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Lanthanide ion (Ln3+)‐doped halide double perovskites (DPs) have evoked tremendous interest due to their unique optical properties. However, Ln3+ ions in these DPs still suffer from weak emissions due to their parity‐forbidden 4f–4f electronic transitions. Herein, the local electronic structure of Ln3+‐doped Cs2NaInCl6 DPs is unveiled. Benefiting from the localized electrons of [YbCl6]3− octahedron in Cs2NaInCl6 DPs, an efficient strategy of Cl−‐Yb3+ charge transfer sensitization is proposed to obtain intense near‐infrared (NIR) luminescence of Ln3+. NIR photoluminescence (PL) quantum yield (QY) up to 39.4% of Yb3+ in Cs2NaInCl6 is achieved, which is more than three orders of magnitude higher than that (0.1%) in the well‐established Cs2AgInCl6 via conventional self‐trapped excitons sensitization. Density functional theory calculation and Bader charge analysis indicate that the [YbCl6]3− octahedron is strongly localized in Cs2NaInCl6:Yb3+, which facilitates the Cl−‐Yb3+ charge transfer process. The Cl−‐Yb3+ charge transfer sensitization mechanism in Cs2NaInCl6:Yb3+ is further verified by temperature‐dependent steady‐state and transient PL spectra. Furthermore, efficient NIR emission of Er3+ with the NIR PLQY of 7.9% via the Cl−‐Yb3+ charge transfer sensitization is realized. These findings provide fundamental insights into the optical manipulation of Ln3+‐doped halide DPs, thus laying a foundation for the future design of efficient NIR‐emitting DPs. [ABSTRACT FROM AUTHOR]

Currently, lanthanide (Ln3+)‐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 Ln3+‐doped Cs2(Na/Ag)BiCl6. Benefiting from the Na+‐induced breakdown of local site symmetry in the Cs2AgBiCl6 DPs, effective NIR emissions of Ln3+ are realized through Bi3+ sensitization. Specifically, 7.3‐fold and 362.9‐fold enhanced NIR emissions of Yb3+ and Er3+ are achieved in Cs2Ag0.2Na0.8BiCl6 DPs relative to those in Na‐free Cs2AgBiCl6 counterparts, respectively. The optimal absolute NIR PLQYs for Yb3+ and Er3+ in Cs2Ag0.2Na0.8BiCl6 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 Cs2(Na/Ag)BiCl6 DPs via Na+ doping. These findings provide fundamental insights into the design of efficient NIR‐emitting Ln3+‐doped DPs for versatile optoelectronic applications. [ABSTRACT FROM AUTHOR]

Currently, lanthanide (Ln3+)‐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 Ln3+‐doped Cs2(Na/Ag)BiCl6. Benefiting from the Na+‐induced breakdown of local site symmetry in the Cs2AgBiCl6 DPs, effective NIR emissions of Ln3+ are realized through Bi3+ sensitization. Specifically, 7.3‐fold and 362.9‐fold enhanced NIR emissions of Yb3+ and Er3+ are achieved in Cs2Ag0.2Na0.8BiCl6 DPs relative to those in Na‐free Cs2AgBiCl6 counterparts, respectively. The optimal absolute NIR PLQYs for Yb3+ and Er3+ in Cs2Ag0.2Na0.8BiCl6 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 Cs2(Na/Ag)BiCl6 DPs via Na+ doping. These findings provide fundamental insights into the design of efficient NIR‐emitting Ln3+‐doped DPs for versatile optoelectronic applications. [ABSTRACT FROM AUTHOR]

Zero-dimensional (0D) organic-inorganic metal halides (OIMHs), which combine the emissions from organics and self-trapped exciton (STE) of metal halides, have been highly anticipated as a new kind of white light-emitting material for a variety of applications. However, the correlated color temperature (CCT) of the white light-emitting OIMHs is generally not tunable, which severely limits their potential applications in diverse scenarios. Herein, a new class of OIMH based on PMA 2 ZrCl 6 is developed as a white light-emitting material that exhibits broad emissions from 400 nm to 720 nm under 370 nm excitation with the Commission Internationale de l'Eclairage (CIE) color coordinate of (0.30, 0.34). By doping with Sb3+ in PMA 2 ZrCl 6 , excitation-dependent CCT manipulation can be achieved through the combination of the tunable emission of benzylamine (PMA) and STE induced by Sb3+ doping. Upon excitation from 270 nm to 390 nm, CCT values can be tuned from 9179 K to 3107 K, covering warm white light, cool white light, and standard white light. Furthermore, we employed the PMA 2 ZrCl 6 :Sb3+ phosphors as excellent luminescence converters for white light-emitting diodes, wherein CCT values with 5915 K and 7198 K were achieved upon excitation with 310 nm and 365 nm chips, respectively. This research establishes the groundwork for controlling CCT in OIMHs and highlights their great potential in various optoelectronic applications. • A new class of 0D organic-inorganic metal halides based on PMA 2 ZrCl 6 exhibiting white-light emission is developed. • Excitation-dependent CCT manipulation of white-light emission is achieved in Sb3+-doped PMA 2 ZrCl 6. • WLEDs with tunable CCT and high CRI values are fabricated by coating PMA 2 ZrCl 6 :Sb3+ on different commercial chips. [ABSTRACT FROM AUTHOR]

The point‐of‐care detection of tumor markers in saliva with high sensitivity and specificity remains a daunting challenge in biomedical research and clinical applications. Herein, a facile and ultrasensitive detection of tumor marker in saliva based on luminescence‐amplification strategy of lanthanide nanoprobes is proposed. Eu2O3 nanocrystals are employed as bioprobes, which can be easily dissolved in acidic enhancer solution and transform into a large number of highly luminescent Eu3+ micelles. Meanwhile, disposable syringe filter equipped with nitrocellulose membrane is used as bioassay platform, which facilitates the accomplishment of detection process within 10 min. The rational integration of dissolution enhanced luminescent bioassay strategy and miniaturized detection device enables the unique lab‐in‐syringe assay of tumor marker like carcinoembryonic antigen (CEA, an important tumor marker in clinic diagnosis and prognosis of cancer) with a detection limit down to 1.47 pg mL−1 (7.35 × 10−15m). Upon illumination with a portable UV flashlight, the photoluminescence intensity change above 0.1 ng mL−1 (0.5 × 10−12m) of CEA can be visually detected by naked eyes, which allows one to qualitatively evaluate the CEA level. Moreover, we confirm the reliability of using the amplified luminescence of Eu2O3 nanoprobes for direct quantitation of CEA in patient saliva samples, thus validates the practicality of the proposed strategy for both clinical diagnosis and home self‐monitoring of tumor marker in human saliva. [ABSTRACT FROM AUTHOR]

Lanthanide (Ln3+)-doped upconversion nanoparticles (UCNPs), exhibiting excellent optical properties such as long photoluminescence lifetime, narrow emission bandwidth, and low autofluorescence background, have been applied in many fields, especially in biological analysis and medical diagnostics. Despite the exciting progress, the applications of Ln3+-doped UCNPs are hindered by the small absorption cross-section and low upconversion luminescence efficiency of Ln3+. To this regard, several effective strategies associated with energy transfer designing have been proposed to modulate the upconversion luminescence properties of Ln3+ in the past few decades. In this feature article, we focus on the most recent development of optical property designing in Ln3+-doped UCNPs on the basis of energy transfer between Ln3+–Ln3+, Ln3+–dyes, and Ln3+–quantum dots. Some future efforts towards the energy transfer designing in Ln3+-doped UCNPs are also proposed. [ABSTRACT FROM AUTHOR]

Highlights • The fundamental photophysics of Eu3+-activated luminescent nanoprobes are overviewed. • The strategies for enhancing the downshifting/upconverting luminescence of Eu3+-activated nanoprobes are summarized. • Heterogeneous and homogeneous biodetections based on Eu3+-activated luminescent nanoprobes are exemplified. • In vitro and in vivo bioimagings based on Eu3+-activated luminescent nanoprobes are specifically outlined. Abstract Trivalent europium ions (Eu3+) activated inorganic materials, known as one of the most important red-emitting phosphors, are emerging as an attractive class of luminescent materials over the past decades. Specifically, Eu3+ ion is considered as an ideal spectroscopic probe to decipher the local environment in view of its non-degenerate ground state of 7F 0 and excitation state of 5D 0. Benefiting from the intense long-lived luminescence from 5D 0 , Eu3+-activated inorganic nanoparticles are also frequently reported as luminescent probes in biological assays and medical imaging. With the development of advanced synthesis strategies and characterization techniques, more new understanding or progress in Eu3+-activated luminescent nanoprobes have been gained with regard to their fundamental photophysics/photochemistry properties and versatile bioapplications. As such, it is urgent to renew the knowledge in this field. Rather than being exhaustive, this review aims to highlight the latest progress in the electronic structures, optical properties and emerging bioapplications of Eu3+-activated nanoprobes, which covers from spectroscopic site symmetry, excited-state dynamics, downshifting/upconversion luminescence enhancement strategies, and luminescent biosensing, with an emphasis on their heterogeneous/homogeneous biodetection as well as in vitro and in vivo bioimaging. Some future prospects and efforts toward this rapidly developing field are also discussed. [ABSTRACT FROM AUTHOR]

Lanthanide ions (Ln 3+ ) doped disordered crystals, which exhibit excellent downshifting/upconversion luminescent properties, are widely used in a variety of optical and optoelectronic fields. The optical properties of Ln 3+ ions are critically dependent on the local structure around Ln 3+ ions. Therefore, by employing Ln 3+ ( e.g. , Eu 3+ ) as the sensitive structural probe, the local structure and site symmetry of Ln 3+ dopants in the disordered crystals can be determined. Furthermore, through modification of the local site symmetry of Ln 3+ ions, various highly efficient Ln 3+ -doped luminescent materials have been designed over the past decade. As such, it is urgent to renew the knowledge about the huge family of Ln 3+ -doped disordered crystals. Rather than being exhaustive, this review aims to highlight the most recent advances in the site symmetry and optical properties of Ln 3+ -doped disordered crystals, with an emphasis on probing the local site symmetry and tuning downshifting/upconversion luminescent properties based on modification of the microstructures around Ln 3+ dopants. Finally, the challenges and future perspectives of this important kind of phosphors are proposed. [ABSTRACT FROM AUTHOR]

The Ce- and Sm-co-doped NaBa(BO) phosphors were synthesized by a traditional high-temperature solid-state reaction method. The morphology of NaBa(BO) phosphors was characterized by scanning electron microscope. The crystal structures of Ce- and/or Sm-doped NaBa(BO) phosphors were studied by X-ray powder diffraction. The results suggested that Ce occupied the two Ba sites, while Sm might enter into the interstices of NaBa(BO) crystal. The four emission lines of Ce situating at two Ba sites can be well distinguished by Gaussian fitting. The emission lines from Sm in NaBa(BO) were significantly enhanced by 25-fold when co-doped with 1 mol% Ce ions. New Sm emission center characterized by the intensified excitation band at around 472 nm was produced as a result of Ce co-doping, which significantly extended the excitation wavelength region for matching both the near-ultraviolet and blue-light-emitting diodes. [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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Time-resolved (TR) photoluminescence (PL) biosensing has been widely adopted in many research and medical institutions. However, commercial molecular TRPL bioprobes like lanthanide (Ln3+)-chelates suffer from poor photochemical stability and long-term toxicity. Inorganic Ln3+-doped nanocrystals (NCs), owing to their superior physicochemical properties over Ln3+-chelates, are regarded as a new generation of luminescent nanoprobes for TRPL biosensing. The long-lived PL of Ln3+-doped NCs combined with the TRPL technique is able to completely suppress the interference of the short-lived background, resulting in a background-free signal and therefore a remarkable sensitivity for biosensing. In this feature article, we summarize the latest advancements in inorganic Ln3+-doped NCs as TRPL nano-bioprobes from their fundamental optical properties to their potential applications for ultrasensitive biodetection and high-resolution bioimaging. Future efforts towards the commercialization of these nanoprobes are also proposed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lanthanide-doped nanomaterials with unique optical properties are proposed as new-generation luminescent nanoprobes. [•] Lanthanide-doped nanoprobes for heterogeneous or homogeneous luminescent biodetection are surveyed. [•] Luminescent bioassays of a variety of analytes based on lanthanide-doped nanoprobes are reviewed. [Copyright &y& Elsevier]

Lanthanide-doped inorganic nanoparticles possess superior physicochemical features such as long-lived luminescence, large antenna-generated Stokes or anti-Stokes shifts, narrow emission bands, high resistance to photobleaching and low toxicity, and thus are regarded as a new generation of luminescent bioprobes as compared to conventional molecular probes like organic dyes and lanthanide chelates. These functional nanoparticles, although most of their bulk counterparts were well studied previously, have attracted renewed interest for their biomedical applications in areas as diverse as biodetection, bioimaging, and disease diagnosis and therapeutics. In this review, we provide a comprehensive survey of the latest advances made in developing lanthanide-doped inorganic nanoparticles as potential luminescent bioprobes, which covers areas from their fundamental chemical and physical features to bioapplications including controlled synthesis methodology, surface modification chemistry, optical spectroscopy, and their promising applications in diverse fields, with an emphasis on heterogeneous and homogeneous in vitro biodetection of tumor markers and multimodal bioimaging of various tumor tissues. Some future prospects and challenges in this rapidly growing field are also summarized. [ABSTRACT FROM AUTHOR]

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. [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]

High‐resolution photoluminescence spectroscopy employing Eu3+ as the structural probe unambiguously revealed a universal breakdown of crystallographic site symmetry in lanthanide‐doped disordered crystals. The spectroscopic site symmetries of Eu3+ descend from crystallographic Oh to Cs (or C2) in α‐NaYF4, and from crystallographic C3h to Cs in β‐NaYF4, which were further verified by crystal‐field level fitting. [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]

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]

Highly efficient luminescence of AgInTe2: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 AgInTe2:Zn/ZnS nanoprobes were employed for sensitive homogeneous biodetection of xanthine oxidase with the limit of detection down to 25 nU L−1. [ABSTRACT FROM AUTHOR]

Lanthanide (Ln3+)‐doped upconversion (UC) nanoprobes, which have drawn extensive attention for various bioapplications, usually suffer from small absorption cross‐sections and weak luminescence intensity of Ln3+ ions. Herein, we report the controlled synthesis of a new class of Ln3+‐doped UC nanoprobes based on CsLu2F7: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 CsLu2F7: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. [ABSTRACT FROM AUTHOR]

Lanthanide (Ln3+)‐doped upconversion (UC) nanoprobes, which have drawn extensive attention for various bioapplications, usually suffer from small absorption cross‐sections and weak luminescence intensity of Ln3+ ions. Herein, we report the controlled synthesis of a new class of Ln3+‐doped UC nanoprobes based on CsLu2F7: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 CsLu2F7: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. [ABSTRACT FROM AUTHOR]

Homogeneous core–shell structured nanoparticles (NPs) are prevailingly designed to accommodate lanthanide emitters, and such an epitaxial shell deposited on core NP is generally believed to help eliminate surface traps or defects on the as‐prepared core. However, upon electron‐beam irradiation to core–shell–shell NaLuF4:Gd/Yb/Er@NaLuF4:Nd/Yb@NaLuF4 upconversion NPs (UCNPs), it is revealed that interfacial defects actually exist at the core–shell and shell–shell interfaces, even with a higher density than the bulk‐phase defects in inner core. Because of such higher density of interfacial defects, the kinetic energies transferred from energetic electrons to atoms may trigger the faster Na/F atom ejections and outward atom migrations in the coating layers than in the inner core of NPs, which ultimately results in the in situ formation of novel yolk–shell UCNPs. These findings provide new insights into interfacial defects in homogeneous core–shell structured NaLnF4 NPs, and pave the way toward utilizing the interactions of high‐energy particles with materials for in situ fabrication of novel nanostructures. In situ solid‐to‐yolk‐shell structure conversion in core–shell–shell NaLuF4 upconversion nanoparticles (UCNPs) is achieved upon electron‐beam irradiation. It is revealed that, because of the existence of interfacial defects, the kinetic energies transferred from energetic electrons to atoms trigger faster Na/F atom ejections and outward atom migrations in the coating layers than in the inner core, resulting in the formation of yolk–shell nanostructures. [ABSTRACT FROM AUTHOR]

Herein, we report the design of novel ultraviolet luminescent CsPbCl3 nanocrystals (NCs) with the emission peak at 381 nm through doping of cadmium ions. Subsequently, a surface passivation strategy with CdCl2 is adopted to improve their photoluminescence quantum yield (PLQY) with the maximum value of 60.5 %, which is 67 times higher than that of the pristine counterparts. The PLQY of the surface passivated NCs remains over 50 % after one week while the pristine NCs show negligible emission. By virtue of density functional theory calculations, we reveal that the higher PLQY and better stability after surface passivation may result from the significant elimination of surface chloride vacancy (VCl) defects. These findings provide fundamental insights into the optical manipulation of metal ion‐doped CsPbCl3 NCs. [ABSTRACT FROM AUTHOR]

Herein, we report the design of novel ultraviolet luminescent CsPbCl3 nanocrystals (NCs) with the emission peak at 381 nm through doping of cadmium ions. Subsequently, a surface passivation strategy with CdCl2 is adopted to improve their photoluminescence quantum yield (PLQY) with the maximum value of 60.5 %, which is 67 times higher than that of the pristine counterparts. The PLQY of the surface passivated NCs remains over 50 % after one week while the pristine NCs show negligible emission. By virtue of density functional theory calculations, we reveal that the higher PLQY and better stability after surface passivation may result from the significant elimination of surface chloride vacancy (VCl) defects. These findings provide fundamental insights into the optical manipulation of metal ion‐doped CsPbCl3 NCs. [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]

In this reply, the authors of the Communication “Breakdown of Crystallographic Site Symmetry in Lanthanide‐Doped NaYF4 Crystals” respond to the comment by Karbowiak et al., who criticized the crystal‐field (CF) analysis of Eu3+ in disordered NaYF4. The authors clarify their interpretations of the issues raised. [ABSTRACT FROM AUTHOR]

Review: 244 refs. [ABSTRACT FROM AUTHOR]

Review: 364 refs. [ABSTRACT FROM AUTHOR]

Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted considerable interest due to their superior physicochemical features, such as large anti-Stokes shifts, low autofluorescence background, low toxicity and high penetration depth, which make them extremely suitable for use as alternatives to conventional downshifting luminescence bioprobes like organic dyes and quantum dots for various biological applications. A fundamental understanding of the photophysics of lanthanide-doped UCNPs is of vital importance for discovering novel optical properties and exploring their new applications. In this review, we focus on the most recent advances in the development of lanthanide-doped UCNPs as potential luminescent nano-bioprobes by means of our customized lanthanide photophysics measurement platforms specially designed for upconversion luminescence, which covers from their fundamental photophysics to bioapplications, including electronic structures (energy levels and local site symmetry of emitters), excited-state dynamics, optical property designing, and their promising applications for in vitro biodetection of tumor markers. Some future prospects and efforts towards this rapidly growing field are also envisioned. [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]

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 Cs2(Ag/Na)InCl6 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 Cs2(Ag/Na)InCl6, thereby laying a foundation for the future design of new lead‐free DPs with efficient STE emission. [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]

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]

All‐inorganic lead‐free metal halides doped with ns2‐metal ions have shown great promise in optoelectronics and photovoltaics owing to their superior optical properties. Herein, a strategy is reported for tailoring the optical properties of 0D A2InX5⋅H2O and A3InX6 (A = Cs, Rb; X = Cl, Br) crystals via Sb3+ doping, and the excited‐state dynamics of Sb3+ is unveiled through temperature‐dependent photoluminescence (PL) and femtosecond transient absorption spectroscopies. Owing to the spatially confined 0D structure of the In‐based halides, Sb3+ ions experience a strong Jahn–Taller distortion on the excited state, which results in intense PL from Sb3+ with a broad emission band and a large Stokes shift. Through the control of A cation and the octahedral unit, tunable Sb3+ emissions (490−750 nm) with PL quantum yields up to 91.8% are achieved in these 0D In‐based halides. These findings provide fundamental insights into the excited‐state dynamics of Sb3+ in 0D metal halides, thus laying a foundation for future design of luminescent lead‐free 0D metal halides through ns2‐metal doping towards versatile applications. [ABSTRACT FROM AUTHOR]

Optical thermal sensing holds great promise for disease theranostics. However, traditional ratiometric thermometry methods, in which intensity ratio of two nonoverlapping emissions is defined as the thermosensitive parameter, may have a limited accuracy in temperature read‐out due to the deleterious interference from wavelength‐ and temperature‐dependent photon attenuation in tissue. To overcome this limitation, a dual‐excitation decoding strategy based on NIR hybrid nanocomposites comprising self‐assembled quantum dots (QDs) and Nd3+ doped fluoride nanocrystals (NCs) is proposed for thermal sensing. Upon excitation at 808 nm, the intensity ratio of two emissions at identical wavelength (1057 nm) from QDs and NCs, respectively, is defined as the thermometric parameter R. By employing another 830 nm laser beam following the same optical path as 808 nm laser to exclusively excite QDs, the two overlapping emissions can be easily decoded. The acquired R proves to be inert to the detection depth in tissue, with a minimized temperature reading error of ≈2.3 °C at 35 °C (at a depth of ≈1.1 mm), while the traditional thermometry mode based on the nonoverlapping 1025 and 863 nm emissions may exhibit a large error of ≈43.0 °C. The insights provided by this work pave the way toward high‐accuracy deep‐tissue biosensing. [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]

The synthesis of hydrophilic lanthanide‐doped nanocrystals (Ln3+‐NCs) with molecular recognition ability for bioimaging currently remains a challenge. Herein, we present an effective strategy to circumvent this bottleneck by encapsulating Ln3+‐NCs in graphene oxide (NCs@GO). Monodisperse NCs@GO was prepared by optimizing GO size and core–shell structure of NaYF4:Yb,Er@NaYF4, thus combining the intense visible/near‐infrared II (NIR‐II) luminescence of NCs and the unique surface properties and biomedical functions of GO. Such nanostructures not only feature broad solvent dispersibility, efficient cell uptake, and excellent biocompatibility but also enable further modifications with various agents such as DNA, proteins, or nanoparticles without tedious procedures. Moreover, we demonstrate in proof‐of‐concept experiments that NCs@GO can realize simultaneous intracellular tracking and microRNA‐21 visualization, as well as highly sensitive in vivo tumor‐targeted NIR‐II imaging at 1525 nm. [ABSTRACT FROM AUTHOR]

The synthesis of hydrophilic lanthanide‐doped nanocrystals (Ln3+‐NCs) with molecular recognition ability for bioimaging currently remains a challenge. Herein, we present an effective strategy to circumvent this bottleneck by encapsulating Ln3+‐NCs in graphene oxide (NCs@GO). Monodisperse NCs@GO was prepared by optimizing GO size and core–shell structure of NaYF4:Yb,Er@NaYF4, thus combining the intense visible/near‐infrared II (NIR‐II) luminescence of NCs and the unique surface properties and biomedical functions of GO. Such nanostructures not only feature broad solvent dispersibility, efficient cell uptake, and excellent biocompatibility but also enable further modifications with various agents such as DNA, proteins, or nanoparticles without tedious procedures. Moreover, we demonstrate in proof‐of‐concept experiments that NCs@GO can realize simultaneous intracellular tracking and microRNA‐21 visualization, as well as highly sensitive in vivo tumor‐targeted NIR‐II imaging at 1525 nm. [ABSTRACT FROM AUTHOR]

Applications of persistent luminescence phosphors as night or dark‐light vision materials in many technological fields have fueled up a growing demand for rational control over the emission profiles of the phosphors. This, however, remains a daunting challenge. Now a unique strategy is reported to fine‐tune the persistent luminescence by using all‐inorganic CsPbX3 (X=Cl, Br, and I) perovskite quantum dots (PeQDs) as efficient light‐conversion materials. Full‐spectrum persistent luminescence with wavelengths covering the entire visible spectral region is achieved through tailoring of the PeQD band gap, in parallel with narrow bandwidth of PeQDs and highly synchronized afterglow decay owing to the single energy storage source. These findings break through the limitations of traditional afterglow phosphors, thereby opening up opportunities for persistent luminescence materials for applications such as a white‐emitting persistent light source and dark‐light multicolor displays. [ABSTRACT FROM AUTHOR]

Applications of persistent luminescence phosphors as night or dark‐light vision materials in many technological fields have fueled up a growing demand for rational control over the emission profiles of the phosphors. This, however, remains a daunting challenge. Now a unique strategy is reported to fine‐tune the persistent luminescence by using all‐inorganic CsPbX3 (X=Cl, Br, and I) perovskite quantum dots (PeQDs) as efficient light‐conversion materials. Full‐spectrum persistent luminescence with wavelengths covering the entire visible spectral region is achieved through tailoring of the PeQD band gap, in parallel with narrow bandwidth of PeQDs and highly synchronized afterglow decay owing to the single energy storage source. These findings break through the limitations of traditional afterglow phosphors, thereby opening up opportunities for persistent luminescence materials for applications such as a white‐emitting persistent light source and dark‐light multicolor displays. [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]

The complete and correct sentence is as follows: The phonon energy ( I h i SB phonon sb ) and the Huang-Rhys factor ( I S i ) were calculated to be B 20.6 meV b and B 46.4 b , respectively. At the bottom of page 3, in the right-hand column, the fitted phonon energy and the Huang-Rhys factor are incorrect. Tailoring the Broadband Emission in All-Inorganic Lead-Free 0D In-Based Halides through Sb3+ Doping. [Extracted from the article]

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]

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]

Small but bright—just right! Codoping with sodium enabled the synthesis of highly emissive and ultrasmall (<10 nm) CaF2:Ln3+ nanoparticles that were effective as sensitive probes for the detection of soluble uPAR (an important tumor marker) by time‐resolved fluorescence resonance energy transfer (FRET; see picture; FITC=fluorescein isothiocyanate). The nanoprobes were also used successfully for uPAR‐targeted cancer‐cell imaging. [ABSTRACT FROM AUTHOR]

The exploitation of smart nanoagents based drug delivery systems (DDSs) has proven to be a promising strategy for fighting cancers. Hitherto, such nanoagents still face challenges associated with their complicated synthesis, insufficient drug release in tumors, and low cancer cell chemosensitivity. Here, the engineering of an adenosine triphosphate (ATP)‐activatable nanoagent is demonstrated based on self‐assembled quantum dots‐phenolic nanoclusters to circumvent such challenges. The smart nanoagent constructed through a one‐step assembly not only has high drug loading and low cytotoxicity to normal cells, but also enables ATP‐activated disassembly and controlled drug delivery in cancer cells. Particularly, the nanoagent can induce cell ATP depletion and increase cell chemosensitivity for significantly enhanced cancer chemotherapy. Systematic in vitro and in vivo studies further reveal the capabilities of the nanoagent for intracellular ATP imaging, high tumor accumulation, and eventual body clearance. As a result, the presented multifunctional smart nanoagent shows enhanced antitumor efficacy by simultaneous ATP‐responsive chemodrug release and cancer cell sensitization. These findings offer new insights toward the design of smart nanoagents for improved cancer therapeutics. Superior antitumor therapy is demonstrated by simultaneous adenosine triphosphate (ATP)‐responsive chemodrug release and cancer cell sensitization based on a quantum dots‐phenolic nanoagent. The nanoagent constructed through one‐step assembly features high drug loading capacity, ATP‐activated chemodrug delivery, ATP depletion induced cancer cell sensitization, tumor accumulation, and eventual body clearance. Therefore, complete inhibition of tumor growth can be achieved without causing any side effects. [ABSTRACT FROM AUTHOR]