Retention Of Activity Research Articles

Support Materials of Organic and Inorganic Origin as Platforms for Horseradish Peroxidase Immobilization: Comparison Study for High Stability and Activity Recovery.

In the presented study, a variety of hybrid and single nanomaterials of various origins were tested as novel platforms for horseradish peroxidase immobilization. A thorough characterization was performed to establish the suitability of the support materials for immobilization, as well as the activity and stability retention of the biocatalysts, which were analyzed and discussed. The physicochemical characterization of the obtained systems proved successful enzyme deposition on all the presented materials. The immobilization of horseradish peroxidase on all the tested supports occurred with an efficiency above 70%. However, for multi-walled carbon nanotubes and hybrids made of chitosan, magnetic nanoparticles, and selenium ions, it reached up to 90%. For these materials, the immobilization yield exceeded 80%, resulting in high amounts of immobilized enzymes. The produced system showed the same optimal pH and temperature conditions as free enzymes; however, over a wider range of conditions, the immobilized enzymes showed activity of over 50%. Finally, a reusability study and storage stability tests showed that horseradish peroxidase immobilized on a hybrid made of chitosan, magnetic nanoparticles, and selenium ions retained around 80% of its initial activity after 10 repeated catalytic cycles and after 20 days of storage. Of all the tested materials, the most favorable for immobilization was the above-mentioned chitosan-based hybrid material. The selenium additive present in the discussed material gives it supplementary properties that increase the immobilization yield of the enzyme and improve enzyme stability. The obtained results confirm the applicability of these nanomaterials as useful platforms for enzyme immobilization in the contemplation of the structural stability of an enzyme and the high catalytic activity of fabricated biocatalysts.

Uranium biomineralization by immobilized Chryseobacterium sp. strain PMSZPI cells for efficient uranium removal

Uranium (U) contamination is hazardous to human health and the environment owing to its radiotoxicity and chemical toxicity and needs immediate attention. In this study, the immobilized biomass of Chryseobacterium sp. strain PMSZPI isolated from U enriched site, was investigated for U(VI) biomineralization in batch and column set-up. Under batch mode, the fresh or lyophilized cells successfully entrapped in calcium alginate beads demonstrated effectual U precipitation under acid and alkaline conditions. The maximum removal was detected at pH 7 wherein ∼98–99% of uranium was precipitated from 1 mM uranyl carbonate solution loading ∼350 mg U/g of biomass within 24 h in the presence of organic phosphate substrate. The resulting uranyl phosphate precipitates within immobilized biomass loaded beads were observed by SEM-EDX and TEM while the formation of U biomineral was confirmed by FTIR and XRD. Retention of phosphatase activity without any loss of uranium precipitation ability was observed for alginate beads with lyophilized biomass stored for 90 d at 4 °C. Continuous flow through experiment with PMSZPI biomass immobilized in polyacrylamide gel exhibited U loading of 0.8 g U/g of biomass at pH 7 using 1 l of 1 mM uranyl solution. This investigation established the feasibility for the application of immobilized PMSZPI biomass for field studies. Environmental implicationUranium contamination is currently a serious environmental concern owing to anthropogenic activities and needs immediate attention. We have developed here a biotechnological method for successful uranium removal using immobilized cells of a uranium tolerant environmental bacterium, Chryseobacterium sp. strain PMSZPI isolated from U ore deposit via phosphatase enzyme mediated uranium precipitation. The ability of immobilized PMSZPI cells to precipitate U(VI) as long-term stable U phosphates under environmental conditions relevant for contaminated waters containing high concentrations of U that exerts toxicity for biological systems is explored here. The long term stability of the immobilized biomass without compromising its U removal capacity shows the relevance of the bioremediation strategy for uranium contamination proposed in this work.

Low‐Electronegativity Mn‐Contraction of PtMn Nanodendrites Boosts Oxygen Reduction Durability

AbstractPlatinum metal (PtM, M=Ni, Fe, Co) alloys catalysts show high oxygen reduction reaction (ORR) activity due to their well‐known strain and ligand effects. However, these PtM alloys usually suffer from a deficient ORR durability in acidic environment as the alloyed metal is prone to be dissolved due to its high electronegativity. Herein, we report a new class of PtMn alloy nanodendrite catalyst with low‐electronegativity Mn‐contraction for boosting the oxygen reduction durability of fuel cells. The moderate strain in PtMn, induced by Mn contraction, yields optimal oxygen reduction activity at 0.53 A mg−1 at 0.9 V versus reversible hydrogen electrode (RHE). Most importantly, we show that relative to well‐known high‐electronegativity Ni‐based Pt alloy counterpart, the PtMn nanodendrite catalyst experiences less transition metals’ dissolution in acidic solution and achieves an outstanding mass activity retention of 96 % after 10,000 degradation cycles. Density functional theory calculation reveals that PtMn alloys are thermodynamically more stable than PtNi alloys in terms of formation enthalpy and cohesive energy. The PtMn nanodendrite‐based membrane electrode assembly delivers an outstanding peak power density of 1.36 W cm−2 at a low Pt loading and high‐performance retention over 50 h operations at 0.6 V in H2‐O2 hydrogen fuel cells.

Low-Electronegativity Mn-Contraction of PtMn Nanodendrites Boosts Oxygen Reduction Durability.

Platinum metal (PtM, M=Ni, Fe, Co) alloys catalysts show high oxygen reduction reaction (ORR) activity due to their well-known strain and ligand effects. However, these PtM alloys usually suffer from a deficient ORR durability in acidic environment as the alloyed metal is prone to be dissolved due to its high electronegativity. Herein, we report a new class of PtMn alloy nanodendrite catalyst with low-electronegativity Mn-contraction for boosting the oxygen reduction durability of fuel cells. The moderate strain in PtMn, induced by Mn contraction, yields optimal oxygen reduction activity at 0.53 A mg-1 at 0.9 V versus reversible hydrogen electrode (RHE). Most importantly, we show that relative to well-known high-electronegativity Ni-based Pt alloy counterpart, the PtMn nanodendrite catalyst experiences less transition metals' dissolution in acidic solution and achieves an outstanding mass activity retention of 96 % after 10,000 degradation cycles. Density functional theory calculation reveals that PtMn alloys are thermodynamically more stable than PtNi alloys in terms of formation enthalpy and cohesive energy. The PtMn nanodendrite-based membrane electrode assembly delivers an outstanding peak power density of 1.36 W cm-2 at a low Pt loading and high-performance retention over 50 h operations at 0.6 V in H2 -O2 hydrogen fuel cells.

Rare Earth Evoked Subsurface Oxygen Species in Platinum Alloy Catalysts Enable Durable Fuel Cells

AbstractAlleviating the degradation issue of Pt based alloy catalysts, thereby simultaneously achieving high mass activity and high durability in proton exchange membrane fuel cells (PEMFCs), is highly challenging. Herein, we provide a new paradigm to address this issue via delaying the place exchange between adsorbed oxygen species and surface Pt atoms, thereby inhibiting Pt dissolution, through introducing rare earth bonded subsurface oxygen atoms. We have succeeded in introducing Gd−O dipoles into Pt3Ni via a high temperature entropy‐driven process, with direct spectral evidence attained from both soft and hard X‐ray absorption spectroscopies. The higher rated power of 0.93 W cm−2 and superior current density of 562.2 mA cm−2 at 0.8 V than DOE target for heavy‐duty vehicles in H2‐air mode suggest the great potential of Gd−O−Pt3Ni towards practical application in heavy‐duty transportation. Moreover, the mass activity retention (1.04 A mgPt−1) after 40 k cycles accelerated durability tests is even 2.4 times of the initial mass activity goal for DOE 2025 (0.44 A mgPt−1), due to the weakened Pt−Oads bond interaction and the delayed place exchange process, via repulsive forces between surface O atoms and those in the sublayer. This work addresses the critical roadblocks to the widespread adoption of PEMFCs.

Rare Earth Evoked Subsurface Oxygen Species in Platinum Alloy Catalysts Enable Durable Fuel Cells.

Alleviating the degradation issue of Pt based alloy catalysts, thereby simultaneously achieving high mass activity and high durability in proton exchange membrane fuel cells (PEMFCs), is highly challenging. Herein, we provide a new paradigm to address this issue via delaying the place exchange between adsorbed oxygen species and surface Pt atoms, thereby inhibiting Pt dissolution, through introducing rare earth bonded subsurface oxygen atoms. We have succeeded in introducing Gd-O dipoles into Pt3 Ni via a high temperature entropy-driven process, with direct spectral evidence attained from both soft and hard X-ray absorption spectroscopies. The higher rated power of 0.93 W cm-2 and superior current density of 562.2 mA cm-2 at 0.8 V than DOE target for heavy-duty vehicles in H2 -air mode suggest the great potential of Gd-O-Pt3 Ni towards practical application in heavy-duty transportation. Moreover, the mass activity retention (1.04 A mgPt -1 ) after 40 k cycles accelerated durability tests is even 2.4 times of the initial mass activity goal for DOE 2025 (0.44 A mgPt -1 ), due to the weakened Pt-Oads bond interaction and the delayed place exchange process, via repulsive forces between surface O atoms and those in the sublayer. This work addresses the critical roadblocks to the widespread adoption of PEMFCs.

New insights into the enhanced CO2RR durability caused by electron-donating substitution of heterogeneous CoPc

Enhanced long-term CO2RR electrolysis durability with heterogeneous CoPc–NH2, is derived from the activity retention along with ligand hydrogenation based on the unfolding–folding mechanism.

Antimicrobial nanocomposite coatings for rapid intervention against catheter-associated urinary tract infections.

Catheter-associated urinary tract infections (CAUTIs) pose a significant challenge in hospital settings. Current solutions available on the market involve incorporating antimicrobials and antiseptics into catheters. However, challenges such as uncontrolled release leading to undesirable toxicity, as well as the prevalence of antimicrobial resistance reduce the effectiveness of these solutions. Additionally, conventional antibiotics fail to effectively eradicate entrenched bacteria and metabolically suppressed bacteria present in the biofilm, necessitating the exploration of alternative strategies. Here, we introduce a novel polymer-nanocomposite coating that imparts rapid antimicrobial and anti-biofilm properties to coated urinary catheters. We have coated silicone-based urinary catheters with an organo-soluble antimicrobial polymer nanocomposite (APN), containing hydrophobic quaternized polyethyleneimine and zinc oxide nanoparticles, in a single step coating process. The coated surfaces exhibited rapid eradication of drug-resistant bacteria within 10-15 min, including E. coli, K. pneumoniae, MRSA, and S. epidermidis, as well as drug-resistant C. albicans fungi. APN coated catheters exhibited potent bactericidal activity against uropathogenic strains of E. coli, even when incubated in human urine. Furthermore, the stability of the coating and retention of antimicrobial activity was validated even after multiple washes. More importantly, this coating deterred biofilm formation on the catheter surface, and displayed rapid inactivation of metabolically repressed stationary phase and persister cells. The ability of the coated surfaces to disrupt bacterial membranes and induce the generation of intracellular reactive oxygen species (ROS) was assessed through different techniques, such as electron microscopy imaging, flow cytometry as well as fluorescence spectroscopy and microscopy. The surface coatings were found to be biocompatible in an in vivo mice model. Our simple one-step coating approach for catheters holds significant potential owing to its ability to tackle multidrug resistant bacteria and fungi, and the challenge of biofilm formation. This work brings us one step closer to enhancing patient care and safety in hospitals.

Coffee Pulp Activated Carbon for Immobilizing Cellulase from Aspergillus niger ICP2: Enhancing Enzyme Stability, Activity, and Its Reusability

Cellulase from Aspergillus niger ICP2 was successfully immobilized on coffee pulp activated carbon using adsorption. Carbon was derived from coffee pulp via controlled carbonization at 200 °C for 2 hours, followed by activation with 3M ZnCl2 for 150 minutes. Reusability analysis exhibited over 50% relative activity retention after four cycles. The immobilized cellulase demonstrated stability at pH 4.0-6.0, retaining over 80% relative activity after 4 hours at 37℃. This approach proves economical for enhancing cellulase stability, activity, and reusability.

Reduction of renal activity retention of radiolabeled albumin binding domain‑derived affinity proteins using a non‑residualizing label strategy compared with a cleavable glycine‑leucine‑glycine‑lysine‑linker.

The feasibility of targeted imaging and therapy using radiolabeled albumin‑binding domain‑derived affinity proteins (ADAPTs) has been demonstrated. However, high renal uptake of radioactivity limits the maximum tolerated dose. Successful reduction of renal retention of radiolabeled Fab fragments has been demonstrated by incorporating a cleavable linker between the targeting agent and the radiometal chelator. The present study investigated if the introduction of a glycine‑leucine‑glycine‑lysine (GLGK)‑linker would reduce the kidney uptake of radiolabeled ADAPT6 and also compared it with the non‑residualizing [125I]I‑[(4‑hydroxyphenyl)ethyl]maleimide ([125I]I‑HPEM) labeling strategy. GLGK was site‑specifically coupled to human epidermal growth factor receptor 2 (HER2)‑targeting ADAPT6. Conjugates without the cleavable linker were used as controls and all constructs were labeled with lutetium‑177 (177Lu). [125I]I‑HPEM was coupled to ADAPT6 at the C‑terminus. Biodistribution of all constructs was evaluated in NMRI mice 4h after injection. Specific binding to HER2‑expressing cells invitro was demonstrated for all constructs. No significant difference in kidney uptake was observed between the [177Lu]Lu‑2,2',2",2"'‑(1,4,7,10‑tetraazacyclododecane‑1,4,7,10‑tetrayl)tetraacetic acid‑GLGK‑conjugates and the controls. The renal activity of [125I]I‑HPEM‑ADAPT6 was significantly lower compared with all other constructs. In conclusion, the incorporation of the cleavable GLGK‑linker did not result in lower renal retention. Therefore, the present study emphasized that, in order to achieve a reduction of renal retention, alternative molecular design strategies may be required for different targeting agents.

Fabrication of long-term stable electrochromic device based on high-quality PEDOT film

As one of representative conducting polymers (CPs), poly(3,4-ethylenedioxythiophene) (PEDOT) possesses fascinating electrochromic properties and commercial applications, but it suffers from the poor cycling stability in the charge-discharge process. In this work, we adopted a dual-approach mode to prepare high-quality PEDOT film in boron trifluoride etherate (BFEE) system via reducing the initial oxidation potential (Eonset) of 3,4-ethylenedioxythiophene (EDOT) monomers to increasing the conjugation degree of PEDOT films and no requiring the addition of other supporting electrolytes to protect the initial structure of PEDOT films. The Eonset of EDOT monomers in BFEE system was only 0.5 V, which was much smaller than other systems reported (1.00–1.26 V). The obtained PEDOT film with porous structure showed remarkable stability with an electrochemical activity retention rate of 91.5% after 190,000 cycles, and that of its electrochromic device (ECD) was 94.23% after 41,000 s. During the redox process, ECD had three color transformations (brown red, cyan, and blue) and the oxidation time and the reduction time were 0.4 s and 1.2 s, respectively. The calculated CE value reached 120 cm2 C−1. All these results suggest that the dual-approach mode can significantly enhance the quality of PEDOT film and thus enhance its cycling stability. In addition to that, the dual-approach mode can provide an effective strategy for the design of highly stable CPs for fabricating long-term stable ECD.

TiNxOy/TiN Supported Ir-Oxide/Ir As Efficient OER Electrocatalyst for Acidic Water Electrolysis

Increasing the mass activity of Iridium-based electrocatalysts for oxygen evolution reaction (OER) is of significant importance for sustainable acidic water electrolyzers generating green hydrogen. Here, we have studied surface oxidized TiN (TiNxOy/TiN) as a catalyst support for Ir-based OER electrocatalysts with high mass activity. TiNxOy/TiN supported Ir-oxide/Ir nanoparticles were synthesized using a microwave-assisted approach. The synthesized IrO2@Ir/TiN with an Ir loading of 40 wt% exhibits a mass-normalized OER activity of ~2.4 times that of a commercial benchmark IrO2 OER electrocatalyst. The synthesized TiNxOy/TiN supported Ir-oxide/Ir catalyst, owing to superior utilization of the active catalyst surface and improved intrinsic activity through catalyst-support interaction, enables significant (~60 wt.%) reduction in the Ir metal loading required to obtain equivalent OER performance, compared to commercial benchmark. In addition, accelerated stress test (AST) involving potential cycling in acidic media suggest the IrO2@Ir/TiN catalyst to be of relatively higher durability (activity retention: 79%) compared to that of the commercial equivalent (activity retention: 66%). In the presentation, we discuss the findings focusing on impacts of surface chemistry of the synthesized catalysts on their mass-activity and the degradation mechanisms during AST. The study opens a new perspective for further research towards development of low-Ir loading OER electrocatalysts. Reference Karade, S. S.; Sharma, R.; Gyergyek, S.; Morgen, P.; Andersen, S. M., ChemCatChem 2023, e202201470, DOI: https://doi.org/10.1002/cctc.202201470.

(Invited) Durable Hybrid Electrocatalysts for Fuel Cells

Proton exchange membrane fuel cell converts hydrogen and oxygen into electricity with zero emission. The high cost and low durability of Pt-based electrocatalysts for oxygen reduction reaction hinder its wide applications. The development of non-precious metal electrocatalysts also reaches the bottleneck because of the low activity and durability. Here we rationally design a hybrid electrocatalyst consisting of atomically dispersed Pt and Fe single atoms and Pt-Fe alloy nanoparticles. The Pt mass activity of the hybrid catalyst is 3.7 times higher than that of commercial Pt/C in a fuel cell. More importantly, the fuel cell with an ultra-low Pt loading in the cathode (0.015 mgPt cm-2) shows excellent durability, with 97 % activity retention after 100,000 cycles and no noticeable current drop at 0.6 V for over 200 h. These results highlight the importance of the synergistic effects among active sites in hybrid electrocatalysts and provide an alternative way to design more active and durable low-Pt electrocatalysts for electrochemical devices.

Structural Effects on ORR Performances of Carbon-Free Connected Platinum–Cobalt Catalysts with Chemically Ordered Superlattice Structures

Polymer electrolyte fuel cells (PEFCs) have been considered as the promising next-generation energy-conversion technology, owing to their high energy efficiency and clean emissions. However, a sluggish oxygen reduction reaction (ORR) rate and the low durability of conventional catalysts in PEFCs limit the wider commercialization. To address these issues, our group has developed a carbon-free, connected Pt1–Fe1 catalyst with a porous hollow capsule structure. This catalyst comprises the nano-sized network formed by the connection of Pt1–Fe1 nanoparticles and exhibits an enhanced ORR specific activity (9 times higher than a commercial Pt/C) as well as excellent durability against start-stop operations due to the carbon-free structure.[1,2] However, during the load cycle operation, iron is dissolved from the catalyst, leading to the loss of ORR activity and the degradation of polymer electrolytes caused by the Fenton reaction.In this work, carbon-free and iron-free connected Ptx-Co1 catalysts with chemically ordered superlattice structures have been developed for the first time, as shown in Fig. 1(a). In addition, the metal compositions and chemically ordered (superlattice) degrees in the catalysts were controlled to investigate the structural effects on ORR activity and durability of the connected Ptx-Co1 catalysts.Herein, we employed the silica-coating method for the catalyst synthesis, which involves the combination of silica coating and high-temperature annealing. As shown in Fig. 1(b), the surface of the Ptx-Co1 nanoparticles/SiO2 sample was coated with thin silica layers to prevent the detachment of Ptx–Co1 nanoparticles from the SiO2 template as well as the large catalyst agglomeration and coalescence during the annealing process. We controlled the chemically ordered degrees of the connected Pt1–Co1 and Pt3–Co1 catalysts by using different annealing temperatures. The XRD patterns of the catalysts showed the peaks corresponding to L10 type and L12 type chemically ordered structures for the connected Pt1–Co1 and Pt3–Co1 catalysts annealed at 600°C, respectively. These two catalysts possessed ordered degrees (S) of ca. 50–60%. The TEM images of the connected Ptx–Co1 catalysts showed the formation of connected Ptx–Co1 nanonetwork and porous hollow capsule structures.The electrochemical measurements of ORR activity and durability were conducted in a 0.1 M HClO4 electrolyte solution. The connected Pt1–Co1 and Pt3–Co1 catalysts achieved 6- and 10-times higher ORR specific activities than that of Pt/C, respectively. Subsequently, the ORR activity and load cycle durability (0.6 V for 3 s Û 1.0 V for 3 s at 60 °C) of the connected Pt3–Co1 catalyst with different ordered degrees (S = 0%, 28%, and 58%) were evaluated. As the ordered degrees in the connected Pt3–Co1 catalysts were higher, the ORR specific activity was increased. Also, the retention of the specific activity of the ordered catalyst (S = 58%) was higher than that of the disordered catalyst (S = 0%) after 10,000 load cycles. The STEM-EDX line mapping results showed that 83% of the alloyed Co retained in the catalyst with a higher ordered degree even after 10000 load cycles, whereas the disordered and lower ordered catalysts retained lower Co ratios after the test, indicating the suppression effect of an ordered structure on metal dissolution. In addition, the L12 ordered Pt3–Co1 structure remained in the connected catalyst (S = 58%) after load cycle test, confirmed by the TEM diffraction analysis.In summary, we successfully developed the connected Ptx-Co1 catalysts with chemically ordered superlattice structures. In addition, we clarified the structural effects of metal composition and ordered degree in connected Ptx-Co1 catalysts on ORR activity and load cycle durability. These results provide useful guidelines for the design of advanced ORR catalysts towards high-performance PEFCs. Acknowledgement The part of this presentation is based on results obtained from a project, JPNP20003, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

Highly Durable Electrocatalyst with Low-Loading Pt-Co Dispersed over Graphene Nanofiber for Oxygen Reduction Reaction Under PEMFC Condition

Proton exchange membrane fuel cell (PEMFC) has been demonstrated as a highly efficient energy conversion technology. The sluggish oxygen reduction reaction (ORR) at the fuel cell cathode requires 3 to 5 times more catalysts than the hydrogen oxidation reaction at the anode (1). Currently, platinum is still the catalyst material of choice. However, the heavy use of scarce Pt in the electrodes represents a major cost barrier to the commercialization of PEMFCs. Tremendous efforts have been dedicated to reduce or remove Pt usage through the development of Pt-transition metal catalysts, as highlighted recently by dealloyed PtNi (2), Mo-doped PtNi(3), and ordered PtCo (4); or through the development of transition metals-nitrogen-carbon based PGM-free catalysts (5, 6).In the fuel cell, catalysts should be highly dispersed over the electrode surface to be easily accessible by the reactants, especially at the high fuel cell current density where a large influx of O2 must be converted. For the Pt alloy catalyst of large crystallites, there won’t be enough crystallites available to spread over the electrode surface to encounter the incoming O2 if the total loading of platinum has to be maintained ultralow. Furthermore, unprotected Pt nano-alloys may lose their nanostructure and crystallinity from the dissolution and agglomeration during the ORR process. The PGM-free catalysts, on the other hand, have high catalytic site density with uniform distribution when prepared by homogenous precursors such as metal-organic framework or porous organic polymer, rendering them highly efficient in interacting with O2 flux. Their key drawback, however, is the poor stability operated under PEMFC condition.In this presentation, we will describe a method of preparing highly active yet stable electrocatalysts containing ultralow Pt content using polymer fiber containing cobalt zeolitic imidazolate framework as precursor. The new catalyst contains Pt-Co nanoparticels situated over the PGM-free catalystically active support (7,8). The ORR activities of the new catalyst was first tested in O2 saturated acidic electrolyte by rotating ring disk electrode (RRDE) before fabricated into the membrane electrode assembly (MEA) and evaluated under fuel cell operating condition. The synergistic catalysis between PtCo NPs and the PGM-free active substrate led to an unprecedented oRR performance in both RRDE and fuel cell. For example, the fuel cell test demonstrated a mess activity of 2.43 A/mgPt for the new catalysts and > 80% retention of the initial mass activity after 60000 continuous voltage cycles from 0.6 – 1.0 V.The characterizations of the fresh and the post-electrochemical test samples were investigated by x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), x-ray absorption near-edge structure (XANES), extended x-ray absorption fine structure (EXAFS), transmission electron microscopy (TEM), Raman spectroscopy and BET surface analysis. We also performed DFT calculation on the ORR thermodynamic barriers over both Pt-Co NPs and PGM-free site as the descriptors for reaction pathway. The results reveal that the synergistic interaction between Pt-Co and PGM active substrate contribute significantly to both activity and durability enhancements.Acknowledgments:This work was supported by Argonne National Laboratory through Maria Goeppert Mayer Fellowship, US; Overseas Outstanding Youth Fund project, shanghai Jiao Tong university, Shanghai, China, State Key Laboratory of Metal Matrix Composites, shanghai Jiao Tong university, Shanghai, China. The works performed at Argonne National Laboratory’s Center for Nanoscale Materials and Advanced Photo Source, and Hydrogen research center, shanghai Jiao Tong university.Reference: H. A. Gasteiger, N. M. Markovic, Just a Dream-or Future Reality? Science 324, 48-49 (2009).B. Han et al., Record activity and stability of dealloyed bimetallic catalysts for proton exchange membrane fuel cells. Energy & Environmental Science 8, 258-266 (2015).X. Huang et al., High-performance transition metal–doped Pt3Ni octahedra for oxygen reduction reaction. Science 348, 1230-1234 (2015).D. Wang et al., Structurally ordered intermetallic platinum-cobalt core-shell nanoparticles with enhanced activity and stability as oxygen reduction electrocatalysts. Nat Mater 12, 81-87 (2013).L. Chong et al., Investigation of Oxygen Reduction Activity of Catalysts Derived from Co and Co/Zn Methyl-Imidazolate Frameworks in Proton Exchange Membrane Fuel Cells. ChemElectroChem 3, 1541-1545 (2016).J. Shui, C. Chen, L. Grabstanowicz, D. Zhao, D. J. Liu, Highly efficient nonprecious metal catalyst prepared with metal-organic framework in a continuous carbon nanofibrous network. Proc Natl Acad Sci U S A 112, 10629-10634 (2015).L. Chong et al., Ultralow-loading platinum-cobalt fuel cell catalysts derived from imidazolate frameworks. Science, (2018).L. Chong et al., Highly durable fuel cell electrocatalyst with low-loading Pt-Co nanoparticles dispersed over single-atom Pt-Co-N-graphene nanofiber. Chem Catalysis 3, 100541.

In Situ Anchoring of Small-Sized Silver Nanoparticles on Porphyrinic Triazine-Based Frameworks for the Conversion of CO2 into α-Alkylidene Cyclic Carbonates with Outstanding Catalytic Activities under Ambient Conditions.

The preparation of catalytic hybrid materials by introducing highly dispersed metallic nanoparticles into porous organic polymers (POPs) may be an ideal and promising strategy for integrated CO2 capture and conversion. In terms of the carboxylative cyclization of propargyl alcohols with CO2, the anchoring of silver nanoparticles (AgNPs) on functional POPs to fabricate efficient heterogeneous catalysts is considered to be quite intriguing but remains challenging. In the contribution, well-dispersed AgNPs were successfully anchored onto the porphyrinic triazine-based frameworks by a simple "liquid impregnation and in situ reduction" strategy. The presence of N-rich dual active sites, porphyrin and triazine, which acted as the electron donor and acceptor, respectively, offered a huge opportunity for the nucleation and growth of metal nanoparticles. Significantly, the as-prepared catalyst Ag/TPP-CTF shows excellent catalytic activity (up to 99%) toward the carboxylative cyclization of propargyl alcohols with CO2 at room temperature, achieving record-breaking activities (TOF up to 615 h-1 at 1 bar and 3077 h-1 at 10 bar). Moreover, the catalyst can be easily recovered and reused at least 10 times with retention of high catalytic activity. The possible mechanism involves small-sized AgNP-mediated alkyne activation, which may promote highly efficient and green conversion of CO2. This work paves the way for immobilizing metal nanoparticles onto functional POPs by surface structure changes for enhanced CO2 catalysis.

Unexpected Periodicity in Cationic Group 5 Initiators for the Ring-Opening Polymerization of Lactones.

ε-Caprolactone (ε-CL) adducts of cationic, amine tris(phenolate)-supported niobium(V) and tantalum(V) ethoxides initiate the ring-opening polymerization of lactones. The Ta(V) species prepared and applied catalytically herein exhibits higher activity in the ring-opening polymerization (ROP) of ε-caprolactone than the previously reported, isostructural Nb(V) complex, contradicting literature comparisons of Nb(V)- and Ta(V)-based protocols. Both systems also initiate the ROP of δ-valerolactone and rac-β-butyrolactone, kinetic studies confirming retention of higher activity by the Ta congener. Polymerizations of rac-β-butyrolactone and δ-valerolactone were previously unrealized under Group V- or Ta-mediated conditions, respectively, although the former has afforded only low molecular weight, cyclic poly-3-hydroxybutyrate. Cationic ethoxo-Nb(V) and -Ta(V) δ-valerolactone adducts are also reported, demonstrating the facility of δ-valerolactone as a ligand and the generality of the synthetic method. Both δ-valerolactone-bearing complexes initiate the ROP of ε-caprolactone, δ-valerolactone, and rac-β-butyrolactone. Accordingly, we have elucidated trends in reactivity and investigated the initiation mechanism for such systems, the insertion event being predicated upon intramolecular nucleophilic attack on the coordinated lactone by the adjacent alkoxide moiety. This mechanism enables quantitative, stoichiometric installation of a single monomer residue distinct from the bulk of the polymer chain, and permits modification of polymer properties via both manipulation of the molecular architecture and tuning of the polymerization kinetics, and thus dispersity, through hitherto inaccessible independent control of the initiation event.

Biological stabilization of Arthrospira bioactive-peptides within biopolymers: Functional food formulation; bitterness-masking and nutritional aspects

Physicochemical/biological instability and bitterness are among the major challenges limiting the shelf life and direct use of bioactive-peptides in the production of functional foods. This study focused on the structural modification and improvement of biological, nutritional and techno-functional properties of blue-green algae protein by alcalase (30–180 min). Then, the optimal sample (H-120) was stabilized with maltodextrin (MD), gum-arabic (GA), WPC, alginate (A), and pectin (P) biopolymeric-carriers by the spray-drying process. The MD-WPC-encapsulated peptide presented the highest production yield (∼65%), retention of antioxidant activity, functional, flowability, and stability properties. Morphological (formation of wrinkled, irregular, and dented particles) and chemical (FTIR) evaluations respectively indicated the effect of feed composition on the structural properties and entrapment of peptides (through hydrogen bonds and hydrophobic reactions) in the polymer matrix. Finally, the optimal sample (SDP: MD-WPC) was used at different ratios (1, 2, and 4% w/w) for pan-bread fortification. The examination of physicochemical properties (moisture content, water activity, and specific volume), textural (porosity and compressive strength) indices, a color histogram (crust and crumb), antioxidant activity (DPPH• and ABTS• scavenging), and sensory analysis (color, texture, chewiness, taste, and overall acceptability) indicated biological stability, bitterness-masking, and the feasibility of functional bread production with 2%-SDP.

The emerging concept of glycocalyx damage as the trigger of heart failure onset and progression

The suppression of adrenergic and renin-angiotensin-aldosterone system (RAAS) activity, exaggerated due to hypoperfusion-related hypoxia and/or sodium retention, is crucial for drugs’ efficacy in heart failure (HF). Both, insufficient oxygenation and excess sodium impair the glycocalyx-dependent microcroperfusion and peripheral metabolism, therefore enhancing the adrenergic and RAAS activity. The local renal and pulmonary RAAS activity and hypoxia increase sodium retention. Interstitial sodium accumulation activates interstitial inflammation and coagulation disorders that further diminish glycocalyx-supported microperfusion and peripheral metabolism. The main trigger of glycocalyx damage in reduced ejection fraction (EF) HF is hypoxia; whereas, in HF preserved EF sodium retention prevails; both stimulate left ventricular (LV) cardiac output (CO), however, impair microperfusion and metabolic heat production. Infrared-dependent, surface-induced flow (SIF) and diamagnetic properties of oxygenated haemoglobin; both improve non-Newtonian blood flow. Therefore, the temperature-driven SIF augments the deoxygenated erythrocytes' flow, while the pulmonary oxygenation of haemoglobin, by diamagnetic properties, enables frictionless erythrocytes’ flow in the oxygenated blood compartments complementing the cardiac function in HF.

Enzyme Cascade Electrode Reactions with Nanomaterials and Their Applicability towards Biosensor and Biofuel Cells.

Nanomaterials, including carbon nanotubes, graphene oxide, metal-organic frameworks, metal nanoparticles, and porous carbon, play a crucial role as efficient carriers to enhance enzyme activity through substrate channeling while improving enzyme stability and reusability. However, there are significant debates surrounding aspects such as enzyme orientation, enzyme loading, retention of enzyme activity, and immobilization techniques. Consequently, these subjects have become the focus of intensive research in the realm of multi-enzyme cascade reactions. Researchers have undertaken the challenge of creating functional in vitro multi-enzyme systems, drawing inspiration from natural multi-enzyme processes within living organisms. Substantial progress has been achieved in designing multi-step reactions that harness the synthetic capabilities of various enzymes, particularly in applications such as biomarker detection (e.g., biosensors) and the development of biofuel cells. This review provides an overview of recent developments in concurrent and sequential approaches involving two or more enzymes in sequence. It delves into the intricacies of multi-enzyme cascade reactions conducted on nanostructured electrodes, addressing both the challenges encountered and the innovative solutions devised in this field.