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Measuring pH with an optical sensor requires the immobilization of a chemical recognition phase on a solid surface. Neutral red (NR), an acid base indicator was used to develop two different optical probe configurations. The chemistry of aryl diazonium salts was chosen for the elaboration of this chemical phase, as it enables strong covalent bonds to be established on the surface of metallized glass or metallic surfaces. It also allows the formation of a thick film required to obtain an exploitable spectral response. The surfaces of interest (metallized optical fiber and 316 L stainless-steel mirror) are modelized by flat surfaces (metallized glass plates and 316 L stainless-steel plates). The analytical characterizations carried out (IR, XPS, UV-Visible, and profilometry) show that NR was covalently grafted onto the model surfaces as well as on the surfaces of interest. The supports grafted with NR to develop optical pH probes exhibit spectral changes, particularly the values of pKa, the pH range, and the isosbestic point wavelength. The experimental results show that the optical probe can be used for pH measurements between 4 and 8. [ABSTRACT FROM AUTHOR]

Fresh meat and fish are widely consumed foods with short and very short shelf lives, respectively. Efficient supply chains and the judicious use of food packaging are the most effective means of extending shelf life and thus reducing food waste and improving food safety. Food packaging that allows for the use of a modified atmosphere (MAP) is effective in extending the period where the food is both palatable and safe. However, monitoring the state of aging and the onset of spoilage of the product poses challenges. Microbial counts, pH measurements, and sensory evaluations are all informative but destructive and are therefore only useful for monitoring quality via sampling. More attractive would be a technology that can follow the progress of ageing in an individual product while leaving the food packaging intact. Here, we present a pH indicator to be placed inside each package that may be read by the naked eye. It is a colorimetric indicator with a matrix made of pure amylose (AM; 99% linear α-glucans) and cellulose nanofibers (CNFs). Suitable mechanical properties of films cast of the two polysaccharides were achieved via the optimization of the blending ratio. The films were loaded with either of two pH indicators: anthocyanin extracts from red cabbage (RCA) and the synthetic dye neutral red (NR). Mechanical, thermal, permeability, microstructural, and physical properties were tested for all composite films. Films with 35% CNF (35AC-RCA) and (35AC-NR) were selected for further study. Minced meat was packaged under MAP conditions (70% O2 + 30% CO2), while minced fish was packaged under MAP (70% N2 + 30% CO2) and stored at 5 °C for 20 days. Microbial growth, pH, and sensory scores of the minced meat systems differentiated between fresh (0–6 days) and medium-fresh (7–10 days), and minced fish between fresh (0–10 days) and medium-fresh (11–20 days). The total color difference showed that the RCA indicator was able to differentiate between fresh (red) and medium-fresh (pink-red) minced meat, while for minced fish, this indicator discriminated between three stages: fresh (red), medium-fresh (pink-red), and spoiled (pink-blue). The NR indicator failed to discriminate the freshness of either meat or fish under the effect of MAP. Pearson correlation statistical models showed a correlation between color change of the indicator, pH, content of gases, and gas content. In summary, RCA immobilized in an AM + 35% CNF nanocomposite film can monitor the freshness of packaged minced meat/fish under the effect of MAP via color change that may be evaluated with the naked eye. [ABSTRACT FROM AUTHOR]

Background and Aim: Feline immunodeficiency virus (FIV) is a retroviral pathogen globally responsible for immunodeficiency disease in cats. However, the current diagnosis based on antibody detection has limitations and can also produce false-positive results. This study aimed to develop a one-pot loop-mediated isothermal amplification (LAMP) process integrated with neutral red (NR-LAMP) assay for detection of FIV proviral DNA. Materials and Methods: We developed a one-pot, gag gene-based NR-LAMP for convenient, rapid, specific, and sensitive colorimetric inspection of FIV proviral DNA. Results: The developed NR-LAMP was capable of amplifying at an optimum temperature of 65°C for 40 min. No cross-amplification was detected between FIV and other feline viruses tested, indicating the high specificity (98.44%) of the novel FIV-LAMP primer. Our NR-LAMP assay has a detection limit of 4.2 × 101 copies/μL. A total of 80 clinical samples with a background of FIV infection were collected and tested using the proposed method. The NR-LAMP assay showed a high sensitivity of 100% compared to conventional polymerase chain reaction assay. Conclusion: These results support the suitability of NR-LAMP as a potential future alternative clinical molecular approach for further use in the diagnosis of FIV-infected cats.

AbstractFor the first time, Neutral Red (NR) has been used as a redox probe for comparative evaluation of the electrochemical performance of screen-printed carbon electrodes (SPCEs) modified with bismuth under different potentiostatic pre-plating conditions (Bi/SPCEs). It was shown that protonated NR undergoes quasi-reversible redox transformations at bare-SPCE and Bi/SPCEs in the pH range 5–6 in phosphate buffer solutions (PBS) in the potential range of (−0.2)–(−0.8) V, where bismuth is not electroactive. Bi/SPCEs have been characterized morphologically by scanning electron microscopy (SEM) and electrochemically by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) employing NR as a redox probe. The obtained SEM, CV, and EIS data are in good agreement. The highest charge transfer resistance (Rct) values (3.9 and 3.3 kΩ) were obtained at bare-SPCE and Bi/SPCE having low degree of bismuth coverage. Contrarily, the lowest Rct value (8 Ω) was recorded at Bi/SPCE, with the highest degree of bismuth coverage. CV experiments showed a significant increase in the electrochemical performances of Bi/SPCEs, whose surface is half or more covered with bismuth, in comparison to the bare-SPCE. Nickel (II) ions and formaldehyde (FM), in the form of formaldehyde hydrazone (FAH), were used as model analytes to determine the electroanalytical performance of Bi/SPCEs. A comparison of roughness factor and sensitivity toward both analytes for Bi/SPCEs with two-tailed Pearson’s criterion showed a high degree of correlation between their electrochemical and electroanalytical characteristics. The data acquired indicates that the use of NR as a redox probe may be quite helpful to control modification processes when developing novel bismuth-containing sensors. [ABSTRACT FROM AUTHOR]

We report herein a method for investigating lysosome clearance function based on colorimetric analysis of neutral red (NR) that had accumulated in lysosomes of a neuroblastoma cell line. The NR in lysosome can be easily observed as red puncta under microscope and has a characteristic absorbance maximum at 525 nm. Clearance of NR from lysosomes can be monitored by observing red signal fading under a light microscope and can also be monitored by measuring its change in characteristic absorbance using a microplate reader. Clearance kinetics of NR in lysosomes were found to obey simplified one phase decay kinetics. By fitting the data, we were able to parameterize the rate constant (k) which was implemented in the lysosome clearance function. Notably, dys‐regulated lysosome induced by bafilomycin A1, had less k value, implying a lower lysosome clearance efficiency. Obviously, the cells with less k value were found to have been less capable of clearing amyloid beta out of the cells. These results substantiate that this method can be utilized as a new method for assessment of lysosome clearance function. [ABSTRACT FROM AUTHOR]

Background and Aim: Feline immunodeficiency virus (FIV) is a retroviral pathogen globally responsible for immunodeficiency disease in cats. However, the current diagnosis based on antibody detection has limitations and can also produce false-positive results. This study aimed to develop a one-pot loop-mediated isothermal amplification (LAMP) process integrated with neutral red (NR-LAMP) assay for detection of FIV proviral DNA. Materials and Methods: We developed a one-pot, gag gene-based NR-LAMP for convenient, rapid, specific, and sensitive colorimetric inspection of FIV proviral DNA. Results: The developed NR-LAMP was capable of amplifying at an optimum temperature of 65°C for 40 min. No crossamplification was detected between FIV and other feline viruses tested, indicating the high specificity (98.44%) of the novel FIV-LAMP primer. Our NR-LAMP assay has a detection limit of 4.2 × 101 copies/µL. A total of 80 clinical samples with a background of FIV infection were collected and tested using the proposed method. The NR-LAMP assay showed a high sensitivity of 100% compared to conventional polymerase chain reaction assay. Conclusion: These results support the suitability of NR-LAMP as a potential future alternative clinical molecular approach for further use in the diagnosis of FIV-infected cats. [ABSTRACT FROM AUTHOR]

This study compares the electrochemical performance of screen-printed carbon electrodes (SPCEs) modified with antimony (Sb/SPCEs) under different potentiostatic pre-plating conditions. Neutral Red (NR) was employed as a novel redox probe to evaluate the electrochemical performance of Sb/SPCEs. It was demonstrated that NR in the protonated form performs quasi-reversible redox transformations at bare SPCE and Sb/SPCEs in phosphate buffer solutions (pH 5.5±0.5) in the potential range of (−0.30)–(−0.75) V, where the antimony is not electroactive. Sb/SPCEs were studied electrochemically by cyclic voltammetry (CV) / electrochemical impedance spectroscopy (EIS), and morphologically by scanning electron microscopy (SEM). Cyclic voltammetry investigations revealed the dependence of the electrochemical performance of Sb/SPCEs on the degree of coverage of the substrate with the metal. The obtained CV, EIS, and SEM data are consistent. The lowest charge transfer resistance (Rct) value (6 Ω) was obtained at Sb/SPCE with the highest degree of antimony coverage. To investigate the electroanalytical performance of Sb/SPCEs, nickel (II) ions were utilized as a model analyte. A study of roughness factors and sensitivity towards nickel (II) ions for Sb/SPCEs using two-tailed Pearson's criterion revealed a high degree of correlation between their electrochemical and electroanalytical properties. The results show that using NR as a redox probe can help controlling modification processes during the development of innovative antimony-containing sensors.

Measuring pH with an optical sensor requires the immobilization of a chemical recognition phase on a solid surface. Neutral red (NR), an acid base indicator was used to develop two different optical probe configurations. The chemistry of aryl diazonium salts was chosen for the elaboration of this chemical phase, as it enables strong covalent bonds to be established on the surface of metallized glass or metallic surfaces. It also allows the formation of a thick film required to obtain an exploitable spectral response. The surfaces of interest (metallized optical fiber and 316 L stainless-steel mirror) are modelized by flat surfaces (metallized glass plates and 316 L stainless-steel plates). The analytical characterizations carried out (IR, XPS, UV-Visible, and profilometry) show that NR was covalently grafted onto the model surfaces as well as on the surfaces of interest. The supports grafted with NR to develop optical pH probes exhibit spectral changes, particularly the values of pKa, the pH range, and the isosbestic point wavelength. The experimental results show that the optical probe can be used for pH measurements between 4 and 8.

The use of spoilage indicator films has become widespread in food safety due to their ability to detect the freshness of food in real-time through color change. Here, a novel spoilage indicator film was prepared by combining polyvinyl alcohol (PVA)/cassava starch (CS) with neutral red (NR) as a pH-sensitive indicator. The microstructural properties of NR/PVA/CS film indicated that the addition of NR could greatly increase the compatibility of the membrane. The successful mixing of PVA, CS and NR was confirmed by Fourier transform infrared (FTIR). The film was attached to the upper layer of the inner package relying on the stickiness to avoid contacting with meat. Subsequently, the NR/PVA/CS film was successfully applied as a sticker indicator to monitor the spoilage of meat over time. Changes in color of the film from dark red to orange were observed by the naked eye, and quantified using the CIE color difference (ΔE). Finally, polynomial model between ΔE and TVB-N content in pork, mutton, and chicken during storage were successfully constructed with the coefficient of determination (R2) of 0.8286, 0.9426 and 0.9585, respectively. The results demonstrate the potential of the developed system to monitor the freshness of meat in food packaging. [ABSTRACT FROM AUTHOR]

Antimicrobial photodynamic therapy (aPDT) is a promising therapeutic strategy for treating bacterial infections resistant to conventional antibiotics. In the search for ideal photosensitizers (PSs), we became interested in phenazine compounds, such as Neutral Red (NR) and its halogenated derivative (NRBr). Although they have shown good results in the inactivation of Staphylococcus aureus in their free form, they have some undesirable properties that could be overcome by using drug delivery systems. In this work, we propose the use of polymeric micelles for the development of nanophotosensitizers from Pluronic P123 and F108. The micellar systems developed had a size close to 30–40 nm and allowed us to obtain seven nanophotosensitizers. All of them increased the chemical stability of NRBr and did not modify the stability of NR, which was already stable in buffer solution (pH = 7.4). Furthermore, the Pluronic micelles markedly decreased the aggregation of PSs and increased their photochemical reactivity. The nanophotosensitizers prepared from Pluronic P123 micelles (5% wt/vol) gave the best results and optimized the properties of NR and NRBr. In agreement with that, the new nanophotosensitizers of P123‐5% showed better photodynamic inactivation of NR and NRBr against methicillin resistant S. aureus than the free photosensitizers and the other micellar systems. Both photosensitizers loaded into the P123‐5% eradicated this microorganism using 30 min of irradiation. Therefore, it is concluded that these polymeric micelles are an excellent alternative for the vehiculization of PSs and that their combination with NR and NRBr enhances the photodynamic efficiency for their use in aPDT. [ABSTRACT FROM AUTHOR]

Neutral red (NR) and safranin-O (SO) dyes are used in industrial processes, which their inappropriate disposal in surface waters causes negative impacts. Alternative techniques have been investigated for the complete removal of dyes, in which the adsorption presents itself as a feasible option, especially when low-cost adsorbents obtained from industrial waste are used, such as soybean hulls (SBH). This study proposed the use of SBH for the adsorption of NR and SO dyes. The characterization showed heterogeneous and porous morphology with predominantly negative surface charges, which favored the fixation of the cationic dyes. The comparative study of SO and NR adsorption onto SBH and commercial granular activated carbon confirmed the good performance of the biosorbent material. The maximum adsorption capacities were 287.30 and 221.74 mg g−1 for NR and SO onto SBH, respectively. The equilibrium time was reached in 90 minutes for both dyes. The experimental data was adjusted to the Langmuir and pseudo-second-order models. Thermodynamics inferred endothermic, spontaneous and reversible characteristics to adsorptive processes. The main proposed adsorption mechanisms were hydrogen bonds, π-interactions and electrostatic interactions. The regeneration study showed the possibility of reusing SBH for 6 cycles, and the effect of ionic strength found that the adsorption efficiency was not reduced. Therefore, SBH demonstrated versatility and efficiency in the removal of cationic dyes from wastewater, evidencing its industrial applicability. [ABSTRACT FROM AUTHOR]

Copepod carcasses and non‐predatory mortality can occur due to natural senescence, disease, pollution, and physicochemical stress. Our objective is to evaluate and characterize the rates of non‐predatory mortality and the contribution of zooplankton community carcasses, represented by the copepods, in tropical estuarine ecosystems with different degrees of urbanization. During the study, there was a significant difference between environments and copepod carcasses, with Suape Bay (moderately urbanized) being the environment with the highest abundance of adult copepod carcasses (93.3%). The average non‐predatory mortality rate of adult copepods was 0.15 day−1: Santa Cruz Channel (sparsely urbanized) contributed the lowest values, with a mortality rate of 0.01 day−1, and Suape (moderately urbanized) had the highest rate (2.80 day−1). The families Paracalanidae (0.554 day−1) and Oithonidae (0.122 day−1) had the highest values, with an average carcass decomposition of 4.7 days. Among the environments studied, there was little differentiation between carcass percentages and mortality rate, not supporting the hypothesis that the higher rates of mortality among non‐predatory copepods were related to large urban centers. However, there was an almost proportional contribution of carcasses and non‐predatory mortality in all but a few areas, agreeing with the hypothesis that there is spatial variation with respect to carcasses in tropical estuaries. With our work, we show that estuaries can provide the estuarine food web with a significant portion of copepod carcasses, which may vary by family, and that it is not necessarily environments with a higher degree of urbanization that will have higher mortality rates. [ABSTRACT FROM AUTHOR]

The degradation of methyl orange (MO) and neutral red (NR) was studied by the direct electrooxidation using nitrogen and sulfur co-doped graphene (NSG) supported antimony doped tin oxide (SnO2-Sb). Sol-gel and microwave technics were used to prepare the material (Ti/SnO2-Sb-NSG). Raman, XRD, FTIR and TGA/DSC analyses help to confirm the coating of titanium substrate with the SnO2-Sb-NSG film. Linear sweet voltammetry results show that Ti/SnO2-Sb-NSG material possesses high oxygen overvoltage. Three independent variables including electrolysis time, current density and dye concentration on the performance of the anodic oxidation system was modeled using the Box-Behnken Design. The optimum conditions for MO and NR degradation were for current density 18 mA/cm² and 58 mA/cm², electrolysis time 6 h and 6 h and dye concentration 29 mg/L and 82 mg/L, respectively. However, based on these optimums, MO was degraded at 98.71 % while NR was just degraded at 82.7%. Based on the intermediate compounds, the degradation mechanism of MO at the Ti/SnO2-Sb-NSG anode was proposed. Ti/SnO2-Sb-NSG electrode showed a higher efficient electrocatalytic performance for NR and MO degradation than that of Ti/Sb-SnO2 or Ti/Sb-SnO2-NG electrodes. Furthermore, the lifetime of Ti/SnO2-Sb-NSG was about 31.6 h while Ti/SnO2-Sb electrode was 9.0 h. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the power of four microporous materials synthesized not incorporated (S-1, ZSM-5) and incorporated into metals (VS-1, CuZSM-5) in the degradation of a cationic dye (Neutral Red). These materials were synthesized in a fluorinated medium under well-defined temperature and crystallization time conditions. They were characterized by different techniques, X-ray diffraction (XRD), infrared spectroscopy (IR), and ultraviolet-visible spectroscopy (UV-Vis). The degradation of the neutral red (NR) dye on the four adsorbents was analyzed using two kinetic models to study the adsorption process: pseudo-first-order and pseudo-second-order. Parameters affecting the dye adsorption, such as pH and contact time also were studied. The adsorption kinetics were better described by the pseudo-first-order model. Isothermal models were also applied in this study, Langmuir, Freundlich, and Temkin. The adsorption of NR dye on Cu/ZSM-5 seemed to conform to the Langmuir model with a high correlation coefficient R² value of 0.999 and the highest adsorption capacity of 16.129 mg/g was achieved at a pH level of 5.19 and a removal rate of 98.75% could be achieved within 50 min. [ABSTRACT FROM AUTHOR]

In this study, sodium dodecyl sulfate (SDS) was used to modify soybean dregs. Modified soybean dregs (MSD) and soybean dregs (SD) were used as adsorbents, and the adsorbents were characterized by the infrared spectrum and pore size analysis. The influencing factors of SD and MSD on the adsorption of neutral red (NR) and malachite green (MG) were studied, and the thermodynamics of the adsorption isotherm and adsorption process were discussed. The findings revealed that the adsorption process was significantly affected by varying pH values and salt ion concentrations within the solution. However, altering the quantity of adsorbent added had no considerable impact on the removal rate of NR. The results of the adsorption isotherm fitting demonstrated that the adsorption process complied with the Langmuir and Temkin isothermal adsorption models. The saturation adsorption amount of NR on SD and MSD are 208 and 227 mg/g, respectively, and that of MG are 41.0 and 125 mg/g, respectively. Moreover, it was observed that the adsorption of NR and MG on SD and MSD followed a spontaneous exothermic pattern, with the SDS-treated MSD adsorbent exhibiting a higher adsorption capacity. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate prolonged storage at 4˚ C on the survival of cat cumulus oocyte complexes. The ovaries were obtained from 20 domestic cats. The ovaries were evaluated at different time intervals. The viability test for cumulus oocyte complexes was performed at 2 hours, 24 hours and 72 hours after being sampled. Tests for the viability of cumulus oocyte complexes were performed with Neutral red and Trypan blue. Storage conditions for cumulus oocyte complexes are a critical step in establishing fertility conservation protocols in animals, as well as for assisted reproduction. [ABSTRACT FROM AUTHOR]

In this study, activated carbon (AC) obtained with apple peel was used for removal of Neutral Red (NR) from aqueous solutions. The characterization of AC was evaluated with the Brunauer-Emmett-Teller (BET), Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analyses. Isotherm, kinetic, and thermodynamic parameters were determined for NR removal with AC. Eighteen isotherm models and eight kinetic models were analyzed for three temperatures and six initial dye concentrations. The experimental data best agree with the Langmuir model among the isotherm models, and the maximum adsorption capacity (qm) was calculated 142.857 mg/g at 318 K. It was determined that the pseudo-second-order (PSO) model was the best choice among the kinetic models with the highest correlation coefficients. The removal percentage of NR dye with AC obtained 82.13%, 84.79%, and 87.20% for 120 mg/L initial dye concentration at 298 K, 308 K, and 318 K, respectively. The negative free energy, enthalpy, and entropy values of adsorption obtained − 6386 J/mol, 46280 J/mol, and 165.48 J/mol.K for 20 mg/L NR concentration at 318 K, respectively. The results of this separation process shown spontaneous essence, and workability coinciding with the negative free energy and activation energy was found 13.651 kJ/mol. The assessment of the isotherm, kinetic, and thermodynamic results were evaluated with error functions. The highest correlation coefficient (R2) values and the lowest sum of squares (SS), sum of the square of error (SE), and mean square of error (MSE) values were determined with Langmuir isotherm and PSO kinetic models. This research showed that AC prepared from biomass can be used effectively for wastewater treatment using adsorption technique. [ABSTRACT FROM AUTHOR]

Phage therapy has been successfully used as an experimental therapy in the treatment of multidrug-resistant strains of Staphylococcus aureus (MDRSA)-caused skin infections and is seen as the most promising alternative to antibiotics. However, in recent years a number of reports indicating that phages can interact with eukaryotic cells emerged. Therefore, there is a need to re-evaluate phage therapy in light of safety. It is important to analyze not only the cytotoxicity of phages alone but also the impact their lytic activity against bacteria may have on human cells. As progeny virions rupture the cell wall, lipoteichoic acids are released in high quantities. It has been shown that they act as inflammatory agents and their presence could lead to the worsening of the patient's condition and influence their recovery. In our work, we have tested if the treatment of normal human fibroblasts with staphylococcal phages will influence the metabolic state of the cell and the integrity of cell membranes. We have also analyzed the effectiveness of bacteriophages in reducing the number of MDRSA attached to human fibroblasts and the influence of the lytic activity of phages on cell viability. We observed that, out of three tested anti-Staphylococcal phages—vB_SauM-A, vB_SauM-C and vB_SauM-D—high concentrations (109 PFU/mL) of two, vB_SauM-A and vB_SauM-D, showed a negative impact on the viability of human fibroblasts. However, a dose of 107 PFU/mL had no effect on the metabolic activity or membrane integrity of the cells. We also observed that the addition of phages alleviated the negative effect of the MDRSA infection on fibroblasts' viability, as phages were able to effectively reduce the number of bacteria in the co-culture. We believe that these results will contribute to a better understanding of the influence of phage therapy on human cells and encourage even more studies on this topic. [ABSTRACT FROM AUTHOR]

With the emergence of host-guest systems, a novel branch of complexation chemistry has found wide application in industries such as food, pharmacy, medicine, environmental protection and cosmetics. Along with the extensively studied cyclodextrins and calixarenes, the innovative cucurbiturils (CB) have enjoyed increased popularity among the scientific community as they possess even better qualities as cavitands as compared to the former molecules. Moreover, their complexation abilities could further be enhanced with the assistance of metal cations, which can interestingly exert a dual effect on the complexation process: either by competitively binding to the host entity or cooperatively associating with the CB@guest structures. In our previous work, two metal species (Mg2+ and Ga3+) have been found to bind to CB molecules in the strongest fashion upon the formation of host–guest complexes. The current study focuses on their role in the complex formation with three dye molecules: thiazole orange, neutral red, and thioflavin T. Various key factors influencing the process have been recognized, such as pH and the dielectric constant of the medium, the cavity size of the host, Mn+ charge, and the presence/absence of hydration shell around the metal cation. A well-calibrated DFT methodology, solidly based and validated and presented in the literature experimental data, is applied. The obtained results shed new light on several aspects of the cucurbituril complexation chemistry. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate prolonged storage at 4˚ C on the survival of cat cumulus oocyte complexes. The ovaries were obtained from 20 domestic cats. The ovaries were evaluated at different time intervals. The viability test for cumulus oocyte complexes was performed at 2 hours, 24 hours and 72 hours after being sampled. Tests for the viability of cumulus oocyte complexes were performed with Neutral red and Trypan blue. Storage conditions for cumulus oocyte complexes are a critical step in establishing fertility conservation protocols in animals, as well as for assisted reproduction.

The study was to establish a fast spectrometric method for determination of tylosin tartrate. The intensity difference of resonance light scattering spectra before and after the reaction of tylosin tartrate with cationic dye neutral red was measured by resonance light scattering spectroscopy under the condition of pH value 6.4. The results showed that when the scanning speed was 2 000 nm/min and the excitation light and emission light bandwidth were both 5.0 nm, the charge transfer reaction occurred between tylosin tartrate and the cationic dye neutral red in Clark-Lubs buffer solution, and the charge transfer complex was formed, which weakened the resonance light scattering intensity of the system. When the resonance light scattering spectrum peak of neutral red is located at 324 nm, the intensity difference of the resonance scattering spectrum of the system reaches the maximum, with a linear relationship between 0.05 and 0.60 mg/L, and the correlation coefficient R is 0.999 6. The detection limit (3 d/k) of the test method was 0.011 5 mg/L. The study indicates that the method is simple and sensitive, and can be used to determine the content of tylosin tartrate. [ABSTRACT FROM AUTHOR]

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A novel imine-linked COF is synthesized by the condensation of 2,4,6-tris(4-aminophenyl)−1,3,5-triazine (TAPT) and 2-hydroxy-5-methoxyisophthalaldehyde (HMIPA) under solvothermal conditions. This COF adsorbs preferentially the neutral dye Neutral Red (NR) over the positively charged dye Methylene Blue (MB) at pH 7, and the negatively charged Methyl Orange (MO) over the positively charged Methylene Blue (MB) at pH 3. The maximum adsorption capacities (q e) obtained within very short times (11–60 min) under optimized conditions were 108, 185 and 429 mg.g−1 for the MB, MO, and NR dyes, respectively. These adsorptions obey the Langmuir isotherm and pseudo-second-order kinetics. The prepared TAPT-HMIPA-COF is used successfully for the removal of the dyes from real water and treated wastewater samples. The adsorption data, BET, FTIR, and zeta potential measurements show that the electrostatic, π-π stacking and hydrogen bond interactions are responsible for the adsorption of organic dyes on the surface of the prepared COF. Due to recyclability, high capacity and efficiency for the adsorption of positive, negative and neutral organic dyes, this COF can be considered promising for simultaneous removal of various dyes from aqueous solutions at adjusted pHs. [Display omitted] • TAPT-HMIPA-COF was synthesized through a solvothermal Schiff-base reaction. • The adsorption of MB, MO, and NR dyes were studied. • The obtained q max for MB, MO, and NR was 108, 185, 429 mg.g−1, respectively. • Neutral dyes were preferentially adsorbed compared charged dyes. • TAPT-HMIPA-COF has excellent stability and reusability during the adsorption process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ag-HKUST-1 composite material were synthesized by impregnating Ag+ into the HKUST-1 precursor solution using the impregnation method. • The adsorption of AH1 on NR is consistent with the Langmuir model and the pseudo-second-order kinetic model. • Ag-HKUST-1 composite material have better stability and recyclability. • The possible mechanism of NR adsorption by Ag-HKUST-1 composite materials was proposed through experiments and kinetic fitting. HKSUT-1 is often used as an adsorbent because of its excellent adsorption properties. In this study, Ag+ was impregnated into the HKSUT-1 precursor solution using the impregnation method, with sodium borohydride (NaBH 4) serving as the reducing agent. This was done to examine the removal efficiency of NR dye. The Ag-HKSUT-1 composites were prepared by varying the additions of AgNO 3 and NaBH 4. The morphology and structure of the Ag-HKSUT-1 composites were characterized by TG, FT-IR, BET and TEM. The adsorption performance of AH1 for neutral red dye in wastewater was investigated. The adsorption process was described by the Langmuir model and the pseudo-second-order kinetic model. The adsorption capacity of AH1 for NR dye at 298 K was calculated to be 64.59 mg/g, indicating that Ag-HKUST-1 effectively adsorbed NR dye. The adsorption process is driven by a chemisorption mechanism, where intermolecular forces between Ag-HKUST-1 and NR, electrostatic interactions, and π-π conjugation between benzene rings play key roles. The results enhance our understanding of the surface interactions between Ag-HKUST-1 and NR dyes and broaden the application of HKUST-1 as an adsorbent for pollutant removal in water. [ABSTRACT FROM AUTHOR]

This experimental study was conducted to synthesize magnesium oxide (MgO) nanoparticles and investigate their efficiency in removing arsenic, brilliant cresyl blue, and neutral red from aqueous solutions. The MgO nanoparticles were characterized using X-ray diffraction (XRD), energy dispersive X-ray (EDS), Fourier-transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM) analyses. The results revealed that the synthesized MgO nanoparticles had a spherical structure with an estimated average size of approximately 30 nm. The influence of solution pH, concentration, adsorbent amount, type of eluent, and interference of interfering ions was examined and optimized for removing arsenic, brilliant cresyl blue, and neutral red. The optimal conditions for the removal process were determined as pH of 7, MgO amount of 0.037 g, ultrasonication time of 16 min, and concentration of 25 mg L−1. The experimental removal efficiencies of arsenic, brilliant cresyl blue, and neutral red in aqueous samples ranged from 88.49% to 96.03%. The results of eluent selection showed that ethanol had the highest removal efficiency of analytes from the absorbent surface. The reusability of the MgO adsorbent demonstrated its effective use for the continuous removal of arsenic, brilliant cresyl blue, and neutral red for at least four consecutive cycles. Overall, the results suggest that MgO nanoparticles could be an effective and cost-efficient adsorbent for removing arsenic, brilliant cresyl blue, and neutral red from real samples. [Display omitted] • Synthesis and characterization of MgO nanoparticles. • Selection and optimization of the important parameters by RSM. • Under optimum conditions, remove 93.04% arsenic, 95.58% brilliant cresyl blue, and 97.09% neutral red by MgO nanoparticles. • Close concurrence between experimental values and RSM-responses of dyes and heavy metals removal. [ABSTRACT FROM AUTHOR]

The shallow hydrothermal vents (HVs) of Kueishan Island are considered as a template for studying the extremes of sulfide-polluted and acidified water. The present study examined the biological and spatiotemporal aspects of mesozooplankton mortality in waters around this extreme HV environment. Zooplankton sample collection was carried out in three monsoonal periods and the results revealed that there was a significant decrease in the mortality of total mesozooplankton with increasing distance from the HVs. The overall mortality of mesozooplankton showed a significant negative correlation with sea surface temperature and pH. Particularly, mortality of copepods showed a significant negative correlation with pH, whereas it was significantly positive correlated with sea surface temperature in the southwest monsoon prevailing period. Overall, the results may imply a situation that zooplankton will encounter in the more acidified environment of a future ocean. • Hydrothermal vents exert different mortalities on different mesozooplankton taxa. • Low pH significantly increases mesozooplankton mortality. • Lethal mesozooplankton effects decrease with increasing distance from hydrothermal vents. • Mesozooplankton mortalities differ with monsoonal periods. [ABSTRACT FROM AUTHOR]

[Display omitted] • Resonance Rayleigh scattering spectrometry can determine glycyrrhizic acid rapidly. • Methyl violet or neutral red with water can form supramolecular polymers. • Supramolecular polymers can produce resonance Rayleigh scattering intensity. • Adding glycyrrhizic acid further weakened resonance Rayleigh scattering intensity. • Glycyrrhizic acid and cationic dyes form ion-association complexes in acidic media. This study used cationic dyes methyl violet (MV) and neutral red (NR) as probes, based on dual-wavelength overlapping resonance Rayleigh scattering (RRS), and designed two highly sensitive methods for the determination of the natural sweetener glycyrrhizic acid (GZA). In the Clark-Lubs buffer solution, when only MV or NR was present in the solution, they formed supramolecular polymers through hydrogen bonding. When adding GZA at different concentrations, the formation of ionic association complexes led to a subsequent decrease in RRS intensity at two wavelengths in the MV − GZA system and NR − GZA system, and the amount of the decline was proportional to the GZA concentration. The linear ranges were determined as 0.1 − 0.6 mg/L and 0.1 − 0.7 mg/L, with correlation coefficients of 0.9972 and 0.9996, and limits of detection were 0.052 mg/L and 0.016 mg/L, respectively. For this study, reaction conditions were optimized, potential interfering substances were investigated, and the mechanisms behind RRS generation and intensity decrease were discussed. The proposed methods were sensitive, fast, time-saving and efficient, and have been successfully applied to licorice and dried ginger decoction analysis, yielding satisfactory results. [ABSTRACT FROM AUTHOR]

The adsorption of dyes in water and wastewater using metallic nanoparticles stands out due to its high removal capacity and low environmental impact. The present study proposed the use of copper oxide nanoparticles (CuO_NP), synthesized with pomegranate leaves extract (Punica granatum) to remove the neutral red (NR) dye from the aqueous medium. The characterization confirmed the efficiency of the redox process and the formation of nanoparticles. The adsorption results were promising, wherein the maximum adsorption capacity was 283 mg/g (298 K), with 0.4 g/L of adsorbent concentration, equilibrium time at 120 min, and removal rate of 96%. The pseudo‐second‐order and Langmuir models had a better fit concerning the kinetic and isothermal data, respectively. Thermodynamic parameters revealed an exothermic, spontaneous, and reversible process. The mechanisms that described the adsorptive process were hydrogen bonds, π‐interactions, and electrostatic attraction. CuO_NP showed good regeneration performance up to four reuse cycles (98–52 mg/g). In addition, not pronounced changes were verified in its adsorption capacity with dissociated ions (90–102 mg/g, in relation to the adsorption with no salts 104 mg/g). This secures the material versatility and cost‐effectiveness, justifying its high potential for industrial application to remove NR from water and wastewater. [ABSTRACT FROM AUTHOR]

Carbon nanodots modified with Neutral Red covalently inserted in the nanostructure (NR-CDs) have been prepared by a simple synthesis method based on microwave irradiation under controlled temperature and pressure. The synthetized NR-CDs have been characterized by different techniques, demonstrating the covalent bonding of Neutral Red molecules to the carbon dots nanostructure. Fluorescence activity of the prepare NR-CDs has been explored showing different interaction pathways with singled and doubled stranded DNA. These studies have been successfully applied to develop a new fluorescence DNA hybridization assay to the detection of a specific DNA sequence of Escherichia coli bacteria. [ABSTRACT FROM AUTHOR]

The applications of ferrimagnetic nanoparticles (F-MNPs) in magnetic hyperthermia (MH) are restricted by their stabilization in microscale aggregates due to magnetostatic interactions significantly reducing their heating performances. Coating the F-MNPs in a silica layer is expected to significantly reduce the magnetostatic interactions, thereby increasing their heating ability. A new fast, facile, and eco-friendly oil-in-water microemulsion-based method was used for coating Zn0.4Fe2.6O4 F-MNPs in a silica layer within 30 min by using ultrasounds. The silica-coated clusters were characterized by various physicochemical techniques and MH, while cytotoxicity studies, cellular uptake determination, and in vitro MH experiments were performed on normal and malignant cell lines. The average hydrodynamic diameter of silica-coated clusters was approximately 145 nm, displaying a high heating performance (up to 2600 W/gFe). Biocompatibility up to 250 μg/cm2 (0.8 mg/mL) was recorded by Alamar Blue and Neutral Red assays. The silica-coating increases the cellular uptake of Zn0.4Fe2.6O4 clusters up to three times and significantly improves their intracellular MH performances. A 90% drop in cellular viability was recorded after 30 min of MH treatment (20 kA/m, 355 kHz) for a dosage level of 62.5 μg/cm2 (0.2 mg/mL), while normal cells were more resilient to MH treatment. [ABSTRACT FROM AUTHOR]

This investigation probes the role of the electron mediator, neutral red (NR), in the electrosynthesis process, specifically examining its effect on the production of succinic acid by Actinobacillus succinogenes. Our findings reveal that NR, when integrated into the cell membrane, is pivotal for sustaining MEC efficiency. Nevertheless, it is susceptible to both intrinsic and MECs-induced degradation. Notably, during the exponential growth phase of the bacteria, NR is readily incorporated into the cell membrane. However, the supplemental addition of NR fails to significantly enhance the MEC's capacity for succinic acid synthesis, no matter what stage of bacterial growth. And significant depletion of membrane-associated NR is not adequately compensated by the NR present in the fermentation liquid. The ORP feedback-regulated MECs adeptly conserve the NR on the cell membrane, which is essential for maintaining the efficiency of long-term electrosynthesis. The presence of NR on the cell membrane is essential for the functionality of MECs, yet its external replenishment hard. Implementing precise electro-potential regulation strategies can effectively diminish the degradation of NR, thus maintaining the system's efficiency., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

We evaluated the environmental quality in mangrove areas of the Western Atlantic with different levels and history of contamination, considering biomarkers for the crab Ucides cordatus. For this purpose, specimens were collected in two climatic seasons (rainy and dry seasons) and assays of genotoxicity (MN, micronucleus), cytotoxicity (NRRT, neutral red retention time) and biochemical (MT, metallothionein; and LPO, lipoperoxidation) were conducted. In the most impacted mangroves, there was an increase in the mean of micronucleus (frequency of MN/1000), which was associated with a shorter retention time (minutes of NRRT). In contrast, the most pristine areas showed MN < 3 and NRRT < 100 min, with no seasonal effect, indicating a lower effect of degenerative processes by xenobiotics. The rainy season was more harmful, especially regarding cytogenotoxicity. The use of bioindicator species for environmental monitoring should be guided by an analysis of biomarkers considering the season, because during the period of highest rainfall, biomarkers values can change. [ABSTRACT FROM AUTHOR]

To determine the proportion of inviable oocytes that are spawned along with normal oocytes in marine bivalves, we turned to a time‐honored technique not previously used on invertebrate oocytes: the neutral red vital stain. Despite the difficulty in obtaining induced spawns from field‐collected Cerastoderma edule (L), the results and insights from this simple procedure to answer a simple question were unexpected and far‐reaching. Mean proportions of inviable oocytes in the spawns of cockle C. edule ranged from 35% to 85%, with the vast majority represented by atresic (autolyzing) oocytes. These levels are in agreement with previous quantitative histological observations of prespawning atresia in both C. edule and the Manila clam Tapes philippinarum. Such elevated prefertilization inviability mirrors the known high level of postfertilization inviability in bivalves. Together, these high levels of inviability may account for much of the early mortality in the type III survivorship curves typical of marine bivalves. The combination of high fecundity and high oocyte inviability suggests a Red Queen‐type reproductive dilemma in these species. In addition, the great degree of interindividual variation observed in oocyte inviability suggests that cockles, and perhaps other intertidal bivalves, present a Sweepstakes Reproductive Strategy, in which highly variable individual fecundity confronts a highly variable environment. The neutral red technique promises to be a useful tool for investigating prespawning inviability in other marine taxa, as well as for aquaculture, conservation, restocking, ecophysiology, and environmental monitoring. [ABSTRACT FROM AUTHOR]

BACKGROUND Butanol is a versatile chemical that can be used as fuel, solvent or intermediate in chemical synthesis. Several strategies have been used to increase the availability of reducing power in Clostridium sp. with the aim of maximizing the production of butanol, the use of electron carriers being one of the most effective. Moreover, electrons from an external power source can be transferred to cells through electron carriers such neutral red, or directly reducing NAD+. From a previous metabolic analysis, we hypothesized that adding butyrate to the culture medium and using an external electron source as a co‐reducing agent, along with glucose‐derived reducing power (electro‐fermentation), would result in an increase in the specific butanol productivity. RESULTS: Butyrate caused a decrease in the maximum concentration of butanol reached at the concentration used (6 g L−1). The supplementation of neutral red to the culture medium by itself and along with electro‐fermentation were effective in stimulating the production of butanol. The mean specific rate of butanol production obtained for electro‐fermentation in medium supplemented with butyrate and neutral red was 307% and 156% higher than that recorded using medium supplemented with butyrate, or butyrate and neutral red, respectively, this value being even 113% higher than that recorded for the non‐supplemented medium. CONCLUSIONS: The presence of butyrate and absence of neutral red in the electro‐fermentation were detrimental for the microorganism. The electro‐fermentation in medium supplemented with neutral red led to an increase in both volumetric and specific productivities of butanol. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The detection of small molecules interacting with DNA is important for the assessment of potential hazards related to the application of rather toxic antitumor drugs, and for distinguishing the factors related to thermal and oxidative DNA damage. In this work, a novel electrochemical DNA sensor has been proposed for the determination of antitumor drugs. For DNA sensor assembling, a glassy carbon electrode was modified with carbon black dispersed in DMF. After that, pillar [5]arene was adsorbed and Methylene blue and Neutral red were consecutively electropolymerized onto the carbon black layer. To increase sensitivity of intercalator detection, DNA was first mixed with water-soluble thiacalixarene bearing quaternary ammonium groups in the substituents at the lower rim. The deposition of the mixture on the electropolymerized dyes made it possible to detect doxorubicin as model intercalator by suppression of the redox activity of the polymerization products. The DNA sensor made it possible to determine 0.5 pM–1.0 nM doxorubicin (limit of detection 0.13 pM) with 20 min of incubation. The DNA sensor was successfully tested on spiked samples of human plasma and doxorubicin medication. [ABSTRACT FROM AUTHOR]

The main goal of this work was the theoretical interpretation of the absorption spectra of neutral red in an aqueous solution (both neutral NR0 and protonated NR+ forms). To achieve this problem, TD-DFT/DFT calculations with different hybrid functionals, the IEFPCM solvent model, and the 6–31 + + G(d,p) basis set were used. MN12SX functional provided the best agreement with the experiment for both dye forms. While the absorption band of the cationic form of the dye in the visible region of the spectrum is due to one transition S0 → S1 (HOMO–LUMO), for its neutral form, there are two transitions S0 → S1 (HOMO → LUMO) and S0 → S2 (HOMO-1 → LUMO), with the latter having a higher intensity. The protonation of the dye chromophore introduces significant changes in HOMO shape. At the same time, LUMOs are almost the same for the protonated and neutral forms of the NR. During the transition from NR0 to the S1 state, its dipole moment increases more significantly than during the transition to the S2 state. Calculations confirmed the assumption of Singh et al. about the existence of two closely spaced excited states of NR0, the first of which has a larger dipole moment. However, the hypothesis of these authors about the corresponding intramolecular charge transfer, as well as the huge value of the dipole moment of this excited state (~ 20 D) declared by them, was not confirmed by present calculations. It was shown that the photoinduced charge redistribution in both the neutral and cationic forms of the dye is local, and the corresponding dipole moment is ~ 10 D. This agrees with other early theoretical work by Aaron et al. The influence on the NR+ absorption spectrum of hydrating water molecules was also analyzed. It was found that the interplay of electrostatic and site-specific contributions leads to the fact that NR solvatochromism does not have a pronounced dependence on the polarity of the solvent. [ABSTRACT FROM AUTHOR]

Inspired by the natural world's fascinating capacity for color change, researchers have developed various responsive hydrogels that shift colors. Among these, hydrogels that react to pH changes are particularly notable for their unique properties. The urea-urease autocatalytic reaction, a key pH clock reaction, is especially effective in temporarily adjusting these hydrogels' properties and enabling color changes in response to stimuli. In this study, we synergize the urea-urease clock reaction with the pH-sensitive color transformation of neutral red (NR), thereby establishing an NR-urea-urease clock reaction system. This system exhibits a dynamic color cycle from yellow to red and back to yellow. By incorporating this color transition mechanism into polymer hydrogels, we successfully initiate a pH change within the system. This innovation paves the way for a smart material capable of displaying temporary information through enzymatic reactions. The temporal variation in information display is finely tuned by adjusting the urea and urease concentrations. Such reversible color-changing hydrogels hold promising prospects for applications in secure information transmission and dynamic camouflage, marking a significant step forward in systems chemistry and materials science. [Display omitted] • This study develops reversible, color-changing hydrogels for dynamic displays. • Smart hydrogels enable secure information transmission and adaptive camouflage. • Optimized hydrogel formulations enhance water retention and mechanical strength. • A novel method for on-demand encoding and erasing of information is introduced. [ABSTRACT FROM AUTHOR]

Abstract To determine the proportion of inviable oocytes that are spawned along with normal oocytes in marine bivalves, we turned to a time‐honored technique not previously used on invertebrate oocytes: the neutral red vital stain. Despite the difficulty in obtaining induced spawns from field‐collected Cerastoderma edule (L), the results and insights from this simple procedure to answer a simple question were unexpected and far‐reaching. Mean proportions of inviable oocytes in the spawns of cockle C. edule ranged from 35% to 85%, with the vast majority represented by atresic (autolyzing) oocytes. These levels are in agreement with previous quantitative histological observations of prespawning atresia in both C. edule and the Manila clam Tapes philippinarum. Such elevated prefertilization inviability mirrors the known high level of postfertilization inviability in bivalves. Together, these high levels of inviability may account for much of the early mortality in the type III survivorship curves typical of marine bivalves. The combination of high fecundity and high oocyte inviability suggests a Red Queen‐type reproductive dilemma in these species. In addition, the great degree of interindividual variation observed in oocyte inviability suggests that cockles, and perhaps other intertidal bivalves, present a Sweepstakes Reproductive Strategy, in which highly variable individual fecundity confronts a highly variable environment. The neutral red technique promises to be a useful tool for investigating prespawning inviability in other marine taxa, as well as for aquaculture, conservation, restocking, ecophysiology, and environmental monitoring.

• A selective chromo-fluorogenic probe (AMP) has been introduced to detect sarin & tabun mimics. • A ratiometric UV–visible absorption spectral and colorimetric change from yellow to bright pink is observed. • A "turn-off" photoluminescence from yellow color to non-fluorescence is noticed in the presence of both mimics. • The spectral and chromo-fluorgenic behavior is reversed in the presence of triethyl amine (TEA). • The sensitivity of AMP towards the detection is found in the μM range. The abuse of nerve agents has become a severe threat to peaceful modern civilization. Hence, it is of paramount importance to the scientific communities to detect and degrade them for a modern society. In the present contribution, we have introduced a selective chromo-fluorogenic probe (AMP) based on neutral red dye for visual detection of the solution and vapor phase of sarin & tabun mimics, namely diethyl chlorophosphate (DCP) and diethyl cyanophosphonate (DCNP), respectively. A ratiometric UV–visible absorption spectral change with colorimetric visualization from yellow to bright pink is observed in the presence of both mimics. A "turn-off" photoluminescence from yellow color to non-fluorescence is observed in the presence of both mimics. The spectral and chromo-fluorgenic behavior is reversed in the presence of triethylamine (TEA). The sensitivity of AMP towards the detection of targeted analytes is recorded in the μM range. Additionally, filter paper-based strips are fabricated for the actual applicability of the current probe to identify trace amounts of both analytes in the presence of various types of analogous target analytes. The vapor phase sensing and two types of soil analysis are also employed to check the sensor's potential in real-life applications. The present report has revealed prompt, sensitive, selective, in-situ, accurate sample detectors of sarin & tabun gas in actual threatening situations. A selective chromo-fluorogenic probe (AMP) based on neutral red dye has been introduced for visual detection of the solution and vapor phase of sarin & tabun mimics, namely diethyl chlorophosphate (DCP) and diethyl cyanophosphate (DCNP), respectively displaying a colorimetric change from yellow to bright pink and "turn-off" photoluminescence behavior. [Display omitted] [ABSTRACT FROM AUTHOR]

With the emergence of host-guest systems, a novel branch of complexation chemistry has found wide application in industries such as food, pharmacy, medicine, environmental protection and cosmetics. Along with the extensively studied cyclodextrins and calixarenes, the innovative cucurbiturils (CB) have enjoyed increased popularity among the scientific community as they possess even better qualities as cavitands as compared to the former molecules. Moreover, their complexation abilities could further be enhanced with the assistance of metal cations, which can interestingly exert a dual effect on the complexation process: either by competitively binding to the host entity or cooperatively associating with the CB@guest structures. In our previous work, two metal species (Mg2+ and Ga3+) have been found to bind to CB molecules in the strongest fashion upon the formation of host–guest complexes. The current study focuses on their role in the complex formation with three dye molecules: thiazole orange, neutral red, and thioflavin T. Various key factors influencing the process have been recognized, such as pH and the dielectric constant of the medium, the cavity size of the host, Mn+ charge, and the presence/absence of hydration shell around the metal cation. A well-calibrated DFT methodology, solidly based and validated and presented in the literature experimental data, is applied. The obtained results shed new light on several aspects of the cucurbituril complexation chemistry.

Nitrite level estimation in soil and water bodies is critical to monitor the ecosystem of our environment and agricultural yield. Herein, we report a carbon nanodots (C-dots) and neutral red (NR)-based photometric and fluorescence mode sensing scheme using which trace detection of nitrite in water and soil has been done. The proposed scheme utilizes a handheld compact sensing platform developed on a smartphone. For the present sensing studies, the C-dots and NR act as donors and acceptors, respectively, in the frequency resonance energy transfer (FRET) process. The presence of nitrite in the C-dot-NR mixture affects the FRET process, which causes a decrease in the absorption wavelength conditions at 560 nm while increasing the fluorescence intensity at 563 nm upon excitation with a source of wavelength 375 nm. These variations have been correlated to quantify the concentration of the nitrite level in the medium. With the designed sensing system, variations of nitrite concentration from 0.1 to 3.0 μg/mL have been measured with a high degree of accuracy. The designed sensor has been implemented to estimate the nitrite level of infield water and soil samples, and the experimental results are compared with the laboratory standard tools. With the advantages of being low-cost, field portable, and relatively convenient to handle, it is anticipated that the proposed smartphone sensor could emerge as a potential avenue for onsite assessment of other parameters of water and soil as well. [ABSTRACT FROM AUTHOR]

Although a portion of all copepods in the natural environment are physiologically inactive or dead, there is little data on this aspect in Indian seas. Using the classical neutral red live staining technique, the dead percentage of copepods in the western Bay of Bengal (BoB) is determined for the first time in this study, which takes into account hydrography and zooplankton samples collected on April 2015 (Spring Intermonsoon [SIM]) from 6 inshore and 8 offshore locations in the western BoB. The offshore parts of the research area were infested with a persistent and extensive warm-core eddy/gyre during the sampling time, as demonstrated by satellite data of sea surface temperature, mean sea level anomaly, and surface currents. As a result, the mixed layer depth in the offshore zone was higher, whereas nutrients, chlorophyll a, and turbidity were significantly lower than inshore. Copepods dominated the zooplankton community (> 80%), with abundances ranging from 112 to 2580 No m−3 in the study area. Calanoids (particularly Paracalanidae) dominated nearshore waters (35–65%), whereas cyclopoids (notably Corycaeidae and Oncaeidae) dominated offshore (49–71%). There were 48 species of copepods identified in total, and all of them had dead individuals (carcasses). Offshore waters had a larger percentage of copepod carcasses (27–39%) than inshore seas (18–28%). The larger percentage of carcasses is possibly related to a higher top-down feeding pressure on cyclopoids in offshore waters due to extreme oligotrophy and the dominance of the microbial food web. [ABSTRACT FROM AUTHOR]

The ZnO/CeO2 nanocomposites (Zn1−xCexO2) were fabricated for different concentrations with x = 0(ZC-1), 0.05(ZC-2), 0.1(ZC-3) and 0.3(ZC-4) via the hydrothermal method. We observed a decrease in particle size by an increase in the concentration of CeO2 to ZnO. To ensure this Transmission Electron Microscopy (TEM) analysis has been done and the obtained particles size around 42 nm, 26 nm, 22 nm, and 12 nm for ZC-1, ZC-2, ZC-3, and ZC-4 respectively. The purity and chemical composition were investigated by Energy Dispersive X-ray Analysis (EDX) & X-ray Photoelectron Spectroscopy (XPS) analysis. For the first time, the synthesized ZnO/CeO2 nanocomposites were used as photocatalysts for photocatalytic degradation of the dye neutral red. Initially, the degradation efficiency (ɳ) of ZnO nano catalyst was 45.35%, as we increase the CeO2 concentration the efficiency of the dye degradation increased appreciably to 56.86%. This is because of more occupancy of surface defects by smaller size particles. Furthermore, the synthesized nanocomposites were studied for their antibacterial activity. Due to the doping of CeO2, we observed eventually an increase in the zone of inhibition from 12 mm to 19 mm for gram-negative bacteria. We obtained good results for gram-negative bacteria for the higher concentration of the CeO2 than gram-positive. So, the synthesized Nanocomposites are effective for photocatalytic as well as antibacterial applications. Highlights: ZnO/CeO2 nanocomposites were synthesized by a simple hydrothermal method for different concentrations. Optical and physicochemical properties were investigated thoroughly. For the first time, photo-induced degradation is explained by the effect of particles size over neutral red. The effect of surface morphology and size of NPs examined for antibacterial activities. [ABSTRACT FROM AUTHOR]

We proposed a voltammetric DNA sensor based on glassy carbon modified with carbon black, pillar[5]arene, and electropolymerized Neutral Red. To increase signal sensitivity, Methylene Blue in monomeric and polymeric forms was introduced into the surface layer of the DNA sensor as a specific DNA intercalator and electron transfer mediator. The electrochemical characteristics of the coating are determined, depending on the composition and the preparation method; a consistent change in the peak currents of dyes is observed during the incubation of a DNA sensor in a solution of doxorubicin as a model anticancer drug. Under optimal conditions, the DNA sensor enables the determination of 10 nM to 0.1 mM of doxorubicin. Doxorubicin can also be determined in synthetic blood plasma. [ABSTRACT FROM AUTHOR]

Neospora caninum (N. caninum) is a protozoan parasite that poses a serious risk to livestock by infecting various domestic and wild animals. Loop-Mediated Isothermal Amplification (LAMP) offers a cost-effective, highly sensitive, and specific method for detecting protozoan parasites. This study aims to develop a precise, rapid, and visually assessable colorimetric LAMP method, improving on traditional techniques. We employed a rigorous screening process to identify the optimal primer set for this experiment. Subsequently, we fine-tuned the LAMP reaction at 65 °C for 40 min with 270 μmol/L neutral red. We then confirmed the specificity of primers for N. caninum through experimental validation. The LAMP method demonstrated a lower detection limit compared to traditional Polymerase Chain Reaction (PCR) techniques. While LAMP offers clear advantages, the prevalence of DNA detected in 89 sheep serum and 59 bovine serum samples using the nested PCR method was 3.37 % (3/89) and 1.69 % (1/59), respectively. In contrast, when the LAMP method was employed, the prevalence of detected DNA rose to 5.61 % (5/89) for sheep and 3.38 % (2 /59) for bovine. A comparison of two molecular assays using the intragroup correlation coefficient (ICC) resulted in a value of 0.999 (95 % CI: 0.993-0.996, p < 0.001), indicating the LAMP method is in the "better" range according to James Lee's categorization. The LAMP technique, optimized with specific primers of N. caninum and neutral red dye, not only exhibited higher sensitivity but also provided convenience over conventional PCR methods, highlighting its potential for on-site applications and cost-effective field detection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Blue light is known to be antimicrobial, but its effect on normal cutaneous and subcutaneous cells remains unclear. Therefore, we studied the effect of 470-nm light on the viability of adult and neonatal human dermal fibroblasts, Jurkat T-cells, and THP-1 monocytes in vitro. Each culture was irradiated with 0, 3, 55, or 110 J/cm2 of 470-nm light and subjected to trypan blue assay to ascertain viability. Further, MTT, neutral red, and fluorescence assays of fibroblasts were performed, and cell morphology visualized using bright field and fluorescence microscopy. At each dose and in each of the four cell lines, there was no significant difference in cell concentration between irradiated and non-irradiated cultures, even though irradiation with 55 J/cm2 or 110 J/cm2 slightly decreased cell count. Light microscopy showed progressive morphological changes in the fibroblasts as energy fluence increased from 55 to 110 J/cm2. Irradiation at 3 J/cm2 produced a slight but non-significant increase in the viability of Jurkat T-cells and THP-1 monocytes. In contrast, at 110 J/cm2 radiant exposure, irradiation slightly decreased the viability of all four cells. While 3 J/cm2 appears stimulatory, our finding that 110 J/cm2 produces a slight decrease in viability and engenders morphological changes in fibroblasts, suggesting that such high doses should be avoided in blue light treatments. [ABSTRACT FROM AUTHOR]

Cobalt-grafted-mesoporous silica nanoparticles with the Si/Co molar ratio of 70 were synthesized by using sol–gel method (denoted as Co-MSN). Characterization of the Co-MSN was carried out by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), and N2 adsorption/desorption analysis. Photocatalytic activity of the Co-MSN sample was studied for removal of neutral red as one of the most widely used dye pollutants, in presence of H2O2 and UV irradiation. In this regard, effect of various influencing parameters such as pH, Co content, dye concentration, amount of oxidant, and presence/absence of UV irradiation were investigated. It was found that incorporation of the Co2+ ions into the mesoporous silica nanostructure significantly improves the photocatalytic degradation of neutral red. Under the optimized conditions including 0.3 mmol of H2O2 (as an oxidant), catalyst dosage of 0.075 mg, initial dye concentration of 0.08 mM, and UV irradiation (32 W, 254 nm), up to 81% of neutral red was degraded at room temperature for 220 min. [ABSTRACT FROM AUTHOR]