Expression of concern: Palladium supported on mixed-metal-organic framework (Co-Mn-MOF-74) for efficient catalytic oxidation of CO.

Expression of Concern for 'Palladium supported on mixed-metal-organic framework (Co-Mn-MOF-74) for efficient catalytic oxidation of CO' by Reda S. Salama et al., RSC Adv., 2021, 11, 4318-4326, https://doi.org/10.1039/D0RA09970H.

Investigation of the anticorrosion and adsorption properties of two polymer compounds on the corrosion of SABIC iron in 1 M HCl solution by practical and computational approaches.

The anticorrosion efficiency of two polymer compounds, namely polystyrene (PS), polybutylene terephthalate (PBT), against the corrosion of SABIC iron (S-Fe) in 1.0 M HCl solution was investigated. The anticorrosion efficiency was estimated by chemical and electrochemical measurements. The anticorrosion efficiency increased with the increase in the concentration of the polymer compounds and reduction in temperature. All the obtained corrosion data confirmed the anticorrosion strength in the presence of PS and PBT compounds, such as the decreasing values of the corrosion current density, capacity of the double layer, and weight reduction, while the values of the charge-transfer resistance increased. Also, the pitting potential values moved in the noble (+) direction. The anticorrosion efficiency of the PBT compound was higher than that of the PS compound, which was 95.98% at 500 ppm concentration for PBT while for PS it was 93.34% according to polarization measurements. The anticorrosion activity occurred by the adsorption of PS and PBT compounds on the surface of S-Fe according to the Langmuir isotherm. The polarization curves indicated that the PS and PBT compounds were mixed-type inhibitors. Density functional theory (DFT) and Monte Carlo simulation (MC) were performed for the two polymer compounds. The computational quantum functions were found to be in agreement with the experimental results.

High-Efficacy Hierarchical Dy2O3/TiO2 Nanoflower toward Wastewater Reclamation: A Combined Photoelectrochemical and Photocatalytic Strategy.

Developing a sustainable photocatalyst is crucial to mitigate the foreseeable energy shortage and environmental pollution caused by the rapid advancement of global industry. We developed Dy2O3/TiO2 nanoflower (TNF) with a hierarchical nanoflower structure and a near-ideal anatase crystallite morphology to degrade aqueous rhodamine B solution under simulated solar light irradiation. The prepared photocatalyst was well-characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, energy-dispersive spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, diffuse reflectance UV-vis spectra, and X-ray photoelectron spectroscopy. Further analysis was performed to highlight the photoelectrochemical activity of the prepared photocatalysts such as electrochemical impedance spectroscopy, linear sweep voltammetry, photocurrent response, and a Mott-Schottky study. The crystalline Dy2O3/TNF exhibits superb photocatalytic activity attributed to the improved charge transfer, reduced recombination rate of the electron-hole pairs, and a remarkable red-shift in light absorption.

A portable spectroscopic instrument for multiplexed monitoring of acute water toxicity: Design, testing, and evaluation.

The deteriorating water environment worldwide, mainly due to population explosion and uncontrolled direct disposal of harmful industrial and farming wastes, earnestly demands new approaches and accurate technologies to monitor water quality before consumption overcoming the shortcomings of the current methodologies. A spectroscopic water quality monitoring and early-warning instrument for evaluating acute water toxicity are the need of the hour. In this study, we have developed a prototype capable of the quantification of dissolved organic matter, dissolved chemicals, and suspended particulate matter in trace amounts dissolved in the water. The prototype estimates the water quality of the samples by measuring the absorbance, fluorescence, and scattering of the impurities simultaneously. The performance of the instrument was evaluated by detecting common water pollutants such as Benzopyrene, Crystal Violet, and Titanium di-oxide. The limit of detection values was found to be 0.50, 23.9, and 23.2 ppb (0.29 µM), respectively.

Implementation of surface functionalization of MnS nanoparticles for achieving novel optical properties and improving therapeutic potential.

In the past few years, metal sulfide nanoparticles (NPs) have achieved enormous interest due to their photo and electrochemical properties, which can compete with the existing metal oxide NPs. However, there are fewer reports on the synthesis and the mechanism of surface functionalization of these NPs to achieve intrinsic optical properties. Here, we demonstrate a novel method for the synthesis and the surface modification of manganese sulfide (MnS) NPs to achieve intrinsic photoluminescence and special electrochemical properties. The MnS NPs were characterized using electron microscopy and optical spectroscopic methods. Fourier-transform infrared spectroscopy (FTIR) demonstrated the attachment of citrate on the surface of MnS NPs. The surface modification of insoluble as-prepared MnS NPs by citrate makes them soluble in water. The UV-vis absorption spectra show distinct d-d and ligand to metal charge transfer (LMCT) bands of the citrate-MnS NP nanohybrid. The citrate-MnS NPs exhibited strong photoluminescence. They generated a huge amount of ROS at neutral/acidic pH without any photo-activation which was shown to degrade bilirubin. In addition, the higher ROS generation at pH 5 and pH 7 was exploited to evaluate their anti-bacterial efficacy against Staphylococcus hominis (S. hominis). These observations could pave the path for the designing and development of new-age surface-functionalized metal sulfide NPs for the benefit of human health.

Molecular co-localization of multiple drugs in a nanoscopic delivery vehicle for potential synergistic remediation of multi-drug resistant bacteria.

Anti-microbial resistant infection is predicted to be alarming in upcoming years. In the present study, we proposed co-localization of two model drugs viz., rifampicin and benzothiazole used in anti-tuberculosis and anti-fungal agents respectively in a nanoscopic cationic micelle (cetyl triethyl ammonium bromide) with hydrodynamic diameter of 2.69 nm. Sterilization effect of the co-localized micellar formulation against a model multi-drug resistant bacterial strain viz., Methicillin resistant Staphylococcus aureus was also investigated. 99.88% decrease of bacterial growth in terms of colony forming unit was observed using the developed formulation. While Dynamic Light Scattering and Forsters Resonance Energy Transfer between benzothiazole and rifampicin show co-localization of the drugs in the nanoscopic micellar environment, analysis of time-resolved fluorescence decays by Infelta-Tachiya model and the probability distribution of the donor-acceptor distance fluctuations for 5 µM,10 µM and 15 µM acceptor concentrations confirm efficacy of the co-localization. Energy transfer efficiency and the donor acceptor distance are found to be 46% and 20.9 Å respectively. We have also used a detailed computational biology framework to rationalize the sterilization effect of our indigenous formulation. It has to be noted that the drugs used in our studies are not being used for their conventional indication. Rather the co-localization of the drugs in the micellar environment shows a completely different indication of their use in the remediation of multi-drug resistant bacteria revealing the re-purposing of the drugs for potential use in hospital-born multi-drug resistant bacterial infection.

Microwave-assisted synthesis of gold nanoparticles supported on Mn3O4 catalyst for low temperature CO oxidation.

In the present work, Mn3O4 was prepared by various methods and successfully loaded with metallic Au nanoparticles reduced by hydrazine hydrate using microwave irradiation (MWI) method. The surface morphology and composition of the prepared samples were characterized with X-ray diffraction (XRD), N2 adsorption-desorption, temperature programmed reduction (H2-TPR), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The experimental results showed that no significant changes in some textural and structural properties of the samples due to preparation method or Au nanoparticles deposition. While the surface composition and reducibility of the samples were greatly affected by preparation method and Au deposition. The CO oxidation reaction over the samples was selected as a model reaction to study the relation between surface properties of the samples and their catalytic performance. The results showed that a direct proportionality exists between the reducibility and the CO oxidation activity of catalysts. The kinetic study of the reaction showed that the reaction is first order. Moreover, the samples exhibited good stability in CO oxidation at 100% conversion for around 30 h under the reaction conditions.

Palladium supported on mixed-metal-organic framework (Co-Mn-MOF-74) for efficient catalytic oxidation of CO.

Successful monometallic and bimetallic metal-organic frameworks with different Co/Mn ratios have been synthesized under solvothermal conditions. The as-synthesized MOFs followed by deposition of Pd nanoparticles with 0.5 to 7 wt%. The XRD, BET, SEM, TEM, EDAX and FT-IR characterization results reveal that bimetallic MOFs and Pd nanoparticles were finely dispersed on the prepared MOFs surfaces. XRD results confirm the formation of the desire MOFs and show the high degree of dispersion of Pd nanoparticles. TEM images show that Pd nanoparticles are nano-sized with almost uniform shape. EDAX shows that Pd nanoparticles successfully loaded on Co0.5-Mn0.5-MOF-74 catalyst. CO oxidation as a model reaction was then used to assess the catalytic performance of the prepared catalysts. The catalytic activity results show enhancement in the catalytic activities of monometallic MOFs after introducing another metal in the same framework and show an excellent improvement in CO conversion after loading with Pd nanoparticles. Furthermore, the samples that contain Pd nanoparticles exhibits higher catalytic activities which raised with increasing the content of Pd nanoparticles.

Novel Pyran-Linked Phthalazinone-Pyrazole Hybrids: Synthesis, Cytotoxicity Evaluation, Molecular Modeling, and Descriptor Studies.

A series of novel pyran-linked phthalazinone-pyrazole hybrids were designed and synthesized by a facile one-pot three-component reaction employing substituted phthalazinone, 1H-pyrazole-5-carbaldehyde, and active methylene compounds. Optimization studies led to the identification of L-proline and ethanol as efficient catalyst and solvent, respectively. This was followed by evaluation of anticancer activity against solid tumor cell lines of lung and cervical carcinoma that displayed IC50 values in the range of 9.8-41.6 µM. Molecular modeling studies were performed, and crucial interactions with the target protein were identified. The drug likeliness nature of the compounds and molecular descriptors such as molecular flexibility, complexity, and shape index were also calculated to understand the potential of the synthesized molecules to act as lead-like molecule upon further detailed biological investigations as well as 3D-QSAR studies.

Rational Design and Synthesis of Naphthalene Diimide Linked Bis-Naphthalimides as DNA Interactive Agents.

A molecular modeling assisted rational design and synthesis of naphthalene diimide linked bis-naphthalimides as potential DNA interactive agents is described. Chemical templates incorporating naphthalene diimide as a linker in bis-naphthalimide motif were subjected to molecular docking analysis at specific intercalation and telomeric DNA G-quadruplex sites. Excellent results were obtained, which were better than the standards. A short and convenient synthetic route was employed to access these hybrids experimentally, followed by evaluation of their ability to cause thermal denaturation of DNA and cytotoxic properties along with ADME predictions. The obtained results provided useful insights and two potential molecules were identified for further development.

New Imidazole-Based N-Phenylbenzamide Derivatives as Potential Anticancer Agents: Key Computational Insights.

An efficient atom-economical synthetic protocol to access new imidazole-based N-phenylbenzamide derivatives is described. A one-pot three-component reaction was utilized to provide a series of N-phenylbenzamide derivatives in a short reaction time (2-4 h) with an 80-85% yield. The cytotoxic evaluation revealed that derivatives 4e and 4f exhibited good activity, with IC50 values between 7.5 and 11.1 µM against the tested cancer cell lines. Computational studies revealed interesting insights: the docking of the active derivatives (4e and 4f) showed a higher affinity toward the target receptor protein than the control. Molecular dynamic simulations revealed that the active derivatives form stable complexes with the ABL1 kinase protein. Moreover, the ADME and drug-likeness of the derivatives reinforced the potential of the derivatives to be taken up for further development as anticancer agents.

Bioactive fluorenes. Part III: 2,7-dichloro-9H-fluorene-based thiazolidinone and azetidinone analogues as anticancer and antimicrobial against multidrug resistant strains agents.

BACKGROUND: Thiazoles, thiazolidinones and azetidinones are highly ranked amongst natural and synthetic heterocyclic derivatives due to their great pharmaceutical potential. RESULTS: New thiazolidinone and azetidinone class of bioactive agents based on 4-(2,7-dichloro-9H-fluoren-4-yl)thiazole moiety have been successfully synthesized. 4-(2,7-dichloro-9H-fluoren-4-yl)thiazol-2-amine was synthesized and allowed to react with various aryl/heteroaryl aldehydes to afford the corresponding Schiff base intermediates. The target thiazolidinone and azetidinone analogues have derived from Schiff bases by their reactions with thioglycolic acid and chloroacetyl chloride, respectively. The newly synthesized compounds were then evaluated for their antimicrobial activity against some multidrug resistant strains and examined for cytotoxic activity against normal lung fibroblast (WI-38), human lung carcinoma (A549), and human breast carcinoma (MDA-MB-231) cell lines to develop a novel class of fluorene-based bioactive agents. The mode of action and the binding interaction of the synthesized compound with the active sites of dihydrofolate reductase enzyme were well identified by fluorescence-activated cell sorting (FACS) analysis and molecular docking study. CONCLUSION: Some of the synthesized compounds showed remarkable activity against A-549 and MDA-MB-231 when compared to Taxol, which was used as a reference drug. 2,7-dichloro-9H-fluorene-based azetidinones are more efficient as antimicrobial and anticancer agents compared to dichloro-9H-fluorene-based thiazolidinones derivatives.

Combating Essential Metal Toxicity: Key Information from Optical Spectroscopy.

Chelation therapy is one of the most effective and widely accepted methods of treatment to reduce metal toxicity caused by an excess amount of essential metals. Essential minerals play an important role in maintaining healthy human physiology. However, the presence of an excess amount of such essential metals can cause cell injury, which finally leads to severe life-threatening diseases. Chelating complexes can efficiently capture the targeted metal and can easily be excreted from the body. Commonly utilized metal chelators have major side effects including long-term damage to some organs, which has pointed out the need of less harmful biocompatible chelating agents. In this work, we have investigated the iron chelating property of curcumin through various spectroscopic tools by synthesizing and characterizing the iron-curcumin (Fe-Cur) complex. We have also investigated whether the synthesized materials are able to retain their antioxidant activity after the chelation of a substantial amount of metal ion. Our study unravels the improved antioxidant activity of the synthesized chelate complex. We further demonstrate that the proposed complex generates no significant reactive oxygen species (ROS) under dark conditions, which makes it a promising candidate for chelation therapy of iron toxicity. Femtosecond-resolved fluorescence studies further provide insight into the mechanism of activity of the new complex where electron transfer from ligand to metal has been observed prominently. Thus, the Fe-Cur complex has a potential to act as a dual activity medicine for excretion of toxic metal ions via chelation and as a therapeutic agent of oxidative stress caused by the metal ion as well.

Nano-MOFs as targeted drug delivery agents to combat antibiotic-resistant bacterial infections.

The drug resistance of bacteria is a significant threat to human civilization while the action of antibiotics against drug-resistant bacteria is severely limited owing to the hydrophobic nature of drug molecules, which unquestionably inhibit its permanency for clinical applications. The antibacterial action of nanomaterials offers major modalities to combat drug resistance of bacteria. The current work reports the use of nano-metal-organic frameworks encapsulating drug molecules to enhance its antibacterial activity against model drug-resistant bacteria and biofilm of the bacteria. We have attached rifampicin (RF), a well-documented antituberculosis drug with tremendous pharmacological significance, into the pore surface of zeolitic imidazolate framework 8 (ZIF8) by a simple synthetic procedure. The synthesized ZIF8 has been characterized using the X-ray diffraction (XRD) method before and after drug encapsulation. The electron microscopic strategies such as scanning electron microscope and transmission electron microscope methods were performed to characterize the binding between ZIF8 and RF. We have also performed picosecond-resolved fluorescence spectroscopy to validate the formation of the ZIF8-RF nanohybrids (NHs). The drug release profile experiment demonstrates that ZIF8-RF depicts pH-responsive drug delivery and is ideal for targeting bacterial disease corresponding to its inherent acidic nature. Most remarkably, ZIF8-RF gives enhanced antibacterial activity against methicillin-resistant Staphylococcus aureus bacteria and also prompts entire damage of structurally robust bacterial biofilms. Overall, the present study depicts a detailed physical insight for manufactured antibiotic-encapsulated NHs presenting tremendous antimicrobial activity that can be beneficial for manifold practical applications.

Large scale validation of a new non-invasive and non-contact bilirubinometer in neonates with risk factors.

The study was aimed to evaluate the performance of a newly developed non-invasive and non-contact bilirubin measurement device (AJO-Neo) as an alternative to the conventional invasive biochemical method of total serum bilirubin (TSB) estimation in preterm and term neonates suffering from hyperbilirubinemia associated with risk factors, and/or undergoing phototherapy. The safety and efficacy of the device were assessed in 1968 neonates with gestational ages ranging from 28 to 41 weeks and suffering from incidences of hyperbilirubinemia. Linear regression analysis showed a good correlation between AJO-Neo and the conventional method of TSB (Pearson's coefficient, r = 0.79). The small bias (0.27 mg/dL) and limits of agreements (- 3.44 to 3.99 mg/dL) were within the range of clinical acceptance. The device was also precise in the measurement of bilirubin levels in all subgroups of the study. The receiver operator curve (ROC), that takes account of both sensitivity and specificity of a device showed high efficacy of the device (area under the curve, AUC = 0.83) in the detection of bilirubin. While monitoring the bilirubin level during phototherapy, the device indicated promising results showing good agreement with TSB. Specificities and sensitivities of the device indicated a much higher accuracy in neonates with associated risk factors for hyperbilirubinemia. Hence, the newly developed device (AJO-Neo) is reliable in measuring bilirubin level in preterm, and term neonates irrespective of gestational or postnatal age, sex, risk factors, feeding behavior or skin color.

Enhanced Water Stability and Photoresponsivity in Metal-Organic Framework (MOF): A Potential Tool to Combat Drug-resistant Bacteria.

In this work, we have successfully synthesized a bimetallic (Zinc and Cobalt) Zeolitic Imidazolate Framework (Zn50Co50-ZIF), a class in a wider microporous Metal-Organic Framework (MOF) family. The synthesized nanostructures maintain both water stability like ZIF-8 (solely Zn containing) and charge transfer electronic band in the visible optical spectrum as ZIF-67 (solely Co containing). Crystal structure from XRD, high resolution transmission electron microscopy (HRTEM) followed by elemental mapping (EDAX) confirm structural stability and omnipresence of the metal atoms (Zn and Co) across the nanomaterial with equal proportion. Existence of charge transfer state consistent with ZIF67 and intact ultrafast excited state dynamics of the imidazolate moiety in both ZIF-8 and ZIF-67, is evidenced from steady state and time resolved optical spectroscopy. The thermal and aqueous stabilities of Zn50Co50-ZIF are found to be better than ZIF-67 but comparable to ZIF-8 as evidenced by solubility, scanning electron microscopy (SEM) and XRD studies of the material in water. We have evaluated the photoinduced ROS generation by the mixed ZIF employing dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay. We have also explored the potentiality of the synthesized material for the alternate remediation of methicillin resistant Staphylococcus aureus (MRSA) infection through the photoinduced reactive oxygen species (ROS) generation and methylene blue (MB) degradation kinetics.