling manifests that the blueshift‐redshift crossover of bandgap in the NPLs is attributed to the significantly larger weight of contribution from electron‐optical phonon interaction to the bandgap renormalization in the NPLs than in the NCs. These new findings may gain deep insights into the origin of bandgap shift with temperature for both fundamentals and applications of perovskite semiconductor materials. [ABSTRACT FROM AUTHOR]

• A novel NIR-CPL-responsive hybrid upconversion nanoparticle hydrogel was proposed. • UCMBs were attached to helical nanofibers self-assembled from amino acids precursors. • Highly improved ground state chirality and upconversion CPL activity were obtained. • UCMBs@L/D-Gel exhibited chirality-dependent ROS generation and tumor cell killing. • Efficient tumor inhibition was achieved without causing any toxic side effects. Recently, chiral inorganic nanomaterials have attracted considerable interest for their chiroptical property and chirality-dependent phototherapeutic performance. Herein, for the first time, we propose a near-infrared circularly polarized light (NIR-CPL) responsive supramolecular hydrogels with high ground state chirality (| g abs | up to 3.2 × 10−2) and intense upconverted circularly polarized luminescence activity (| g lum | up to 2.6 × 10−2) for tumor photodynamic therapy. After supramolecular co-assembly, methylene blue loaded lanthanide upconversion nanoparticles (UCMBs) are effectively attached to the helical nanofibers constructed by amino acid precursors, which can achieve NIR-CPL triggered reactive oxygen species (ROS) production. The obtained hybrid hydrogels exhibit efficient NIR light conversion, improved photodynamic performance and efficient tumor inhibition. These findings provide a new perspective for exploring NIR-CPL responsive upconversion materials with outstanding chirality-dependent phototherapy characteristic and efficient therapeutic outcomes for further biomedical application. [ABSTRACT FROM AUTHOR]

Lanthanide-doped upconversion (UC) luminescent materials display multicolor emissions, making them ideal for a variety of applications, such as multi-channel biological imaging, fluorescence encryption, anti-counterfeiting, and 3D display. Manipulating the UC emissions of the luminescent materials with a fixed composition is crucial for their applications. Herein, we propose a facile strategy to achieve pulse-width-dependent multicolor UC emissions in NaYF4:Yb/Er/Tm nanocrystals. Upon excitation with a 980 nm continuous-wave laser diode, Er3+ ions in NaYF4:20%Yb,15%Er,1%Tm nanocrystals exhibited UC emissions with a red-to-green (R/G) ratio of 11.3. Nevertheless, by employing a 980 nm pulse laser with pulse widths from 0.1 to 10 ms, the UC R/G ratio can be easily adjusted from 0.9 to 11.3, resulting in continuous and remarkable color transformation from green, yellow, orange, to red. By virtue of the dynamic luminescence color variation of these NaYF4:20%Yb,15%Er,1%Tm nanocrystals, we demonstrated their potential applications in the areas of anti-counterfeiting and information encryption. These findings provide deep insights into the excited-state dynamics and energy transfer of Er3+ in NaYF4:Yb/Er/Tm nanocrystals upon 980 nm pulse excitation, which may pave the way for designing multicolor UC materials toward versatile applications., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Highly efficient near-infrared (NIR) luminescent nanomaterials are urgently required for portable mini or micro phosphors-converted light-emitting diodes (pc-LEDs). However, most existing NIR-emitting phosphors are generally restricted by their low photoluminescence (PL) quantum yield (QY) or large particle size. Herein, a kind of highly efficient NIR nanophosphors is developed based on copper indium selenide quantum dots (CISe QDs). The PL peak of these QDs can be exquisitely manipulated from 750 to 1150 nm by altering the stoichiometry of Cu/In and doping with Zn 2+ . Their absolute PLQY can be significantly improved from 28.6% to 92.8% via coating a ZnSe shell. By combining the phosphors with a commercial blue chip, an NIR pc-LED is fabricated with remarkable photostability and a record-high radiant flux of 88.7 mW@350 mA among the Pb/Cd-free QDs-based NIR pc-LEDs. Particularly, such QDs-based nanophosphors acted as excellent luminescence converter for NIR micro-LEDs with microarray diameters below 5 µm, which significantly exceeds the resolutions of current commercial inkjet display pixels. The findings may open new avenues for the exploration of highly efficient NIR micro-LEDs in a variety of applications., (© 2023 Wiley-VCH GmbH.)

Urinary sensing of synthetic biomarkers that are released into urine after specific activation in an in vivo disease environment is an emerging diagnosis strategy to overcome the insensitivity of a previous biomarker assay. However, it remains a great challenge to achieve sensitive and a specific urinary photoluminescence (PL) diagnosis. Herein, we report a novel urinary time-resolved PL (TRPL) diagnosis strategy by exploiting europium complexes of diethylenetriaminepentaacetic acid (Eu-DTPA) as synthetic biomarkers and designing the activatable nanoprobes. Notably, TRPL of Eu-DTPA in the enhancer can eliminate the urinary background PL for ultrasensitive detection. We achieved sensitive urinary TRPL diagnosis of mice kidney and liver injuries by using simple Eu-DTPA and Eu-DTPA-integrated nanoprobes, respectively, which cannot be realized by traditional blood assays. This work demonstrates the exploration of lanthanide nanoprobes for in vivo disease-activated urinary TRPL diagnosis for the first time, which might advance the noninvasive diagnosis of diverse diseases via tailorable nanoprobe designs.

Lanthanide ion (Ln 3+ )-doped halide double perovskites (DPs) have evoked tremendous interest due to their unique optical properties. However, Ln 3+ ions in these DPs still suffer from weak emissions due to their parity-forbidden 4f-4f electronic transitions. Herein, the local electronic structure of Ln 3+ -doped Cs 2 NaInCl 6 DPs is unveiled. Benefiting from the localized electrons of [YbCl 6 ] 3- octahedron in Cs 2 NaInCl 6 DPs, an efficient strategy of Cl - -Yb 3+ charge transfer sensitization is proposed to obtain intense near-infrared (NIR) luminescence of Ln 3+ . NIR photoluminescence (PL) quantum yield (QY) up to 39.4% of Yb 3+ in Cs 2 NaInCl 6 is achieved, which is more than three orders of magnitude higher than that (0.1%) in the well-established Cs 2 AgInCl 6 via conventional self-trapped excitons sensitization. Density functional theory calculation and Bader charge analysis indicate that the [YbCl 6 ] 3- octahedron is strongly localized in Cs 2 NaInCl 6 :Yb 3+ , which facilitates the Cl - -Yb 3+ charge transfer process. The Cl - -Yb 3+ charge transfer sensitization mechanism in Cs 2 NaInCl 6 :Yb 3+ is further verified by temperature-dependent steady-state and transient PL spectra. Furthermore, efficient NIR emission of Er 3+ with the NIR PLQY of 7.9% via the Cl - -Yb 3+ charge transfer sensitization is realized. These findings provide fundamental insights into the optical manipulation of Ln 3+ -doped halide DPs, thus laying a foundation for the future design of efficient NIR-emitting DPs., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Surface groups of carbon nanodots (CNDs) play a key role in modulating their photoluminescence (PL) properties. However, most of the as-prepared CNDs are complex mixtures of CNDs bearing different surface groups. Thus, the purification of CNDs is essential to reveal the PL mechanism of CNDs. Herein, we present a facile method to synthesize hydroxyl (-OH) free CNDs, followed by intelligently guided column chromatographic separation of CNDs with specific functional groups according to their degree of polarity. After systematic investigation of the separated non-polar CNDs (NP-CNDs) and polar CNDs (P-CNDs), it is revealed that radiative photon emission dominates in the NP-CNDs, which exhibits excitation wavelength-independent emissions. In contrast, an increase in the solvent polarity of P-CNDs improves Frank-Condon excited state stabilization to achieve excitation wavelength-dependent emissions. In particular, white-light emitting P-CNDs with CIE coordinates of (0.332, 0.336) are produced. These findings provide new insights into the nature of the PL mechanism for CNDs, which may pave the way towards the rational design of highly efficient and emission tunable CNDs for various applications.

Currently, lanthanide (Ln 3+ )-doped near-infrared (NIR)-emitting double perovskites (DPs) suffer from low photoluminescence quantum yield (PLQY). Herein, we develop a new class of NIR-emitting DPs based on Ln 3+ -doped Cs 2 (Na/Ag)BiCl 6 . Benefiting from the Na + -induced breakdown of local site symmetry in the Cs 2 AgBiCl 6 DPs, effective NIR emissions of Ln 3+ are realized through Bi 3+ sensitization. Specifically, 7.3-fold and 362.9-fold enhanced NIR emissions of Yb 3+ and Er 3+ are achieved in Cs 2 Ag 0.2 Na 0.8 BiCl 6 DPs relative to those in Na-free Cs 2 AgBiCl 6 counterparts, respectively. The optimal absolute NIR PLQYs for Yb 3+ and Er 3+ in Cs 2 Ag 0.2 Na 0.8 BiCl 6 DPs are determined to be 19.0 % and 4.3 %, respectively. Raman spectroscopy and first-principles density functional theory calculations verify the sublattice distortion in Cs 2 (Na/Ag)BiCl 6 DPs via Na + doping. These findings provide fundamental insights into the design of efficient NIR-emitting Ln 3+ -doped DPs for versatile optoelectronic applications., (© 2022 Wiley-VCH GmbH.)

Rare earth (RE 3+ )-doped phosphors generally suffer from thermal quenching, in which their photoluminescence (PL) intensities decrease at high temperatures. Herein, we report a class of unique two-dimensional negative-thermal-expansion phosphor of Sc 2 (MoO 4 ) 3 :Yb/Er. By virtue of the reduced distances between sensitizers and emitters as well as confined energy migration with increasing the temperature, a 45-fold enhancement of green upconversion (UC) luminescence and a 450-fold enhancement of near-infrared downshifting (DS) luminescence of Er 3+ are achieved upon raising the temperature from 298 to 773 K. The thermally boosted UC and DS luminescence mechanism is systematically investigated through in situ temperature-dependent Raman spectroscopy, synchrotron X-ray diffraction and PL dynamics. Moreover, the luminescence lifetime of 4 I 13/2 of Er 3+ in Sc 2 (MoO 4 ) 3 :Yb/Er displays a strong temperature dependence, enabling luminescence thermometry with the highest relative sensitivity of 12.3%/K at 298 K and low temperature uncertainty of 0.11 K at 623 K. These findings may gain a vital insight into the design of negative-thermal-expansion RE 3+ -doped phosphors for versatile applications., (© 2022. The Author(s).)

Fundamental understanding of the effect of doping on the optical properties of 3D double perovskites (DPs) especially the dynamics of self-trapped excitons (STEs) is of vital importance for their optoelectronic applications. Herein, a unique strategy via Cu + doping to achieve efficient STE emission in the alloyed lead-free Cs 2 (Ag/Na)InCl 6 DPs is reported. A small amount (1.0 mol%) of Cu + doping results in boosted STE emission in the crystals, with photoluminescence (PL) quantum yield increasing from 19.0% to 62.6% and excitation band shifting from 310 to 365 nm. Temperature-dependent PL and femtosecond transient absorption spectroscopies reveal that the remarkable PL enhancement originates from the increased radiative recombination rate and density of STEs, as a result of symmetry breakdown of the STE wavefunction at the octahedral Ag + site. These findings provide deep insights into the STE dynamics in Cu + -doped Cs 2 (Ag/Na)InCl 6 , thereby laying a foundation for the future design of new lead-free DPs with efficient STE emission., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Highly efficient luminescence of AgInTe 2 :Zn/ZnS nanocrystals with the maximum NIR-II quantum yield of 25.2% has been designed through elaborately manipulating the structure to reduce their internal and surface defects. These AgInTe 2 :Zn/ZnS nanoprobes were employed for sensitive homogeneous biodetection of xanthine oxidase with the limit of detection down to 25 nU L -1 .

Lanthanide (Ln 3+ )-doped upconversion (UC) nanoprobes, which have drawn extensive attention for various bioapplications, usually suffer from small absorption cross-sections and weak luminescence intensity of Ln 3+ ions. Herein, we report the controlled synthesis of a new class of Ln 3+ -doped UC nanoprobes based on CsLu 2 F 7 :Yb/Er nanocrystals (NCs), which can effectively increase the intersystem crossing (ISC) efficiency from singlet excited state to triplet excited state of IR808 up to 99.3 % through the heavy atom effect. By virtue of the efficient triplet sensitization of IR808, the optimal UC luminescence (UCL) intensity of IR808-modified CsLu 2 F 7 :Yb/Er NCs is enhanced by 1309 times upon excitation at 808 nm. Benefiting from the intense dye-triplet-sensitized UCL, the nanoprobes are demonstrated for sensitive assay of extracellular and intracellular hypochlorite with an 808-nm/980-nm dual excited ratiometric strategy., (© 2021 Wiley-VCH GmbH.)

Lanthanide (Ln3+)-doped upconversion (UC) nanocrystals have drawn tremendous attention because of their intriguing optical properties. Currently, it is highly desired but remains challenging to achieve efficient multiphoton UC emissions. Herein, we report the controlled synthesis of a new class of UC nanocrystals based on Cs2NaYF6:Yb/Tm nanoplatelets (NPs), which can effectively convert the 980 nm light to five-photon and four-photon UC emissions of Tm3+ without the fabrication of a complicated core/multishell structure required in traditional nanocrystals. Particularly, the as-prepared Cs2NaYF6:Yb/Tm NPs exhibit a maximal UV-to-NIR emission intensity ratio of 1.2, which is the highest among Tm3+-doped core-only UC nanocrystals. We reveal that the enhanced multiphoton UC emissions may benefit from the confined energy migration of Ln3+ dopants in the unique two-dimensional-like structure of Cs2NaYF6 NPs. As such, intense red and green UC emissions of Eu3+ and Tb3+ can further be generated via the cascade sensitization of Tm3+ and Gd3+ in Cs2NaYF6:Yb/Tm/Gd/Eu and Cs2NaYF6:Yb/Tm/Gd/Tb NPs, respectively. These results validate the superiority of Cs2NaYF6 for the future design of efficient UC nanocrystals towards versatile applications.

Luminescent biosensing in the second near-infrared window (NIR-II, 1000-1700 nm) region, which has weak tissue scattering and low autofluorescence, draws extensive attention owing to its deep tissue penetration, good spatial resolution and high signal-to-background ratio. As a new generation of NIR-II probes, lanthanide (Ln 3+ )-containing nanoprobes exhibit several superior properties. With the rapid development of Ln 3+ -containing NIR-II nanoprobes, many significant advances have been accomplished in their optical properties tuning and surface functional modification for further bioapplications. Rather than being exhaustive, this review aims to survey the recent advances in the design strategies of inorganic Ln 3+ -containing NIR-II luminescent nanoprobes by highlighting their optical performance optimization and surface modification approaches. Moreover, challenges and opportunities for this kind of novel NIR-II nanoprobes are envisioned., Competing Interests: The authors declare no conflict of interest., (© 2021 The Author(s).)

Nd 3+ -doped near-infrared (NIR) luminescent nanocrystals (NCs) have shown great promise in various bioapplications. A fundamental understanding of the electronic structures of Nd 3+ in NCs is of vital importance for discovering novel Nd 3+ -activated luminescent nanoprobes and exploring their new applications. Herein, the electronic structures of Nd 3+ in LiLuF 4 NCs are unraveled by means of low-temperature and high-resolution optical spectroscopy. The photoactive site symmetry of Nd 3+ in LiLuF 4 NCs and its crystal-field (CF) transition lines in the NIR region of interest are identified. By taking advantage of the well-resolved and sharp CF transition lines of Nd 3+ , the application of LiLuF 4 :Nd 3+ NCs as sensitive NIR-to-NIR luminescent nanoprobes for ratiometric detection of cryogenic temperature with a linear range of 77-275 K is demonstrated. These findings reveal the great potential of LiLuF 4 :Nd 3+ NCs in temperature sensing and also lay a foundation for future design of efficient Nd 3+ -based luminescent nanoprobes., Competing Interests: The authors declare no conflict of interest.

All-inorganic CsPbX 3 (X = Cl, Br, and I) perovskite quantum dots (PeQDs) have shown great promise in optoelectronics and photovoltaics owing to their outstanding linear optical properties; however, nonlinear upconversion is limited by the small cross-section of multiphoton absorption, necessitating high power density excitation. Herein, we report a convenient and versatile strategy to fine tuning the upconversion luminescence in CsPbX 3 PeQDs through sensitization by lanthanide-doped nanoparticles. Full-color emission with wavelengths beyond the availability of lanthanides is achieved through tailoring of the PeQDs bandgap, in parallel with the inherent high conversion efficiency of energy transfer upconversion under low power density excitation. Importantly, the luminescent lifetimes of the excitons can be enormously lengthened from the intrinsic nanosecond scale to milliseconds depending on the lifetimes of lanthanide ions. These findings provide a general approach to stimulate photon upconversion in PeQDs, thereby opening up a new avenue for exploring novel and versatile applications of PeQDs.

Lanthanide (Ln3+)-doped NaREF4 (RE = rare earth) nanocrystals (NCs) are one of the most widely studied upconversion and downshifting luminescent nanoprobes. However, the size and optical performance of the Ln3+-doped NaREF4 NCs produced by the available lab-scale synthesis may vary from batch to batch, which inevitably limits their practical bioapplications. Herein, we report the synthesis of uniform Ln3+-doped NaREF4 NCs via a facile solid-liquid-thermal-decomposition (SLTD) method by directly employing NaHF2 powder as a fluoride and sodium precursor. The proposed SLTD strategy is easy to perform, time-saving and cost-effective, making it ideal for scale-up syntheses. Particularly, over 63 g of β-NaGdF4:Yb,Er@NaYF4 core/shell NCs with narrow size variation (<7%) were synthesized via a one-pot reaction. By virtue of their superior upconversion and downshifting luminescence, we employed the synthesized core/shell nanoprobes for the in vitro detection of prostate-specific antigen with a limit of detection down to 1.8 ng mL-1, and for in vivo near-infrared imaging with a high signal-to-noise ratio of 12. These findings may pave the way for the commercialization of Ln3+-doped nanoprobes in bioassay kits for versatile clinical applications.

Near-infrared (NIR) II luminescence between 1000 and 1700 nm has attracted reviving interest for biosensing due to its unique advantages such as deep-tissue penetration and high spatial resolution. Traditional NIR-II probes such as organic fluorophores usually suffer from poor photostability and potential long-term toxicity. Herein, we report the controlled synthesis of monodisperse NaCeF 4 :Er/Yb nanocrystals (NCs) that exhibit intense NIR-II emission upon excitation at 980 nm. Ce 3+ in the host lattice was found to enhance the luminescence of Er 3+ at 1530 nm with a maximum NIR-II quantum yield of 32.8%, which is the highest among Er 3+ -activated nanoprobes. Particularly, by utilizing the intense NIR-II emission of NaCeF 4 :Er/Yb NCs, we demonstrated their application as sensitive homogeneous bioprobes to detect uric acid with the limit of detection down to 25.6 nM. Furthermore, the probe was detectable in tissues at depths of up to 10 mm, which enabled in vivo imaging of mouse organs and hindlimbs with high resolution, thus revealing the great potential of these NaCeF 4 :Er/Yb nanoprobes in deep-tissue diagnosis.

Lanthanide (Ln 3+ )-doped upconversion nanoparticles (UCNPs) have attracted tremendous interest owing to their potential bioapplications. However, the intrinsic photophysics responsible for upconversion (UC) especially the cooperative sensitization UC (CSU) in colloidal Ln 3+ -doped UCNPs has remained untouched so far. Herein, we report a unique strategy for the synthesis of high-quality LiYbF 4 :Ln 3+ core-only and core/shell UCNPs with tunable particle sizes and shell thicknesses. Energy transfer UC from Er 3+ , Ho 3+ and Tm 3+ and CSU from Tb 3+ were comprehensively surveyed under 980 nm excitation. Through surface passivation, we achieved efficient non-cooperative sensitization UC with absolute UC quantum yields (QYs) of 3.36%, 0.69% and 0.81% for Er 3+ , Ho 3+ and Tm 3+ , respectively. Particularly, we for the first time quantitatively determined the CSU efficiency for Tb 3+ with an absolute QY of 0.0085% under excitation at a power density of 70 W cm -2 . By means of temperature-dependent steady-state and transient UC spectroscopy, we unraveled the dominant mechanisms of phonon-assisted cooperative energy transfer (T > 100 K) and sequential dimer ground-state absorption/excited-state absorption (T < 100 K) for the CSU process in LiYbF 4 :Tb 3+ UCNPs.

Nanocomposites consisting of upconversion nanoparticles (UCPs) and plasmonic materials have been widely explored for bio-imaging and cancer photothermal therapy (PTT). However, several challenges, including incomprehensible efficiency of energy transfer processes and optimization of the conditions for plasmon-induced photothermal effects, still exist. In this study, we fabricated NaYF 4 :Yb 3+ /Er 3+ nanoparticles (NPs) conjugated with gold nanomaterials (Au NMs), such as Au NPs and gold nanorods (Au NRs). NaYF 4 :Yb 3+ /Er 3+ NPs were used as photoconverters, which could emit green and red light under excitation of a 980 nm laser; Au NPs and Au NRs were also prepared and used as heat producers. The silica shell was further coated around UCPs to improve biocompatibility and as a bridge linking UCPs and the Au NMs. Most importantly, the thickness of the silica shell was tuned precisely to investigate the effective distance of the plasmonic field for heat induction. Energy transfer was confirmed by the declining UCL photoluminescence and emission decay time after connecting to the Au NMs. Moreover, a simulative model was built using the finite element method to assess the differences in heat generation between UCP@SiO 2 -NPs and UCP@SiO 2 -NRs. The surfaces of the hybrid nanocomposites were modified with folic acid to improve the specific targeting to cancer cells. The performance of the modified hybrid nanocomposites in PTT for OECM-1 oral cancer cells was evaluated.

A NaYF4 host matrix with a new cubic phase is fabricated to offer high upconversion luminescence efficiency. The new cubic phase is formed through a hexagonal-to-cubic phase transition by shining intense near-infrared light on lanthanide-doped hexagonal NaYF4 materials., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great promise in versatile bioapplications. For the first time, organosilica-shelled β-NaLuF4:Gd/Yb/Er nanoprobes with a rattle structure have been designed for dual-modal imaging and photodynamic therapy (PDT). Benefiting from the unique rattle structure and aromatic framework, these nanoprobes are endowed with a high loading capacity and the disaggregation effect of photosensitizers. After loading of β-carboxyphthalocyanine zinc or rose Bengal into the nanoprobes, we achieved higher energy transfer efficiency from UCNPs to photosensitizers as compared to those with conventional core-shell structure or with pure-silica shell, which facilitates a large production of singlet oxygen and thus an enhanced PDT efficacy. We demonstrated the use of these nanoprobes in proof-of-concept X-ray computed tomography (CT) and UC imaging, thus revealing the great potential of this multifunctional material as an excellent nanoplatform for cancer theranostics., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Conventional dissociation-enhanced lanthanide fluoroimmunoassays (DELFIA) using molecular probes suffer from a low labeling ratio of lanthanide ions (Ln(3+) ) per biomolecule. Herein, we develop a unique bioassay based on the dissolution-enhanced luminescence of inorganic lanthanide nanoparticles (NPs). As a result of the highly concentrated Ln(3+)  ions in a single Ln(3+)  NP, an extremely high Ln(3+)  labeling ratio can be achieved, which amplifies significantly the luminescence signal and thus improves the detection sensitivity compared to DELFIA. Utilizing sub-10 nm NaEuF4  NPs as dissolution-enhanced luminescent nanoprobes, we demonstrate the successful in vitro detection of carcinoembryonic antigen (CEA, an important tumor marker) in human serum samples with a record-low detection limit of 0.1 pg mL(-1) (0.5 fM). This value is an improvement of approximately 3 orders of magnitude relative to that of DELFIA. The dissolution-enhanced luminescent bioassay shows great promise in versatile bioapplications, such as ultrasensitive and multiplexed in vitro detection of disease markers in clinical diagnosis., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Sr2YF7, as an important matrix for trivalent lanthanide (Ln(3+)) ions to fabricate upconversion (UC) or downshifting (DS) phosphors, has been rarely reported. Herein, monodisperse and size-controllable tetragonal-phase Ln(3+)-doped Sr2YF7 nanoparticles (NPs) were synthesized via a facile thermal decomposition method. Upon excitation at 980 nm, UC luminescence properties of Sr2YF7:Ln(3+)/Yb(3+) (Ln = Tm, Er) NPs were systematically surveyed. Particularly, after coating an inert Sr2YF7 shell, the UC luminescence intensities of Sr2YF7:Tm(3+)/Yb(3+) and Sr2YF7:Er(3+)/Yb(3+) NPs were enhanced by ∼22 and 4 times, respectively. Furthermore, intense multicolor DS luminescence was also achieved in Ce(3+)/Tb(3+) or Eu(3+) doped Sr2YF7 NPs, with absolute quantum yields of 55.1% (Tb(3+)) and 11.2% (Eu(3+)). The luminescence lifetimes of (5)D4 (Tb(3+)) and (5)D0 (Eu(3+)) were determined to be 3.7 and 8.1 ms, respectively. By utilizing the long-lived luminescence of Ln(3+) in these Sr2YF7 NPs, we demonstrated their application as sensitive heterogeneous time-resolved photoluminescence bioprobes to detect the protein of avidin and the tumor marker of the carcinoembryonic antigen (CEA) with their limits of detection down to 40.6 and 94.9 pM, and thus reveal the great potential of these Sr2YF7:Ln(3+) nanoprobes in cancer diagnosis.

Lanthanide-doped upconversion nanoparticles (UCNPs) have shown great promise in bioapplications. Exploring new host materials to realize efficient upconversion luminescence (UCL) output is a goal of general concern. Herein, we develop a unique strategy for the synthesis of novel LiLuF4 :Ln(3+) core/shell UCNPs with typically high absolute upconversion quantum yields of 5.0 % and 7.6 % for Er(3+) and Tm(3+) , respectively. Based on our customized UCL biodetection system, we demonstrate for the first time the application of LiLuF4 :Ln(3+) core/shell UCNPs as sensitive UCL bioprobes for the detection of an important disease marker β subunit of human chorionic gonadotropin (β-hCG) with a detection limit of 3.8 ng mL(-1) , which is comparable to the β-hCG level in the serum of normal humans. Furthermore, we use these UCNPs in proof-of-concept computed tomography imaging and UCL imaging of cancer cells, thus revealing the great potential of LiLuF4 :Ln(3+) UCNPs as efficient nano-bioprobes in disease diagnosis., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Multimodal bioprobes, which integrate the advantages of different diagnostic modes into one single particle, can overcome the current limitations of sensitivity and resolution in medical assays and significantly improve the outcome of existing therapeutics. Lanthanide-doped inorganic multimodal bioprobes, which are emerging as a promising new class of optical/magnetic multimodal bioprobes, have been long sought-after and have recently attracted revived interest owing to their distinct optical and magnetic properties. In this concept article, we introduce the controlled synthesis of lanthanide-doped inorganic multimodal bioprobes, including core-shell structured and single-phase nanoparticles, and demonstrate different design strategies for achieving dual-modal functionalization of nanoprobes. In particular, we highlight the most recent advances in biodetection, bioimaging, targeted drug delivery, and therapy based on these nanoparticles., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Amine-functionalized lanthanide-doped KGdF(4) nanocrystals, synthesized via a facile one-step solvothermal route by employing polyethylenimine as the surfactant and capping ligand, have been demonstrated to be sensitive time-resolved FRET bioprobes to detect a trace amount of biomolecules such as avidin at a concentration of 5.5 nM and to be potential T(1)-MRI contrast agents due to a large longitudinal relaxivity of Gd(3+) (5.86 S(-1)·mM(-1) per Gd ion and 3.99 × 10(5) S(-1)·mM(-1) per nanocrystal)., (© 2011 American Chemical Society)