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1.
Water Sci Technol ; 87(6): 1465-1495, 2023 Mar.
Article in English | MEDLINE | ID: mdl-37001160

ABSTRACT

Although spinel ferrite (MFe2O4, M = Zn, Ni, Mn, etc.) has been reported as a promising catalyst, its low photocatalytic activity under visible light greatly restricts its practical application. Spinel ferrite-based photocatalytic composites have exhibited improved efficiency for pollutant degradation, due to interface charge carrier mobility and structural modification. Meanwhile, due to its magnetism and stability, spinel ferrite composite can be easily recycled for long-term utilization, showing its high application potential. In this review, the recent advances in the construction and photocatalytic degradation of spinel ferrite composites are discussed, with an emphasis on the relationship between structural property and photocatalytic activity. In addition, to improve their photocatalytic application, the challenges, gaps and future research prospects are proposed.


Subject(s)
Aluminum Oxide , Environmental Pollutants , Light
2.
Ultrason Sonochem ; 92: 106265, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36527763

ABSTRACT

Hybrid methods with an enhanced oxidation capacity have been proposed for the removal of organic contaminants based on combining hydrodynamic cavitation (HC) with advanced oxidation processes (AOPs). In this study, we utilize the synergetic effect between photocatalytic processes and HC to strengthen ciprofloxacin (CIP) degradation by P-doped TiO2 catalysts. In comparison to a degradation ratio of 20.37 % in HC and 55.7 % in P-TiO2-based photocatalytic processes alone, the CIP degradation ratio reached as high as 90.63 % in HC-assisted photocatalytic processes with the optimal experimental parameters. The mechanic microjets treatment originated from HC make P-TiO2 nano photocatalysts with significantly increased surface area, smaller particle sizes, cleaner surface and improved dispersion, which were found using SEM, TEM, and BET analysis. Possible degradation mechanisms and reaction pathways of CIP during hybrid HC + photocatalytic processes were explored by coupling free radical capture experiments and liquid chromatography-mass spectrometry . This hybrid HC + photocatalytic technique has a potential application in the treatment of antibiotic sewage at the industrial level.


Subject(s)
Ciprofloxacin , Hydrodynamics , Ciprofloxacin/analysis , Ciprofloxacin/chemistry , Anti-Bacterial Agents/chemistry , Titanium/chemistry , Catalysis
3.
Bioresour Technol ; 360: 127627, 2022 Sep.
Article in English | MEDLINE | ID: mdl-35850389

ABSTRACT

The work aimed to explore effects of polytetrafluoroethylene nanoplastics on joint inhibitions of ciprofloxacin and bivalent copper on the nitrogen removal in a sequencing batch reactor and its potential mechanisms. The addition of bivalent copper and/or ciprofloxacin reduced the ammonia nitrogen elimination rate with or without polytetrafluoroethylene nanoplastics. Adsorption kinetics and thermodynamics showed the binary bivalent copper and ciprofloxacin promoted their adsorptions by polytetrafluoroethylene nanoplastics. Polytetrafluoroethylene nanoplastics enhanced combined toxicities of ciprofloxacin and bivalent copper to sludge activities and microbial community involved into nitrification and denitrification due to the adsorption of ciprofloxacin and bivalent copper by polytetrafluoroethylene nanoplastics. With or without polytetrafluoroethylene nanoplastics, bivalent copper and/or ciprofloxacin caused more obvious level changes of protein than polysaccharide. This study provides novel insights for understanding the effect of combined heavy metals and antibiotics on the performance in a sequencing batch reactor with the nanoplastics stress.


Subject(s)
Microbiota , Sewage , Bioreactors , Ciprofloxacin/pharmacology , Copper/pharmacology , Denitrification , Microplastics , Nitrification , Nitrogen/metabolism , Polytetrafluoroethylene/pharmacology
4.
Sci Total Environ ; 847: 157449, 2022 Nov 15.
Article in English | MEDLINE | ID: mdl-35863564

ABSTRACT

Nature reserves (NRs) are designated as a result of the ecosystem, species, economy, population, and land use coordination. However, the extent to which these factors influence the geographical pattern of NRs is unclear. Here, 11 indices (seven natural and four anthropogenic) were examined to identify these relationships in over 2600 terrestrial NRs in mainland China at the provincial level. Correlation analysis between natural and anthropogenic factors and NRs showed that desert and grassland had a positive correlation with NR coverage and area, and a negative correlation with NR density. This result was reversed in the correlation analysis between forest wetland coverage, endangered species, wildlife and NR coverage, area, and density. Similar results were found in the correlation analysis of all anthropogenic factors (population density, agricultural land, roads, and per capita GDP) with the coverage, area, and density of NRs. Canonical correspondence analysis (CCA) showed that three significant natural indicators (desert ecosystems, grasslands ecosystems, and forested and wetlands ecosystems) could explain 64.2 % of the pattern of NRs. The largest contributor was desert coverage, explaining 48.3 % (P = 0.002) of all indicators, followed by grassland coverage, explaining 8.6 % (P = 0.012), and forest and wetland coverage, explaining 7.3 % (P = 0.008). Human activities were significantly positively correlated with forest and wetland coverage, flora, and fauna, and negatively correlated with desert and grassland coverage. Compared with sand and grassland in the western region, the forest wetlands and wildlife in the eastern and central provinces were under greater pressure from anthropogenic activities. Therefore, natural factors determine the general layout of NRs, while the influence of anthropogenic activities makes the distribution of NRs patchy. When establishing national parks, governments must design strategies to coordinate areas with high biodiversity and high levels of human activity.


Subject(s)
Conservation of Natural Resources , Ecosystem , Animals , Animals, Wild , Anthropogenic Effects , Biodiversity , China , Conservation of Natural Resources/methods , Grassland , Humans , Sand
5.
Environ Pollut ; 306: 119424, 2022 Aug 01.
Article in English | MEDLINE | ID: mdl-35537554

ABSTRACT

Ground-based Multi-Axis Differential Optical Absorption Spectroscopy (Max-DOAS) measurements of nitrogen dioxide (NO2) were continuously obtained from January to November 2019 in northeastern China (NEC). Seasonal variations in the mean NO2 vertical column densities (VCDs) were apparent, with a maximum of 2.9 × 1016 molecules cm-2 in the winter due to enhanced NO2 emissions from coal-fired winter heating, a longer photochemical lifetime and atmospheric transport. Daily maximum and minimum NO2 VCDs were observed, independent of the season, at around 11:00 and 13:00 local time, respectively, and the most obvious increases and decreases occurred in the winter and autumn, respectively. The mean diurnal NO2 VCDs at 11:00 increased to at 08:00 by 1.6, 5.8, and 6.7 × 1015 molecules cm-2 in the summer, autumn and winter, respectively, due to increased NO2 emissions, and then decreased by 2.8, 4.2, and 5.1 × 1015 molecules cm-2 at 13:00 in the spring, summer, and autumn, respectively. This was due to strong solar radiation and increased planetary boundary layer height. There was no obvious weekend effect, and the NO2 VCDs only decreased by about 10% on the weekends. We evaluated the contributions of emissions and transport in the different seasons to the NO2 VCDs using a generalized additive model, where the contributions of local emissions to the total in the spring, summer, autumn, and winter were 89 ± 12%, 92 ± 11%, 86 ± 12%, and 72 ± 16%, respectively. The contribution of regional transport reached 26% in the winter, and this high contribution value was mainly correlated with the northeast wind, which was due to the transport channel of air pollutants along the Changbai Mountains in NEC. The NO2/SO2 ratio was used to identify NO2 from industrial sources and vehicle exhaust. The contribution of industrial NO2 VCD sources was >66.3 ± 16% in Shenyang due to the large amount of coal combustion from heavy industrial activity, which emitted large amounts of NO2. Our results suggest that air quality management in Shenyang should consider reductions in local NO2 emissions from industrial sources along with regional cooperative control.


Subject(s)
Air Pollutants , Nitrogen Dioxide , Air Pollutants/analysis , China , Coal/analysis , Environmental Monitoring/methods , Nitrogen Dioxide/analysis , Seasons
7.
Environ Int ; 160: 107048, 2022 02.
Article in English | MEDLINE | ID: mdl-34959197

ABSTRACT

In this study, tropospheric formaldehyde (HCHO) vertical column densities (VCDs) were measured using multi-axis differential optical absorption spectroscopy (MAX-DOAS) from January to November 2019 in Shenyang, Northeast China. The maximum HCHO VCD value appeared in the summer (1.74 × 1016 molec/cm2), due to increased photo-oxidation of volatile organic compounds (VOCs). HCHO concentrations increased from 08:00 and peaked near 13:00, which was mainly attributed to the increased release of isoprene from plants and enhanced photolysis at noon. The HCHO VCDs observed by MAX-DOAS and OMI have a good correlation coefficient (R) of 0.78, and the contributions from primary and secondary HCHO sources were distinguished by the multi-linear regression model. The anthropogenic emissions showed unobvious seasonal variations, and the primary HCHO was relatively stable in Shenyang. Secondary HCHO contributed 82.62%, 83.90%, 78.90%, and 41.53% to the total measured ambient HCHO during the winter, spring, summer, and autumn, respectively. We also found a good correlation (R = 0.78) between enhanced vegetation index (EVI) and HCHO VCDs, indicating that the oxidation of biogenic volatile organic compounds (BVOCs) was the main source of HCHO. The ratio of secondary HCHO to nitrogen dioxide (NO2) was used as the tracer to analyze O3-NOx-VOC sensitivities. We found that the VOC-limited, VOC-NOx-limited, and NOx-limited regimes made up 93.67%, 6.23%, 0.11% of the overall measurements, respectively. In addition, summertime ozone (O3) sensitivity changed from VOC-limited in the morning to VOC-NOx-limited in the afternoon. Therefore, this study offers information on HCHO sources and corresponding O3 production sensitivities to support strategic management decisions.


Subject(s)
Air Pollutants , Ozone , Volatile Organic Compounds , Air Pollutants/analysis , China , Environmental Monitoring/methods , Nitrogen Dioxide/analysis , Ozone/analysis , Spectrum Analysis , Volatile Organic Compounds/analysis
9.
Sci Total Environ ; 763: 142960, 2021 04 01.
Article in English | MEDLINE | ID: mdl-33109374

ABSTRACT

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editors-in-Chief. Jun Wang and Youtao Song are listed as authors on the manuscript but have informed the journal that this occurred without their consent or knowledge of the submission and the email addresses provided were fake. Jun Wang and Youtao Song do not support the scientific conclusions of the article. Qiong Wu and Yan Chen furthermore note significant scientific errors with the article (including the wrong deconvolution method used for analysis of the XPS data, misuse of some characterization images and inability to reproduce some of the photodegradation data). One of the conditions of submission of a paper for publication is that all authors must be aware of and agree with its submission. As such this article represents a misuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.


Subject(s)
Diatomaceous Earth , Ibuprofen , Catalysis , Light , Plastics , Titanium
10.
Bioresour Technol ; 314: 123769, 2020 Oct.
Article in English | MEDLINE | ID: mdl-32623283

ABSTRACT

The responses of nitrification and denitrification to the divalent zinc (Zn(II)) and tetracycline (TC) co-selective pressure were evaluated in a sequencing batch reactor (SBR). The removal rates of organics and nitrogen, nitrifying and denitrifying enzymatic activity, and microbial diversity and richness at the Zn(II) and TC co-selective pressure were higher than those at the alone Zn(II) selective pressure, while were lower than those at the individual TC selective pressure. The Zn(II) and TC co-selective pressure induced the TC resistance genes abundance increase and the Zn(II) resistance genes levels decrease, and enhanced bacterial enzymatic modification resistance to TC and bacterial outer membrane resistance to Zn(II). The network analysis showed that the genera Nitrospira and Nitrosomonas of nitrifiers and the genera Ferruginibacter, Dechloromonas, Acidovorax, Rhodobacter, Thauera, Cloacibacterium, Zoogloea and Flavobacterium of denitrifiers were the potential hosts of antibiotics resistance genes (ARGs) and/or heavy metals resistance genes (HMRGs).


Subject(s)
Denitrification , Nitrification , Anti-Bacterial Agents , Bioreactors , Nitrogen/analysis , Wastewater , Zinc
11.
Theranostics ; 10(2): 898-909, 2020.
Article in English | MEDLINE | ID: mdl-31903158

ABSTRACT

Gene promoter hypermethylation is a vital step in tumorigenesis. This paper set out to explore the use of polymerase chain reaction - surface-enhanced Raman spectroscopy (PCR-SERS) for the detection of gene methylation levels, with a focus on cancer diagnosis. Methods: PCR with methylation independent primers were used on DNA samples to amplify target genes regardless of their methylation states. SERS was used on the obtained PCR products to generate spectra that contained peak changes belonging to CG and AT base pairs. Multiple linear regression (MLR) was then used to deconvolute the SERS spectra so that the CG/AT ratios of the sample could be obtained. These MLR results were used to calculate methylation levels of the target genes. For protocol verification, three sets of seven reference DNA solutions with known methylation levels (0%, 1%, 5%, 25%, 50%, 75%, and 100%) were analysed. Clinically, blood plasma samples were taken from 48 non-small-cell lung cancer (NSCLC) patients and 51 healthy controls. The methylation levels of the genes p16, MGMT, and RASSF1 were determined for each patient using this method. Results: Verification experiment on the mixtures with known methylation levels resulted in an error of less than 6% from the actual levels. When applied to our clinical samples, the frequency of methylation in at least one of the three target genes among the NSCLC patients was 87.5%, but this percentage decreased to 11.8% for the control group. The methylation levels of p16 were found to be significantly higher in NSCLC patients with more pack-years smoked (p=0.04), later cancer stages (p=0.03), and cancer types of squamous cell and large cell versus adenocarcinoma (p=0.03). Prediction accuracy of 88% was achieved from classification and regression trees (CART) based on methylation levels and states, respectively. Conclusion: This research showed that the PCR-SERS protocol could quantitatively measure the methylation levels of genes in plasma. The methylation levels of the genes p16, MGMT, and RASSF1 were higher in NSCLC patients than in controls.


Subject(s)
Biomarkers, Tumor/genetics , Carcinoma, Non-Small-Cell Lung/genetics , DNA Methylation , Lung Neoplasms/genetics , Plasma/chemistry , Polymerase Chain Reaction/methods , Spectrum Analysis, Raman/methods , Adult , Aged , Carcinoma, Non-Small-Cell Lung/blood , Carcinoma, Non-Small-Cell Lung/pathology , Case-Control Studies , Female , Healthy Volunteers , Humans , Lung Neoplasms/blood , Lung Neoplasms/pathology , Male , Middle Aged , Neoplasm Grading , Predictive Value of Tests , Promoter Regions, Genetic , Smokers/statistics & numerical data
12.
RSC Adv ; 10(29): 17163-17170, 2020 Apr 29.
Article in English | MEDLINE | ID: mdl-35521450

ABSTRACT

Three-dimensional electrodes serve as more efficient cathodes for the in situ generation of H2O2 in microbial fuel cells (MFCs) than two-dimensional electrodes and possess significant electric potentials in the advanced oxidation of organics. In this study, we investigated the performance of a three-dimensional MFC-Fenton system in degrading p-nitrophenol (PNP) in an aqueous solution with the objective of optimizing the operating parameters, including the initial pH, iron dosage, and loading resistance. A corresponding reaction pathway for PNP in the system was also proposed. The results showed that the three-dimensional electrode bioelectrochemical system efficiently oxidized PNP and removed total organic carbon over a short period (64 h). In addition, experiments showed that a lower initial pH enhanced the removal of PNP by the system. The highest removal efficiency of PNP was achieved with an initial iron concentration of 0.025 mol L-1, and a lower or higher iron concentration resulted in decreased PNP degradation. Furthermore, the treatment capacity of the system was remarkably enhanced at a low loading resistance of 20 Ω. Under optimal conditions, the three-dimensional MFC-Fenton system achieved 95.7% PNP removal (within 8 h). Furthermore, the system showed a stable high treatment efficiency of approximately 90% for low PNP concentrations in wastewater over as long as 96 h.

13.
Ultrason Sonochem ; 60: 104806, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31563794

ABSTRACT

In this paper, a novel method, hydrodynamic cavitation (HC) combined with Fe3+-doped TiO2, for the degradation of organic pollutants in aqueous solution is reported. The venturi tubes with different geometric parameters (size, shape and half divergent angle) are designed to obtain a strong HC effect. The structure, morphology and chemical composition of prepared Fe3+-doped TiO2 as catalyst are characterized via using XRD, SEM, TEM, XPS, UV-vis DRS and PL methods. The effects of added TiO2 (heat-treated at different temperatures for different times) and Fe3+-doped TiO2 (with different mole ratios of Fe and Ti) on the HC catalytic degradation of RhB are discussed. The influences of operation parameters including inlet pressure, initial RhB concentration and operating temperature on the HC catalytic degradation of RhB are studied by Box-Behnken design (BBD) and response surface methodology (RSM). Under 3.0 bar inlet pressure for 10 mg/L initial concentration of RhB solution at 40 °C operating temperature in the presence of Fe3+-doped TiO2 with 0.05:1.00 M ratio of Fe and Ti, the best HC degradation ratio can be obtained (91.11%). Furthermore, a possible mechanism of HC degradation of organic pollutants in the presence of Fe3+-doped TiO2 is proposed. Perhaps, this study may provide a feasible method for a large-scale treatment of dye wastewater.

14.
Sci Total Environ ; 689: 178-192, 2019 Nov 01.
Article in English | MEDLINE | ID: mdl-31279185

ABSTRACT

In this work, a novel Z-scheme sonocatalyst, KTaO3/FeVO4/Bi2O3, is prepared via ultrasonic-assisted isoelectric point method. The prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. The catalytic activity of Z-scheme KTaO3/FeVO4/Bi2O3 sonocatalyst is studied in degradation of ceftriaxone sodium under ultrasonic irradiation. In addition, the influences of ultrasonic irradiation time, scavengers and sonocatalyst used times on sonocatalytic degradation of ceftriaxone sodium are examined. Under the experimental conditions of 150 min ultrasonic irradiation time, 1.00 g/L KTaO3/FeVO4/Bi2O3 addition amount and 10.00 mg/L ceftriaxone sodium concentration, the sonocatalytic degradation ratio of ceftriaxone sodium achieves 81.30%. Finally, the possible sonocatalytic degradation mechanism of ceftriaxone sodium caused by Z-scheme KTaO3/FeVO4/Bi2O3 sonocatalyst is proposed. The enhanced sonocatalytic activity may be attributed to the fact that the FeVO4 as a special conductive channel provides a strong driving force to transfer electrons through valence state changes of iron and vanadium, which accelerates electron transfer from conduction band (CB) of Bi2O3 to valence band (VB) of KTaO3. Perhaps, the KTaO3/FeVO4/Bi2O3 composite is an excellent Z-scheme sonocatalyst which can be used to effectively degrade the organic pollutants in wastewater under ultrasonic irradiation.

15.
Environ Sci Pollut Res Int ; 26(26): 26593-26604, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31292873

ABSTRACT

The development of powdery photocatalyst has long been studied, yet the low recovery in water is still its bottleneck. In this work, magnetic recyclable lanthanum-doped TiO2/copper ferrite/diatomite (La-TCD) ternary composite was synthesized via sol-gel method. The physicochemical properties of various hybrid catalysts were characterized and studied, and their photocatalytic properties were evaluated via the decomposition of antibiotic oxytetracycline and disinfection of bacteria Escherichia coli under visible light. The formation of heterojunction between La-doped TiO2 and copper ferrite hindered the recombination of photo-induced charge carriers and improved the photocatalytic activity. The photodecomposition rate of OTC was accelerated by the high adsorption ability of diatomite, due to the adsorption and decomposition synergistic effect between catalysts and substrate diatomite. The optimal La dopant amount as well as optimal catalyst dosage was determined. The composite could simply be recovered from waterbody via an external magnet, and the repetition tests indicated no obvious decrease of photoactivity. This nanocomposite presented good potential to be applied in environmental remediation process, due to its high photocatalytic efficiency under visible light, as well as its good reusability and stability.


Subject(s)
Anti-Bacterial Agents/chemistry , Copper/chemistry , Diatomaceous Earth/chemistry , Environmental Restoration and Remediation , Escherichia coli/radiation effects , Ferric Compounds/chemistry , Oxytetracycline/chemistry , Titanium/chemistry , Adsorption , Catalysis , Disinfection/methods , Lanthanum , Light , Magnetics , Nanocomposites/chemistry
16.
J Am Chem Soc ; 141(16): 6527-6536, 2019 04 24.
Article in English | MEDLINE | ID: mdl-30938994

ABSTRACT

Rhodamine derivatives and analogues have been widely used for different super-resolution imaging techniques, including photoactivated localization microscopy (PALM). Among them, rhodamine spirolactams exhibit great superiority for PALM imaging due to a desirable bright-dark contrast during the photochromic switching process. Although considerable attention has been paid to the chemical modifications on rhodamine spirolactams, the on-time of photochromic switching, one of the key characteristics for PALM imaging, has never been optimized in previous developments. In this study, we proposed that simply installing a carboxyl group close to the lactam site could impose an intramolecular acidic environment, stabilize the photoactivated zwitterionic structure, and thus effectively increase the on-time. On the basis of this idea, we have synthesized a new rhodamine spirolactam, Rh-Gly, that demonstrated considerably longer on-time than the other tested analogues, as well as an enhancement of single-molecule brightness, an improvement on signal-to-noise ratio and an enlargement of total collected photons of a single molecule before photobleaching. Finally, super-resolution images of live cell mitochondria stained with Rh-Gly have been obtained with a good temporal resolution of 10 s, as well as a satisfactory localization precision of ∼25 nm. Through self-labeling protein tags, Rh-Gly modified with a HaloTag ligand enabled super-resolution imaging of histone H2B proteins in live HeLa cells; through immunostaining antibodies labeled with an isothiocyanate-substituted Rh-Gly, super-resolution imaging of microtubules was achieved in fixed cells. Therefore, our simple and effective strategy provides novel insight for developing further enhanced rhodamine spirolactams recommendable for PALM imaging.

17.
Sci Total Environ ; 663: 97-109, 2019 May 01.
Article in English | MEDLINE | ID: mdl-30710788

ABSTRACT

The coated Z-scheme Pd-BaZrO3@WO3 composite as a new-type sonocatalyst with highly sonocatalytic performance is first constructed through sol-gel and hydro-thermal synthesis methods. The chemical configuration, structure and component are characterized by a series of characterization methods. The sonocatalytic degradation of diazinon as a model pollutant is studied to estimate the sonocatalytic performance of coated Z-scheme Pd-BaZrO3@WO3 composite. Some affecting factors such as Pd-BaZrO3 and WO3 mass proportions, ultrasonic (US) irradiation time, reusability and catalyst dosage are researched in detail through UV-vis spectra and gas chromatography (GC). The produced intermediates are detected in the degradation process of diazinon by using gas chromatography-mass spectrometer (GC-MS). The possible reaction mechanism of coated Z-scheme Pd-BaZrO3@WO3 sonocatalyst in sonocatalytic degradation process is also explored. Subsequently, the hydroxyl radicals (OH) and holes (h+) are discriminated to further elaborate the possible sonocatalytic mechanism. The experimental results manifest that the coated Z-scheme Pd-BaZrO3@WO3 sonocatalyst displays a preeminent sonocatalytic performance under ultrasonic irradiation because it can efficaciously suppress recombination of electrons (e-) and holes (h+), extend light response scope and provide almost 100% oxidization surface. In addition, the introduced palladium (Pd) nanorods connecting BaZrO3 and WO3 can expedite e- transfer. Under optimal conditions, the most of diazinon molecules can be disintegrated in the existence of the coated Z-scheme Pd-BaZrO3@WO3 under ultrasonic irradiation for 150 min. This study provides a feasible method for the treatment of environmental pollutions.

18.
Nano Lett ; 19(1): 8-18, 2019 01 09.
Article in English | MEDLINE | ID: mdl-30335394

ABSTRACT

The nanoparticle (nano)-cell membrane interface is one of the most important interactions determining the fate of nanoparticles (NPs), which can stimulate a series of biological events, allowing theranostic and other biomedical applications. So far, there remains a lack of knowledge about the mechanisms governing the nanoparticle-cell membrane interface, especially the impact of ligand exchange, in which molecules on the nanosurface become replaced with components of the cell membrane, resulting in unique interfacial phenomena. Herein, we describe a family of gold nanoparticles (AuNPs) of the same core size (∼13 nm core), modified with 12 different kinds of surface ligands, and the effects of their exchangeable ligands on both nanoparticle-supported lipid bilayers (SLBs) and nanoparticle-natural cell membrane interfaces. The ligands are categorized according to their molecular weight, charge, and bonding modes (physisorption or chemisorption). Importantly, we found that, depending on the adsorption affinity and size of ligand molecules, physisorbed ligands on the surface of NPs can be exchanged with lipid molecules. At a ligand exchange-dominated interface, the AuNPs typically aggregated into an ordered monolayer in the lipid bilayers, subsequently affecting cell membrane integrity, NP uptake efficiency, and the NP endocytosis pathways. These findings advance our understanding of the underlying mechanisms of the biological effects of nanoparticles from a new point of view and will aid in the design of novel, safe, and effective nanomaterials for biomedicine.


Subject(s)
Adsorption , Cell Membrane/chemistry , Lipid Bilayers/chemistry , Metal Nanoparticles/chemistry , Cell Membrane/drug effects , Endocytosis/genetics , Gold/chemistry , Ligands , Metal Nanoparticles/administration & dosage , Signal Transduction/drug effects , Surface Properties
19.
J Comput Aided Mol Des ; 32(11): 1217-1227, 2018 11.
Article in English | MEDLINE | ID: mdl-30392073

ABSTRACT

Genetics experiments have identified six mutations located in the subdomain IA (A17V, R23H, G32D, G32S, R34K, V372I) of Ssa1 that influence propagation of the yeast [PSI+] prion. However, the underlining molecular mechanisms of these mutations are still unclear. The six mutation sites are present in the IA subdomain of the nucleotide-binding domain (NBD). The ATPase subdomain IA is a critical mediator of inter-domain allostery in Hsp70 molecular chaperones, so the mutation and changes in this subdomain may influence the function of the substrate-binding domain. In addition, ADP release is a rate-limiting step of the ATPase cycle and dysregulation of the ATPase cycle influences the propagation of the yeast [PSI+] prion. In this work, steered molecular dynamics (SMD) simulations were performed to explore the interaction between ADP and NBD. Results suggest that during the SMD simulations, hydrophobic interactions are predominant and variations in the binding state of ADP within the mutants is a potential reason for in vivo effects on yeast [PSI+] prion propagation. Additionally, we identify the primary residues in the ATPase domain that directly constitute the main hydrophobic interaction network and directly influence the ADP interaction state with the NBD of Ssa1. Furthermore, this in silico analysis reaffirms the importance of previously experimentally-determined residues in the Hsp70 ATPase domain involved in ADP binding and also identifies new residues potentially involved in this process.


Subject(s)
Adenosine Diphosphate/chemistry , Adenosine Triphosphatases/chemistry , HSP70 Heat-Shock Proteins/chemistry , Molecular Dynamics Simulation , Saccharomyces cerevisiae Proteins/chemistry , Adenosine Triphosphatases/genetics , Binding Sites , Computer Simulation , HSP70 Heat-Shock Proteins/genetics , Mutation , Peptide Termination Factors/chemistry , Protein Binding , Protein Conformation , Protein Domains , Saccharomyces cerevisiae Proteins/genetics
20.
Biomed Opt Express ; 9(7): 3167-3176, 2018 Jul 01.
Article in English | MEDLINE | ID: mdl-29984090

ABSTRACT

Thalassemias are widely occurring genetic hemoglobin disorders; patients with severe thalassemia often require regular blood transfusions for survival. Prenatal detection of thalassemia is currently invasive and carries the risk of miscarriage and infection. A polymerase chain reaction (PCR)-based surface enhanced Raman spectroscopy (SERS) technique was investigated in this paper for the purpose of detecting prenatal α-thalassemia Southeast Asian (SEA) type deletion using maternal plasma. Couples with the same SEA thalassemia (-SEA/αα) were selected, and the quantification of SEA and wild type (WT) alleles in the maternal plasma sample predicted the fetal genotype. PCR was performed using two pairs of fluorescence tag-labeled primers to produce tag-labeled PCR products for both the SEA (labeled with R6G) and WT (labeled with Cy3) alleles. Then, the labeled PCR products containing the two fluorescence tags were measured by SERS. The ratios between the R6G and Cy3 tags were obtained using multiple linear regressions (MLR), and these ratios corresponded with the physical ratio of WT and SEA concentrations in maternal plasma. After verifying this technique on DNA mixtures with known SEA and WT ratios, the plasma from 24 pregnant women was screened. An accuracy of 91.7% was achieved for detecting the fetal genotypes of Hb Bart's, alpha-trait, and normal trait. The results indicated that the simple PCR-SERS method may be sensitive enough for use on cell free fetal DNA (cffDNA) in maternal plasma for non-invasive prenatal detection (NIPD).

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