Shanyong Zhou

Lanthanide-doped LiLuF(4) upconversion nanoprobes for the detection of disease biomarkers.

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.

Amine-Functionalized Lanthanide-Doped Zirconia Nanoparticles: Optical Spectroscopy, Time-Resolved Fluorescence Resonance Energy Transfer Biodetection, and Targeted Imaging

Ultrasmall inorganic oxide nanoparticles doped with trivalent lanthanide ions (Ln(3+)), a new and huge family of luminescent bioprobes, remain nearly untouched. Currently it is a challenge to synthesize biocompatible ultrasmall oxide bioprobes. Herein, we report a new inorganic oxide bioprobe based on sub-5 nm amine-functionalized tetragonal ZrO(2)-Ln(3+) nanoparticles synthesized via a facile solvothermal method and ligand exchange. By utilizing the long-lived luminescence of Ln(3+), we demonstrate its application as a sensitive time-resolved fluorescence resonance energy transfer (FRET) bioprobe to detect avidin with a record-low detection limit of 3.0 nM. The oxide nanoparticles also exhibit specific recognition of cancer cells overexpressed with urokinase plasminogen activator receptor (uPAR, an important marker of tumor biology and metastasis) and thus may have great potentials in targeted bioimaging.

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

Lanthanide-doped luminescent nanoparticles (NPs) haveevoked considerable interest due to their superior features,such as sharp f–f emission peaks, a long photoluminescence(PL) lifetime, low toxicity, and high resistance to photo-bleaching, which make them extremely suitable for use asalternatives to organic fluorescent dyes or quantum dots forvarious bioapplications.

Lanthanide-doped upconversion nanoparticles electrostatically coupled with photosensitizers for near-infrared-triggered photodynamic therapy

Lanthanide-doped upconversion nanoparticles (UCNPs) have recently shown great promise in photodynamic therapy (PDT). Herein, we report a facile strategy to fabricate an efficient NIR-triggered PDT system based on LiYF4:Yb/Er UCNPs coupled with a photosensitizer of a β-carboxyphthalocyanine zinc (ZnPc-COOH) molecule via direct electrostatic interaction. Due to the close proximity between UCNPs and ZnPc-COOH, we achieved a high energy transfer efficiency of 96.3% from UCNPs to ZnPc-COOH, which facilitates a large production of cytotoxic singlet oxygen and thus an enhanced PDT efficacy. Furthermore, we demonstrate the high efficacy of such a NIR-triggered PDT agent for the inhibition of tumor growth both in vitro and in vivo, thereby revealing the great potential of the UCNP-based PDT systems as noninvasive NIR-triggered PDT agents for deep cancer therapy.

Zinc phthalocyanine conjugated with the amino-terminal fragment of urokinase for tumor-targeting photodynamic therapy.

Photodynamic therapy (PDT) has attracted much interest for the treatment of cancer due to the increased incidence of multidrug resistance and systemic toxicity in conventional chemotherapy. Phthalocyanine (Pc) is one of main classes of photosensitizers for PDT and possesses optimal photophysical and photochemical properties. A higher specificity can ideally be achieved when Pcs are targeted towards tumor-specific receptors, which may also facilitate specific drug delivery. Herein, we develop a simple and unique strategy to prepare a hydrophilic tumor-targeting photosensitizer ATF-ZnPc by covalently coupling zinc phthalocyanine (ZnPc) to the amino-terminal fragment (ATF) of urokinase-type plasminogen activator (uPA), a fragment responsible for uPA receptor (uPAR, a biomarker overexpressed in cancer cells), through the carboxyl groups of ATF. We demonstrate the high efficacy of this tumor-targeting PDT agent for the inhibition of tumor growth both in vitro and in vivo. Our in vivo optical imaging results using H22 tumor-bearing mice show clearly the selective accumulation of ATF-ZnPc in tumor region, thereby revealing the great potential of ATF-ZnPc for clinical applications such as cancer detection and guidance of tumor resection in addition to photodynamic treatment.

Dissolution‐Enhanced Luminescent Bioassay Based on Inorganic Lanthanide Nanoparticles

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.

Pentalysine β-Carbonylphthalocyanine Zinc: An Effective Tumor-Targeting Photosensitizer for Photodynamic Therapy

Unsymmetrical phthalocyanine derivatives have been widely studied as photosensitizers for photodynamic therapy (PDT), targeting various tumor types. However, the preparation of unsymmetrical phthalocyanines is always a challenge due to the presence of many possible structural isomers. Herein we report a new unsymmetrical zinc phthalocyanine, pentalysine β‐carbonylphthalocyanine zinc (ZnPc‐(Lys)5), that was prepared in large quantity and high purity. This is a water‐soluble cationic photosensitizer and maintains a high quantum yield of singlet oxygen generation similar to that of unsubstituted zinc phthalocyanine (ZnPc). Compared with anionic ZnPc counterparts, ZnPc‐(Lys)5 shows a higher level cellular uptake and 20‐fold higher phototoxicity toward tumor cells. Pharmacokinetics and PDT studies of ZnPc‐(Lys)5 in S180 tumor‐bearing mice showed a high ratio of tumor versus skin retention and significant tumor inhibition. This new molecular framework will allow synthetic diversity in the number of lysine residues incorporated and will facilitate future QSAR studies.

A Novel Tumor Targeting Drug Carrier for Optical Imaging and Therapy

Human serum albumin (HSA), a naturally abundant protein in blood plasma and tissue fluids, has an extraordinary ligand-binding capacity and is advocated as a drug carrier to facilitate drug delivery. To render it tumor targeting specificity, we generated a recombinant HSA fused with the amino-terminal fragment (ATF) of urokinase, allowing the fusion protein to bind to urokinase receptor (uPAR), which is shown to have a high expression level in many tumors, but not in normal tissues. To test the efficacy of this bifunctional protein (ATF-HSA), a hydrophobic photosensitizer (mono-substituted β-carboxy phthalocyanine zinc, CPZ) was chosen as a cytotoxic agent. A dilution-incubation-purification (DIP) strategy was developed to load the ATF-HSA with this CPZ, forming a 1:1 molecular complex (ATF-HSA:CPZ). We demonstrated that CPZ was indeed embedded inside ATF-HSA at the fatty acid binding site 1 (FA1) of HSA, giving a hydrodynamic radius of 7.5 nm, close to HSAs (6.5 nm). ATF-HSA:CPZ showed high stability and remarkable optical and photophysical properties in aqueous solution. In addition, the molecular complex ATF-HSA:CPZ can bind to recombinant uPAR in vitro and uPAR on tumor cell surfaces, and was efficient in photodynamic killing of tumor cells. The tumor-killing potency of this molecular complex was further demonstrated in a tumor-bearing mouse model at a dose of 0.080 μmol / kg, or 0.050 mg CPZ / kg of mouse body weight. Using fluorescent molecular tomography (FMT), ATF-HSA:CPZ was shown to accumulate specifically in tumors, and importantly, such tumor retention was higher than that of HSA:CPZ. Together, these results indicate that ATF-HSA:CPZ is not only an efficient tumor-specific cytotoxic agent, but also an useful tumor-specific imaging probe. This bifunctional protein ATF-HSA can also be used as a drug carrier for other types of cytotoxic or imaging agents to render them specificity for uPAR-expressing tumors.

Enhanced Photodynamic Efficacy of Zinc Phthalocyanine by Conjugating to Heptalysine

Zinc phthalocyanine (ZnPc) is a promising photosensitizer for photodynamic therapy, but faces some challenges: ZnPc is insoluble in water and thus requires either special formulation of ZnPc by, e.g., liposome or Cremophor EL, or chemical modification of Pc ring to enhance its bioavailability and photodynamic efficacy. Here, we conjugated monosubstituted ZnPc-COOH with a series of oligolysine moieties with different numbers of lysine residues (ZnPc-(Lys)(n) (n = 1, 3, 5, 7, 9) to improve the water solubility of the ZnPc conjugates. We measured the photosensitizing efficacies and the cellular uptakes of this series of conjugates on a normal and a cancerous cell line. In addition, we developed a sensitive in situ method to distinguish the difference in photodynamic efficacy among conjugates. Our results showed that ZnPc-(Lys)(7) has the highest photodynamic efficacy compared to the other conjugates investigated.

Inorganic lanthanide nanoprobes for background-free luminescent bioassays

Luminescent bioassay techniques have been widely adopted in a variety of research and medical institutions. However, conventional luminescent bioassays utilizing traditional bioprobes like organic dyes and quantum dots often suffer from the interference of background noise from scattered lights and autofluorescence from biological matrices. To eliminate this disadvantage, the use of inorganic lanthanide (Ln3+)-doped nanoparticles (NPs) is an excellent option in view of their superior optical properties, such as the long-lived downshifting luminescence, near-infrared triggered anti-Stokes upconverting luminescence and excitation-free persistent luminescence. In this review, we summarize the latest advances in the development of inorganic Ln3+-doped NPs as sensitive luminescent bioprobes from their fundamental physicochemical properties to biodetection, including the chemical synthesis, surface functionalization, optical properties and their promising applications for back-ground-free luminescent bioassays. Future efforts and prospects towards this rapidly growing field are also proposed.摘要荧光生物分析技术在科研及医疗机构已获得广泛应用. 常规的荧光免疫分析方法由于采用传统生物探针(如荧光染料及量子点等)作为标记, 易受到杂散光及生物组织自荧光的干扰. 利用无机稀土纳米荧光探针优异的发光性能, 如长荧光寿命的下转移发光、 近红外激发的上转换发光以及无需激发源的长余辉发光, 可有效解决背景荧光的干扰. 本文从基础的物理化学性能到生物应用角度出发综述了无机稀土纳米发光材料的最新进展, 包括材料的控制合成、 表面功能化、 光学性能及其在无背景荧光生物分析方面的应用示范, 并对该类材料未来的发展趋势与努力的方向作了进一步的远景展望.