Hydrolysis Of Bond Research Articles

Macromorphological characterization of filamentous fungi isolated from ripened cheese samples as potential protease producers

Proteases catalyze the hydrolysis of amide bonds of peptides and proteins, thereby playing crucial roles in the functioning of organisms, as well as having an important role in industrial processes. They are one of the three most widely commercially marketed enzymes. This study aimed to analyze the macromorphological characteristics of seventeen filamentous fungi and identify potential protease producers. The microorganisms were cultivated on a solid culture medium containing skim milk powder at 30 °C for seven days. After the incubation period, macroscopic morphological characteristics of the fungi were observed, and the strain diameters and the enzymatic halos around the colonies were measured. As a result, a wide variety of characteristics among the filamentous fungi was observed, highlighting the diversity of this group. Additionally, Potentials asprotease producers under the conditions presented were observed for eight filamentous fungi. These findings suggest that the these fungal strains might be valuable resources for the production of proteases with high biotechnological potentials.

Nitrogen-Rich Molybdenum Nitride with Intrinsic CD39 Nucleotidase Activity.

CD39 is one of the important nucleotidases to adjust extracellular adenosine triphosphate (ATP) and adenosine diphosphate (ADP) concentration. However, the enzyme mimics to simulate the activity of CD39 still remains to be explored. Herein nitrogen-rich molybdenum nitride (Mo5N6) nanosheets are explored to possess CD39-like activity, which are able to catalyze the hydrolysis of the high-energy phosphate bonds (HEPBs) in ATP and ADP but not the common phosphate bonds in adenosine monophosphate (AMP). The catalytic hydrolysis of the phosphate bond over Mo5N6-700 nanosheets is first investigated using para-nitrophenyl phosphate as the model substrate and then the CD39-like activity is further explored and verified by 31p NMR spectroscopy. Mo4+ on the surface of Mo5N6-700 nanosheets are the catalytic active sites. Using ATP as the model substrate, the Km and Vmax values of CD39-like activity at optimal pH 9.0 are 3.2µmol L-1 and 18.5µmol L-1 h-1, respectively. The CD39-like activity of Mo5N6-700 nanosheets enabled the down-regulation of intracellular ATP concentration to a larger degree for cancer cells than normal cells, which makes Mo5N6-700 nanosheets a potential therapeutic reagent for cancers.

Novel Ratiometric Surface-Enhanced Raman Scattering (SERS) Biosensor for Ultrasensitive Quantitative Monitoring of Human Carboxylesterase-1 in Hepatocellular Carcinoma Cells Using Ag-Au Nanoflowers as SERS Substrate.

In this study, we developed ratiometric surface-enhanced Raman scattering (SERS) biosensors using Ag-Au alloy nanoflowers as SERS substrates, molecules having amide bonds and alkyne groups (Tag A) as Raman reporters, and sodium thiocyanate as an internal standard molecule (Tag B) for the sensitive detection of human carboxylesterase-1 (hCE1) in HepG-2 cells. The correlation between HepG-2 cell damage and hCE1 activity levels was investigated. Both Tag A's alkyne group and Tag B's cyanide group produced characteristic SERS signals in the Raman-silent region (I2000cm-1 and I2115cm-1, respectively). The hydrolysis of the amide bond in Tag A via hCE1 and the shedding of the alkyne group led to a reduction in the SERS signal intensity observed at I2000cm-1. Conversely, the SERS signal intensity of Tag B at I2115cm-1 exhibited a consistent pattern. As the activity level of hCE1 and the ratiometric peak intensity (I2000cm-1/I2115cm-1) correlated negatively, hCE1 could be quantitatively detected within the range of 10-2 to 2 × 102 ng·mL-1, with a detection limit of 7.3 pg·mL-1. The ratiometric SERS probe strategy, in which a ratio response is employed, permits sensitive and reproducible SERS detection by facilitating intrinsic calibration to rectify signal fluctuations resulting from temporal and spatial variations in the detection conditions. Concurrently, the implementation of Raman-silent region reporter molecules mitigates the interference from endogenous biomolecules in SERS measurements and offers a novel approach for achieving highly sensitive and interference-free detection of intracellular hCE1.

A novel mechanocatalytic process by vibratory disk mill for efficient hydrolysis of cellulose, chitin and xylan

Polysaccharides are primary sources to manufacture chemical products with low carbon footprints, owing to their carbons from atmospheric carbon dioxide fixed through photosynthesis. Breaking down such polysaccharides into water-soluble saccharides through the hydrolysis of glycosidic bonds is one of key steps to produce valuable chemicals; however, previous chemical and enzymatic processes have been suffered from their fundamental drawbacks (e.g. not environmentally benign, high production cost) and are not regarded as feasible approaches. Recently, mechanocatalytic process, which proceeds hydrolysis of polysaccharides by simply milling with solid acids, attracts attentions owing to its cost-effectiveness and environmental beingness. Herein, we propose the novel mechanocatalytic system to efficiently proceed the hydrolysis of glycosidic bonds in polysaccharides by using “vibratory disk mill”, which can produce strong shear and impact force. By milling polysaccharides (cellulose, chitin and xylan) with solid acid kaolin, the polysaccharides can be efficiently hydrolysed to water-soluble saccharides with a rate twice higher than the previous milling devices, achieving quantitative conversion of polysaccharide to water soluble products (solubility: >99 %). We elucidated the reaction mechanism of polysaccharides with kaolin by X-ray diffractograms: forces produced by the vibratory disk mill can efficiently delaminate layered aluminosilicate nanosheets in kaolin, leading to better accessibility of polysaccharides on the acidic surface of the nanosheets. This novel mechanocatalytic system can also be applicable to produce oligosaccharides directly from crude biomass samples (birchwood chips and shrimp shells) without any chemical purification steps, demonstrating that this system can be used in industrial biomass processing.

Interfacial engineering to create ionically bonded heterostructures for ampere-level chlorine-free anodic reactions in seawater

Production of hydrogen directly from seawater can be a sustainable method; however, corrosive and competitive chlorine chemistry at the anode interfere with the oxygen evolution reaction (OER). Special materials need to be designed to avoid chlorine chemistry; hence, a two-dimensional metal-organic framework@WO3.B2O3 (MOF@WB) heterostructure with ionic bonds was engineered, which can deliver ~10x better performance and is ~65% more economical than commercial IrO2 for OER. Our system is stable in alkaline seawater for over 1000h without chlorine evolution and remains functional even after sitting idle for 5 days, making it integrable with renewable power sources. The catalyst also operated stably at the industrial-scale current density of 1.58Acm-2 for over 100h with 99% performance retention in alkaline seawater. Theoretical calculations reveal that B assists in the adsorption of the MOF on the WO3 substrate via the creation of ionic bonds, resulting in optimized surface geometries for selective reactions, which safeguard against chlorine chemistry. B2O3 helps modulate the B-OH sites at the interface via B-O-B bond hydrolysis, activating the OER kinetics, hence providing an ideal platform for effective direct seawater catalysis to produce low-cost hydrogen.

A dual-capture-system polymer based on imprinted cavities and post-imprinting modification sites with significantly improved affinity and specificity for sialic acid and sialylated glycoprotein

The abnormal expression of N-acetylneuraminic acid (SA) and sialylated glycoproteins in biological fluids are closely associated with various diseases including cancer. However, the low content of SA and the strong interference of complex matrix greatly influence the effective capture of SA in biosamples prior to analysis. Herein, a dual-capture-system strategy based on molecular imprinting and post-imprinting modification (PIM) was proposed to precisely capture SA with improved binding affinity and specificity. After imprinting with SA as template, dynamic imine bonds are introduced by post-imprinting modification, enabling sufficiently high specificity to capture SA through imprinting cavities and the dynamic imine bonds hydrolysis reaction simultaneously. The prepared magnetic PIM polymers (Mag-MIPs-PIM) exhibited significantly high specificity both for SA (IF = 4.24) and sialylated glycoprotein (IFTRF = 3.50). In addition, the feasibility of Mag-MIPs-PIM for practical application was demonstrated by association with HPLC for the determination of SA in human serum, and an LOD of 0.01 × 10−2 g L−1 was obtained. The proposed strategy based on molecular imprinting and PIM provides a new inspiration for the improvement of selectivity of the molecularly imprinted polymers.

Structural and Solution Speciation Studies on fac-Tricarbonylrhenium(I) Complexes of 2,2'-Bipyridine Analogues.

In this study, we report the synthesis and characterization of 12 novel rhenium(I) complexes with the general formula fac-[Re(CO)3(NN)X]n+ where (NN) is a 2,2'-bipyridine analogue ligand, X = Cl-, Br-, or H2O, and n = 0 or 1, focusing on their speciation in an aqueous solution. The prepared organorhenium complexes are stable in a wide pH range in an aqueous solution, and no release of the bidentate ligands or the carbonyl ligands was observed. The stability of the complexes in various biologically relevant matrices (cell culture medium and real blood serum) was also demonstrated. However, the simultaneous substitution of the halido ligand by water and slow hydrolysis of the ester bonds in the ligands were observed, affecting both the solubility and the lipophilicity of the compounds. The aqua complexes became more lipophilic in the presence of chloride ions, while the hydrophilicity increased significantly with time due to the hydrolysis of the ester bonds, which probably contributed to their weak pharmacological activity. The results also showed kinetically hindered aqueous solvation of the halido complexes and low chloride ion affinity of the aqua complexes. The deprotonation of the coordinated aqua ligand in the complexes occurs in the pH = 7-10 range, leading to significant formation (18-30%) of hydroxido species at pH = 7.4. The halido complexes showed somewhat higher cytotoxicity (IC50 = 60-99 μM) on human colon adenocarcinoma cancer cells (Colo205 and Colo320) than the corresponding aqua complexes (IC50 > 100 μM). In all cases, no antibacterial effect was observed (MIC > 100 μM), but some of the complexes showed moderate antiviral activity (IC50 ∼ 50 μM) on Herpes simplex virus 2.

The phosphodiester dissociative hydrolysis of a DNA model promoted by metal dications.

Phosphodiester bonds, which form the backbone of DNA, are highly stable in the absence of catalysts. This stability is crucial for maintaining the integrity of genetic information. However, when exposed to catalytic agents, these bonds become susceptible to cleavage. In this study, we investigated the role of different metal dications (Ca2⁺, Mg2⁺, Zn2⁺, Mn2⁺, and Cu2⁺) in promoting the hydrolysis of phosphodiester bonds. A minimal DNA model was constructed using two pyrimidine nucleobases (cytosine and thymine), two deoxyribose units, one phosphate group, and one metallic dication coordinated by six water molecules. The results highlight that Cu2⁺ is the most efficient in lowering the energy barrier for bond cleavage, with an energy barrier of 183kJ/mol, compared to higher barriers for metals like Zn2⁺ (202kJ/mol), Mn2⁺ (202kJ/mol), Mg2⁺ (210kJ/mol), and Ca2⁺ (223kJ/mol). Understanding the interaction between these metal ions and phosphodiester bonds offers insight into DNA stability and organic data storage systems. DFT calculations were employed using Gaussian 16 software, applying the B3LYP hybrid functional with def2-SVP basis sets and GD3BJ dispersion corrections. Full geometry optimizations were performed for the initial and transition states, followed by identifying energy barriers associated with phosphodiester bond cleavage. The optimization criteria included maximum force, root-mean-square force, displacement, and energy convergence thresholds.

Microenvironmental pH modulating oxygen self-boosting microalgal prodrug carboxymethyl chitosan/hyaluronic acid/puerarin hydrogel for accelerating wound healing in diabetic rats

Chronic diabetic wounds are characterized by a range of detrimental features, including hypoxia, elevated levels of reactive oxygen species, impaired angiogenesis, chronic inflammation, and an increased susceptibility to bacterial infections. We have developed an innovative multifunctional hydrogel system based on carboxymethyl chitosan, which incorporates embedded microalgae PCC7942 along with hyaluronic acid and puerarin, termed PCC7942@carboxymethyl chitosan/hyaluronic acid/puerarin hydrogel. It demonstrated outstanding capabilities in exudate absorption, mechanical flexibility, hemostatic action, and antibacterial efficacy. Furthermore, it effectively modulated the pH of wound microenvironment through the hydrolysis of amide bonds, thereby establishing a favorable low-pH microenvironment. Microalgae in hydrogel covered in the wound exhibited stable and continuous oxygen production within 24 h, with more efficiency in dissolved oxygen penetration through skin. Furthermore, prodrugs such as hyaluronic acid and puerarin from hydrogel displayed the controlled release behavior and facilitated the fast and enhanced accumulation of drugs at wound site, thereby accelerating the process of wound healing via enhanced angiogenesis and anti-inflammation effects. In summary, the healing-promoting effect of PCC7942@carboxymethyl chitosan/hyaluronic acid/puerarin hydrogel in type 1 diabetic rats can be attributed to the synergistic effects of microalgae, hyaluronic acid, and puerarin, which collectively accelerated wound healing rate and improved the quality of wound recovery.

Photochemical and electrochemical behavior of a molecular probe: Fluorescence on-off-on response to detect multiple ions (Cu2+, ClO− and CN−) with different rate of reaction

A molecular probe 3 containing phenyl substituted imidazolyl unit and diaminomaleonitrile (DAMN) moiety has been synthesized and characterized. Photophysical and electrochemical behavior probe 3 were studied in partial aqueous medium (ACN/H2O, 9.5:0.5 v/v). Probe 3 upon interaction with different class of ions showed sensitivity for Cu2+, ClO− and CN− ions with different response time and reaction rates due to variation in intramolecular charge transfer (ICT) process. Both Cu2+ and ClO− ions displayed enhanced emission due to hydrolysis of imine bond to form compound 2 in the medium whereas, with CN− fluorescence quenching was observed due to the deprotonation of –OH/–NH2 functions. The kinetic and optical behavior of the probe suggested that interaction occurred in two steps with Cu2+ (complexation and hydrolysis; absk1,2,3(Cu2+) = 1.17, 0.74 and 0.06 s−1) and ClO− (hydrolysis and deprotonation; absk1,2(ClO−) = 3.0 and 0.60 s−1) ions while CN− (absk1,2(CN−) = 2.13 and 1.66 s−1) induces deprotonation in one step. The interaction of probe 3 with ClO− was relatively fast than with Cu2+/CN− ions. Job's plot analysis between probe 3 and ions revealed a 1:1 (Cu2+/ClO−) and 1:2 (CN−) ratio stoichiometry with good limit of detection (nM) and binding affinity (LOD, 17; KCu2+ = 3.23 × 106 M−1; LOD, 18.5; KClO− = 5.23 × 105 M−1 and LOD, 23.2; KCN− = 5.50 × 109 M−2) respectively. Probe 3 displayed a naked–eye sensitive fluorescence response to detect tested ions on test paper strips and good recovery percentage of ions in real water sample analysis.

A Cell-Free Kinetic Analysis of Ionizable Lipid Hydrolysis.

The prolonged retention of ionizable lipids within the body limits the repeated dosing of lipid nanoparticles (LNPs) for nucleic acid delivery. While most ionizable lipids are primarily metabolized in the liver via the enzymatic hydrolysis of ester bonds, elimination half-lives can range from several hours to days. The development of compounds that undergo rapid biodegradation remains a major engineering challenge in the absence of standardized biodegradability assessments in the early stages of drug discovery. Here, we analyze and compare the hydrolysis kinetics of well-known ionizable lipids (ALC-0315, DLin-MC3-DMA, LP-01, L319, and SM-102) using optimized cell-free reactions monitored by 1H NMR. Unlike conventional analytical techniques, these NMR-based methods are universal and suitable for high-throughput screening. We demonstrate that enzyme-catalyzed and base hydrolysis reactions can predict whether ionizable lipids undergo fast or slow liver elimination, as our results are in alignment with prior pharmacokinetic studies. Furthermore, we show that the hydrolysis kinetics of ionizable lipids vary by several orders of magnitude depending on steric effects. This study provides a framework to expedite the discovery of rapidly degradable ionizable lipids, with implications for improving the therapeutic index of LNP-based drugs.

Recycling Valuable Phenol from Polycarbonate Plastic Waste Via Direct Depolymerization and Csp2-Csp3 Bond Cleavage Under Mild Conditions.

Upcycling plastic waste into commodity chemicals is recognized as an environmentally benign solution and beneficial for the sustained growth of humanity. Nevertheless, transition metal-free catalysts and energy-efficient conditions pose significant challenges due to the robust mechanical properties of plastics. Here, a strategy for selective production of phenol by upcycling polycarbonate waste via direct depolymerization and Csp2-Csp3 bond cleavage in an aqueous medium under mild conditions is reported. The commercial zeolites efficiently catalyze the depolymerization, Csp2-Csp3 bond hydrolysis, and direct Csp2-Csp3 bond scission at Cα of PC. Among all evaluated zeolites, HY (Si/Al=15) showed excellent catalytic performance, attributed to the ~75 % yield of phenol and ~15 % of acetone. The approach also employs different municipal waste PC for upcycling. Studies reveal that HY (15) exhibits high catalytic efficiency and phenol yield due to its optimum acid sites and textual properties. A scale-up experiment demonstrated that 3.1 g of phenol was produced from 5.0 g of PC, and the mass balance was 90 %. A combination of control experiments, NMR analysis, and DFT studies proposed the reaction pathway. Our findings present a sustainable avenue for upcycling PC waste and offer a new way to produce phenol, contributing to the advancement of a circular economy.

A biophysical insight into the mechanism of anticancer activity of salicylidene cyclohexanediamine based cobalt and nickel complexes through CT-DNA, BSA binding and docking study

Two novel metal Schiff base complexes, [Co(L)(OH2)(Cl)].2DMF (1) and [Ni(L)].H2O (2) [H2L=N,N'-bis(5-bromo-3-(methoxy)salicylidene)cyclohexane-1,2-diamine] were prepared and structurally characterized through single crystal X-ray crystallography and usual spectroscopic techniques. The inhibitory action of H2L, 1 and 2 via MTT assay on MDA-MB 231, HCT-116, and A549 cell lines was assessed. The complexes exhibit lower IC50 values than the ligand (H2L> 2> 1). On the other hand, with normal human PBMC, they were found to be significantly nontoxic. The interaction of 1 and 2, with CT-DNA and serum albumin (BSA) through different biophysical experiments was checked to have a plausible understanding of their anticancer activity as well as pharmacological relevance. These investigations inferred that 1 had a greater affinity for CT-DNA and BSA than 2. 1 interacts with CT-DNA through intercalation whereas 2 exhibits a mixed mode of interaction (intercalation and groove binding). The complexes exhibit a predominantly hydrophobic interaction with BSA, which is static in nature and causes a prominent structural change of BSA, from α-helix to β-sheet. The rate of hydrolysis of the phospho-ester bond in PNPP was found to be four times faster with 1 than with 2. A molecular docking study was conducted to gain a deeper insight into the molecular interactions along with possible theoretical binding energies of the complexes with CT-DNA and BSA, and this was found to be in agreement with the experimental findings.

Proteases: Role in Various Human Diseases.

Proteases, a group of hydrolytic enzymes catalyzing the hydrolysis of peptide bonds, play pivotal roles in various physiological processes and have emerged as key contributors to the pathogenesis of diverse diseases. This work provides an insight into the impact of protease activity on different disease contexts, highlighting their involvement in cancer, inflammatory disorders, cardiovascular diseases, infectious diseases, and neurodegenerative conditions. In cancer, proteases facilitate tumor growth, invasion, and metastasis, while in inflammatory diseases, dysregulated protease activity exacerbates tissue damage and inflammation. Cardiovascular diseases involve proteases in extracellular matrix remodeling, affecting arterial structure. In infectious diseases, proteases play crucial roles in pathogen invasion and immune evasion. Neurodegenerative diseases are characterized by protease dysregulation, contributing to protein misfolding and aggregation. As research progresses, understanding the intricate relationships between proteases and diseases becomes essential for developing targeted therapeutic strategies. This review aims to provide a comprehensive glimpse into the diverse impact of protease activities on various diseases, emphasizing their potential as crucial players in the landscape of disease pathology and potential therapeutic interventions.

An innovative functional compatibility strategy for poly (lactic acid) and polypropylene carbonate blends to achieve superior toughness, degradability, and optical properties

This study, for the first time, unveils the potential of dibutyl itaconate (DBI) in enhancing the compatibility between PLA (poly (lactic acid)) and PPC (polypropylene carbonate), systematically investigating the effects of DBI amount on the thermal, optical, rheological, mechanical, and degradation properties and microstructure of the PLA/PPC/DBI blends. The results showed that DBI could chemically react with PLA and PPC, forming a PLA-co-DBI-co-PPC copolymer structure, thereby improving the compatibility between PLA and PPC. When the DBI amount reached 8 wt%, only one Tg was observed in the blend system, and no distinct phase interface was visible in the fracture surface of the blend specimens. This indicated that at this DBI amount, the PLA and PPC had transitioned from a partially compatible system to a fully compatible system. With the increase in DBI amount in the system, the elongation at break and notched impact strength of the blends initially increased and then decreased, while the storage modulus, loss modulus, and complex viscosity showed a gradual downward trend. When the DBI amount increased to 10 wt%, the flexibility of the blends reached its peak, with the values rising to 494.7 % and 8494.1 J/m2, respectively, representing 13.7 times and 2.5 times those of the neat PLA/PPC blends. At this point, the impact specimens exhibited significant plastic flow in the direction of force, showing distinct ductile fracture characteristics. Meanwhile, the degradation performance of the PLA/PPC blends increased with the addition of DBI. The introduction of DBI effectively facilitated the penetration of water molecules into the PLA/PPC molecular chains, enhancing the hydrolysis of ester bonds, leading to a maximum mass loss rate of 84.1 %, which was significantly higher than the 20.3 % of the neat PLA/PPC blends. In addition, the addition of DBI significantly reduced the haze of the blends while maintaining high light transmittance, demonstrating excellent optical properties (light transmittance remained above 92.4 %, and haze decreased from 37.1 % to 11.1 %). In conclusion, this study provides a new approach for the development of high-performance PLA-based biodegradable composites. The resulting blends exhibit excellent toughness, degradation performance, and optical properties, significantly enhancing their application potential in fields such as disposable products, packaging, agriculture, and 3D printing materials.

Phototransformation of tetrabromobisphenol A bis (allyl ether) in an aqueous solution: Role of environmentally persistent free radicals

Tetrabromobisphenol A bis (allyl ether) (TBBPA-BAE) represents an extensively used brominated flame retardant (BFRs) in the production of many fields and their phototransformation in natural water is still unclear. The environmentally persistent free radicals (EPFRs) with preserved activities could exist in the environment for a long time and involve in the phototransformation of many organic pollutants. Here, the photodegradation of TBBPA-BAE with the degradation rate constant (k = 0.060 h−1) under simulate sunlight and the promoting effect of EPFRs on TBBPA-BAE photodegradation (k = 0.135 h−1) were investigated. According to the detected photogenerated electrons (e−) and singlet oxygen (1O2) rather than hydroxyl radicals (•OH) by the electron paramagnetic resonance (EPR), the effect mechanism may not be related to the typical •OH induced by EPFRs. The possible transformation pathways of the ether cleavage, hydrolysis and hydroxylation of propenyl bond and the debromination were proposed by the primary byproducts identified by UPLC-Q-Exactive Orbitrap MS. EPFRs caused a further debromination and ether cleavage and probably be due to EPFRs directly providing electrons to TBBPA-BAE which promoted the photodegradation of TBBPA-BAE, and their reaction mechanism needed further attention. Overall, this study provided useful information to understand the role of EPFRs on phototransformation of TBBPA-BAE in water.

Esterification-Induced Spontaneous Deposition of Nanoparticle Monolayers on Substrates with Percolation Network Morphology.

Nanoparticle monolayers (NPMLs) exhibit unique collective properties that are highly desirable for applications in sensors, catalysts, and optics. However, their practical use is often hindered by structural instability, especially when they are exposed to solvents. In this study, we developed a method for the spontaneous deposition of gold nanoparticle monolayers (AuNPMLs) on silicon substrates via covalent bonding interactions that provides excellent structural stability in solvents with varying polarities. The esterification reaction between carboxyl-functionalized gold nanoparticles and alkyl-chloride-functionalized silicon substrates spontaneously forms AuNPMLs on the substrate in which single-crystalline domains are interconnected, forming a percolation network morphology. The ex situ scanning electron microscopy measurements show that the surface coverage of AuNPMLs rapidly increases up to ca. 60% during the initial 10 min, followed by gradual growth and saturation at ca. 70% at 360 min of deposition time. On the other hand, the single-crystalline domain size reaches its maximum at 45 min and then gradually decreases, which may be attributed to the desorption of AuNPs by the hydrolysis of ester bonds. The reflectance spectra of AuNPMLs showed the red shift as the deposition time increases up to 45 min with a subsequent blue shift thereafter, which is consistent with the change of the single-crystalline domain size with the deposition time. The covalent bonding interaction-mediated nanoparticle deposition method can be used to form stable AuNPMLs with controlled surface coverage and domain size, allowing for fine control of the optical properties and possibly other properties. The excellent structural stability of AuNPMLs and their controlled properties may provide new opportunities for practical applications of NPMLs.

Lanthanide Complexes Containing a Terminal LnIII−O Bond: Hydrolysis as a Tool to Assess f‐Element Bond Covalency

AbstractWe report the preparation, isolation, and reactivity of gas‐phase lanthanide nitrate and acetate complexes featuring the elusive trivalent LnIII=O bond. Complexes [LnIII(O)(X)2]− (X=NO3− or CH3CO2−; Ln=La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Tm, Lu) are prepared from [LnIII(CH3CO2)(X)3]− precursors through decarboxylation followed by nitromethane or acetone elimination. The oxo complexes hydrolyze at rates indicating LnIII=O bond stability. The rates for [LnIII(O)(NO3)2]− are essentially invariant, whereas those for [LnIII(O)(CH3CO2)2]− exhibit a moderate decrease across the lanthanide series. The kinetics of lanthanide‐oxo bond hydrolysis are assessed in the context of participation of 5d2 electrons in bonding, changes in covalency via variations in 5d orbital energies and radial extensions, and steric crowding around the lanthanide center. The observed fast hydrolysis rates and lack of correlation to electronic and qualitative covalent considerations confirm the expected strong polarization in LnIII=O bonding, with variations in covalency minimally impacting reactivity. The LnIII=O bond reactivity is compared with previous results for LnIII−O⋅ and LnIV=O, and actinide AnIII=O and AnIV=O; implications for lanthanide/actinide and lanthanide/lanthanide partitioning are discussed. Additionally, nitromethane and acetone elimination are demonstrated as useful for inducing a 2e− O‐atom transfer resulting in non‐oxidative formation of lanthanide‐oxos.

Gold(III) complexes with chloride and cyanopyridines: Facilitated hydrolysis of nitrile ligand to amide and antibacterial activity

A range of novel simple gold(III) compounds has been synthesized in their monocrystalline form, including two previously unknown chloro-complexes of Au3+ with 2-cyanopyridine or 3-cyanopyridine, respectively. Our investigations have revealed the intricate nature of the reaction between 2-cyanopyridine and tetrachloroauric acid, yielding at least three distinct products. The main product, obtained in high yield, is a salt featuring a tetrachloroauric anion and a pyridinium cation stabilized by a hydrogen bond to a further 2-cyanopyridine molecule. Moreover, we observed the in-situ formation of a 2-cyanopyridine-AuCl3 complex, which undergoes hydrolysis of the nitrile bond to yield a picolinamide-Au(III) complex. The complexes were characterized by IR and Raman spectroscopies, NMR spectroscopy, and single-crystal XRD studies. Additional computational studies were conducted to explain unusual spectral features, the observed disparities in the complexation reactions of the three isomeric cyanopyridine ligands and the distinct reactivity of the complex with 2-cyanopyridine. Based on these studies, we propose a mechanism for the catalyzed hydrolysis of the nitrile bond within the Au(III) complex. Finally, we assessed the antimicrobial efficacy of the synthesized gold(III) complexes against a spectrum of bacteria and fungi.

A ratiometric fluorescent probe for the detection of γ-glutamyl transpeptidase activity and its application in garlic

A novel ratiometric fluorescent probe for the detection of γ-glutamyl transpeptidase (GGT) activity was developed. The recognition of GGT by this probe is achieved by its enzymatic hydrolysis of peptide bonds in the probe. Under optimized conditions, the probe exhibited obvious ratiometric fluorescence responsiveness after interaction with GGT, avoiding potential background interference. The linear concentration range was 0.0350–2 U / mL, with good selectivity and stability. Under a 365 nm UV lamp, as the concentration of GGT increased, the probe aqueous solution gradually changed from dark blue to light blue. In addition, the B/G value of the probe's solution and the GGT activity were linearly correlated. More significantly, the probe was able to effectively identify the GGT activity of garlic.