An 800 nm driven NaErF4@NaLuF4 upconversion platform for multimodality imaging and photodynamic therapy

Achieving Orthogonal Upconversion Luminescence of a Single Lanthanide Ion in Crystals for Optical Encryption

Optical encryption shows great potential in meeting the growing demand for advanced anti-counterfeiting in the information age. The development of upconversion luminescence (UCL) materials capable of emitting different colors of light in response to different external stimuli holds great promise in this field. However, the effective realization of multicolor UCL materials usually requires complex structural designs. In this work, orthogonal UCL is achieved in crystals with a simple structure simply by introducing modulator Tm3+ ions to control the photon transition processes between different energy levels of activator Er3+ ions. The obtained crystals emit red and green UCL when excited by 980 nm and 808 nm lasers, respectively. The orthogonal excitation-emission properties of crystals are shown to be very suitable for high-level optical encryption, which is important for information security and anti-counterfeiting. This work provides an effective strategy for obtaining orthogonal UCL in simple structural materials, which will encourage researchers to further explore novel orthogonal UCL materials and their applications, and has important implications for the development of the frontier photonic upconversion fields.

Eosin Y-Functionalized Upconverting Nanoparticles: Nanophotosensitizers and Deep Tissue Bioimaging Agents for Simultaneous Therapeutic and Diagnostic Applications

Functionalized upconverting nanoparticles (UCNPs) are promising theragnostic nanomaterials for simultaneous therapeutic and diagnostic purposes. We present two types of non-toxic eosin Y (EY) nanoconjugates derived from UCNPs as novel nanophotosensitizers (nano-PS) and deep-tissue bioimaging agents employing light at 800 nm. This excitation wavelength ensures minimum cell damage, since the absorption of water is negligible, and increases tissue penetration, enhancing the specificity of the photodynamic treatment (PDT). These UCNPs are uniquely qualified to fulfil three important roles: as nanocarriers, as energy-transfer materials, and as contrast agents. First, the UCNPs enable the transport of EY across the cell membrane of living HeLa cells that would not be possible otherwise. This cellular internalization facilitates the use of such EY-functionalized UCNPs as nano-PS and allows the generation of reactive oxygen species (ROS) under 800 nm light inside the cell. This becomes possible due to the upconversion and energy transfer processes within the UCNPs, circumventing the excitation of EY by green light, which is incompatible with deep tissue applications. Moreover, the functionalized UCNPs present deep tissue NIR-II fluorescence under 808 nm excitation, thus demonstrating their potential as bioimaging agents in the NIR-II biological window.

Anti-counterfeiting system based on luminescent varnish enriched by NIR- excited nanoparticles for paper security

Up-converting nanoparticles can be a demand for requirements in many areas, including bioimaging and conversion of energy, but also in the battle against counterfeiting. The properties of lanthanide ions make falsification difficult or even impossible using appropriately designed systems. The proposition of such an approach is the NaErF₄:Tm³⁺@NaYF₄ core@shell up-converting nanoparticles combined with transparent varnishes. Given the spectroscopic properties of Er³⁺ ions present in the fluoride matrix, the obtained up-converting nanoparticles absorb light by 808 and 975 nm wavelengths. The intentionally co-doped Tm³⁺ ions enable tuning characteristic green Er³⁺ emission to red luminescence, particularly desirable in anti-counterfeiting applications. The article includes a thorough analysis of structural and morphological properties. Moreover, this work shows that exclusive luminescent properties of NaErF₄:Tm³⁺@NaYF₄ NPs can be given to the transparent varnish, providing an excellent anti-counterfeiting system, revealing red emission under two different excitation wavelengths.

In-depth insight into the Yb3+ effect in NaErF4-based host sensitization upconversion: a double-edged sword

NaErF₄ is the most extensively studied host for self-sensitized upconversion (UC), and Yb³⁺ is the most commonly used energy absorber. It has been reported that the red luminescence of Er³⁺ can be enhanced by introducing Yb³⁺ into the NaErF₄ host lattice, where Yb³⁺ ions serve as trapping centers to confine the excitation energy. Also, it has been pointed out that the Yb³⁺ doping in the shell of NaErF₄-hosted core-shell nanocrystals can further improve the red emission intensity. Conversely, it can be argued that the Yb³⁺ doping in the shell always results in the luminescence quenching of the NaErF₄ core. These imply that the impact of Yb³⁺ on NaErF₄-based host-sensitized UC is rather complicated and must be probed deeply. In this study, we thoroughly discussed the effect of Yb³⁺ located in the core/shell on the NaErF₄-based host sensitization UC and afforded the related mechanism interpretations. In the NaErF₄ core nanocrystals, the green-dominated UCL presented an enhancement on increasing the concentration of the Yb³⁺ dopant owing to the promoted energy harvesting for luminescence. Furthermore, the emission properties of NaErF₄:10%Yb shelled with diverse inert layers were also investigated, and the intensity difference of these core-inert shell nanoparticles could be explained by the lattice mismatch and shell thickness. In NaErF₄:10%Yb@NaYF₄:Yb with variable Yb³⁺ doping in the shell, the red-dominated UCL was generally weakened with more Yb³⁺ localized in the shell, which was ascribed to the competition of energy pooling and energy dissipation of Yb³⁺ in the outer layer. Therefore, Yb³⁺ ions wield a two-sided influence (termed a "double-edged sword") on the UC emissions of the Er³⁺ host. Additionally, we demonstrated the application potential of such UCNPs in water sensing and high-level anti-counterfeiting. This work offers an in-depth insight into the UC mechanism of Yb³⁺-doped NaErF₄ nanocrystals and inspires the engineering of novel luminescent materials with distinguished properties.

Bioimaging guided pharmaceutical evaluations of nanomedicines for clinical translations

Nanomedicines (NMs) have emerged as an efficient approach for developing novel treatment strategies against a variety of diseases. Over the past few decades, NM formulations have received great attention, and a large number of studies have been performed in this field. Despite this, only about 60 nano-formulations have received industrial acceptance and are currently available for clinical use. Their in vivo pharmaceutical behavior is considered one of the main challenges and hurdles for the effective clinical translation of NMs, because it is difficult to monitor the pharmaceutic fate of NMs in the biological environment using conventional pharmaceutical evaluations. In this context, non-invasive imaging modalities offer attractive solutions, providing the direct monitoring and quantification of the pharmacokinetic and pharmacodynamic behavior of labeled NMs in a real-time manner. Imaging evaluations have great potential for revealing the relationship between the physicochemical properties of NMs and their pharmaceutical profiles in living subjects. In this review, we introduced imaging techniques that can be used for in vivo NM evaluations. We also provided an overview of various studies on the influence of key parameters on the in vivo pharmaceutical behavior of NMs that had been visualized in a non-invasive and real-time manner.

Rare earth nanoparticles for sprayed and intravenous NIR II imaging and photodynamic therapy of tongue cancer

In this research, rare earth nanoparticles coupled with dihydroartemisinin (DHA) and a targeted antibody (RENP-DHA-Cap) for sprayed NIR II imaging and photodynamic therapy (PDT) of tongue cancer were designed. Genetic algorithms combined with combinatorial chemistry were proposed and successfully achieved in a single optimized luminescent phosphor with enhanced NIR II and high upconversion luminescence (UCL) under a NIR laser of wavelength 980 nm or/and 808 nm. In particular, T1 magnetic resonance imaging (MRI) signals can be adjusted with the Gd ion concentration. In combination with the targeted antibody of capmatinib (Cap), precise NIR II imaging for in situ tongue cancer by a simple spray method can be achieved. Most importantly, NIR II imaging and PDT treatment can be realized with RENP-DHA-capmatinib injected intravenously. This orthogonal theranostic mode with precise diagnosis under 808 nm and targeted effective treatment under 980 nm may promote tongue cancer theranostics.

Engineering the Compositional Architecture of Core-Shell Upconverting Lanthanide-Doped Nanoparticles for Optimal Luminescent Donor in Resonance Energy Transfer: The Effects of Energy Migration and Storage

Förster Resonance Energy Transfer (FRET) between single molecule donor (D) and acceptor (A) is well understood from a fundamental perspective and is widely applied in biology, biotechnology, medical diagnostics, and bio-imaging. Lanthanide doped upconverting nanoparticles (UCNPs) have demonstrated their suitability as alternative donor species. Nevertheless, while they solve most disadvantageous features of organic donor molecules, such as photo-bleaching, spectral cross-excitation, and emission bleed-through, the fundamental understanding and practical realizations of bioassays with UCNP donors remain challenging. Among others, the interaction between many donor ions (in donor UCNP) and many acceptors anchored on the NP surface and the upconversion itself within UCNPs, complicate the decay-based analysis of D-A interaction. In this work, the assessment of designed virtual core-shell NP (VNP) models leads to the new designs of UCNPs, such as …@Er, Yb@Er, Yb@YbEr, which are experimentally evaluated as donor NPs and compared to the simulations. Moreover, the luminescence rise and decay kinetics in UCNP donors upon RET is discussed in newly proposed disparity measurements. The presented studies help to understand the role of energy-transfer and energy migration between lanthanide ion dopants and how the architecture of core-shell UCNPs affects their performance as FRET donors to organic acceptor dyes.

Hybrid Nanoplatform: Enabling a Precise Antitumor Strategy via Dual-Modal Imaging-Guided Photodynamic/Chemo-/Immunosynergistic Therapy

Photodynamic therapy (PDT) has been widely used in tumor therapy due to its high spatial-temporal control and noninvasiveness. However, its clinical application is limited by weak efficacy, shallow tissue penetration, and phototoxicity. Herein, a facile theranostic nanoplatform based on photoswitchable lanthanide-doped nanoparticles was designed. Typically, these nanoparticles had UV-blue and 1525 nm emission upon 980 nm excitation and 1525 nm emission upon 800 nm excitation. We further used these nanoparticles for achieving real-time near-infrared (NIR)-IIb imaging (800 nm) with a high signal-to-noise ratio and imaging-guided PDT (980 nm). Moreover, such a photoswitchable nanoplatform capping with pH-sensitive calcium phosphate for coloading doxorubicin (a chemotherapeutic immunogenic cell death [ICD] inducer) and paramagnetic Mn²⁺ ions enhances T₁-magnetic resonance imaging in the tumor microenvironment. Our results suggest that this theranostic nanoplatform could not only kill tumor cells directly through dual-modal image-guided PDT/chemotherapy but also inhibit distant tumor and lung metastasis through ICD. Therefore, it has great potential for clinical application .

Facile Synthesis of Holmium-Based Nanoparticles as a CT and MRI Dual-Modal Imaging for Cancer Diagnosis

The rapid development of medical imaging has boosted the abilities of modern medicine. As single modality imaging limits complex cancer diagnostics, dual-modal imaging has come into the spotlight in clinical settings. The rare earth element Holmium (Ho) has intrinsic paramagnetism and great X-ray attenuation due to its high atomic number. These features endow Ho with good potential to be a nanoprobe in combined x-ray computed tomography (CT) and T₂-weighted magnetic resonance imaging (MRI). Herein, we present a facile strategy for preparing HoF₃ nanoparticles (HoF₃ NPs) with modification by PEG 4000. The functional PEG-HoF₃ NPs have good water solubility, low cytotoxicity, and biocompatibility as a dual-modal contrast agent. Currently, there is limited systematic and intensive investigation of Ho-based nanomaterials for dual-modal imaging. Our PEG-HoF₃ NPs provide a new direction to realize in vitro and vivo CT/MRI imaging, as well as validation of Ho-based nanomaterials will verify their potential for biomedical applications.

Upconversion Luminescent Nanostructure with Ultrasmall Ceramic Nanoparticles Coupled with Rose Bengal for NIR-Induced Photodynamic Therapy

We designed a biodegradable hybrid nanostructure for near-infrared (NIR)-induced photodynamic therapy (PDT) using an ultrasmall upconversion (UC) phosphor (β-NaYF₄:Yb³⁺, Er³⁺ nanoparticle: NPs) and a hydrocarbonized rose bengal (C₁₈RB) dye, a hydrophobized rose bengal (RB) derivative. The UC-NPs were encapsulated along with C₁₈RB in the hydrophobic core of the micelle composed of poly(ethylene glycol) (PEG)-block-poly(ε-caprolactone) (PCL). The UC-NPs were well shielded from the aqueous environment, owing to the encapsulation in the hydrophobic PCL core, to efficiently emit green UC luminescence by avoiding the quenching by the hydroxyl groups. The hydrophobic part of C₁₈ of C₁₈RB worked well to be involved in the PCL core and located RB on the surface of the PCL core, making the efficient absorption of green light and the emission of singlet oxygen to surrounding water possible. Moreover, as the location is covered by PEG, the direct contact of RB to cells is prohibited to avoid their irradiation-free toxic effect on the cells. The hybrid nanostructure proved to be degradable by the hydrolysis of PEG-b-PCL. This degradation potentially results in renal excretion by the decomposition of the nanostructure into sub-10 nm size particles and makes them viable for clinical uses. These nanostructures can potentially be used for PDT of cancer in deep tissues.

Fe3O4-Au Core-Shell Nanoparticles as a Multimodal Platform for In Vivo Imaging and Focused Photothermal Therapy

In this study, we report the synthesis of gold-coated iron oxide nanoparticles capped with polyvinylpyrrolidone (Fe@Au NPs). The as-synthesized nanoparticles (NPs) exhibited good stability in aqueous media and excellent features as contrast agents (CA) for both magnetic resonance imaging (MRI) and X-ray computed tomography (CT). Additionally, due to the presence of the local surface plasmon resonances of gold, the NPs showed exploitable "light-to-heat" conversion ability in the near-infrared (NIR) region, a key attribute for effective photothermal therapies (PTT). In vitro experiments revealed biocompatibility as well as excellent efficiency in killing glioblastoma cells via PTT. The in vivo nontoxicity of the NPs was demonstrated using zebrafish embryos as an intermediate step between cells and rodent models. To warrant that an effective therapeutic dose was achieved inside the tumor, both intratumoral and intravenous routes were screened in rodent models by MRI and CT. The pharmacokinetics and biodistribution confirmed the multimodal imaging CA capabilities of the Fe@AuNPs and revealed constraints of the intravenous route for tumor targeting, dictating intratumoral administration for therapeutic applications. Finally, Fe@Au NPs were successfully used for an in vivo proof of concept of imaging-guided focused PTT against glioblastoma multiforme in a mouse model.

Lanthanide-Doped Near-Infrared Nanoparticles for Biophotonics

Light in the near-infrared (NIR) spectral region is increasingly utilized in bioapplications, providing deeper penetration in biological tissues owing to the lower absorption and scattering in comparison with light in the visible range. Lanthanide-doped luminescent nanoparticles with excitation and/or emission in the NIR range have recently attracted tremendous attention as one of the prime candidates for noninvasive biological applications due to their unique optical properties, such as large Stokes shift, spectrally sharp luminescence emissions, long luminescence lifetimes, and excellent photostability. Herein, recent advances of lanthanide-doped nanoparticles with NIR upconversion or downshifting luminescence and their uses in cutting-edge biophotonic applications are presented. A set of efficient strategies for overcoming the fundamental limit of low luminescence brightness of lanthanide-doped nanoparticles is introduced. An in-depth literature review of their state-of-art biophotonics applications is also included, showing their superiority for high-resolution imaging, single-nanoparticle-level detection, and efficacy for tissue-penetrating diagnostics and therapeutics.

High-Performance Perovskite Solar Cells Based on NaCsWO3@ NaYF4@NaYF4:Yb,Er Upconversion Nanoparticles

Extending photoelectric response to the near-infrared (NIR) region using upconversion luminescent (UCL) materials is one promising approach to obtain high-efficiency perovskite solar cells (PSCs). However, challenges remain due to the shortage of highly efficient UCL materials and device structure. NaCsWO₃ nanocrystals exhibit near-infrared absorption arising from the local surface plasmon resonance (LSPR) effect, which can be used to boost the UCL of rare-earth-doped upconversion nanoparticles (UCNPs). In this study, using NaCsWO₃ as the LSPR center, NaCsWO₃@NaYF₄@NaYF₄:Yb,Er nanoparticles were synthesized and the UCL intensity could be enhanced by more than 124 times when the amount of NaCsWO₃ was 2.8 mmol %. Then, such efficient UCNPs were not only doped into the hole transport layer but also used to modify the perovskite film in PSCs, resulting in the highest power conversion efficiency (PCE) reaching 18.89% (that of the control device was 16.01% and the PCE improvement was 17.99%). Possible factors for the improvement of PSCs were studied and analyzed. It is found that UCNPs can broaden the response range of PSCs to the NIR region due to the LSPR-enhanced UCL and increase the visible light reabsorption of PSCs due to the scattering and reflection effect, which generate more photocurrent in PSCs. In addition, UCNPs modify the perovskite film by effectively filling the holes and gaps at the grain boundary and eliminating the perovskite surface defects, which lead to less carrier recombination and then effectively improve the performance of PSC devices.

Local-structure-dependent luminescence in lanthanide-doped inorganic nanocrystals for biological applications

This feature article overviews the recent advances in the local-structure-dependent luminescence in lanthanide-doped inorganic nanocrystals for various biological applications.

Water dispersible ligand-free rare earth fluoride nanoparticles: water transfer versus NaREF4-to-REF3 phase transformation

The chemical stability of oleate-capped sub-10 nm α- and β-NaREF4 NPs (RE = Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu for α- and RE = Pr, Nd, Sm, Eu, Gd, Tb, Dy for β-phase NPs) was evaluated under the acidic conditions used for ligand removal towards water dispersibility. It was found that for such small NPs, a pH lower than 3 was necessary for the water transfer to be efficient and to yield well-dispersed ligand-free NPs. In stark contrast to the generally considered good chemical stability of NaREF4, these conditions were observed to pose a risk to phase transformation of the NaREF4 NPs into much larger, hexagonal- or orthorhombic-phase REF3, depending on the NP composition. A correlation between the thermodynamic stability of the α/β-NaREF4 and the hexagonal/orthorhombic REF3 phases - dictated by the RE ion choice - and the chemical stability of the NPs was found. For instance, β-NaGdF4 NPs remained stable, while α-NaGdF4 NPs underwent phase transformation into hexagonal GdF3. More general, NaREF4 NPs based on lighter RE ions were more prone towards phase transformation, while those based on heavier RE ions exhibited stability. Herein, within the RE series, the borderline for phase transformation was identified as Tb/Dy for α-NaREF4 NPs and Sm/Eu for β-NaREF4 NPs, respectively. Also, given the large interest in luminescent NPs for, e.g. biomedical applications, optically active Ln3+ ions (Ln = Nd, Eu, Tb, Er/Yb) were doped into α/β-NaGdF4 host NPs, and the dopant influence on the chemical stability was evaluated. Steady state and time-resolved spectroscopy unveiled spectral features characteristic for Ln3+ f-f transitions, i.e. downshifting and upconversion, before and after ligand removal. Overall, the results herein described emphasise the importance of minding the chemical procedure used for ligand removal of NaREF4 NPs of different crystalline phases and RE compositions.

Dual-Wavelength Excited Intense Red Upconversion Luminescence from Er3+-Sensitized Y2O3 Nanocrystals Fabricated by Spray Flame Synthesis

Er³⁺-sensitized upconversion nanoparticles (UCNPs) have attracted great attention due to their tunable upconversion (UC) emissions, low cytotoxicity, high resistance to photobleaching and especially multiple effective excitation wavelengths. However, detailed energy conversion between Er³⁺ and Tm³⁺ ions in Y₂O₃ UCNPs is still a problem, especially under multi-wavelength and variable pulse width excitation. In this work, we successfully fabricated a series of Er³⁺-sensitized Y₂O₃ nanocrystals by a spray flame synthesis method with a production rate of 40.5 g h⁻¹. The as-prepared UCNPs are a pure cubic phase with a mean size of 14 nm. Excited by both 980 and 808 nm lasers, the tunable upconversion luminescence (UCL) from Er³⁺ ions was achieved by increasing the Er³⁺ doping concentration, co-doping Tm³⁺ ions and extending excitation pulse-width. The investigations of the lifetimes and the laser power dependence of UC emissions further support the proposed mechanism, which provides guidance for achieving effective color control in anticounterfeiting and multiplexed labeling applications. In addition, the red UC emission at about 5 mm beneath the tissue surface was observed in an ex vivo imaging experiment under the excitation of 808 nm laser, indicating that the Y₂O₃:Er³⁺/Tm³⁺ UCNPs have great prospects in further biological applications.

Recent advances of lanthanide-doped upconversion nanoparticles for biological applications

Near infrared (NIR) excited lanthanide-doped upconversion nanoparticles (UCNPs) are emerging as a new type of fluorescent tag for biological applications, which can emit multi-photon ultraviolet, visible or NIR luminescence for imaging or activation of photosensitive molecules. Here, we present a comprehensive review on recent advances of UCNPs for a manifold of biological applications, including upconversion mechanisms, building bright multicolor upconversion nanocrystals, single nanoparticle and super resolution imaging, in vivo optical and multimodal imaging, photodynamic therapy, light-controlled drug release, biosensing, and toxicities. Our perspectives on the future development of UCNPs are also described.

A near infrared dye-coated silver nanoparticle/carbon dot nanocomposite for targeted tumor imaging and enhanced photodynamic therapy

An excellent photosensitizer for imaging-guided high efficiency photodynamic therapy (PDT) requires certain features, such as near-infrared (NIR) light emission, high singlet-to-triplet intersystem crossing (ISC) efficiency, and tumor targeting. However, synthetizing photosensitizers that meet the aforementioned characteristics still remains a challenge. In this study, we synthetized a NIR dye (CyOH)-coated silver nanoparticle/carbon dot nanocomposite (CyOH-AgNP/CD) as a novel nanophotosensitizer for targeted tumor imaging and high-efficiency PDT. The CyOH-AgNP/CD nanophotosensitizer was constructed using a NIR dye (CyOH) and an AgNP/CD nanohybrid via Ag-O interaction. Relative to the AgNP/CD nanohybrid, CyOH-AgNP/CD exhibited a high singlet oxygen yield, mitochondrial accumulation, superior tissue penetration of 660 nm laser irradiation, and enhanced tumor targeting. The developed nanophotosensitizer exerted a higher antitumor effect than the CyOH dye or AgNP/CD nanohybrid. This result provides a new idea for the design of excellent photosensitizers that can benefit high-efficiency PDT.

A single-component yet multifunctional tongue-mimicking sensor array for upconversion fluorescence biosensing

A novel single-component nanoprobe has been created for the pattern recognition of antioxidants in a “turn on” manner by integrating with the prevention of PDA formation with an antioxidant.

A novel one-pot strategy to rapidly synthesize bright red emitting upconversion nanocrystals with core–shell–shell structure

By growing NaYbF₄ and NaYF₄ on β-NaErF4:0.005Tm in one pot, the upconversion intensity was tremendously enhanced.

Facile synthesis of sub-10 nm-sized bright red-emitting upconversion nanophosphors via tetrahedral YOF:Yb,Er seed-mediated growth

Ultrasmall and uniform tetrahedral-shaped YOF:Yb,Er upconversion nanophosphors (UCNs) are synthesized and sub-10 nm YOF:Yb,Er/YOF core/shell UCNs are formed via YOF:Yb,Er seed-mediated synthesis. The ultrasmall YOF:Yb,Er/YOF core/shell UCNs realize intense red emission under near infrared light (λ_ex = 980 nm).

Nanotechnology based therapeutic application in cancer diagnosis and therapy

Due to the lack of early diagnosis, cancer remains as one of the leading cause of human mortality. Inability to translate research into clinical trials and also inability of chemotherapeutics delivery to targeted tumor sites are major drawbacks in cancer therapeutics. With the emergence of nanomedicine, several nanoprobes (conjugated with targeting ligands and chemotherapeutic drugs) are developed. It can interact with biological system and thus sense and monitor the biological events with high efficiency and accuracy along with therapy application. Nanoparticles like gold and iron oxide are frequently used in the computed tomography and magnetic resonance imaging applications, respectively. Moreover, enzymatic activity of gold and iron oxide nanoparticles enables the visible colorimetric diagnostic of cancer cells, whereas, fluorescence property of quantum dots and upconversion nanoparticles helps in in vivo imaging application. Other than this, drug conjugation with nanoparticles also reduces the systemic toxic effect of chemotherapeutic drugs. Due to their several unique intrinsic properties, nanoparticles itself can also be employed as therapeutics in cancer treatment by photothermal therapy (PTT) and photodynamic therapy (PDT). Thus, the main focus of this review is to emphasize on current progress in diagnostic and therapeutic application of nanoprobes in cancer.

ROS-responsive targeting micelles for optical imaging-guided chemo-phototherapy of cancer

The combination of chemotherapy and phototherapy gives rise to a boom in cancer therapy methodology. An all-in-one nanoplatform is of particular interest for increased safety and efficacy geared toward personalized precision medicine. However, low drug loading efficiency, random dispersion and distribution without visualization are widespread concerns. Here, a reactive oxygen species (ROS) responsive drug delivery system for imaging-guided chemo-phototherapy was developed. Polymeric micelles were designed and synthesized using PTX (drug) and Cypate (fluorescence and photosensitizer) as hydrophobic segments and PEG as hydrophilic ones encapsulating PTX. Furthermore, folic acid, as a targeting moiety, was conjugated to PEG for directed drug delivery. We evaluated the ROS-responsive drug release profiles and chemo-phototherapy application in an anticancer therapy. The results suggest these biocompatible amphiphilic polymer conjugates would be promising for applications in imaging-guided chemo-phototherapy.

Intense upconversion red emission from Gd-doped NaErF4:Tm-based core/shell/shell nanocrystals under 980 and 800 nm near infrared light excitations

Strong upconversion red-emitting Gd-doped NaErF₄:Tm-based upconversion nanophosphors (UCNPs) are successfully synthesized by the formation of a core/intermediate shell/active shell structure.

Large-scale synthesis of uniform lanthanide-doped NaREF4 upconversion/downshifting nanoprobes for bioapplications

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.