Low Concentration Range Research Articles

Novel pyrazole‐biphenyl‐carboxamides for SARS‐CoV2 entry‐level restriction and microbial infections

AbstractMicrobial diseases including viral infection are big issues globally. Effective medicinal discovery for them is the need for the day. In this study, we report pyrazole‐biphenyl‐carboxamides (4a‐l) validated for their SARS‐CoV2 entry‐level restriction effect over studying the protein–protein interaction of SARS‐CoV2 with human ACE protein. Their extended antimicrobial properties were also evaluated. Online and offline software tools predicted MD simulation and ADMET druggability in silico. The antimicrobial efficacy of all compounds was also evaluated against Gram+ve Streptococcus pneumoniae (MTCC 1936), Staphylococcus aureus (MTCC 737) and Gram‐ve Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 424) (bacteria). In the results, compounds 4g and 4i were evenly active against both bacteria at a low concentration range (MIC: 1.00 to 9.5 μg/mL) and displayed lesser toxicity to tested mammalian cells (EC100 = 75 μg/mL). Furthermore, it was able to kill metabolically inactive bacterial cells and eradicate established biofilms of Methicillin‐resistant Staphylococcus aureus (MRSA). Both the compounds inhibited DNA gyrase well with an IC50 0.25 μM (96% relative activity) and 0.52 μM (97% relative activity) respectively. Compounds (4a‐l) showed restrictive efficiency of SARS‐CoV2 spike protein (SC2SP) and human angiotensin‐converting enzyme 2 (hACE2) entry‐level association in COVID‐19 in silico. To assess this ability, firstly, we identified the crucial amino acid residues involved in the interface of SARS‐CoV‐2 and hACE2 virtually. We recognized the ability of 4a‐l binding to the binding interface to SARS‐CoV2; thus, the interaction of SC2SP‐hACE2 was effectively inhibited.

Identification and evaluation of antiviral activity of novel compounds targeting SARS-CoV-2 virus by enzymatic and antiviral assays, and computational analysis

The viral genome of the SARS-CoV-2 coronavirus, the aetiologic agent of COVID-19, encodes structural, non-structural, and accessory proteins. Most of these components undergo rapid genetic variations, though to a lesser extent the essential viral proteases. Consequently, the protease and/or deubiquitinase activities of the cysteine proteases Mpro and PLpro became attractive targets for the design of antiviral agents. Here, we develop and evaluate new bis(benzylidene)cyclohexanones (BBC) and identify potential antiviral compounds. Three compounds were found to be effective in reducing the SARS-CoV-2 load, with EC50 values in the low micromolar concentration range. However, these compounds also exhibited inhibitory activity IC50 against PLpro at approximately 10-fold higher micromolar concentrations. Although originally developed as PLpro inhibitors, the comparison between IC50 and EC50 of BBC indicates that the mechanism of their in vitro antiviral activity is probably not directly related to inhibition of viral cysteine proteases. In conclusion, our study has identified new potential noncytotoxic antiviral compounds suitable for in vivo testing and further improvement.

Engineered DNA bonsai system for ultrasensitive wide-field determination and intracellular dynamic imaging of protein with tunable dynamic range and sensitivity

Herein, an engineered DNA bonsai system was assembled using DNA nanocube (DNC) as pot and a group of DNA recognition hairpins (RHpn, n = 1–5) as plants for ultrasensitive wide-field detection and dynamic intracellular imaging of matrix metalloproteinase-2 (MMP-2) with tunable dynamic range and sensitivity. Impressively, by changing the stem length of the RHpn (n = 1–5), the thermodynamic parameter free energy (△G) of RHpn was regulated to control the binding reaction between RHpn and output target (OT) (like changing the plants species of bonsai, Bonsai 4-RHpn, n = 1–5). When the △G of RHpn was low, the target detection in high concentration range could be achieved. Conversely, the target detection within the low concentration range also could be realized with the high △G of RHpn. Therefore, the developed biosensing platform based on the engineered DNA bonsai system could achieve the ultrasensitive wide-field determination of MMP-2 with 150000-fold tuned detection sensitivity. Meanwhile, by virtue of the spatial restriction effect of DNC to vary the loaded number and the local concentration of RHp1 (like changing the plants density of bonsai, Bonsai n-RHp1, n = 1–4), the kinetic property of the binding process between RHp1 and OT could be manipulated, in which a low substrate concentration leaded to a low reaction efficiency and a high local concentration resulted in a quick reaction rate with high collision probability. Moreover, the designed DNA bonsai system with the highest local concentration (Bonsai 4-RHp1) could achieve rapid detection of the target MMP-2, which easily conquered the main predicaments of dynamic detection methods: limited dynamic range and low detection efficiency. Most importantly, the programmable DNA bonsai system had been successfully applied in ultrasensitive and high-efficient dynamic visualization of protein MMP-2 in living cells, which could not only make it possible to quickly and precisely monitor disease related proteins with tiny changes at different concentration ranges, but also possess tremendous potential to provide high-precision disease information at different stages in disease diagnosis and prognosis monitoring.

Highly selective detection of 2,4-dinitrophenol by fluorescent NH2-MIL-125(Ti) via dual-parameter sensing technology.

The organic contaminant 2,4-dinitrophenol (2,4-DNP) is widely prevalent and poses significant risks to human health. Although numerous in-depth studies having been reported on the highly sensitive detection of 2,4-DNP, there are still challenges to its selective detection. Here, the fluorescence intensity ratio (I0/I) and emission peak shift (Δλ) were utilized for selective detection of 2,4-DNP by NH2-MIL-125(Ti). Notably, the emission peak of the NH2-MIL-125(Ti) suspension exhibited a remarkable red shift in the presence of 2,4-DNP (Δλ = 26 nm), accompanied by the blue shift or weak red shift of analogs, which provided a solid basis for selective detection of 2,4-DNP. Meanwhile, the I0/I ratio of the NH2-MIL-125(Ti) suspension exhibited a robust linear correlation with 2,4-DNP at the low concentration range (0-70 μM). The interaction of the analyte with NH2-MIL-125(Ti) was revealed to involve intermolecular charge transfer (ICT) and fluorescence resonance energy transfer (FRET) through XPS, FTIR, and UV-vis absorption spectroscopy. Additionally, we achieved the detection of 2,4-DNP using a smartphone by recognizing both the blue (B) values and the luminance (L) values. The obtained results demonstrated that the NH2-MIL-125(Ti) probe based on dual-parameter sensing technology exhibited excellent potential for selectively detecting 2,4-DNP in water environments, thereby offering significant prospects for its application in water quality assessment.

Enzyme-modified Pt nanoelectrodes for glutamate detection.

We present here a glutamate oxidase (GluOx)-modified platinum (Pt) nanoelectrode with a planar geometry for glutamate detection. The Pt nanoelectrode was characterized using electrochemistry and scanning electron microscopy (SEM). The radius of the Pt nanoelectrode measured using SEM is ∼210 nm. GluOx-modified Pt nanoelectrodes were generated by dip coating GluOx on the Pt nanoelectrode in a solution of 0.9% (wt%) bovine serum albumin (BSA), 0.126% (wt%) glutaraldehyde, and 100 U mL-1 GluOx. An increase in current was observed at +0.7 V vs. Ag/AgCl/1 M KCl with adding increasing concentrations of glutamate. Two-sample t-test results showed that there is a significant difference for current at +0.7 V between the blank and the added lowest glutamate concentration, as well as between adjacent glutamate concentrations, confirming that the increase in current is related to the increased glutamate concentration. The experimental current-concentration curve of glutamate detection fitted well to the theoretical Michaelis-Menten curve. At the low concentration range (50 μM to 200 μM), a linear relationship between the current and glutamate concentration was observed. The Michaelis-Menten constants of Imax and Km were calculated to be 1.093 pA and 0.227 mM, respectively. Biosensor efficiency (the ratio of glutamate sensitivity to H2O2 sensitivity) is calculated to be 57.9%. Enzact (Imax/H2O2 sensitivity, an indicator of the amount of enzyme loaded on the electrode) of the GluOx-modified Pt nanoelectrode is 0.243 mM. We further compared the sensitivity of a GluOx-modified Pt nanoelectrode with a GluOx-modified carbon fiber microelectrode (7 μm diameter and a sensing length of ∼350 μm). Glutamate detection on the GluOx-modified carbon fiber microelectrode fitted well to a Michaelis-Menten like response. Based on the fitting, the GluOx-modified carbon fiber microelectrode exhibited an Imax of 0.689 nA and a Km of 301.2 μM towards glutamate detection. The best linear range of glutamate detection on the GluOx-modified carbon fiber microelectrode is from 50 μM to 150 μM glutamate. The GluOx-modified carbon fiber microelectrode exhibited a higher potential requirement for glutamate detection compared to the GluOx-modified Pt nanoelectrode.

Dioctylsulfosuccinate Functionalized NiAl-Layered Double Hydroxide for Sensitive Fenuron Electroanalysis Using a Carbon Paste Electrode.

Environmental pollution resulting from the use of pesticides such as fenuron poses significant health risks due to the carcinogenic and teratogenic properties of these compounds. There is an urgent need to develop rapid and cost-effective detection methods for quantifying fenuron. In this study, an inorganic-organic composite material was obtained by intercalating sodium dioctylsulfosuccinate (DSS) within the interlayer space of a nickel-aluminum-layered double hydroxide (NiAl-LDH). The pristine and modified LDHs (NiAl-LDH) were characterized using Fourier transform infrared, X-ray diffraction, and thermogravimetric analysis, confirming the successful intercalation of DSS in the mineral structure. The modified LDH was used to elaborate a sensor for detecting fenuron herbicide via differential pulse voltammetry (DPV) employing a carbon paste electrode (CPE). The electrochemical procedure for fenuron analysis consisted of immersing the working electrode in an electrolytic solution containing the appropriate amount of fenuron, followed by voltammetry detection without any preconcentration step. Compared to CPE modified by pristine LDH, the peak current obtained on the organo-LDH-modified CPE was twice as high. The increase in the fenuron signal was attributed to the high organophilic feature of this composite material induced by DSS modification. To optimize the sensitivity of the organo-LDH modified electrode, the effects of several experimental parameters such as pH of the medium and proportion of the modifier in the paste on the stripping response were examined. Linear calibration curves were obtained for the fenuron concentrations ranging from 0.5 × 10-6 to 1 × 10-6 mol.L-1 and 1 × 10-6 to 5 × 10-6 mol.L-1. The limit of detection (LOD) calculated on the basis of a signal-to-noise ratio of 3 was found to be 1.8 × 10-8 mol.L-1 for the low concentration range with a limit of quantification (LOQ) which was 6 × 10-8 mol.L-1. Furthermore, the interference effect of several inorganic ions and other pesticides potentially affecting fenuron stripping was explored, and the method's applicability was confirmed by determining fenuron levels in a river sample taken from down-town Yaoundé.

Impact of gate electrode on free chlorine sensing performance in solution-gated graphene field-effect transistors.

Free chlorine is widely used to disinfect water used for drinking and food processing. This requires highly sensitive, simple, and capable continuous-measurement sensors to enable the concentration of free chlorine in water to be monitored and controlled. Free chlorine sensors based on solution-gated graphene field-effect transistors (GFETs) are a suitable platform for highly sensitive and continuous measurements. However, their sensing mechanisms require further elucidation to improve their performance. In this study, we focused on the gate electrode and investigated its influence on the sensing performance. Using the free chlorine sensor based on the solution-gate GFET, we showed that the Dirac point voltage in the transfer curve changed significantly as the free chlorine concentration changed, and the electric double-layer capacitance of the gate electrode decreased. Furthermore, we demonstrated that a solution-gated GFET using graphene or boron-doped diamond as the gate electrode could be used to detect changes in the free chlorine concentration in the concentration range of tap water. The sensing performance in the low concentration range benefits from the wide potential window of carbon-based electrodes, which do not have electrochemically active sites. Using these carbon-based materials as gate electrodes, GFETs have the potential to be used as durable sensors that are resistant to surface fouling and oxidation.

Rhodanine-based 4-(furan-2-yl)benzoic acids as inhibitors of xanthine oxidase

A series of rhodanine derivatives bearing 4-(furan-2-yl)benzoic acid moiety were synthesized and studied as inhibitors of xanthine oxidase. This enzyme is a known target for allopurinol and febuxostat used in the treatment of hyperuricemia, gout, and other diseases. The synthesized compounds with different substituents in position 3 of the rhodanine ring showed in vitro inhibitory activities towards xanthine oxidase in a low micromolar concentration range. The 4-(furan-2-yl)benzoic acid derivative with a fragment of N-unsubstituted rhodanine was found to have the lowest IC50 value which does not depend on the presence of albumin or Tween-80 under the assay conditions. According to kinetic data, the rhodanine-based 4-(furan-2-yl)benzoic acid was a mixed-type inhibitor with the same affinity for the free enzyme and the enzyme-substrate complex. Molecular docking and molecular dynamic studies were performed to elucidate the binding mode of this compound in the active site of xanthine oxidase

Ammonia Electrosynthesis from Nitrate Using a Ruthenium-Copper Cocatalyst System: A Full Concentration Range Study.

Electrochemical synthesis of ammonia via the nitrate reduction reaction (NO3RR) has been intensively researched as an alternative to the traditional Haber-Bosch process. Most research focuses on the low concentration range representative of the nitrate level in wastewater, leaving the high concentration range, which exists in nuclear and fertilizer wastes, unexplored. The use of a concentrated electrolyte (≥1 M) for higher rate production is hampered by poor hydrogen transfer kinetics. Herein, we demonstrate that a cocatalytic system of Ru/Cu2O catalyst enables NO3RR at 10.0 A in 1 M nitrate electrolyte in a 16 cm2 flow electrolyzer, with 100% faradaic efficiency toward ammonia. Detailed mechanistic studies by deuterium labeling and operando Fourier transform infrared (FTIR) spectroscopy allow us to probe the hydrogen transfer rate and intermediate species on Ru/Cu2O. Ab initio molecular dynamics (AIMD) simulations reveal that adsorbed hydroxide on Ru nanoparticles increases the density of the hydrogen-bonded water network near the Cu2O surface, which promotes the hydrogen transfer rate. Our work highlights the importance of engineering synergistic interactions in cocatalysts for addressing the kinetic bottleneck in electrosynthesis.

Electrochemically Obtained Poly(3,4-ethylenedioxythiophene) Layers for Electroanalytical Determination of Lipoic Acid

Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conducting polymer with intrinsic redox activity often used to facilitate electrooxidation reactions. PEDOT coatings with different thicknesses are obtained via electrochemical polymerization in the presence of either polysterensulfonate (PSS) or dodecylsulfate (SDS) anions. The electrooxidation of alfa lipoic acid (ALA) is studied depending on the thickness of the polymer coatings and the counterions used for their synthesis. The kinetics of ALA oxidation is found to differ for thin and thick PEDOT coatings with diffusion limitations observed for thin layers. For thick coatings, the rate-determining step varies from adsorption to diffusion depending on the ALA concentration. The type of counterion affects both the ALA oxidation peak currents and the peak potential. SDS-doped PEDOT coatings show a shift in the oxidation peak to positive potentials and higher ALA oxidation currents. The effect is commented in terms of a larger electroactive surface area and possible specific hydrophobic polymer/analyte interactions. For thin PEDOT coatings, the concentration dependence of the voltammetric peaks is linear in a wide concentration range (40 to 1000 µM), whereas the use of differential pulse voltammetry results in a linear response in a lower concentration range (8–200 µM) suitable for practical applications.

Adsorption/Desorption Performances of Simulated Radioactive Nuclide Cs+ on the Zeolite-Rich Geopolymer from the Hydrothermal Synthesis of Fly Ash

The operation of nuclear power plants generates a large amount of low- and intermediate-level radioactive waste liquid. Zeolite-rich geopolymers, which are synthesized under hydrothermal conditions from industrial waste fly ash, can effectively immobilize radioactive nuclides. In this study, the synthesis law of zeolite-rich geopolymers and the adsorption/desorption performances of radioactive nuclide Cs+ were researched using XRD, SEM and ICP. The results show that the increase in curing temperatures and NaOH concentrations leads to the transformation of Y-type zeolite to chabazite and cancrinite at low NaNO3 concentrations. However, at high NaNO3 concentrations, NaOH above 2 M has no obvious effect on the phase transformation of the main zeolite of chabazite and cancrinite. In the adsorption and desorption experiment of Cs+ on the chabazite/garronite-rich geopolymer, it was found that the adsorption of Cs+ in the low initial concentration range is more suitable for the Freundlich equation, while the Langmuir equation fits in the adsorption process at the high initial concentration range. Moreover, the desorption kinetics of Cs+ are in good agreement with the pseudo-second-order rate equation. Thus, the adsorption of Cs+ on chabazite/garronite-rich geopolymers is controlled by both physical and chemical reactions, while desorption is a chemical process.

Transcriptome-wide profiling of acute stress induced changes in ribosome occupancy level using external standards.

Acute cellular stress is known to induce a global reduction in mRNA translation through suppression of cap dependent translation. Selective translation in response to acute stress has been shown to play important roles in regulating the stress response. However, accurately profiling translational changes transcriptome-wide in response to acute cellular stress has been challenging. Commonly used data normalization methods operate on the assumption that any systematic shifts are experimental artifacts. Consequently, if applied to profiling acute cellular stress-induced mRNA translation changes, these methods are expected to produce biased estimates. To address this issue, we designed, produced, and evaluated a panel of 16 oligomers to serve as external standards for ribosome profiling studies. Using Sodium Arsenite treatment-induced oxidative stress in lymphoblastoid cell lines as a model system, we applied spike-in oligomers as external standards. We found our spike-in oligomers to display a strong linear correlation between the observed and the expected quantification, with small ratio compression at the lower concentration range. Using the expected fold changes constructed from spike-in controls, we found in our dataset that TMM normalization, a popular global scaling normalization approach, produced 87.5% false positives at a significant cutoff that is expected to produce only 10% false positive discoveries. In addition, TMM normalization produced a systematic shift of fold change by 3.25 fold. These results highlight the consequences of applying global scaling approaches to conditions that clearly violate their key assumptions. In contrast, we found RUVg normalization using spike-in oligomers as control genes recapitulated the expected stress induced global reduction of translation and resulted in little, if any, systematic shifts in the expected fold change. Our results clearly demonstrated the utility of our spike-in oligomers, both for constructing expected results as controls and for data normalization.

Synthesis of Novel Fluorescent Conjugated Polymers and Their Rapid Gas‐Phase Detection of Trace Nitro‐Explosives

AbstractFluorescent conjugated polymers are widely investigated for their excellent performance in detecting explosives. In this work, two simple monomers are used to synthesize two novel fluorescent conjugated polymers, 3 and 6, with different conjugated structures via the linkages of “single bond” and “alkyne bond” by coupling reaction, and the fluorescence sensing performance for 2,4,6‐trinitrotoluene (TNT) is verified in both liquid and gas phases, aiming to demonstrate the influence of two different linkages on the fluorescence sensing properties. The fluorescent intensities of conjugated polymers in organic solvents gradually increase with increasing concentration within the low concentration range, while too high concentration leads to a decrease in the emission intensity because of the concentration quenching effect. The liquid‐phase limit of detection of 3 and 6 for TNT is as low as 1.9 and 1.6 µm in acetonitrile, respectively. The change rule of UV–vis absorption indicates that the static quenching model of TNT is predominant in liquid phase. Using a commercial portable explosives detector, 3 and 6 can effectively achieve the selective detection of gas‐phase TNT above 15 ng within 7 s and 8 ng within 5 s, respectively, demonstrating the great potential for rapid on‐site detection of trace explosives.

Enhancing Soybean Yield: The Synergy of Sulfur and Rhizobia Inoculation.

Sulfur deficiency severely limits soybean growth, inhibiting the rhizobia nitrogenase and soybean protein synthesis. This study assessed the impact of sulfur fertilization and rhizobia inoculation on soybean growth and nitrogen fixation through bacterial culture and hydroponic experiments. We selected three rhizobia strains for bacterial cultures and used six sulfur levels. The test demonstrated severe inhibition of Rhizobium USDA110 growth without sulfur. In hydroponic experiment, we employed five sulfur levels with USDA110 as the inoculum strain. Soybean growth, nitrogen fixation, yield, and root morphology-related parameters, and root nodule growth, were significantly inhibited without sulfur. Following Rhizobium inoculation, low sulfur concentrations (0.15-0.60 mM) stimulated early-stage (V9) root growth and increased shoot nitrogen accumulation, but inhibited root growth at R5 stage. Furthermore, Rhizobium inoculation notably enhanced soybean growth, nitrogen fixation, and yield, especially within the recommended low sulfur concentration range (0.15-0.30 mM). The maximum nodule nitrogenase activity at R5 stage and highest yield was recorded at a 0.3 mM sulfur concentration with Rhizobium inoculation, which was 9.51-1222.07% higher than other treatments. These findings highlight that low sulfur concentration and rhizobia inoculation enhance soybean growth, nitrogen fixation, and yield but reduce soybean root efficacy, increasing reliance on root nodules.

Improvement of Water Vapor Permeability in Polypropylene Composite Films by the Synergy of Carbon Nanotubes and β-Nucleating Agents.

A notable application of polymeric nanocomposites is the design of water vapor permeable (WVP) membranes. "Breathable" membranes can be created by the incorporation of micro/nanofillers, such as CaCO3, that interrupt the continuity of the polymeric phase and when subjected to additional uniaxial or biaxial stretching this process leads to the formation of micro/nanoporous structures. Among the candidate nanofillers, carbon nanotubes (CNTs) have demonstrated excellent intrinsic WVP properties. In this study, chemically modified MWCNTs with oligo olefin-type groups (MWCNT-g-PP) are incorporated by melt processes into a PP matrix; a β-nucleating agent (β-ΝA) is also added. The crystallization behavior of the nanocomposite films is evaluated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The WVP performance of the films is assessed via the "wet" cup method. The nanohybrid systems, incorporating both MWCNT-g-PP and β-NA, exhibit enhanced WVP compared to films containing only MWCNT-g-PP or β-NA. This improvement can be attributed to the significant increase in the growth of α-type crystals taking place at the edges of the CNTs. This increased crystal growth exerts a form of stress on the metastable β-phase, thereby expanding the initial microporosity. In parallel, the coexistence of the inherently water vapor-permeable CNTs, further enhances the water vapor permeability reaching a specific water vapor transmission rate (Sp.WVTR) of 5500 μm.g/m2.day in the hybrid composite compared to 1000 μm.g/m2.day in neat PP. Notably, the functionalized MWCNT-g-PP used as nanofiller in the preparation of the "breathable" PP films demonstrated no noteworthy cytotoxicity levels within the low concentration range used, an important factor in terms of sustainability.

Green and sustainable synthesis of CaO nanoparticles: Its solicitation as a sensor material and electrochemical detection of urea

Urea is recognized as one of the most frequently used adulterants in milk to enhance artificial protein content, and whiteness. Drinking milk having high urea concentrations which causes innumerable health disputes like ulcers, indigestion, and kidney-related problems. Therefore, herein, a simple and rapid electroanalytical platform was developed to detect the presence of urea in milk using a modified electrode sensor. Calcium oxide nanoparticles (CaO NPs) were green synthesized and used as a catalyst material for developing the sensor. Synthesized materials formation was confirmed by different techniques like FTIR, UV–visible, XRD, SEM–EDX, and Raman spectroscopy. The carbon paste electrode (CPE) was modified using the CaO NPs and used as a working electrode during the analysis followed by cyclic voltammetry and differential pulse voltammetry (DPV) techniques. The fabricated calcium oxide modified carbon paste electrode (CaO/CPE) successfully detected the presence of urea in the lower concentration range (lower limit of detection (LLOD) = 0.032 µM) having a wide linear detection range of 10–150 µM. Adsorption-controlled electrode process was achieved at the scan rate variation parameter. The leading parameters like the selectivity, repeatability, and stability of the CaO/CPE were investigated. The relative standard deviation of sensor was ± 3.8% during the interference and stability study.

A novel calibration method for continuous airborne metal measurements: Implications for aerosol source apportionment

Continuous metal monitors have been widely used in environmental monitoring due to the high temporal resolution, high detection limit, and necessity for near real-time source apportionment. However, the reliability of the conventional calibration method, the deviation caused by uncalibrated monitoring data, and the subsequent impact on source identification results are rarely discussed. In this study, a reliable multi-point calibration approach by Primary Standard Aerosol Mass Concentration Calibration System (PAMAS) for the Xact625i Ambient Metals Monitor was developed and applied. The measured data was almost meaningless in the low-concentration range with bias even exceeding 100 % by using the conventional single-point calibration method based on thin-film standards. PAMAS was utilized to generate aerosols with known concentrations of the 20 metal elements including Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Sr, Cd, Sn, Sb, Ba, Tl, Pb, and Bi, in two concentration ranges of 150–1200 ng m−3 and 2.5–30 ng m−3 to validate the Xact625i Monitor. The results showed that the elemental concentrations were underestimated, especially in the low-concentration range, only for Cr, As, and Sr with slopes close to unity (1.00 ± 0.03). After calibration by PAMAS, the slopes of the linear relationships between measured and standard concentrations were all unity for the 19 elements in the high-concentration range, and close to unity for the 15 elements in the low-concentration range, and the accuracy of the remaining elements was also improved. After considering the calibration of aerosol metal data, it was found the number of source factors and their contributions to metals and PM2.5 in Chongming Dongtan, China, based on the PMF model significantly changed. This study highlighted the need of developing reliable calibration methods for online aerosol monitoring instruments and implied that the source apportionment results could be biased without careful data calibration.

Bioenergetic effects of pristine and ultraviolet-weathered polydisperse polyethylene terephthalate and polystyrene nanoplastics on human intestinal Caco-2 cells

The ubiquitous human exposure to nanoplastics (NPs) increasingly raises concerns regarding impact on our health. However, little is known on the biological effects of complex mixtures of weathered NPs with heterogenous size and irregular shape present in the environment. In this study, the bioenergetic effects of four such NPs mixtures on human intestinal Caco-2 cells were investigated. To this aim, Caco-2 cells were exposed to polydisperse nanoPET (<800 nm) and nanoPS (mixture of 100 and 750 nm) samples with and without ultraviolet (UV) weathering at low concentration range (102–107 particles/mL) for 48 h. Mitochondrial respiration, glycolytic functions and ATP production rates of exposed cells were measured by Seahorse XFe96 Analyzer. Among four NPs samples, polydisperse nanoPET with irregular shapes induced significant stimulation of mitochondrial respiration, glycolysis and ATP production rates in Caco-2 cells. Spherical nanoPS caused significant stimulation on glycolytic functions of Caco-2 cells at the highest concentration used (106 particles/mL). ATR-FTIR spectra and carbonyl index indicated formation of carbonyl groups in nanoPET and nanoPS after UV weathering. UV weathering could alleviate bioenergetic stress caused by NPs in Caco-2 cells and even shifted the energy pathways from mitochondrial respiration to glycolysis due to electrostatic repulsion between negatively charged UV-aged NPs and cell membranes. This research is the first to study in-vitro bioenergetic responses of NPs samples with multidimensional features (polymer type, irregular shape, heterogenous size, UV-weathering) on human health. It highlights that effects between pristine and weathered NPs are different at a bioenergetic level, which has important implications for the risk assessment of NPs on human health.

An in-vitro study on post-surgical breast wound healing activity by zinc oxide dots and its optimization using Box Behnken design

The development of effective treatments for post-surgical malignant wounds caused by recurrent breast cancer remains challenging. This study aimed to address this issue by creating a biocompatible fluorescent quantum dot using curcumin-loaded Zinc oxide bionanocomposite (Cur-ZnOBC). The ZnOBC was combined with neem essential oil-Aloe-vera gel complex to produce the nanoconjugate Cur-ZnOBC, which was then transformed into curcumin-based quantum dots (Cur-ZnOQDs) using a microwave-assisted method to enhance drug delivery function. The Box-Behnken design was used to optimize the concentration variables involved in the formation of Cur-ZnOQDs. The synthesized Cur-ZnOQDs were found to have low cytotoxicity to human breast cancer cells and exhibited wound healing activity in malignant wounds of breast cancer cells post-surgery. Cell death was noticed only at a concentration of 0.6 mg/mL, and the wound closure area increased from 22.3% to 44.2% at 48 h, which was 20 times greater than the control. Therefore, Cur-ZnOQDs at lower concentration range may act as bio-enhancers to improve outcomes associated with breast cancer and ultimately improve the survival rate.

CeO2-CePO4 and Ag@CeO2-CePO4 nanocomposites from Penaeus semisulcatus for heavy metals sensing, UV shielding and cytotoxic applications

CeO2-CePO4 and Ag@CeO2-CePO4 nanocomposites (NCs) were prepared using Penaeus semisulcatus and characterized by various analytical techniques. The NCs exhibited spherical morphology, with average particle sizes measuring 2.36 nm, 3.30 nm and 29.64 nm for the samples air dried, annealed at 550 °C and 800 °C respectively, and the Selected Area Electron Diffraction patterns from HR-TEM revealed their crystalline nature. In 3d X-ray Photoelectron Spectra (XPS) of NCs, the highest binding energies were observed at 916.46 eV (3d3/2) and 898.16 eV (3d5/2) with spin–orbit splitting of 18.3 eV. The X-Ray Diffraction (XRD) patterns of the NCs showed peaks typical of both CeO2 and CePO4 phases. The Fourier Transform-Infra Red (FT-IR) spectrum contained bands due to Ce-O stretching at 560 cm−1 and PO43- groups at 1008 and 711 cm−1, which was further substantiated by Raman spectrum, which had an intense peak at 468 cm−1 corresponding to F2g band of CeO2 and another peak at 976 cm−1 due to PO43- tetrahedron. In the Ultraviolet-Visible Diffuse Reflectance Spectra (UV-Vis DRS), the broad absorption peak at 352 nm and minor peaks around 300 nm confirmed the formation of CeO2-CePO4 NCs. The green synthesized NCs were excellent fluorescence sensors for Pb2+, Cd2+ and Hg2+ in a wide range of concentrations, from 5.0x10-9 M to 4.0x10-5 M. The concentration Vs. emission fitting plot had three distinctive linear ranges. At a low concentration range (5x10-9 to 3.5x10-7 M), the limit of detection for Pb2+, Cd2+ and Hg2+ was found to be 2.41x10-8, 2.56x10-8 and 3.11x10-8 M. The sensitive detection of a mixture of heavy metal ions in ppb levels by biocompatible NCs gained insight in treating aqueous industrial wastes. Further, NCs showed cytotoxicity and UV shielding properties.