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ABSTRACT: Glioblastoma multiforme (GBM) is the most common and malignant form of primary brain tumors in human. Small molecular magnetic resonance imaging (MRI) contrast agents are used for GBM diagnosis. However, conventional contrast agents have several limitations, such as low T1 relaxivity, short circulation half lives and absence of tumor targeting. Herein, we develop an upconversion nanoprobe labeled with Gd(3+) -DOTA and RGD (UCNP-Gd-RGD) for dual-modality imaging of glioblastoma. The preparation of UCNP-Gd-RGD starts with amine-functional upconversion nanoparticle core, followed by PEGylation, Gd(3+) DOTA conjugation and RGD labeling. The obtained UCNP-Gd-RGD has improved colloidal stability and reduced cytotoxicity compared with the UCNP core counterpart. Meanwhile, UCNP-Gd-RGD shows strong upconversion luminescence in deep-red region and three times enhancement of T1 relaxivity over Gd(3+) DOTA. Due to the recognition between UCNP-Gd-RGD and integrin αv β3 receptors, the nanoprobe specifically binds to U87MG cells, as evidenced by confocal microscopy and quantified by ICP-MS. Furthermore, UCNP-Gd-RGD demonstrates a preferential retention in subcutaneous U87MG tumor xenograft as shown in both in vivo upconversion fluorescence/MR imaging studies and ex vivo analysis. UCNP-Gd-RGD, conjugated with numerous RGD peptide and T1 contrast enhancing molecules, is promising for MR imaging of glioblastoma and delineating the tumor boundary before surgery. In addition, NIR-to-red upconversion characteristic of UCNP-Gd-RGD facilitates its potential intra-operative use for fluorescence-guided tumor resection.
Advanced healthcare materials. 04/2013;
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ABSTRACT: Small molecules are difficult to detect by conventional quartz crystal microbalance with dissipation (QCM-D) technique directly because the changes in the frequency resulting from the binding processes of small biomolecules are often small. In the present study, an aptamer based gold nanoparticles enhanced sensing strategy for detection of small molecules was developed. The QCM crystal was first modified with a layer of thiolated linker DNA which can be partly base paired with the detection part containing the adenosine aptamer sequence. In the presence of adenosine, the aptamer bound with adenosine and folded to the complex structure which precluded the reporter part carrying AuNPs to combine with random coiled detection part. Therefore, the lower concentration of adenosine, the more AuNPs combined to the crystal. The resulting aptasensor showed a linear response to the increase of the adenosine concentration in the range of 0-2 μM with a linear correlation of r=0.99148 and a detection limit of 65 nM. Moreover, the aptasensor exhibited several excellent characterisitics, such as high sensitivity, selectivity, good stability, and reproducibility.
Analytical Biochemistry 04/2013; · 3.00 Impact Factor
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ABSTRACT: Accumulation and effects of BDE-47 and two analogues, 6-OH-BDE-47 and 6-MeO-BDE-47, on ontogeny and profiles of transcription of genes along the hypothalamus-pituitary-thyroid (HPT) axis of zebrafish (Danio rerio) embryos exposed from 4 hours post fertilization (hpf) to 120 hpf were investigated. The 96 h-LC50 of the most toxic compound, based on teratogenicity was 330 µg 6-OH-BDE-47/L. 6-OH-BDE-47 significantly down-regulated expression of mRNA of thyroid stimulating hormone receptor (TSHR), thyroid hormone receptors (TRs, including TRα and TRβ), sodium/iodide symporter (NIS) and transthyretin (TTR) while up-regulating expression of thyroglobulin (TG) and thyrotropin-releasing hormone (TRH). Spontaneous movement was affected by 1 mg 6-OH-BDE-47/L or 5 mg 6-MeO-BDE-47/L. BDE-47 did not alter activity of larvae at any concentration tested. 6-MeO-BDE-47 significantly up-regulated expression of mRNA of TRH, TRα, TRβ and NIS. 6-OH-BDE-47. 6-MeO-BDE-47 affected the thyroid hormone pathway. BDE-47 and 6-MeO-BDE-47 were accumulated more than 6-OH-BDE-47. 6-MeO-BDE-47 was transformed into 6-OH-BDE-47 but BDE-47 was not transformed into it. In summary, the synthetic brominated flame retardant, BDE-47 did not elicit the adverse effects caused by the other two analogues, and appears to have less toxicological relevance than the two natural product analogues 6-OH- and 6-MeO-BDE-47.
Environmental Science & Technology 10/2012; · 4.80 Impact Factor
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ABSTRACT: Bromophenol glucuronide and sulfate conjugates have been reported to be products of mammalian metabolism of polybrominated diphenyl ethers (PBDEs), a group of additive flame-retardants found ubiquitously in the environment. In order to explore their occurrence in human urine, four water-soluble bromophenol conjugates, namely 2,4-dibromophenyl glucuronide, 2,4,6-tribromophenyl glucuronide, 2,4-dibromophenyl sulfate and 2,4,6-tribromophenyl sulfate, were synthesized, purified and characterized. An analytical protocol using solid-phase extraction and ion-paired liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) quantification has been developed for the direct and simultaneous determination of these glucuronide and sulfate conjugates in human urine samples. Limit of detections for all analytes were below 13 pg per mL, with 73 - 101 % analyte recovery and 7.2 - 8.6 % repeatability. The method was applied to analyze 20 human urine samples collected randomly from voluntary donors in Hong Kong SAR, China. All the samples were found to contain one or more of the bromophenol conjugates, with concentration ranging from 0.13 - 2.45 μg per gram of creatinine. To the best of our knowledge, this is the first analytical protocol for the direct and simultaneously monitoring of these potential Phase II metabolites of PBDEs in human urine. Our results have also suggested the potential of these bromophenol conjugates in human urine to be convenient molecular markers for the quantification of population exposure to PBDEs.
Analytical Chemistry 10/2012; · 5.86 Impact Factor
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ABSTRACT: Polybrominated diphenyl ethers (PBDEs) and their analogues, such as hydroxylated PBDE (HO-PBDEs) and methoxylated PBDE (MeO-PBDEs) are of interest due to their wide distribution, bioaccumulation and potential toxicity to humans and wildlife. While information on the toxicity/biological potencies of PBDEs was available, information on analogues of PBDEs was limited. Dioxin-like toxicity of 34 PBDEs analogues was evaluated by use of the H4IIE-luc, rat hepatoma transactivation bioassay in 384-well plate format at concentrations ranging from 0 to 10 000 ng/mL. Among the 34 target analogues of PBDEs studied here, 19 activated the aryl hydrocarbon receptor (AhR) and induced significant dioxin-like responses in H4IIE-luc cells. Efficacies of the analogues of PBDEs ranged from 5.0% to 101.8% of the maximum response caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD-max) and their respective 2,3,7,8-TCDD potency factors (ReP(H4IIE-luc)) ranged from 7.35 × 10(-12) to 4.00 × 10(-4), some of which were equal to or more potent than some mono-ortho-substituted PCBs (TEF-(WHO) = 3 × 10(-5)). HO-PBDEs exhibited greater dioxin-like activity than did the corresponding MeO-PBDEs. Analogues of PBDEs were detected mostly in marine organisms. Of these 11 detected analogues of PBDEs, 6 were found to have measurable dioxin-like potency. Though some analogues of PBDEs exhibited significant dioxin-like potency as measured by responses of the H4IIE-luc transactivation assay, concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents ((PBDEs analogues)TEQ(H4IIE-luc)), calculated as the sum of the product of concentrations of individual PBDE and their ReP(H4IIE-luc), were less than the tolerance limit proposed by European Union and the oral reference dose (RfD) derived by U.S. Environmental Protection Agency, respectively. (Hazard Quotients (HQ) < 0.005) Additional investigations should be conducted to evaluate the toxic potencies of these chemicals, especially for 2'-MeO-BDE-28, 4-HO-BDE-90, 6-HO-BDE-47, and 6-MeO-BDE-47, which had been detected in other environmental media, including human blood.
Environmental Science & Technology 09/2012; 46(19):10781-8. · 4.80 Impact Factor
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ABSTRACT: Because of their unique characteristics, DNAs have been widely studied for uses in biosensors. In this work, we utilize single-stranded homopolymeric deoxyadenosines (abbreviated as poly (dA)) as recognition elements and gold nanoparticles (abbreviated as AuNPs) as reporter parts for the construction of pH alarms, which are able to produce sharp colorimetric responses upon specific pH thresholds within the range from pH 2 to 4. These biosensors are convenient to prepare and easy to operate. Their pH thresholds for colorimetric response can be easily tuned by changes of DNA strand length, concentration and DNA sequence. With an increase in the number of nucleotide bases per DNA chain while keeping the overall number of nucleotide base in the system constant, the pH threshold can be raised. Increasing the concentration of the single-stranded poly (dA) DNA lowers the pH response threshold. Moreover, as they can sense a range as narrow as a 0.4 pH unit which equals to 2.5 fold [H(+)] change, they can be used as a potential pH alarm for specific pH range.
Analytica chimica acta 09/2012; 741:106-13. · 4.31 Impact Factor
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ABSTRACT: The enhanced electricity generation in a biocathode bio-electrochemical system (BES) with Microcystis aeruginosa IPP as the cathodic microorganism under illumination is investigated. The results show that this cyanobacterium is able to act as a potential cathodic microorganism under illumination. In addition, M. aeruginosa IPP is found to produce reactive oxygen species (ROS) in its growth in the BES. ROS, as more competitive electron acceptors than oxygen, are utilized prior to oxygen. The BES current is substantially reduced when the ROS production is inhibited by mannitol, indicating that the ROS secreted by the cyanobacterium play an important role in the electricity generation of such a biocathode BES. This work demonstrates that the ROS released by cyanobacteria benefit for an enhanced electricity generation of BES.
Biosensors & bioelectronics 07/2012; 39(1):306-10. · 5.43 Impact Factor
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ABSTRACT: Hydroxylated (OH-) and methoxylated (MeO-) polybrominated diphenyl ethers (PBDE) are suspected endocrine disruptors. Little is known about the accumulation or sources of these chemicals in tissues of humans, particularly those residing in Hong Kong, which is one of the most densely populated cities in the world. Seven MeO-BDEs, fifteen OH-BDEs and three bromophenols (BRPs) were analyzed in blood plasma of 116 humans that had been collected by the Hong Kong Red Cross. Total concentrations of MeO-BDEs, OH-BDEs and BRPs ranged from 3.8×10² to 52×10³ pg g⁻¹ lipid (median 4.5×10³ pg g⁻¹), 5.3 to 4.9×10² pg g⁻¹ lipid (81 pg g⁻¹) and ND to 1.1×10² pg g⁻¹ lipid (3.7 pg g⁻¹), respectively. 3-MeO-BDE-47, 6-OH-BDE-47 and 2, 4, 5-TBP were the predominant MeO-BDEs, OH-BDEs and BRPs, respectively. These results are consistent with accumulation of MeO-BDEs, OH-BDEs and BRPs in human plasma being primarily from natural products and inter-conversion of natural products. Coefficients of determination for some pairs of congeners such as 3-OH-BDE-100 and 6-OH-BDE-47, 6-OH-BDE-85 and 5'-OH-BDE-99, and 2, 4-DBP and 6-OH-BDE-85, were near 1.0, which is consistent with them having common sources. Patterns of relative concentrations of the target analytes were similar in the diet, particularly fish, as in blood plasma of humans, which suggests that the diet and particularly seafood might be a source of these compounds and PBDEs. Furthermore, biotransformation of natural chemicals such as OH-BDEs to BRPs might be the primary route of their elimination from humans.
Environment international 07/2012; 47:66-72. · 4.79 Impact Factor
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ABSTRACT: A photo-responsive molecularly imprinted sol–gel organic-inorganic hybrid material prepared by covalent imprinting of the
template-functional monomer complex formed between 4,4′-dihydroxylazobenzene and ibuprofen was developed to explore the photo-regulated
uptake and release of drug by a silicate-based smart molecularly imprinted materials. After imprinting, the template molecules
(ibuprofen) were removed via hydrolysis in acid, and accurate cavities were left, which could be used as the receptor recognition
sites for ibuprofen. The new organic–inorganic hybrid material shows specific affinity to ibuprofen and reversible uptake
and release of ibuprofen upon alternate irradiation at 365 and 440nm, respectively. The favorable binding strength of the
imprinted receptor sites in the molecularly imprinted polymer (MIP) for ibuprofen is found to be 2.28×103M−1. Density of receptor sites in the MIP material was 4.0µmol/g—MIP.
KeywordsSol–gel–Organic–inorganic hybrid materials–Ibuprofen–Photo-responsive–Azobenzene
Journal of Sol-Gel Science and Technology 05/2012; 59(3):495-504. · 1.63 Impact Factor
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ABSTRACT: Two new C,N,N-type ligands (HL(2) and HL(3)), containing a C(phenyl), a N(pyridyl), and a N(imidazolyl) donor, and their cycloplatinated complexes, [Pt(L(2))Cl] (1), [Pt(L(3))Cl] (2), [Pt(L(2))(PPh(3))](+) (3) and [Pt(L(3))(PPh(3))](+) (4), have been successfully synthesized and characterized. Spectroscopic and (3)MLCT luminescent properties of these Pt(II) cyclometalated complexes were found to be pH dependent. This was attributed to the protonation/deprotonation of the acidic 1-imidazolyl-NH moieties on the ligands. All the cycloplatinated complexes (both protonated and deprotonated forms) possessed two-photon excitability with two-photon absorption cross-sections ranging from 6.0 to 30.0 GM (protonated forms) and from 16.2 to 24.9 GM (deprotonated forms).
Dalton Transactions 12/2011; 41(6):1792-800. · 3.84 Impact Factor
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ABSTRACT: A facultative anaerobic bacteria strain GS-4-08, isolated from an anaerobic sequence batch reactor for synthetic dye wastewater treatment, was investigated for azo-dye decolorization. This bacterium was identified as a member of Klebsiella oxytoca based on Gram staining, morphology characterization and 16S rRNA gene analysis. It exhibited a good capacity of simultaneous decolorization and hydrogen production in the presence of electron donor. The hydrogen production was less affected even at a high Methyl Orange (MO) concentration of 0.5 mM, indicating a superior tolerability of this strain to MO. This efficient bio-hydrogen production from electron donor can not only avoid bacterial inhibition due to accumulation of volatile fatty acids during MO decolorization, but also can recover considerable energy from dye wastewater.
Applied Microbiology and Biotechnology 11/2011; 95(1):255-62. · 3.42 Impact Factor
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Shuzhong He,
Hongguang Li,
Yuk-Wang Yip,
Chi-Tung Yeung,
Yuen On Fung,
Hoi-Kuan Kong,
Ho-Lun Yeung,
Ga-Lai Law,
Ka-Leung Wong,
Chi-Sing Lee, Michael Hon-Wah Lam,
Margaret B Murphy,
Paul Kwan-Sing Lam,
Wing-Tak Wong
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ABSTRACT: A water-soluble europium(III) complex (1) has been synthesized and demonstrated to be a specific fluorescence probe for the paralytic shellfish toxin saxitoxin, a neurotoxin that blocks the voltage-gated sodium channels on cell membranes. Saxitoxin binds to the europium complex (K(B) = 6.1 × 10(4) M(-1)) and triggers a two-photon induced f-f emission enhancement by over 100% and increases the two-photon absorption cross-section from 9 to 36 GM.
Organic Letters 09/2011; 13(19):5036-9. · 5.86 Impact Factor
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Pei-Jie Cai,
Xiang Xiao,
Yan-Rong He,
Wen-Wei Li,
Jian Chu,
Chao Wu,
Meng-Xing He,
Zhe Zhang,
Guo-Ping Sheng, Michael Hon-Wah Lam,
Fang Xu,
Han-Qing Yu
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ABSTRACT: In this work, we investigated the anaerobic decolorization of methyl orange (MO), a typical azo dye, by Shewanella oneidensis MR-1, which can use various organic and inorganic substances as its electron acceptor in natural and engineered environments. S. oneidensis MR-1 was found to be able to obtain energy for growth through anaerobic respiration accompanied with dissimilatory azo-reduction of MO. Chemical analysis shows that MO reduction occurred via the cleavage of azo bond. Block of Mtr respiratory pathway, a transmembrane electron transport chain, resulted in a reduction of decolorization rate by 80%, compared to the wild type. Knockout of cymA resulted in a substantial loss of its azo-reduction ability, indicating that CymA is a key c-type cytochrome in the electron transfer chain to MO. Thus, the MtrA-MtrB-MtrC respiratory pathway is proposed to be mainly responsible for the anaerobic decolorization of azo dyes such as MO by S. oneidensis.
Applied Microbiology and Biotechnology 08/2011; 93(4):1769-76. · 3.42 Impact Factor
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Annalen der Chemie und Pharmacie 07/2011; 2011(26):5054 - 5060. · 3.10 Impact Factor
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ABSTRACT: High concentrations of polybrominated diphenyl ethers (PBDEs) and their structural analogues (such as methoxylated (MeO) and hydroxylated (OH) PBDEs) had been observed in environmental samples and human tissues. This study evaluated the occurrence, potential source and human exposure of these organobrominated compounds via market fish consumption in Hong Kong. The contamination of 22 PBDEs, 7 MeO-BDEs, 15 OH-BDEs and 3 bromophenols (BRPs) were analyzed in 20 fish species (279 samples). The estimated daily intakes of PBDEs, MeO-BDEs, OH-BDEs and BRPs via fish consumption ranged from 4.4 to 14, 0.50 to 4.3, 0.02 to 0.43 and 0 to 0.21 ng/kg day for Hong Kong residents, respectively, based on 50(th) and 95(th) centile concentrations. BDE-47 and 99 were found to be the major PBDE congeners while 2'-MeO-BDE-68, 6-MeO-BDE-47 and 3-MeO-BDE-47 were the dominant MeO-BDEs. Concentrations of OH-BDEs and BRPs were 10-100-fold less than those of PBDEs, with small frequencies of detection (max 36.7%). Dietary intake of PBDEs via fish consumption by Hong Kong residents was greater than many developed countries, such as the USA, UK, Japan and Spain. To our knowledge, this is the first report to estimate the dietary intake of MeO/OH-BDEs and BRPs via fish consumption. Our results indicated that the toxicity potential of these compounds should not be neglected.
Journal of hazardous materials 05/2011; 192(1):374-80. · 4.14 Impact Factor
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ABSTRACT: Ultra performance liquid chromatography (UPLC) provides improved resolution, speed and sensitivity compared to conventional high performance liquid chromatography (HPLC). In this study, a robust UPLC-ESI-MS/MS method was developed for the rapid determination of nine hydroxylated polybrominated diphenyl ethers (OH-PBDEs) in rat plasma. Under the optimized conditions, the OH-PBDE congeners were eluted within 7.0 min. The limits of quantification defined at the signal-to-noise ratio of 10 were 0.17-2.78 ng/mL in rat plasma. The method provided good linearity for the calibration curves with recoveries of 93.3-114.0% and repeatability with relative standard deviation (RSD) of 0.6-5.8% for intra-day and 3.2-10.4% for inter-day measurements. The developed method was applied for supporting the pharmacokinetics investigation of 6-OH-BDE-47 in two groups of Sprague-Dawley rats that received, respectively a single dose of 0.60 mg/kg (high dose) and 0.15 mg/kg (low dose) by intravenous injection. The results showed that plasma levels of 6-OH-BDE-47 declined bi-exponentially with elimination half-life of 71.7 and 85.6 min for lower and higher dose group, respectively. The obtained results of short elimination half-life suggested that 6-OH-BDE-47 might not accumulate significantly in rat.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 05/2011; 879(15-16):1086-90. · 2.78 Impact Factor
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ABSTRACT: A model azo dye, methyl orange (MO), was reduced through in situ utilization of the electrons derived from the anaerobic conversion of organics in a microbial fuel cell (MFC). The MO reduction process could be described by a pseudo first-order kinetic model with a rate constant of 1.29 day(-1). Electrochemical impedance spectroscopic analysis shows that the cathode had a high polarization resistance, which could decrease the reaction rate and limit the electron transfer. To improve the MO reduction efficiency, the cathode was modified with redox mediators to enhance the electron transfer. After modification with thionine, the polarization resistance significantly decreased by over 50%. As a consequence, the MO decolorization rate increased by over 20%, and the power density was enhanced by over three times. Compared with thionine, anthraquinone-2, 6-disulfonate modified cathode has less positive effect on the MFC performance. These results indicate that the electrode modification with thionine is a useful approach to accelerate the electrochemical reactions. This work provides useful information about the key factors limiting the azo dye reduction in the MFC and how to improve such a process.
Applied Microbiology and Biotechnology 01/2011; 89(1):201-8. · 3.42 Impact Factor
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ABSTRACT: Adsorption and decolorization kinetics of methyl orange (MO) by anaerobic sludge in anaerobic sequencing batch reactors were investigated. The anaerobic sludge was found to have a saturated adsorption capacity of 36 ± 1 mg g MLSS(-1) to MO. UV/visible spectrophotometer and high-performance liquid chromatography analytical results indicated that the MO adsorption and decolorization occurred simultaneously in this system. This process at various substrate concentrations could be well simulated using a modified two-stage model with apparent pseudo first-order kinetics. Furthermore, a noncompetitive inhibition kinetic model was also developed to describe the MO decolorization process at high NaCl concentrations, and an inhibition constant of 3.67 g NaCl l(-1) was estimated. This study offers an insight into the adsorption and decolorization processes of azo dyes by anaerobic sludge and provides a better understanding of the anaerobic dye decolorization mechanisms.
Applied Microbiology and Biotechnology 01/2011; 90(3):1119-27. · 3.42 Impact Factor
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ABSTRACT: Vrtical profiles ofdissolvedCd, Cr, Cu, Pb, Zn, Fe, and Mn in the sediment pore waters of the intertidal mudflats of the Mai Po and Inner Deep Bay Ramsar Site of Hong Kong, People's Republic of China, were measured using the polyacrylamide gel diffusive equilibration thin film (DET) technique. The ranges of concentrations of dissolved Cd, Cr, Cu, Pb, Zn, Fe, and Mn in the pore water of the top 0 to 20 cm of sediment were 2.2 to 10.0 nM, 346.0 to 950.0 nM 243.8 to 454.8 nM, 23.2 to 51.2 nM, 39.8 to 249.5 μM, and 13.4 to 20.7 μM, respectively. Enrichment of these trace metals was observed in the upper 0- to 7-cm layer. Profiles of conditional distribution coefficient, log(KD), of the trace metals and results of multiple regression analysis have revealed that reduction of Mn (hydrous) oxides was the major remobilization mechanism for Cd, Cr, Cu, Pb, and Zn in the mudflats. Benthic diffusive fluxes of these trace metals from the mudflats were also estimated on the basis of the concentration gradients of trace metals between surface sediments and the overlying water column. The magnitude of the estimated diffusive fluxes followed the order Zn > Cr > Cu > Pb > Cd.
Environmental Toxicology and Chemistry 11/2009; 19(3):535 - 542. · 2.81 Impact Factor
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ABSTRACT: An amphiphilic, water-soluble cyclometalated Pt(II) complex with two-photon emission properties has been developed as a molecular marker specific for in vitro plasma membrane staining.
Inorganic Chemistry 09/2009; 48(16):7501-3. · 4.60 Impact Factor
