miR­125/CDK2 axis in cochlear progenitor cell proliferation.

Hearing loss ranks fourth among the principal causes of disability worldwide, and manipulation of progenitor cells may be a key strategy for hair cell regeneration. The present study investigated the role and mechanism of miR­125 on the proliferation of cochlear progenitor cells (CPCs). CPCs were isolated from the cochleae of neonatal rats, and their morphology was observed. Furthermore, the differentiation ability of CPCs was determined by assessing the expression of 5­bromodeoxyuridine (BrdU), nestin and myosin VII by immunofluorescence. The expression levels of miR­125 and cyclin­dependent kinase 2 (CDK2) as well as the cell proliferation of CPCs were assessed. In addition, following gain­ and loss­of­function assays, the cell cycle was examined by flow cytometry, and the expression levels of miR­125, CDK2, proliferating cell nuclear antigen (PCNA) and nestin were determined by reverse transcription­quantitative PCR and western blotting. The binding sites between miR­125 and CDK2 were predicted by TargetScan and identified by the dual luciferase reporter assay. The results demonstrated that different types of progenitor spheres were observed from CPCs with positive expression of BrdU, nestin and myosin VII. Following in vitro incubation for 2, 4 and 7 days, the spheres were enlarged, and CPC proliferation gradually increased and reached a plateau after further incubation for 3 days. Furthermore, the expression levels of nestin and PCNA in CPCs increased and then decreased during in vitro incubation for 2, 4 and 7 days. Following this incubation, the expression levels of miR­125 in CPCs decreased; thereafter, its expression increased, and the expression pattern was different from that of CDK2. In addition, miR­125 overexpression in CPCs decreased the expression of CDK2 and the number of cells in the S phase. Different expression patterns were found in CPCs in response to the miR­125 knockdown. In addition, miR­125 directly targeted CDK2. Simultaneous knockdown of miR­125 and CDK2 enhanced CPC proliferation compared with CDK2 knockdown alone. Taken together, the findings from the present study suggested that miR­125 may inhibit CPC proliferation by downregulating CDK2. The present study may provide a novel therapeutic direction for treatment of hearing loss.

Nano-selenium functionalized zinc oxide nanorods: A superadsorbent for mercury (II) removal from waters.

In this study, nano selenium functionalized zinc oxide nanorods, NanoSe@ZnO-NR, was prepared, characterized and investigated for Hg(II) removal from waters of different types. The study results revealed that the material showed a superior adsorption capacity (qm, 1110 mg g-1) and excellent distribution coefficient (Kd, 9.11 × 108 mL g-1) which is two or more orders above most of the adsorbents reported in the literature. It should be also known that, 30 mg of the adsorbent can quickly reduce 10 mg L-1 Hg(II) to undetectable level from 10 mL of sample solution. The adsorption data were well explained with the pseudo-second order kinetic model and Langmuir adsorption isotherm model. Besides, the capturing capability of the material is independent on the pH change (2-12), selective against interfering cations, and exhibited fast kinetics (equilibrium time, ∼1 min). The NanoSe@ZnO-NR performance was also tested on real samples from different origin, surface waters (tap, lake and river) and wastewaters (effluent and influent), and complete removal and ≥99.2% removal efficiency was observed at 0.01 and 10 mg L-1 spiking levels, respectively. Therefore, NanoSe@ZnO-NR can be considered as a potential adsorbent in advancing the wastewater treatment technology.

Separation and size characterization of zinc oxide nanoparticles in environmental waters using asymmetrical flow field-flow fractionation.

There are few studies on separation and size characterization of zinc oxide nanoparticles (ZnO-NPs), which have wide applications in several science and technology areas, in the environment. In this work, we report a method for the separation and size characterization of ZnO-NPs by asymmetrical flow field-flow fractionation (AF4) coupled to UV-vis detector. Experimental conditions such as composition of the carrier solution, focus time, crossflow, detector flow rate and injection volume were systematically studied in terms of NPs separation, recovery, and repeatability. Size characterization was achieved using polystyrene nanoparticles as a size standard and a mixture of < 35 nm (NP-A) and < 100 nm (NP-B) ZnO-NPs were separated and size characterized posterior preconcentration using ultracentrifugation. The method was also employed to characterize the size of homemade ZnO-NPs, and the results were in concordance with dynamic light scattering (DLS) analysis and thus, the method can be used as an alternate method. Upon application on environmental water samples, the two ZnO-NPs, NP-A and NP-B, have been separated and size characterized. The estimated hydrodynamic sizes of the NP-A and NP-B were found to be in the range of 83-97 nm and 188-202 nm, respectively, with good precision (RSD, <11%), suggesting that the current method can satisfactorily separate and generate information about sizes of the NPs in samples with a complex matrix. Therefore, the developed technique can be used as a baseline to investigate size related environmental processes of the NPs in environmental water samples.

Hydride generation coupled with thioglycolic acid coated gold nanoparticles as simple and sensitive headspace colorimetric assay for visual detection of Sb(III).

Antimony (Sb) is a toxic element which causes different health problems including cardiac problems and lung cancer in humans, and its levels in surface water can be noticeably increased to 100 µg/L typically in the proximity of anthropogenic sources. Thus, besides instrumental techniques, it is of great significance to develop a simple, sensitive and selective analytical method for direct analysis of Sb(III) at trace level without the need of any expensive and/or complicated instrumentations and sample preparation processes. Herein, a simple and sensitive headspace colorimetric assay was developed for the detection of Sb(III) by hydride generation coupled with thioglycolic acid functionalized gold nanoparticles (TGA-AuNPs). Sb(III) in the 30 mL sample solution was converted into its volatile form (SbH3) through hydride generation reaction and headspace extracted into 100 µL chromogenic reagent, which contains methanol as extractant and TGA-AuNPs as nanosensors, leading to aggregation of TGA-AuNPs and therefore a red-to-blue color change. Parameters influencing the chromogenic and hydride generation reactions were optimized. Addition of 300 µM ethylenediamine tetraacetic acid (EDTA) as masking agent largely suppressed the inferences from mercury and arsenic. The proposed method can tolerate at least 10-fold As(III) and 100-fold other metal ions including Hg(II). The detection limits were 6.0 and 1.2 µg/L Sb(III) by naked-eye and UV-Vis spectrometer, respectively, which meet the maximum admissible level in drinking water (6 µg/L) set by the United States Environmental Protection Agency. The feasibility of the proposed method was demonstrated by rapid detection of Sb(III) in river water, lake water, ground water and sea water samples by naked-eye at a spiking level of 6 µg/L Sb(III).

Single-drop gold nanoparticles for headspace microextraction and colorimetric assay of mercury (II) in environmental waters.

A novel headspace colorimetric nanosensor strategy for specific detection of Hg(II) was developed based upon analyte induced etching and amalgamation of gold nanoparticles (AuNPs). The Hg(II) was first selectively reduced to its volatile form, Hg(0), by stannous chloride (SnCl2) through chemical cold vapor generation (CVG) reaction. Then, the Hg(0) was headspace extracted into 37µL thioglycolic acid functionalized AuNP aqueous suspension containing 10% methanol as extractant and simultaneously reacted with AuNPs through the strong metallophilic Hg-Au interaction, resulting in a red-to-blue color change. Parameters influencing the chromogenic and chemical vapor generation reactions were optimized. The limit of detections were determined as 5nM through inspection by naked-eye and 1nM based on measurements by UV-Vis spectrometer, which are below the safe limit of Hg(II) in drinking water set by the US Environmental Protection Agency, showing excellent potential for monitoring ultralow levels of Hg(II) in environmental water samples. The assay was not interfered by the presence of other common metal ions even at 1000-fold excess over Hg(II) concentration. The outstanding selectivity results from the combined effect of selective reduction of Hg(II) by SnCl2, efficient separation of sample matrix through headspace extraction, and amalgamation process that occurs specifically between Hg and AuNPs. The method was successfully applied to the visual detection of Hg(II) in environmental water samples at a 10nM spiking level, with recoveries in the range of 86.8-99.8%. More importantly, compared to classical colorimetric assays for detection of Hg(II), this method is featured with simplicity, quite high sensitivity and excellent selectivity. The method is also superior to most colorimetric methods for detection of Hg(II) in terms of its applicability to matrix-rich real samples including wastewater.

Tracking the Transformation of Nanoparticulate and Ionic Silver at Environmentally Relevant Concentration Levels by Hollow Fiber Flow Field-Flow Fractionation Coupled to ICPMS.

It is a great challenge to monitor the physical and chemical transformation of nanoparticles at environmentally relevant concentration levels, mainly because the commonly used techniques like dynamic light scattering and transmission electron microscopy are unable to characterize and quantify trace level nanoparticles in complex matrices. Herein, we demonstrate the on-line coupled system of hollow fiber flow field-flow fractionation (HF5), minicolumn concentration, and inductively coupled plasma mass spectrometry (ICPMS) detection as an efficient approach to study the aggregation and chemical transformation of silver nanoparticles (AgNPs) and ionic Ag species in the aqueous environment at ng/mL levels. Taking advantage of the in-line dialysis of HF5, the selective capture of Ag(I) species by the resin in minicolumn, and the high selectivity and sensitivity of ICPMS detection, we recorded the aggregation of 10 ng/mL AgNPs in complex matrices (e.g., NOM, Na+/Ca2+), revealing an interesting tiny AgNPs formation process of photoreduction of trace level Ag(I) that is different from larger AgNPs generated at high concentration of Ag(I) by accurate characterization and respectively identifying and quantifying new thiol-complexed Ag(I) and residual Ag(I) in the intertransformation of Ag(I) and AgNPs in domestic wastewater by simultaneously detecting the S and Ag signals via ICPMS.

Transformation and bioavailability of metal oxide nanoparticles in aquatic and terrestrial environments. A review.

Metal oxide nanoparticles (MeO-NPs) are among the most consumed NPs and also have wide applications in various areas which increased their release into the environmental system. Aquatic (water and sediments) and terrestrial compartments are predicted to be the destination of the released MeO-NPs. In these compartments, the particles are subjected to various dynamic processes such as physical, chemical and biological processes, and undergo transformations which drive them away from their pristine state. These transformation pathways can have strong implications for the fate, transport, persistence, bioavailability and toxic-effects of the NPs. In this critical review, we provide the state-of-the-knowledge on the transformation processes and bioavailability of MeO-NPs in the environment, which is the topic of interest to researchers. We also recommend future research directions in the area which will support future risk assessments by enhancing our knowledge of the transformation and bioavailability of MeO-NPs.

Ionic liquid-based zinc oxide nanofluid for vortex assisted liquid liquid microextraction of inorganic mercury in environmental waters prior to cold vapor atomic fluorescence spectroscopic detection.

Zinc oxide nanofluid (ZnO-NF) based vortex assisted liquid liquid microextraction (ZnO-NF VA-LLME) was developed and employed in extraction of inorganic mercury (Hg(2+)) in environmental water samples, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). Unlike other dispersive liquid liquid microextraction techniques, ZnO-NF VA-LLME is free of volatile organic solvents and dispersive solvent consumption. Analytical signals were obtained without back-extraction from the ZnO-NF phase prior to CV-AFS determination. Some essential parameters of the ZnO-NF VA-LLME and cold vapor generation such as composition and volume of the nanofluid, vortexing time, pH of the sample solution, amount of the chelating agent, ionic strength and matrix interferences have been studied. Under optimal conditions, efficient extraction of 1ng/mL of Hg(2+) in 10mL of sample solution was achieved using 50µL of ZnO-NF. The enrichment factor before dilution, detection limits and limits of quantification of the method were about 190, 0.019 and 0.064ng/mL, respectively. The intra and inter days relative standard deviations (n=8) were found to be 4.6% and 7.8%, respectively, at 1ng/mL spiking level. The accuracy of the current method was also evaluated by the analysis of certified reference materials, and the measured Hg(2+) concentration of GBW08603 (9.6ng/mL) and GBW(E)080392 (8.9ng/mL) agreed well with their certified value (10ng/mL). The method was applied to the analysis of Hg(2+) in effluent, influent, lake and river water samples, with recoveries in the range of 79.8-92.8% and 83.6-106.1% at 1ng/mL and 5ng/mL spiking levels, respectively. Overall, ZnO-NF VA-LLME is fast, simple, cost-effective and environmentally friendly and it can be employed for efficient enrichment of the analyte from various water samples.

Speciation Analysis of Labile and Total Silver(I) in Nanosilver Dispersions and Environmental Waters by Hollow Fiber Supported Liquid Membrane Extraction.

Hollow fiber supported liquid membrane (HFSLM) extraction was coupled with ICP-MS for speciation analysis of labile Ag(I) and total Ag(I) in dispersions of silver nanoparticles (AgNPs) and environmental waters. Ag(I) in aqueous samples was extracted into the HFSLM of 5%(m/v) tri-n-octylphosphine oxide in n-undecane, and stripped in the acceptor of 10 mM Na2S2O3 and 1 mM Cu(NO3)2 prepared in 5 mM NaH2PO4-Na2HPO4 buffer (pH 7.5). Negligible depletion and exhaustive extraction were conducted under static and 250 rpm shaking to extract the labile Ag(I) and total Ag(I), respectively. The extraction equilibration was reached in 8 h for both extraction modes. The extraction efficiency and detection limit were (2.97 ± 0.25)% and 0.1 µg/L for labile Ag(I), and (82.3 ± 2.0)% and 0.5 µg/L for total Ag(I) detection, respectively. The proposed method was applied to determine labile Ag(I) and total Ag(I) in different sized AgNP dispersions and real environmental waters, with spiked recoveries of total Ag(I) in the range of 74.0-98.1%. With the capability of distinguishing labile and total Ag(I), our method offers a new approach for evaluating the bioavailability and understanding the fate and toxicity of AgNPs in aquatic systems.

Toward full spectrum speciation of silver nanoparticles and ionic silver by on-line coupling of hollow fiber flow field-flow fractionation and minicolumn concentration with multiple detectors.

The intertransformation of silver nanoparticles (AgNPs) and ionic silver (Ag(I)) in the environment determines their transport, uptake, and toxicity, demanding methods to simultaneously separate and quantify AgNPs and Ag(I). For the first time, hollow fiber flow field-flow fractionation (HF5) and minicolumn concentration were on-line coupled together with multiple detectors (including UV-vis spectrometry, dynamic light scattering, and inductively coupled plasma mass spectrometry) for full spectrum separation, characterization, and quantification of various Ag(I) species (i.e., free Ag(I), weak and strong Ag(I) complexes) and differently sized AgNPs. While HF5 was employed for filtration and fractionation of AgNPs (>2 nm), the minicolumn packed with Amberlite IR120 resin functioned to trap free Ag(I) or weak Ag(I) complexes coming from the radial flow of HF5 together with the strong Ag(I) complexes and tiny AgNPs (<2 nm), which were further discriminated in a second run of focusing by oxidizing >90% of tiny AgNPs to free Ag(I) and trapped in the minicolumn. The excellent performance was verified by the good agreement of the characterization results of AgNPs determined by this method with that by transmission electron microscopy, and the satisfactory recoveries (70.7-108%) for seven Ag species, including Ag(I), the adduct of Ag(I) and cysteine, and five AgNPs with nominal diameters of 1.4 nm, 10 nm, 20 nm, 40 nm, and 60 nm in surface water samples.

Nanofluid of zinc oxide nanoparticles in ionic liquid for single drop liquid microextraction of fungicides in environmental waters prior to high performance liquid chromatographic analysis.

Using a nanofluid obtained by dispersing ZnO nanoparticles (ZnO NPs) in 1-hexyl-3-methylimidazolium hexafluorophosphate, new single drop microextraction method was developed for simultaneous extraction of three fungicides (chlorothalonil, kresoxim-methyl and famoxadone) in water samples prior to their analysis by high performance liquid chromatography (HPLC-VWD). The parameters affecting the extraction efficiency such as amount of ZnO NPs in the nanofluid, solvent volume, extraction time, stirring rate, pH and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.13-0.19ng/mL, the precision of the method assessed with intra-day and inter-day relative standard deviations were <4.82% and <7.04%, respectively. The proposed method was successfully applied to determine the three fungicides in real water samples including lake water, river water, as well as effluent and influent of wastewater treatment plant, with recoveries in the range of 74.94-96.11% at 5ng/mL spiking level. Besides to being environmental friendly, the high enrichment factor and the data quality obtained with the proposed method demonstrated its potential for application in multi residue analysis of fungicides in actual water samples.

Colorimetric Au nanoparticle probe for speciation test of arsenite and arsenate inspired by selective interaction between phosphonium ionic liquid and arsenite.

The exposure of millions of people to unsafe levels of arsenite (AsIII) and arsenate (AsV) in drinking waters calls for the development of low-cost methods for on-site monitoring these two arsenic species in waters. Herein, for the first time, tetradecyl (trihexyl) phosphonium chloride ionic liquid was found to selectively bind with AsIII via extended X-ray absorption fine structure (EXAFS) analysis. Based on the finding, an AsIII-specific probe was developed by modifying gold nanoparticles with the ionic liquid. Futhermore, Hofmeister effect was primarily observed to significantly affect the sensitivity of gold nanoparticle probe. With the colorimetric probe, we developed a protocol for naked eye speciation test of AsIII and AsV at levels below the World Health Organization (WHO) guideline of 10 µg L(-1). This method featured with high tolerance to common coexisting ions such as 10 mM PO4(3-), and was validated by assaying certified reference and environmental water samples.

Visual test of subparts per billion-level copper(II) by Fe3O4 magnetic nanoparticle-based solid phase extraction coupled with a functionalized gold nanoparticle probe.

By combining Fe(3)O(4) magnetic nanoparticle-based solid phase extraction with a gold nanoparticle-based visual test, a novel method was developed for the field assay of Cu(ii) in environmental water at subparts per billion-levels within 30 min. When a 200 mL water sample was treated with 12.5 mg L(-1) Fe(3)O(4) nanoparticles by the proposed procedure, the detection limit with the naked eye was 0.2 µg L(-1) Cu(ii). The proposed method is very specific to Cu(ii), with tolerance against at least 100-fold amounts of other environmentally relevant metal ions except for Hg(ii) (25-fold), and was successfully applied to the detection of trace Cu(ii) in tap water, river water, and treated wastewater, and results agreed well with that determined by inductively coupled plasma-mass spectrometry (ICP-MS).

Speciation analysis of silver nanoparticles and silver ions in antibacterial products and environmental waters via cloud point extraction-based separation.

The rapid growth in commercial use of silver nanoparticles (AgNPs) will inevitably increase silver exposure in the environment and the general population. As the fate and toxic effects of AgNPs is related to the Ag(+) released from AgNPs and the transformation of Ag(+) into AgNPs, it is of great importance to develop methods for speciation analysis of AgNPs and Ag(+). This study reports the use of Triton X-114-based cloud point extraction as an efficient separation approach for the speciation analysis of AgNPs and Ag(+) in antibacterial products and environmental waters. AgNPs were quantified by determining the Ag content in the Triton X-114-rich phase with inductively coupled plasma mass spectrometry (ICPMS) after microwave digestion. The concentration of total Ag(+), which consists of the AgNP adsorbed, the matrix associated, and the freely dissolved, was obtained by subtracting the AgNP content from the total silver content that was determined by ICPMS after digestion. The limits of quantification (S/N = 10) for antibacterial products were 0.4 µg/kg and 0.2 µg/kg for AgNPs and total silver, respectively. The reliable quantification limit was 3 µg/kg for total Ag(+). The presence of Ag(+) at concentrations up to 2-fold that of AgNPs caused no effects on the determination of AgNPs. In the cloud point extraction of AgNPs in antibacterial products, the spiked recoveries of AgNPs were in the range of 71.7-103% while the extraction efficiencies of Ag(+) were in the range of 1.2-10%. The possible coextracted other silver containing nanoparticles in the cloud point extraction of AgNPs were distinguished by transmission electron microscopy (TEM), scanning electron microscopy (SEM)- energy dispersive spectroscopy (EDS), and UV-vis spectrum. Real sample analysis indicated that even though the manufacturers claimed nanosilver products, AgNPs were detected only in three of the six tested antibacterial products.

Development of a static and exhaustive extraction procedure for field passive preconcentration of chlorophenols in environmental waters with hollow fiber-supported liquid membrane.

A static and exhaustive extraction mode of hollow fiber-supported liquid membrane was developed for field sample passive pretreatment of environmental water samples. The extraction device was prepared by immobilizing dihexyl ether in the wall of a polypropylene hollow fiber membrane (60 cm length, 50 µm wall thickness, and 280 µm id) as liquid membrane and filling the fiber lumen with 0.1 M NaOH as acceptor, and closing the two ends of the fiber with an aluminum foil. Passive extraction was conducted by immersing the device into 15 mL water samples modified with 0.01 M HCl and 20% m/v NaCl. Model analytes including 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol were transferred into acceptor with extraction efficiencies over 79% in 10 h at room temperature, and determined by high-performance liquid chromatography. The proposed method has the enrichment factor of 394-498 and LOD of 0.3-0.4 µg/L for the three chlorophenols. Humic acid and salinity in the environmentally relevant range had no significant influence on the extraction, and chlorophenols in various environmental waters were determined with spike recoveries between 71.6 and 120%. The static passive extraction nature benefited field sample pretreatment without power, whereas the exhaustive extraction mode effectively eliminated the sample matrix effects.

Visual test of subparts per billion-level mercuric ion with a gold nanoparticle probe after preconcentration by hollow fiber supported liquid membrane.

With the combination of the gold nanoparticle (AuNP)-based visual test with hollow fiber supported liquid membrane (HFSLM) extraction, a highly sensitive and selective method was developed for field detection of mercuric ion (Hg(2+)) in environmental waters. Hg(2+) in water samples was extracted through HFSLM and trapped in the aqueous acceptor and then visually detected based on the red-to-blue color change of 3-mercaptopropionic acid-functionalized AuNP (MPA-AuNP) probe. The highest extraction efficiency of Hg(2+) was obtained by using a 600 mL sample (pH 8.0, 2.0% (w/v) NaCl), approximately 35 microL of acceptor (10 mM of 2,6-pyridinedicarboxylic acid, pH 4.0) filled in the lumen of a polypropylene hollow fiber tubing (55 cm in length, 50 microm wall thickness, 280 microm inner diameter), a liquid membrane of 2.0% (w/v) trioctycphosphine oxide in undecane, and a shaking rate of 250 rpm. The chromegenic reaction was conducted by incubating the mixture of MPA-AuNP stock solution (12 microL, 15 nM), Tris-borate buffer solution (18 microL, 0.2 M, pH 9.5), and acceptor (30 microL) at 30 degrees C for 1 h. The detection limit can be adjusted to 0.8 microg/L Hg(2+) (corresponding to an enrichment factor of approximately 1000 in the HFSLM) and 2.0 microg/L Hg(2+) (the U.S. Environmental Protection Agency limit of [Hg(2+)] for drinkable water) by using extraction times of 3 and 1 h, respectively. The proposed method is extremely specific for Hg(2+) with tolerance to at least 1000-fold of other environmentally relevant heavy and transition metal ions and was successfully applied to detect Hg(2+) in a certified reference water sample, as well as real river, lake, and tap water samples.

[Effect of brain-derived neurotrophic factor gene transfected bone-marrow mesenchymal stem cells on damaged cochlear spiral ganglion cells of guinea pigs].

OBJECTIVE: To investigate the protective role of brain-derived neurotrophic factor (BDNF) gene transfected bone-marrow mesenchymal stem cells (BMSC) on cochlear spiral ganglion cells (SGC) impaired by aminoglycoside antibiotics (AmAn). METHODS: The differentiation of BMSC transfected by BDNF gene (BDNF-BMSC) were detected with immunohistochemical examination of Nestin, neuron-specific enolase (NSE), and glial fibrillary acid protein (GFAP) antibody in vitro. BDNF gene transfected BMSC were transplanted into the cochleae of guinea pigs deafened by amikacin, while the control groups were designed in which artificial perilymphatic fluid (APF), BMSC or BDNF gene was injected into cochleae alone. The cochleae were obtained on the week 1, 2 and 4 after injection, respectively, paraffin-embedded, and cut in a paramodiolar plane subsequently. The histopathological changes of cochleae were observed, the density of SGC was calculated by staining with HE, and the corresponding optical density (COD) was calculated with immunohistochemical staining using NSE antibody. And the protective role of various groups on the cochlear SGC were compared. RESULTS: The positive staining rate of BDNF gene transfected BMSC with Nestin, NSE and GFAP antibody were all higher than that of BMSC in vitro (P < 0.01). After transplantation into cochleae, the differences of SGC density and COD among various groups were all significant on the same time points (P < 0.05). The SGC density and COD of the BDNF gene transfected BMSC group were the highest. The SGC density and COD of various groups on week 4 were all obviously decreased than those on week 1 and 2 (P < 0.05). CONCLUSION: AmAn-induced SGC damage could be depressed by BMSC, BDNF gene or BDNF gene transfected BMSC transplantation into cochleae, while BDNF gene transfected BMSC showed the best protective role.

[Expression of brain-derived neurotrophic factor modified bone marrow mesenchymal stem cells in the cochlea of drug deafened guinea pigs and its protection role].

OBJECTIVE: To study the expression of brain-derived neurotrophic factor (BDNF) gene modified bone marrow mesenchymal stem cells (MSC) in the cochlea of drug-deafened guinea pigs and its protection to spiral ganglion cells (SGC). METHODS: Guinea pigs deafened by subcutaneous injection of amikacin were randomly divided into two groups, BDNF gene modified bone marrow MSC were injected into the cochlea through fenestration of scala tympani in the experimental group, while artificial perilymphatic fluid were injected in the control group. Experimental animals were executed at 7 and 28 days post-operation. Expression of BDNF mRNA was examined by quantitate real time RT-PCR, histological images of cochlear sections were analyzed to calculate the cellular density of the SGC, and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) was used to identify the apoptotic neurons. RESULTS: The BDNF expressive level in experimental group was higher than in the control group at 7 d and 28 d post-operation, whose differences were both statistically significant (P < 0.01). And, It showed a higher abundance of ganglion cell numbers, as well as a decreased apoptotic index in experimental group compared with the control group at 7 d and 28 d post-operation, whose differences were all statistically significant (P < 0.01). CONCLUSION: BDNF gene modified MSC could maintain expression for at least 28 days after transplantation into cochlea of drug deafened guinea pigs, and protect SGC.

Visual and colorimetric detection of Hg(2+) by cloud point extraction with functionalized gold nanoparticles as a probe.

Association with Hg(2+) enhances the hydrophobicity and triggers the cloud point extraction of approximately 4 nm-diameter gold nanoparticle probes functionalized with mercaptopropionic acid and homocystine, which results in the color change of the TX-114-rich phase from colorless to red, and therefore provides a novel approach for visual and colorimetric detection of Hg(2+) with ultrahigh sensitivity and selectivity.