Acid Groups Research Articles

Mechanism of unactivated peroxymonosulfate-induced degradation of amino-G acid: Kinetics and transformation pathway

Amino-G acid (7-amino-1,3-naphthalenedisulfonic acid), a pollutant produced during textile preparation and in dyeing industries, is discarded in wastewater and causes ecological problems. In this study, amino-G acid (50.0 μM) could be completely removed by unactivated peroxymonosulfate (PMS) (1.0 mM) within 240 min, and the reaction kinetics exhibited strong pH dependence. A species-specific parallel reaction describes this pH dependence well, and the species-specific reaction rate constants of [amino-G acid]2− and [amino-G acid]− with HSO5− were calculated to be 0.0826 ± 0.0019 and 000122 ± 0.0027 M−1 s−1. The reactivity of the six naphthalene sulfonic acids and unactivated PMS varied according to the structure, and the amino group in naphthalene sulfonic acid, a typical electron-donating group, was more vulnerable to attack by unactivated PMS, which was further confirmed by the density functional theory results. The high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) spectral analysis results indicated that naphthalene sulfonic acid was first oxidized to hydroxylamine products and then further oxidized to nitroso compounds, which exhibited more ecological toxicity. However, as the reaction processing, the toxicity of the product gradually decreased. Our results provide new insights into the in-situ oxidation of unactivated PMS.

A metal–organic frameworks-imprinted emulsion interface with dynamic size- and site-selective recognition for significantly enhanced flavoniods extraction

The boronic acid suspended Cr based MIL-100 (MIL-100-B) sorbents have been widely used to separation of cis-diol containing molecules. However, it’s still challenging in fabrication of high performance metal organic frameworks (MOFs) due to its irregular size and low content of functional groups. For improving identification efficiency, the emulsion microreactor were firstly designed to purify MIL-100-B prior to their use. Herein, a highly ordered MOFs-imprinted polymer microsphere was synthesized by O/W Pickering emulsion template, which can highly selective separation of MIL-100-B via the synergistic effect of boronic acid sites and imprinted cavities. The obtained purified H-MIL-100-B exhibited the uniform size and abundant boronic acid groups (B elements ratio up to 27.37 %). The emulsion imprinted microsphere (EIMs) showed the good selectivity towards MIL-100-B. Additionally, the obtained MOF-imprinted microsphere exhibited green, convenient, sustainable separation process towards the purification and recycle of MIL-100-B. The purified MOFs (H-MIL-100-B) were used to specific bind with cis-diol flavoniods naringin (NRG). Satisfactorily, H-MIL-100-B show high adsorption amount (43.69μmol/g at 308 K), fast capture kinetics (160 min), high selectivity and excellent regenerability (up to seven cycles). Remarkably, the purified NRG solutions displayed lasting antibacterial activity against Staphylococcus aureus (S. aureus) with inhibition zone of 13.47 mm. More importantly, the H-MIL-100-B could effectively promote the specific recognition ability of NRG by reducing matrix interference and improving purification efficiency (93.93 %) from complex natural extracts. A high score (0.75) was predicted via analytical GREEnness (AGREE) approaches, demonstrating environmentally friendly and greenness of separation process. The MOFs-imprinted emulsion microspheres possessed dynamic recognition properties towards target MOFs, thus opening new direction for the development of convenient and efficient microreactor for the purification of other functional MOFs.

Exploring the role of SAP chemical composition in the internal curing of high-performance cementitious materials

This study investigates the impact of the chemical composition of superabsorbent polymers (SAPs) on their effectiveness in internal curing within high-performance cementitious materials. Although the use of commercial SAPs in cementitious systems has been widely researched, there is still no consensus on how different SAP structures influence material properties. For the first time, this research employs photoinitiated free radical polymerization technology to synthesize three structurally distinct SAPs: SAP with sulfonic acid groups (PAMPS), SAP with amide groups (PAM), and SAP with carboxyl groups (PAAs). The effects of these SAPs on the cement hydration process and microstructure were examined by analyzing their water absorption behavior in cement filtrate. The residual cation content on the SAP surface was evaluated using EDS, while XRD and TGA were used to study how SAP structure affects cement hydration products. Furthermore, the impact of these SAPs on the strength and autogenous shrinkage of the material was investigated. The results indicate that PAMPS, with its sulfonic acid groups, exhibited stable water absorption performance in the alkaline cement environment, promoting hydration reactions and increasing the formation of needle-shaped C-S-H. This stability contributed to mitigating the negative effects on mechanical properties. While the inclusion of SAPs generally reduced the strength of the cement matrix, PAMPS was the most effective in mitigating autogenous shrinkage, achieving a shrinkage mitigation efficiency of 86 %. These findings highlight the importance of SAP chemical structure in influencing cement hydration and material performance, offering insights for the development of effective internal curing agents to enhance high-performance concrete.

The Effect of Eco-Friendly Deicing Agents Containing Humic Acid on Plant Growth

Objectives:In this experiment, we used an environmentally friendly snow removal agent containing calcium chloride (CaCl2) and humic acid (HA) to alleviate salt stress on chili pepper seedlings, and analyzed its effect on plant growth. As an alternative to minimize the negative effects of existing chloride-based snow removal agents on plants and soil, we investigated whether humic acids contribute to improving plant physiological responses and soil electrical conductivity (EC). Evaluated.Methods:For 21 days, we set up a control group (Count.), a calcium chloride treatment group (CaCl2), a humic acid treatment group (HA), and a mixed treatment group (HUA2, HUA5, HUA10) in which humic acid and calcium chloride were mixed. The growth of stems and roots was measured. In addition, the high mortality rate of leaves and changes in soil electrical conductivity (EC) were measured to evaluate the effect of alleviating salt stress.Results and Discussion:As a result of the experiment, stem length increased in the control group, humic acid treatment group (HA), and humic acid and calcium chloride mixed treatment groups (HUA2, HUA5, HUA10), and the greatest growth was observed in HUA5 among the mixed treatment groups. On the other hand, in the calcium chloride treatment group (CaCl2), stem growth did not occur and the high leaf mortality rate was 66.7%, which had a negative effect on growth. The soil EC value was lowest at 0.21mS/cm in the humic acid only treatment group (HA) and highest at 1.25mS/cm in the calcium chloride treatment group (CaCl2). In the mixed treatment group, the EC value tended to decrease as the humic acid concentration increased. This indicates that humic acid can play a role in reducing salt stress and promoting plant growth.

Resonance‐Assisted Self‐Doping in Robust Open‐Shell Ladder‐Type Oligoaniline Analogues

AbstractA novel resonance‐assisted self‐doping mechanism has been demonstrated in ladder‐type oligoaniline‐derived organic conductors. The new class of compounds has a unique structure incorporating acidic phenolic hydroxyl groups into the ladder‐type cyclohexadiene‐1,4‐diimine core, enabling efficient resonance‐assisted proton transfer and electronic doping without the need for external dopants. Mechanistic and computational studies confirm the open‐shell, zwitterionic nature of the self‐doped state and the significant role played by the dielectric environment. This new self‐doping mechanism allows for higher stability and durability in the material‘s electronic performance. The self‐doped form retains durability under harsh conditions and maintains its properties over extended periods of time.

Sulfonated Covalent Organic Frameworks Anchoring Cobalt as High-Efficient and Stable Catalysts for Peroxymonosulfate Activation.

Heterogeneous cobalt-based catalysts are highly effective in activing peroxymonosulfate (PMS) and produce free radicals to deal with recalcitrant organic pollutants in water. However, unfeasible recyclability and gradual performance degradation remain challenging due to the easy agglomeration and leaching of active cobalt species. Herein, a strategy is proposed to construct stably anchored and highly dispersed Co2+ sites on dual functional sulfonated covalent organic frameworks (COF-Co). The sulfonic acid groups are able to realize the targeted binding with cobalt ions through a two-step cation-exchange method, leading to strong combination with active Co2+ sites and utmost utilization efficiencies. Moreover, the super-hydrophility of sulfonic acid groups favors the rapid accessibility of organic molecules to the catalyst and accelerates the degradation. Remarkably, COF-Co exhibits high activity in PMS activation, effective oxidation for tetracycline degradation (92% within 30min at 30mg L-1) and other coloring contaminants, and excellent recycle stability. This work can guide the rational design of efficient and environmentally friendly PMS-activated catalyst with great potential for application in wastewater treatment.

Improvement of Properties of Bio-Oil from Biomass Pyrolysis in Auger Reactor Coupled to Fluidized Catalytic Bed Reactor

The goal of this research work was to investigate the improvement of bio-oil issued from beechwood biomass through catalytic de-oxygenation. Pyrolysis was conducted in an auger reactor and the catalytic treatment was performed in a fluidized catalytic bed reactor. Lab-synthesized Fe-HZSM-5 catalysts with different iron concentrations were tested. BET specific surface area, BJH pore size distribution, and FT-IR technologies were used to characterize the catalysts. Thermogravimetric analysis was used to measure the amount of coke deposited on the catalysts after use. Gas chromatography coupled to mass spectrometry (GC-MS), flame ionization detection (GC-FID), and thermal conductivity detection (GC-TCD) were used to identify and quantify the liquid and gaseous products. The pyrolysis temperature proved to be the most influential factor on the final products. It was observed that a pyrolysis temperature of 500 °C, vapor residence time of 18 s, and solid residence time of 2 min resulted in a maximum bio-oil yield of 53 wt%. A high percentage of oxygenated compounds, such as phenolic compounds, guaiacols, and the carboxylic acid group, was present in this bio-oil. Catalytic treatment with the Fe-HZSM-5 catalysts promoted gas production at the expense of the bio-oil yield, however, the composition of the bio-oil was strongly modified. These properties of the treated bio-oil changed as a function of the Fe loading on the catalyst, with 5%Fe-HZSM-5 giving the best performance. A higher iron loading of 5%Fe-HZSM-5 could have a negative impact on the catalyst performance due to increased coke formation.

Tranexamic acid for postpartum bleeding: a systematic review and individual patient data meta-analysis of randomised controlled trials

Tranexamic acid is a recommended treatment for women with a clinical diagnosis of postpartum haemorrhage, but whether it can prevent bleeding is unclear. We conducted a systematic review and individual patient data (IPD) meta-analysis of randomised controlled trials to assess the effects of tranexamic acid in women giving birth. In this systematic review and IPD meta-analysis, we searched the WHO International Clinical Trials Registry Platform from database inception to Aug 4, 2024 for randomised trials that assessed the effects of tranexamic acid in women giving birth. Trials were eligible if they were prospectively registered, placebo-controlled, included more than 500 women, and had a low risk of bias for random sequence generation and allocation concealment. IPD were requested from the trial investigators. The primary outcomes were the numbers of women with life-threatening bleeding and thromboembolic events. We used a one-stage model to analyse the data and explored whether the effect of tranexamic acid varied by the underlying risk of life-threatening bleeding, type of birth, presence of moderate or severe anaemia, or timing of administration (before or after a diagnosis of postpartum haemorrhage). This study is registered with PROSPERO, CRD42022345775. We analysed data on 54 404 women from five trials. We obtained IPD for 43 409 women from four trials and aggregate data on 10 995 women from one trial. All trials had a low risk of bias. Life-threatening bleeding occurred in 178 (0·65%) of 27 300 women in the tranexamic acid group versus 230 (0·85%) of 27 093 women in the placebo group (pooled odds ratio [OR] 0·77 [95% CI 0·63-0·93]; p=0·008). There was no evidence that the effect of tranexamic acid varied by the underlying risk of life-threatening bleeding, type of birth, presence of moderate or severe anaemia or timing of administration. No significant difference was identified between tranexamic acid and placebo groups with regard to thromboembolic events: 50 (0·2%) of 26 571 women in the tranexamic acid group had fatal or non-fatal thromboembolic events versus 52 (0·2%) of 26 373 women in the placebo group (pooled OR 0·96 [0·65-1·41]; p=0·82) with no significant heterogeneity identified in the subgroup analyses. Tranexamic acid reduces the risk of life-threatening postpartum bleeding. We found no evidence that tranexamic acid increases the risk of thrombosis. Although we do not recommend the use of tranexamic acid in all women giving birth, consideration should be given to its use before a diagnosis of postpartum haemorrhage in women at high risk of death. The Bill & Melinda Gates Foundation.

Influence of pH on the Self‐Assembly Properties of Heterofunctional POEGMA‐Based Block Copolymers During RAFT‐PISA

ABSTRACTPOEGMA‐based block copolymers self‐assemblies with surface‐functionalized carboxylic acid or propargyl groups were synthesized by successive reversible addition‐fragmentation chain transfer (RAFT) polymerization of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and RAFT‐mediated polymerization‐induced self‐assembly (RAFT‐PISA) in dispersion of 2‐(methacryloyloxy)‐N,N,N‐trimethylethanaminium hexafluorophosphate (METAPF6). The temperature responsive properties of the carboxylic acid–terminated POEGMA (POEGMACDP) and propargyl‐terminated POEGMA (POEGMACDPy) were studied in aqueous buffer solutions at pH 2.3 and 9.2. At pH 2.3, POEGMACDP aqueous solution exhibits a cloud point while no cloud point was observed at pH 9.2. POEGMACDPy shows a cloud point at both pH levels. The RAFT‐PISA in dispersion of METAPF6 at 75°C in either pH 2.3 or 9.2 buffer solution using POEGMACDP or POEGMACDPy as macro‐RAFT agents led to block copolymers, as confirmed by DOSY analysis. For POEGMACDP (DPn = 9), DPn,NMR,PMETAPF6 was 47 at pH 2.3 and 27 at pH 9.2 and for POEGMACDPy (DPn = 10), DPn,NMR,PMETAPF6 was 36 at pH 2.3 and 22 at pH 9.2, as shown by 1H NMR spectroscopy. Both in situ POEGMACDP‐b‐PMETAPF6 and POEGMACDPy‐b‐PMETAPF6 self‐assemblies in aqueous solutions exhibited an increase in Dh and PDI when the pH increased from 2.3 to 9.2, as measured by DLS at 20°C. TEM analyses revealed almost spherical self‐assemblies, unaffected by pH or chain‐end functionality.

The effect of tranexamic acid on postpartum bleeding in women with moderate and severe anaemia (WOMAN-2): an international, randomised, double-blind, placebo-controlled trial

Tranexamic acid, given within 3 h of birth, reduces bleeding deaths in women with postpartum haemorrhage. We examined whether giving tranexamic acid shortly after birth can prevent postpartum haemorrhage in women with moderate or severe anaemia. This international, randomised, double-blind, placebo-controlled trial was done in 34 hospitals across four countries (Nigeria, Pakistan, Tanzania, and Zambia). We recruited women of any age in active labour with moderate or severe anaemia (haemoglobin <100 g/L). We randomly assigned women (1:1) who had given birth vaginally to receive 1 g of tranexamic acid or matching placebo by slow intravenous injection (over 10 min) within 15 min of the umbilical cord being cut or clamped. Women were randomly assigned by selection of the lowest numbered treatment pack from a box containing 20 packs that were identical apart from the pack number. Participants, care givers, and those assessing outcomes were masked to group assignment. The primary outcome was a clinical diagnosis of primary postpartum haemorrhage, which might be an estimated blood loss of more than 500 mL or any blood loss sufficient to compromise haemodynamic stability within 24 h of randomisation, analysed on an intention-to-treat basis. Safety analyses were performed in all participants included in the intention-to-treat population. This trial was registered on ISRCTN (ISRCTN62396133), ClinicalTrials.gov (NCT03475342), and the Pan African Clinical Trial Registry (PACTR201909735842379) and is closed to recruitment. From Aug 24, 2019, to Sept 19, 2023, 16 586 women aged 14-50 years were invited to take part and 1518 were excluded. 7580 women were randomly assigned to receive tranexamic acid and 7488 to receive placebo. Primary outcome data were unavailable for one woman in each group. The median time interval from the start of the administration of the trial treatment to the diagnosis of postpartum haemorrhage was 18·5 min (IQR 5-58); 20 min (8-64) in women with moderate anaemia and 13 min (7-44) in women with severe anaemia. 358 (35%) of 1024 with postpartum haemorrhage for whom time data were available were diagnosed before the trial treatment had been fully administered. Clinically diagnosed postpartum haemorrhage occurred in 530 (7·0%) of 7579 in the tranexamic acid group and in 497 (6·6%) of 7487 in the placebo group (risk ratio [RR] 1·05, 95% CI 0·94-1·19). There was no strong evidence against the null hypothesis of homogeneity of effects for any of the prespecified subgroup analyses: severity of anaemia (p=0·44), antepartum haemorrhage (p=0·044), birth canal trauma (p=0·37), use of pain control (p=0·37), and baseline risk of postpartum haemorrhage (p=0·31). There were no vascular occlusive events (pulmonary embolism, deep vein thrombosis, stroke, and myocardial infarction) reported in either group. There were no adverse events related to the treatment and no treatment-related deaths. In women with moderate and severe anaemia, giving tranexamic acid within 15 min of the umbilical cord being clamped did not reduce the risk of clinically diagnosed postpartum haemorrhage. The Bill & Melinda Gates Foundation and the Wellcome Trust.

Self-assembled nanoparticles of alginate and paclitaxel-triphenylphosphonium for mitochondrial apoptosis targeting.

Paclitaxel (PTX), an antimitotic drug from the taxanes group, prevents the proliferation of breast cancer cells through mitosis arrest and activation by a cascade of signaling pathways that lead to apoptosis. Mitochondria is one of the important signaling routes for inducing apoptosis. For mitochondria targeting, triphenylphosphonium (TPP) with a delocalized charge and hydrophobic nature was utilized as a moiety to facilitate penetration through a phospholipid membrane of mitochondria. PTX-TPP was synthesized via pH-sensitive ester bond between hydroxyl groups of PTX and carboxylic acid of (4-carboxybutyl) TPP. Then PTX-TPP prodrug encapsulated in alginate nanoparticles, which were self-assembled by the ionotropic complexation technique for enhancement of mitochondrial apoptosis in breast cancer cells. The loading of PTX-TPP conjugation in self-assembled alginate nanoparticles was 16.5% and the particle size of nanoparticles was 123nm with zeta potential around -25.8 Mv. The in vitro cytotoxicity and IC50 of PTX-TPP nanoparticles in the growth of MCF7 cancer cell increased 6.3-fold higher than free PTX. The early apoptotic cells and the late apoptotic/necrotic cells for PTX-TPP nanoparticles were 11.6 and 3.9-fold higher than free PTX. This study indicated this mitochondrial-targeted self-assembled nanoparticles can inhibit the tumor cell growth of breast cancer.

A low-impedance cation exchange membrane for extending the voltage window of a BiFeO3-based hybrid supercapacitor through the pH-decoupling strategy

Aqueous hybrid supercapacitors usually suffer from narrow voltage window and poor energy density limited by the thermodynamic decomposition of water. Based on necessary ion exchange membranes, the pH-decoupling strategy can be employed to extend the voltage windows of hybrid supercapacitors. We propose a novel low-impedance cation exchange membrane (CEM) with the interpenetrating network structure for the pH-decoupling strategy, which can be served as the separator for a AC//BiFeO3 supercapacitor to enhance its electrochemical performances. Two CEMs (CEM-1 and CEM-2) with different contents of the sulfonic acid (-SO3H) groups, are fabricated through the copolymerization of various monomers according to the predetermined stoichiometric ratios. FTIR, Raman and XPS spectra reflect that the CEM-2 has the higher content of the -SO3H groups than the CEM-1. The membrane parameter measurements confirm that the CEM-2 has the higher water content, lower membrane resistance and smaller membrane thickness than the CEM-1. The AC//BiFeO3 supercapacitor with the CEM-2 separator provides the higher gravimetric specific capacitance of 61 F g−1 at 1 A g−1, better coulombic efficiencies (97 % ∼ 103 %) and lower Rs value (39.74 Ω) than the AC//BiFeO3 supercapacitors with the CEM-1 separator. Moreover, the AC//BiFeO3 supercapacitor with the CEM-2 separator delivers the maximum energy density of 41.0 Wh kg−1 at the power density of 1.1 kW kg−1. The pH-decoupling strategy with this low-impedance CEM, opens up a new avenue for developing high-performance aqueous electrochemical energy storage devices.

Palladium(II)-Catalyzed Site-Selective C(sp3)-H Alkenylation of Oligopeptides.

An innovative palladium-catalyzed alkenylation of peptides and vinyl iodides has been developed. This method does not require the introduction of a directing group and uses carboxylic acid groups as endogenous directing groups. It is noteworthy that two key building blocks for the ilamycins and CXCR7 modulators were prepared using our methodology. In addition, the free carboxylic acid residue can be linked to a variety of other compounds, providing a novel approach to the synthesis of peptide drugs in the future.

Understanding CO adsorption in MOFs combining atomic simulations and machine learning

This study introduces a computational method integrating molecular simulations and machine learning (ML) to assess the CO adsorption capacities of synthesized and hypothetical metal–organic frameworks (MOFs) at various pressures. After extracting structural, chemical, and energy-based features of the synthesized and hypothetical MOFs (hMOFs), we conducted molecular simulations to compute CO adsorption in synthesized MOFs and used these simulation results to train ML models for predicting CO adsorption in hMOFs. Results showed that CO uptakes of synthesized MOFs and hMOFs are between 0.02–2.28 mol/kg and 0.45–3.06 mol/kg, respectively, at 1 bar, 298 K. At low pressures (0.1 and 1 bar), Henry’s constant of CO is the most dominant feature, whereas structural properties such as surface area and porosity are more influential for determining the CO uptakes of MOFs at high pressure (10 bar). Structural and chemical analyses revealed that MOFs with narrow pores (4.4–7.3 Å), aromatic ring-containing linkers and carboxylic acid groups, along with metal nodes such as Co, Zn, Ni achieve high CO uptakes at 1 bar. Our approach evaluated the CO uptakes of ~ 100,000 MOFs, the most extensive and diverse set studied for CO capture thus far, as a robust alternative to computationally demanding molecular simulations and iterative experiments.

Evaluating the efficacy of probiotics and ascorbic acid as anti-stress agents against heat stress in broiler chickens

Heat stress poses a substantial challenge to poultry production worldwide, highlighting the urgent need for effective management strategies. This study investigated the efficacy of probiotics (Saccharomyces cerevisiae) and ascorbic acid as antistress agents using cloacal and body surface temperatures (CT and BST) as heat stress biomarkers in broiler chickens. A total of 56 broiler chicks were used for the experiment and were divided into four distinct groups: control, probiotics (1 g/kg of feed), ascorbic acid (200 mg/kg of feed) and the combination of probiotics and ascorbic acid (1 g/kg and 200 mg/kg of feed, respectively). The study lasted 35 days; measurements were taken for ambient temperature (AT), CT, and BST. The ambient temperature in the pens consistently exceeded the thermoneutral zone (TNZ) established for broiler chickens. The CT values for broiler chickens in the probiotic group were significantly lower (p &amp;lt; 0.05) compared to the control group. Additionally, the BST values in the probiotic and probiotic + ascorbic acid groups were significantly lower (p &amp;lt; 0.05) than those in the control group. The findings suggest that incorporating probiotics, with or without ascorbic acid, can effectively reduce CT and BST values in broiler chickens thereby, enhancing thermoregulation when compared to the control group. This implies that using probiotics in poultry diets may enhance health and growth performance, potentially leading to better feed efficiency and reduced reliance on antibiotics. Implementing these dietary strategies could improve the productivity and welfare of broiler chickens in commercial settings.

A Comparative Study of Structural Contribution to Biocidability via Immobilization of Fluorinated and Nonfluorinated Quaternary Ammonium Salts on Top Surfaces.

Higher biocidability of fluorinated quaternary ammonium salt (QAS) is usually contributed to its preferential segregation to the surface to better contact with and kill bacteria. However, whether its structure also elicits better performance is still unclear. Herein, the same amount of a fluorinated QAS and its nonfluorinated counterpart are both immobilized on the top surface to eliminate the effect of concentration distribution to only study their structure-biocidability relationship. Briefly, the fluorinated and nonfluorinated QASs were synthesized by quaternization of N,N-dimethylethanolamine with 2-(perfluorooctyl)ethyl bromide that was prepared by bromination of 2-(perfluorooctyl)ethanol and 1-bromodecane, respectively. Polystyrene (PS) and diblock copolymer poly(styrene)-b-poly(tert-butyl acrylate) (PS-PtBA) were successively spin coated on SiO2 wafers at different concentrations to form bilayer structures that have a PS base layer and a PtBA top layer. The tert-butyl acrylate groups of the PtBA layer of 0.9 nm were converted to carboxylic acid groups with trifluoroacetic acid for respective esterification with the two hydroxy-containing QASs. It was observed that the fluorinated and nonfluorinated surfaces fabricated at the maximum comparable esterification yield of 63.5% fully eradicated ∼104 CFU of Staphylococcus aureus and Escherichia coli in 120 and 150 min, respectively, indicating that the fluorocarbon chain is more biocidal through better interpenetration into bacterial membranes. Immobilization of a functionality on top surface provides a universal strategy to study its structural contribution to activity without interference of the concentration distribution.

The Inhibitory Effects of a Factor B-Binding DNA Aptamer Family Supersede the Gain of Function of Factor B Variants Associated with Atypical Hemolytic Uremic Syndrome.

Aptamers are short, single-stranded oligonucleotides that selectively bind to target biomolecules. Although they generally exhibit good binding specificity, their affinities are often limited because of the relative lack of hydrophobic groups in nucleic acids. Chemically modified nucleotides incorporating hydrophobic structures into uracil have been synthesized to address this obstacle. Modified DNA aptamers containing such nonstandard nucleotides have been developed for >20 different complement proteins. These modified aptamers show increased affinity and enhanced serum stability and have potential value as therapeutic agents. We recently conducted a structure/function study on a family of modified DNA aptamers that bind specifically to complement Factor B (FB). This work revealed that these aptamers selectively inhibit the complement alternative pathway (AP) by preventing the formation of the AP complement component C3 (C3) proconvertase complex, C3bB. Certain patients with atypical hemolytic uremic syndrome express gain-of-function variants of FB that enhance the formation of the proconvertase complex and/or decrease the efficacy of endogenous regulators against the C3 convertases they form. To investigate whether these FB-binding aptamers could override the effects of disease-causing mutations in FB, we examined how they interacted with several FB variants, including D279G, F286L, K323E, and K350N, in various assays of complement function. We found that the inhibitory effect of the FB-binding aptamers superseded the gain-of-function mutations in FB, although the aptamers could not dissociate preformed C3 convertases. These findings suggest that FB-binding aptamers could be further developed as a potential treatment for certain atypical hemolytic uremic syndrome patients or those with other diseases characterized by excessive complement activity.

Hydrogen Fluoride Imidazole: A Simple, Efficient, Mild, and Cost-Effective Silyl-Ether Deprotection Reagent.

Despite the availability of numerous -OH silyl protection and deprotection methods, the selective cleavage of silyl ethers in highly complex molecules can still be a challenge. In this article, we present results from a full investigation of a novel, efficient, and mild desilylation protocol using HF/imidazole. Imidazole significantly enhances the desilylation reaction efficiency of HF, allowing clean and complete deprotection of TBDPS ethers in substrates containing both acid and base sensitive groups. For example, four- and five-mer oligonucleotides were efficiently deprotected where all other conditions failed. HF/imidazole is also an effective reagent for the deprotection of TIPS and TBDMS ethers. The reagent prepared using commercially available HF and imidazole maintained the same reactivity even after 4 years of storage at 4 °C. Residual reagents and byproducts can be readily removed with a simple workup; consequently, deprotection of TBDPS was successfully implemented in a 2.5 kg scale synthesis of a five-mer oligonucleotide.

Enhancing gene delivery efficiency with amphiphilic chitosan modified by myristic acid and tertiary amino groups

The aim of this study is to synthesize new amphiphilic chitosan containing myristic acid as the hydrophobic tail and tertiary amine groups as the hydrophilic head and to evaluate the gene delivery efficiency. In this context, the primary amine groups of chitosan were first modified with myristic acid (Chi-M), followed by the modification of the methylol groups with 3-dimethylamino-1-propyl chloride hydrochloride. The chemical characterization of this chitosan formulation (Chi-MA) was determined using nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR) analysis and gel permeation chromatography-size exclusion chromatography. Chi-MA nanoparticles were prepared via ionic gelation, and particle size, polydispersity and zeta potential were determined. The nanoparticles were evaluated for their proton buffering capacity and gene complexing capacity. Additionally, the cytotoxicity of Chi-MA on HEK293T cells was determined via MTT assay, and the transfection efficiency of Chi-MA was analyzed by a flow cytometer. The results indicate a significant increase in gene complexing capacity (8-fold) and nanoparticle formation ability of Chi-MA compared to other chitosan formulations. Chi-MA nanoparticles showed no toxicity against HEK293T cells and exhibited the highest transfection efficiency with significantly lower nanoparticle: gene ratios compared to previous studies. These findings demonstrate the effective use of amphiphilic Chi-MA as a gene carrier.

Two Squaramide-Based Fluorescent Probes for Cu2+ and Cd2.

The development of potential toxic metal ion probes is of great significance in the field of environmental detection. Herein, two squaramide ligands (2a, 2b) were constructed by combining the characteristics of squaric acid and imine groups. 2a and 2b can recognize Cu2+ and Cd2+, with LOD of 1.26 × 10-8M and 2.04 × 10-8M, respectively, and have the advantages of fast response and wide pH range. The binding ratio and binding mode of the probe and the target ion were determined by Job's plot, ESI-MS, and 1H NMR.