Hollow CoFe Oxide Prisms for Cross-Dehydrogenative Coupling Reactions of 1,2,3,4-Tetrahydroisoquinolines under Mild Conditions.

A three-dimensional hollow CoFe oxide prism catalyst was successfully prepared via a self-template strategy. This bimetallic oxide catalyst demonstrated excellent catalytic activity in cross-dehydrogenative coupling reactions of 1,2,3,4-tetrahydroisoquinolines under mild conditions compared to its monometallic oxide counterparts. A preliminary mechanistic investigation showed the involvement of reactive oxygen species, produced from molecular O2 by the active bimetallic oxide catalyst in the catalytic cycle.

Synthesis and Characterization of Polyaniline Emeraldine Salt (PANI-ES) Colloids Using Potato Starch as a Stabilizer to Enhance the Physicochemical Properties and Processability.

Conductive polymers, such as polyaniline (PANI), have interesting applications, ranging from flexible electronics, energy storage devices, sensors, antistatic or anticorrosion coatings, etc. However, the full exploitation of conductive polymers still poses a challenge due to their low processability. The use of compatible stabilizers to obtain dispersible and stable colloids is among the possible solutions to overcome such drawbacks. In this work, potato starch was used as a steric stabilizer for the preparation of colloidal polyaniline (emeraldine salt, ES)/starch composites by exploiting the oxidative polymerization of aniline in aqueous solutions with various starch-to-aniline ratios. The polyaniline/starch bio-composites were subjected to structural, spectroscopic, thermal, morphological, and electrochemical analyses. The samples were then tested for their dispersibility/solubility in a range of organic solvents. The results demonstrated the formation of PANI/starch biocomposites with a smaller average size than starch particles, showing improved aqueous dispersion and enhanced solubility in organic solvents. With respect to previously reported PANI-EB (emeraldine base)/starch composites, the novel colloids displayed a lower overall crystallinity, but the conductive nature of PANI-ES enhanced its electrochemical properties, resulting in richer redox chemistry, particularly evident in its oxidation behavior, as observed through cyclic voltammetry. Finally, as proof of the improved processability, the colloids were successfully integrated into a thin polyether sulfone (PES) membrane.

Detailed investigation of the binding abilities of the heterodomain of a multiHis cyclopeptide toward Cu(II) ions.

Cyclopeptides hold significant relevance in various fields of science and medicine, due to their unique structural properties and diverse biological activities. Cyclic peptides, characterized by intrinsically higher conformational order, exhibit remarkable stability and resistance to proteolytic degradation, making them attractive candidates for developing targeted drug delivery systems. The aim of this work is to elucidate the unique coordination properties of the multi-His cyclic peptide with c(HDHKHPHHKHHP) sequence (HDCP - heterodomain cyclopeptide). This peptide, indeed, is able to form homo- and hetero-dinuclear complexes in a wide pH range, being thus a good chelator for Cu(II) ions. Herein, we present the results of a combined study, involving potentiometric, spectroscopic (UV-Vis, CD, and EPR), and computational investigations, on its coordination properties. To better understand the interaction pattern with Cu(II) metal ions, two other peptides, each one bearing only one of the two binding domains of HDCP are also considered in this study: c(HDHKHPGGKGGP) = CP1, c(GKGGKPHHKHHP) = CP2, which share sequence fragments of HDCP and allow separate investigations of its coordination domains.

Polymeric Membranes Doped with Halloysite Nanotubes Imaged using Proton Microbeam Microscopy.

Polymeric membranes are useful tools for water filtration processes, with their performance strongly dependent on the presence of hydrophilic dopants. In this study, polyaniline (PANI)-capped aluminosilicate (halloysite) nanotubes (HNTs) are dispersed into polyether sulfone (PES), with concentrations ranging from 0.5 to 1.5 wt%, to modify the properties of the PES membrane. Both undoped and HNT-doped PES membranes are investigated in terms of wettability (static and time-dependent contact angle), permeance, mechanical resistance, and morphology (using scanning electron microscopy (SEM)). The higher water permeance observed for the PES membranes incorporating PANI-capped HNTs is, finally, assessed and discussed vis-à-vis the real distribution of HNTs. Indeed, the imaging and characterization in terms of composition, spatial arrangement, and counting of HNTs embedded within the polymeric matrix are demonstrated using non-destructive Micro Particle Induced X-ray Emission (µ-PIXE) and Scanning Transmission Ion Microscopy (STIM) techniques. This approach not only exhibits the unique ability to detect/highlight the distribution of HNTs incorporated throughout the whole thickness of polymer membranes and provide volumetric morphological information consistent with SEM imaging, but also overcomes the limits of the most common analytical techniques exploiting electron probes. These aspects are comprehensively discussed in terms of practical analysis advantages.

Halloysite Nanotubes as Bimodal Lewis/Brønsted Acid Heterogeneous Catalysts for the Synthesis of Heterocyclic Compounds.

Halloysite nanotubes can be used for the preparation of solid catalysts. Owing to their natural availability at low-cost as well as to their large and easy-to-functionalize surface, they can be conveniently activated with mineral acids or derivatized with acidic groups. Nevertheless, the use of HNTs as catalysts in complex transformations is still limited. Herein, we report two strategies to utilize HNT-based materials as solid acidic catalysts for the Biginelli reaction. To this aim, two methods for increasing the number of acidic sites on the HNTs were explored: (i) the treatment with piranha solution (Pir-HNTs) and (ii) the functionalization with phenylboronic acid (in particular with benzene-1,4-diboronic acid: the sample is denoted as HNT-BOA). Interestingly, both strategies enhance the performance of the multicomponent reaction. Pir-HNTs and HNT-BOA show an increased reactivity (72% and 89% yield, respectively) in comparison with pristine HNTs (52%). Additionally, Pir-HNTs can be reused up to five times without significant performance loss. Moreover, the method also displays good reaction scope, as demonstrated by the preparation of 12 different 3,4-dihydropyrimidinones in up to 71% yield. Therefore, the described strategies are promising for enhancing the acidity of the HNTs as catalysts for the organic reaction.

Fluoropolymer Membranes for Membrane Distillation and Membrane Crystallization.

Fluoropolymer membranes are applied in membrane operations such as membrane distillation and membrane crystallization where hydrophobic porous membranes act as a physical barrier separating two phases. Due to their hydrophobic nature, only gaseous molecules are allowed to pass through the membrane and are collected on the permeate side, while the aqueous solution cannot penetrate. However, these two processes suffer problems such as membrane wetting, fouling or scaling. Membrane wetting is a common and undesired phenomenon, which is caused by the loss of hydrophobicity of the porous membrane employed. This greatly affects the mass transfer efficiency and separation efficiency. Simultaneously, membrane fouling occurs, along with membrane wetting and scaling, which greatly reduces the lifespan of the membranes. Therefore, strategies to improve the hydrophobicity of membranes have been widely investigated by researchers. In this direction, hydrophobic fluoropolymer membrane materials are employed more and more for membrane distillation and membrane crystallization thanks to their high chemical and thermal resistance. This paper summarizes different preparation methods of these fluoropolymer membrane, such as non-solvent-induced phase separation (NIPS), thermally-induced phase separation (TIPS), vapor-induced phase separation (VIPS), etc. Hydrophobic modification methods, including surface coating, surface grafting and blending, etc., are also introduced. Moreover, the research advances on the application of less toxic solvents for preparing these membranes are herein reviewed. This review aims to provide guidance to researchers for their future membrane development in membrane distillation and membrane crystallization, using fluoropolymer materials.

Mechanism of CK2 Inhibition by a Ruthenium-Based Polyoxometalate.

CK2 is a Ser/Thr protein kinase involved in many cellular processes such as gene expression, cell cycle progression, cell growth and differentiation, embryogenesis, and apoptosis. Aberrantly high CK2 activity is widely documented in cancer, but the enzyme is also involved in several other pathologies, such as diabetes, inflammation, neurodegeneration, and viral infections, including COVID-19. Over the last years, a large number of small-molecules able to inhibit the CK2 activity have been reported, mostly acting with an ATP-competitive mechanism. Polyoxometalates (POMs), are metal-oxide polyanionic clusters of various structures and dimensions, with unique chemical and physical properties. POMs were identified as nanomolar CK2 inhibitors, but their mechanism of inhibition and CK2 binding site remained elusive. Here, we present the biochemical and biophysical characterizing of the interaction of CK2α with a ruthenium-based polyoxometalate, [Ru4(µ-OH)2(µ-O)4(H2O)4 (γ-SiW10O36)2]10- (Ru4POM), a potent inhibitor of CK2. Using analytical Size-Exclusion Chromatography (SEC), Isothermal Titration Calorimetry (ITC), and SAXS we were able to unravel the mechanism of inhibition of Ru4POM. Ru4POM binds to the positively-charged substrate binding region of the enzyme through electrostatic interactions, triggering the dimerization of the enzyme which consequently is inactivated. Ru4POM is the first non-peptide molecule showing a substrate-competitive mechanism of inhibition for CK2. On the basis of SAXS data, a structural model of the inactivated (CK2α)2(Ru4POM)2 complex is presented.

Single versus Double Stenting in NSTEMI Patients with Complex Left Main Bifurcation Disease.

Background: Among patients with non-ST-segment elevation myocardial infarction (NSTEMI) the presence of a bifurcation left main (LM) disease represents a particular subset graved by both clinical and technical challenges. We sought to assess the long-term outcomes of patients with NSTEMI treated either by single or double stent strategy, having an LM bifurcation culprit lesion. Methods: We retrospectively analyzed the procedural and medical data of consecutive patients referred to our center for NSTEMI due to complex LM bifurcation disease as the culprit lesion, treated using either single or dual stenting (provisional stenting, T or T-and-Protrusion (TAP), Culotte, and Nano-inverted-T (NIT)) techniques between January 2008 and May 2018. Target lesion failure (TLF) was defined as the composite of cardiovascular death, target-vessel myocardial infarction (MI), and clinically driven target lesion revascularization (TLR). Results: Four hundred and forty-five patients (54.1% males, mean age 70.3 ± 12.8 years, mean Syntax score 31.6 ± 6.3) were evaluated. Of these, 155 patients (34.8%) were treated using a single stent while the remaining were treated with a double stent strategy. After a mean follow-up of 37.1 months (IQR 22.1-39.3), TLF rate was 8.7% (n = 39): 5/155 (3.2%) in the crossover group; 10/53 (18.8%) in T/TAP group, 14/89 (15.7%) in the culotte group, and 10/148 (6.7%) in the NIT group of patients. Cardiovascular mortality rate was 2.9% (n = 13) while stent thrombosis was 0.89% (n = 4). On multivariate analysis dyslipidemia, Syntax score > 25, triple vessel disease, additional LM ostial, or LM body lesions and the use of Rotablator, were independent predictors of TLF. Conclusions: Either a single or double stent strategy resulted in low rates of TLF, cardiovascular death, and stent thrombosis in the long-term period in NSTEMI LM patients with contraindications or refusal of surgery. A single stent strategy appeared to have a slightly better outcome compared to a 2-stent strategy.

Physicochemical Properties and Atomic-Scale Interactions in Polyaniline (Emeraldine Base)/Starch Bio-Based Composites: Experimental and Computational Investigations.

The processability of conductive polymers still represents a challenge. The use of potato starch as a steric stabilizer for the preparation of stable dispersions of polyaniline (emeraldine base, EB) is described in this paper. Biocomposites are obtained by oxidative polymerization of aniline in aqueous solutions containing different ratios of aniline and starch (% w/w). PANI-EB/Starch biocomposites are subjected to structural analysis (UV-Visible, RAMAN, ATR, XRD), thermal analysis (TGA, DSC), morphological analysis (SEM, Laser Granulometry), and electrochemical analysis using cyclic voltammetry. The samples were also tested for their solubility using various organic solvents. The results showed that, with respect to starch particles, PANI/starch biocomposites exhibit an overall decrease in particles size, which improves both their aqueous dispersion and solubility in organic solvents. Although X-ray diffraction and DSC analyses indicated a loss of crystallinity in biocomposites, the cyclic voltammetry tests revealed that all PANI-EB/Starch biocomposites possess improved redox exchange properties. Finally, the weak interactions at the atomic-level interactions between amylopectin-aniline and amylopectin-PANI were disclosed by the computational studies using DFT, COSMO-RS, and AIM methods.

Tuning the Activity of a Hybrid Polymer-Oxocluster Catalyst: A Composition-Selectivity Correlation.

Zr-based oxoclusters MxOy(OR)w(OOR')z are promising catalysts for the activation of hydrogen peroxide. However, they need to be integrated into suitable matrices to increase their hydrolytic stability and allow for their recovery after use. Polymeric materials can be successfully employed for this aim, since they modify the properties of the resulting hybrid materials, in terms of polarity and chemical affinity for the substrates, improving the catalytic activity. Herein, we report the synthesis of different acrylic polymers based on various co-monomers (methyl methacrylate (MMA), 2,2,2-trifluoroethylmethacrylate (TFMA) and 3-methacryloxypropyltrimethoxylsilane (MAPTMS)) covalently cross-linked by a Zr4-based oxocluster, whose composition was tuned to optimise the catalytic oxidation of methyl p-tolyl sulphide. To assess their properties and stability, the materials were characterised via Fourier Transform Infrared (FT-IR) and Raman spectroscopies, Thermogravimetric Analysis (TGA), Solid-State NMR (SS-NMR) and X-Ray Absorption Spectroscopies XAS, before and after catalytic turnover.

Enhancing the biological activity of polyoxometalate-peptide nano-fibrils by spacer design.

Polyoxometalates (POMs) and peptides can be conjugated to yield novel bio-hybrids with potential application as nanodrugs. However, the observed POM-induced folding of the peptide prevents its availability towards biological targets. An Anderson-Evans POM was functionalized with a bombesin analog peptide and engineered by adding a tailored hydrophilic and anionic spacer between the two moieties, to make the targeting sequence more accessible and enable an unprecedented cancer cell recognition capability.

Catalytic processing in ruthenium-based polyoxometalate coacervate protocells.

The development of programmable microscale materials with cell-like functions, dynamics and collective behaviour is an important milestone in systems chemistry, soft matter bioengineering and synthetic protobiology. Here, polymer/nucleotide coacervate micro-droplets are reconfigured into membrane-bounded polyoxometalate coacervate vesicles (PCVs) in the presence of a bio-inspired Ru-based polyoxometalate catalyst to produce synzyme protocells (Ru4PCVs) with catalase-like activity. We exploit the synthetic protocells for the implementation of multi-compartmentalized cell-like models capable of collective synzyme-mediated buoyancy, parallel catalytic processing in individual horseradish peroxidase-containing Ru4PCVs, and chemical signalling in distributed or encapsulated multi-catalytic protocell communities. Our results highlight a new type of catalytic micro-compartment with multi-functional activity and provide a step towards the development of protocell reaction networks.

The QR-max index, a novel electrocardiographic index for the determination of left ventricular conduction delay and selection of cardiac resynchronization in patients with non-left bundle branch block.

Non-left bundle branch block (non-LBBB) remains an uncertain indication for cardiac resynchronization therapy (CRT). Non-LBBB includes right bundle branch block (RBBB) and non-specific LV conduction delay (NSCD), two different electrocardiogram (ECG) patterns which are not generally considered to be associated with LV conduction delay as judged by the invasive assessment of the Q-LV interval. We evaluated whether a novel ECG interval (QR-max index) correlated with the degree of LV conduction delay regardless of the type of non-LBBB ECG pattern, and could, therefore, predict CRT response. In 173 non-LBBB patients on CRT (92 NSCD, 81 RBBB), the QR-max index was measured as the maximum interval from QRS onset to R-wave offset in the limb leads. The correlation between QR-max index and Q-LV interval and the impact of the QR-max index on time to first heart failure hospitalization during 3-year follow-up were assessed. Q-LV correlated better with the QR-max index than with QRSd, particularly in the RBBB group (r = 0.91; p < 0.001 vs. r = 0.19; p < 0.089), while the correlations were r = 0.79 (p < 0.01) and r = 0.68 (p < 0.01), respectively, in the NSCD group. In both groups, the QR-max index was significantly more able than QRSd to identify CRT responders (AUC 0.825 vs. 0.576; p = 0.0008 in RBBB; AUC 0.738 vs. 0.701; p = 0.459 in NSCD). A QR-max index exceeding a cutoff value of 120 ms was associated with CRT response, with predictive values of 86.8 and 81.4% in RBBB and NSCD, respectively. The QR-max index reflects the degree of LV electrical delay regardless of QRS duration in RBBB and NSCD patients and is a useful indicator of suitability for CRT in non-LBBB patients.

Mechanisms of Myocardial Ischemia Inducing Sudden Cardiac Death in Athletes with Anomalous Coronary Origin from the Opposite Sinus: Insights from a computational fluid dynamic study.

AIMS: The left coronary anomalous origin from the opposite sinus (L- ACAOS) constitutes the most clinically relevant arterial abnormality among the wide spectrum of coronary artery anomalies. We investigated the physiology of L-ACAOS with and without intramural course (IM) in athletes, using the computational fluid dynamic (CFD) analysis. METHODS AND RESULTS: The coronary artery circulation with L-ACAOS with and without IM has been segmented and then reconstructed, after reviewing both the angiographic and computed tomography findings of 13 consecutive athletes (10 males, mean age 45.1 ±â€¯8.2 years) with L-ACAOS collected in our institution between 1st January 2003 and 1st January 2018. Vorticity magnitude, static pressure and wall shear stress (WSS) have been analysed in a model of L-ACAOS with no IM course and in L-ACAOS-IM at rest and during exercise. The mean vorticity magnitude and WSS significantly increased from rest to exercise in both models, in right coronary artery, left anterior descending and left circumflex coronary arteries. The mean static pressure significantly increased with exercise in IM (1.118e + 004 vs 1.164e + 004 Pa, p < 0.001) as well as the mean vorticity magnitude and the mean WSS (7012.78 1/s vs 9019.56 1/s, p < 0.001, Δ = 2006.78 1/s and 3.02 Pa vs 2.11 Pa, p < 0.001, Δ = 0.91 Pa). This net increment was transmitted to the entire left coronary system in L-ACAOS-IM but not in L-ACAOS with no IM. CONCLUSIONS: In L-ACAOS, different hemodynamic parameters observed in the intramural segment seem to confirm that IM is compressed during exercise. These rheological properties might propagated along the left coronary system, potentially predisposing, if confirmed in vivo, distal coronary segments to a higher risk of spasm and thrombosis in athletes.

Long-Term Clinical Outcomes of Isolated Ostial Left Anterior Descending Disease Treatment: Ostial Stenting Versus Left Main Cross-Over Stenting.

BACKGROUND: The optimal strategy for treating ostial left anterior descending coronary artery (LAD) disease remains matter of speculation. We evaluated the impact on long-term outcomes of ostial LAD disease treated by means of ostial stenting (the floating-stent) or left main (LM)-to-LAD cross-over stenting. METHODS: Clinical and instrumental records of 74 consecutive patients with isolated ostial LAD disease, enrolled between the 1st January 2012 and the 1st January 2017 were reviewed. Patients have been stratified according the stenting techniques adopted: ostial stenting (OS) or LM cross-over (CO). RESULTS: Seventy-four consecutive patients (54 males, mean age 73.39 ±â€¯9.54 years old) have been analyzed. In CO patients the SYNTAX score (16.2 ±â€¯3.3 vs 24.1 ±â€¯2.5, p < 0.0001) and the percentages of rotablation resulted higher than in OS group. IVUS has been predominantly used in CO groups revealing a significant extension of plaque burden of at least 10 mm of LM proximal to the LAD ostium in all the 18 out of 21 patients (85.7%) undergone IVUS-guided procedure. Fluoroscopy time and contrast medium volume were higher in OS versus CO group of patients. On a mean follow-up of 49.7 ±â€¯7.9 months, MACE and target vessel revascularization (TVR) were 21.0% and 21.0% in OS groups versus 10.1 and 5.6% in the CO group (p = 0.20 and p = 0.04, respectively). Restenosis was higher in the OS than in CO group of patients and was located angiographically at the ostium. CONCLUSIONS: On long-term follow-up CO seems to be superior to OS technique for isolated ostial LAD disease especially in the presence of heavy calcification.

Systemic thrombolysis in haemodynamically unstable pulmonary embolism: The earlier the better?

INTRODUCTION: The temporal window for the administration of systemic thrombolysis (ST) in acute pulmonary embolism (PE) has not yet been clarified. We assessed the relationship between short-term cardiovascular (CV) mortality and time of ST administration. MATERIAL AND METHODS: Among 394 consecutive patients admitted between January 2010 and June 2017 with a confirmed PE, we retrospectively review the clinical and instrumental data of those labelled as high-risk PE (n = 76, 41 males, mean aged 64.7 ±â€¯9.1 years old). RESULTS: A receiving operating curve (ROC) analysis established the optimal temporal threshold for the administration of the ST, in respect to the 30-day CV mortality at 8.5 h from the symptom onset (Area under Curve 0.79 ±â€¯0.6, 95% CI 0.73-0.86, p < 0.0001). Mantel-Cox analysis showed that there was a significant difference in the distribution of survival between patients treated within 8.5 h from the beginning of symptoms onset to those treated after 8.6 h [log rank (Mantel-Cox) chi-square 9.68 p = 0.002]. Cox-regression analysis demonstrated that the administration of ST after 8.6 h from the symptom's onset was an independent predictor of 30-day CV mortality in high-risk PE patients (HR 7.81, 95% CI 1.84-33.05, p = 0.005), independently from the occurrence of major bleeding events (HR 5.89, 95% CI 1.38-25.13, p = 0.01), previous CAD (HR 3.31, 95& CI 1.07-10.231. p = 0.03), RV/LV ratio after 2 h from the administration ST > 1 (HR (12.91, 95% CI 3.04-54.77, p = 0.001) and PAH at discharge (HR 3.86, 95% CI 2.22-4.68, p = 0.002). CONCLUSIONS: ST administered within 8.5 h from symptoms onset may be associated with a reduced 30-day CV mortality in high-risk PE patients.

Culotte versus the novel nano-crush technique for unprotected complex bifurcation left main stenting: difference in procedural time, contrast volume and X-ray exposure and 3-years outcomes.

To assess the procedural performance and 3-years outcomes of unprotected complex bifurcation Left Main (LM) stenting using either Culotte or the novel nano-crush techniques, consisting in the use of two ultra-thin strut stents with a 1-ring stent crushed into the LM. We analysed the records of patients with complex distal/bifurcation LM disease and contraindications and/or refusal of bypass surgery, who from 1 January 2014 to 1 November 2017, received at operators' discretion LM double stenting by means of nano-crush technique using Orsiro (Biotronik Inc, Bulack, Switzerland) or Onyx (Medtronic Inc, Galway, Ireland) stents or Culotte stenting using same stent platforms. Among 65 patients (28 females, mean age 77.2 ± 6.2 years), 32 received nano-crush while 33 patients received Culotte technique. Mean angles between left anterior descending coronary artery and left circumflex was 63.6 ± 21.3°. Post-operative success was achieved in 100% of cases. Nano-crush patients showed lower contrast medium volume and X-ray exposure, shorter fluoroscopy and procedural times compared to Culotte patients group. At a mean follow-up of 27.4 ± 10.8 months, clinical-driven target lesion revascularization, myocardial infarction and cardiovascular death were 0 versus 4/33 (12.1%, p = 0.04), 1/32 (3.1%) versus 6/33 (18.1%, p = 0.03) and 2/32 (6.2%) versus 8/33 (24.2%, p = 0.04) in nano-crush versus Culotte patients, respectively. In this single center study, the nano-crush technique was associated with less use of contrast, less procedural time and less X-ray exposure compared to the culotte technique for the treatment of unprotected left main bifurcation lesions.

Selective Targeting of Proteins by Hybrid Polyoxometalates: Interaction Between a Bis-Biotinylated Hybrid Conjugate and Avidin.

The Keggin-type polyoxometalate [γ-SiW10O36]8- was covalently modified to obtain a bis-biotinylated conjugate able to bind avidin. Spectroscopic studies such as UV-vis, fluorimetry, circular dichroism, coupled to surface plasmon resonance technique were used to highlight the unique interplay of supramolecular interactions between the homotetrameric protein and the bis-functionalized polyanion. In particular, the dual recognition mechanism of the avidin encompasses (i) a complementary electrostatic association between the anionic surface of the polyoxotungstate and each positively charged avidin subunit and (ii) specific host-guest interactions between each biotinylated arm and a corresponding pocket on the tetramer subunits. The assembly exhibits peroxidase-like reactivity and it was used in aqueous solution for L-methionine methyl ester oxidation by H2O2. The recognition phenomenon was then exploited for the preparation of layer-by-layer films, whose structural evolution was monitored in situ by ATR-FTIR spectroscopy. Finally, cell tracking studies were performed by exploiting the specific interactions with a labeled streptavidin.

Highly Sensitive Membrane-Based Pressure Sensors (MePS) for Real-Time Monitoring of Catalytic Reactions.

Functional, flexible, and integrated lab-on-chips, based on elastic membranes, are capable of fine response to external stimuli, so to pave the way for many applications as multiplexed sensors for a wide range of chemical, physical and biomedical processes. Here, we report on the use of elastic thin membranes (TMs), integrated with a reaction chamber, to fabricate a membrane-based pressure sensor (MePS) for reaction monitoring. In particular, the TM becomes the key-element in the design of a highly sensitive MePS capable to monitor gaseous species production in dynamic and temporally fast processes with high resolution and reproducibility. Indeed, we demonstrate the use of a functional MePS integrating a 2 µm thick polydimethylsiloxane TM by monitoring the dioxygen evolution resulting from catalytic hydrogen peroxide dismutation. The operation of the membrane, explained using a diffusion-dominated model, is demonstrated on two similar catalytic systems with catalase-like activity, assembled into polyelectrolyte multilayers capsules. The MePS, tested in a range between 2 and 50 Pa, allows detecting a dioxygen variation of the µmol L-1 s-1 order. Due to their structural features, flexibility of integration, and biocompatibility, the MePSs are amenable of future development within advanced lab-on-chips.

Facile Access to Amides from Oxygenated or Unsaturated Organic Compounds by Metal Oxide Nanocatalysts Derived from Single-Source Molecular Precursors.

Oxidative amidation is a valuable process for the transformation of oxygenated organic compounds to valuable amides. However, the reaction is severely limited by the use of an expensive catalyst and limited substrate scope. To circumvent these limitations, designing a transition-metal-based nanocatalyst via more straightforward and economical methodology with superior catalytic performances with broad substrate scope is desirable. To resolve the aforementioned issues, we report a facile method for the synthesis of nanocatalysts NiO and CuO by the sol-gel-assisted thermal decomposition of complexes [Ni(hep-H)(H2O)4]SO4 (SSMP-1) and [Cu(µ-hep)(BA)]2 (SSMP-2) [hep-H = 2-(2-hydroxylethyl)pyridine; BA = benzoic acid] as single-source molecular precursors (SSMPs) for the oxidative amidation of benzyl alcohol, benzaldehyde, and BA by using N,N-dimethylformamide (DMF) as the solvent and as an amine source, in the presence of tert-butylhydroperoxide (TBHP) as the oxidant, at T = 80 °C. In addition to nanocatalysts NiO and CuO, our previously reported Co/CoO nanocatalyst (CoNC), derived from the complex [CoII(hep-H)(H2O)4]SO4 (A) as an SSMP, was also explored for the aforementioned reaction. Also, we have carefully investigated the difference in the catalytic performance of Co-, Ni-, and Cu-based nanoparticles synthesized from the SSMP for the conversion of various oxygenated and unsaturated organic compounds to their respective amides. Among all, CuO showed an optimum catalytic performance for the oxidative amidation of various oxygenated and unsaturated organic compounds with a broad reaction scope. Finally, CuO can be recovered unaltered and reused for several (six times) recycles without any loss in catalytic activity.