Extracellular Green Synthesis of Silver Nanoparticles Using Extract of Mimosa pudica Leaves and Assessment of Antibacterial and Antifungal Activity

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - In recent years, green chemistry approaches have gained global recognition as eco-friendly processes. Rapid...     

Sunlight Irradiation Induced Green Synthesis of Stable Silver Nanoparticles Using Citrus limon Extract

In the present study, silver nanoparticles were rapidly synthesized photochemically by treating silver ions with lemon (Citrus limon) extract utilizing solar radiation. The effect of time period of the day on reaction rate and nanoparticle formation was investigated in details. In the standardized process, 10^?2 M silver nitrate solution was interacted for 20 min with lemon juice (2 % citric acid and 0.5 % ascorbic acid concentration) in the ratio of 1:4 (vol:vol) in the presence of sunlight. Silver nanoparticles below 50 nm with spherical and spheroidal shape were observed under electron microscopic analysis. The authors have hereby developed an energy efficient bio-based synthesis process which produces silver nanoparticles rapidly.     

In Vitro Anti-Inflammatory Activity of Green Synthesized Silver Nanoparticles and Leaf Methanolic Extract of Solanum khasianum Clarke

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - Inflammation leads to several deleterious effects in the body. The main aim of this study was to evaluate the...     

Synthesis and Characterization of Antimicrobial Silver Nanoparticles by an Endophytic Fungus Isolated from Nyctanthes arbor-tristis

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - Biofabrication of metal nanoparticles is a cost-effective, one-step and ecofriendly technique. Cell filtrate...     

Green Synthesis of Silver and Titanium Dioxide Nanoparticles Using Euphorbia prostrata Extract Shows Shift from Apoptosis to G0/G1 Arrest followed by Necrotic Cell Death in Leishmania donovani

The aim of the present study was to synthesize silver (Ag) and titanium dioxide (TiO₂) nanoparticles (NPs) using green synthesis from aqueous leaf extract of Euphorbia prostrata as antileishmanial agents and to explore the underlying molecular mechanism of induced cell death. In vitro antileishmanial activity of synthesized NPs was tested against promastigotes of Leishmania donovani by alamarBlue and propidium iodide uptake assays. Antileishmanial activity of synthesized NPs on intracellular amastigotes was assessed by Giemsa staining. The leishmanicidal effect of synthesized Ag NPs was further confirmed by DNA fragmentation assay and by cell cycle progression and transmission electron microscopy (TEM) of the treated parasites. TEM analysis of the synthesized Ag NPs showed a spherical shape with an average size of 12.82 ± 2.50 nm, and in comparison to synthesized TiO₂ NPs, synthesized Ag NPs were found to be most active against Leishmania parasites after 24 h exposure, with 50% inhibitory concentrations (IC₅₀) of 14.94 μg/ml and 3.89 μg/ml in promastigotes and intracellular amastigotes, respectively. A significant increase in G₀/G₁ phase of the cell cycle with a subsequent decrease in S (synthesis) and G₂/M phases compared to controls was observed. The growth-inhibitory effect of synthesized Ag NPs was attributed to increased length of S phase. A decreased reactive oxygen species level was also observed, which could be responsible for the caspase-independent shift from apoptosis (G₀/G₁ arrest) to massive necrosis. High-molecular-weight DNA fragmentation as a positive consequence of necrotic cell death was also visualized. We also report that the unique trypanothione/trypanothione reductase (TR) system of Leishmania cells was significantly inhibited by synthesized Ag NPs. The green-synthesized Ag NPs may provide promising leads for the development of cost-effective and safer alternative treatment against visceral leishmaniasis.     

Green Synthesis of Zinc Oxide Nanoparticles (ZnO NPs) Using Cissus quadrangularis: Characterization,Antimicrobial and Anticancer Studies

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - In the present study, zinc oxide nanoparticles (ZnO NPs) were synthesized using the stem aqueous extracts of...     

Vector Flow Mapping in Mitral Valve Disease: a Novel Method for the Assessment of Flow Mechanics and Their Potential Implications for Mitral Valve Repair

In the last few years, the development of new techniques enabling visualization and quantification of flow behavior inside cardiac chambers has increased the interest in flow mechanics, blood-tissue interaction, and the potential application of these new data to diagnosis and guidance of treatment. Several studies have focused on flow dynamics inside the left ventricle and a differential aspect in it: the vortex ring. In this article, we briefly describe the key role of the mitral valve on the generation of physiologic flow dynamics. We also review how mitral valve disease and its treatment can influence the distribution of flow inside the left ventricle and its potential clinical impact.     

Green synthesis of palladium nanoparticles using lentinan for catalytic activity and biological applications

The green synthesis of palladium nanoparticles (Pd NPs) for catalysis and biological applications has been gaining great interest. To replace complex plant extracts, lentinan (LNT) may be a good reducing and stabilizing agent. In this work, a simple and green method using LNT to reduce and stabilize palladium Pd NPs was verified. The resulting LNT stabilized palladium nanoparticles (Pd_n-LNT NPs) were characterized by UV-Vis spectroscopy, DLS, TEM, and XPS. The results indicated that Pd NPs inside of Pd_n-LNT NPs had a small size (2.35–3.32 nm). Pd_n-LNT NPs were stable in solution for 7 days. In addition, Pd_n-LNT NPs had higher catalytic activity towards the reduction of 4-nitrophenol than other catalysts. More importantly, Pd_n-LNT NPs had negligible cytotoxicity towards cells and showed good antioxidant activity. Taken together, the prepared Pd_n-LNT NPs have great potential bio-related applications.

Lentinan stabilized palladium nanoparticles had high catalytic activity, negligible cytotoxicity and good antioxidant activity.     

Synthesis,Bioactivity Evaluation,and Toxicity Assessment of Novel Salicylanilide Ester Derivatives as Cercaricides against Schistosoma japonicum and Molluscicides against Oncomelania hupensis

A series of novel salicylanilide ester derivatives were synthesized, characterized, and evaluated for cercaricidal potential against Schistosoma japonicum and molluscicidal potential against Oncomelania hupensis. Four derivatives exhibited remarkable cercaricidal activity superior to that of niclosamide. Among them, the most active compound, 4-chloro-2-((2-methoxy-4-nitrophenyl)carbamoyl)phenyl 4-methoxybenzoate (compound 4c), showed a marked minimum effective cercaricidal concentration as low as 0.43 μM and significant molluscicidal activity, with a 50% lethal concentration (LC₅₀) of 0.206 g/m². Particularly, compound 4c displayed 88-fold decreased fish toxicity on Danio rerio and 44-fold reduced cytotoxicity on human kidney HEK293 cells in comparison with the toxicity of niclosamide. The results indicated that 4c could serve as a promising drug candidate, with environmental safety properties, against Schistosoma japonicum at transmission stages. The preliminary molecular mechanism of target compounds in Schistosoma japonicum cercariae was also investigated. Salicylanilide ester derivatives exhibited an inhibitory effect on nitric oxide synthase (NOS) but no effect on lactate dehydrogenase (LDH) and acetylcholinesterase (AChE), and a strong and significant correlation between NOS inhibitory efficacy and cercaricidal activity was observed. In addition, 4c could downregulate the expression of NOS in a dose-dependent manner. These results suggested that NOS was probably one of the drug targets of salicylanilide esters.     

Synthesis and kinetics of disassembly for silyl-containing ethoxycarbonyls using fluoride ions

In this study, a series of silyl-containing ethoxycarbonates and ethoxycarbamates on electron poor anilines and phenols were synthesized and their kinetics of disassembly determined in real-time upon exposure to fluoride ion sources at room temperature. The results provide a greater understanding of stability and kinetics for silyl-containing protecting groups that eliminate volatile molecules upon removal, which will allow for simplification of orthogonal protection in complex organic molecules.

Rate constants of disassembly for synthesized silyl-containing ethoxycarbonyls were significantly faster than TEOC, a common protecting group.

Silicon-based groups have demonstrated wide utility in organic syntheses, ranging from orthogonal protection of amine, hydroxyl and acid functionalities in complex drug molecules^1–3 to utilization as a trigger in self-immolative polymers and dendrimers.^4–6 One of the commonly used silicon-based protecting groups is 2-(trimethylsilyl)ethoxycarbonyl (TEOC),⁷ which was originally developed and later optimized for N-protection of amino acids to prevent formation of oligopeptides, but has since been utilized for protection of other functionalities.⁸ The uniqueness of TEOC is that it can be preferentially removed with a mild de-blocking agent, such as fluoride ion, in the presence of other base-sensitive groups to produce low molecular weight and volatile by-products via cascading bond cleavage, thereby easing purification of complex mixtures and enabling greater product yields.During our course of utilizing TEOC to protect amine and hydroxyl functionality on aliphatic oligomers we discovered there was a severe lack of kinetic data in the literature for removal of TEOC using fluoride ion, as most papers generally stated the times for removal as occurring within hours at elevated temperatures⁷ to days at room temperature.^9,10 Furthermore, similar silyl-containing protecting groups, such as (2-phenyl-2-trimethylsilyl)ethoxycarbonyl (PSOC)¹¹ and 2-(triphenylsilyl)ethoxycarbonyl (TPSEOC),¹² were reported to be removed under milder fluoride ion conditions and/or faster times than TEOC due to a more readily formed fluoro-containing penta-coordinated intermediate as a result of phenyl group incorporation. However, while these groups were reported to be removed within minutes to hours at room temperature the studies provide minimal details on the actual kinetics compared to TEOC. As a result, we aimed to generate quantitative kinetic data for the removal of TEOC and other silyl-containing ethoxycarbonyl groups from functionality by performing disassembly experiments with fluoride ion sources at room temperature, as this information is relevant to those utilizing orthogonal protecting group chemistry in multi-step synthesis and potentially in the processing of pharmaceuticals.Herein, we report the kinetics of disassembly (i.e., rate constants (k) for removal) for a series of silyl-terminated ethoxycarbonyl protecting groups, such as TEOC, 2-(methyldiphenylsilyl)ethoxycarbonyl (MDPSEOC), and several extended chain versions of these molecules, from electron poor hydroxyl and amine functionalities. To do this, we utilized non-substituted and para-substituted phenols and anilines, as these molecules provided a UV-visible chromophore for real-time detection during removal of the protecting groups. We also synthesized and determined the kinetics of disassembly for several novel silyl-centered bis(ethoxycarbonyls), as we were interested in studying the reaction of multiple fluoride ions with silicon and their influence on the resulting kinetics.Our study of these molecules commenced by attempting to determine the rate constants of disassembly for 4-nitrophenyl (2-(trimethylsilyl)ethyl) carbonate (1a), a commercially available control,¹³ and synthesized 2-(trimethylsilyl)ethyl (4-nitrophenyl)carbamate (1b), using solutions of different fluoride salts in organic solvents and water. It was initially found that tetrahydrofuran (THF), dichloromethane, and acetonitrile provided good solubility of these organic molecules, with water and water/solvent combinations providing limited solubility. Furthermore, fluoride ion sources, such as tetrabutylammonium fluoride trihydrate (TBAF·3H₂O) and a 1 : 1 molar ratio of TBAF/CsF, provided good solubility in the aforementioned solvents and several solvent/water combinations, whereas solubility of cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), and stannous fluoride (SnF₂) were limited. It should be noted that a 1 : 1 TBAF/CsF mixture in THF provided nearly identical rate constants of disassembly during initial studies as TBAF in THF. However, to maintain fluoride ion solution consistency it was determined that all kinetic experiments would be conducted in THF using commercially available TBAF in THF.Kinetic experiments for 1a and 1b were conducted as 0.1 mM solutions in THF using 1 ml cuvettes and an Agilent 8453 UV-Visible Spectrophotometer. To initiate disassembly, 4 molar equivalents of 1.0 M TBAF in THF were added separately to 1a and 1b at room temperature (Scheme 1), then the absorbance of the solutions were recorded up to 120 minutes. The cuvettes were not stirred upon addition of the fluoride salt solution in effort to prevent an increase in the rate of disassembly due to turbidity. Silyl-terminated carbonate 1a, which has a maximum absorbance (λ_max) at 270 nm, decreased within minutes as a new absorbance at λ_max of 423 nm appeared, corresponding to 4-nitrophenolate (2a).¹⁴ Ethylene and carbon dioxide were detected via gas chromatography/mass spectrometry (GC-MS), thereby supporting the proposed mechanism of disassembly as shown in Scheme 1.⁷ The rate constant of disassembly for 1a was found to be 2196 ± 1380 M⁻¹ min⁻¹ for the second order reaction (15 although this peak quickly decreased as a new absorbance at λ_max of 366 nm was formed. The latter corresponded to 4-nitroaniline (2c),¹⁶ the conjugate acid of 2b, and is proposed to have resulted from beta-elimination of a proton on the tetrabutylammonium cation, thereby forming tributylamine and 1-butene as side products via a Hofmann elimination.¹⁷¹H-NMR and GC-MS analysis of the solution after disassembly supports this hypothesis. The rate constant of disassembly for 1b was determined to be 38.5 ± 0.3 M⁻¹ min⁻¹, and the slower rate compared to 1a is consistent with substituted anilines possessing a larger pKa value than substituted phenols. 2-(methyldiphenylsilyl)ethyl (4-nitrophenyl) carbonate 1c and 2-(methyldiphenylsilyl)ethyl (4-nitrophenyl)carbamate 1d were subsequently synthesized and their rate constants of disassembly determined. Although similar to the triphenylsilyl and 2-phenyl-2-trimethylsilyl ethoxycarbonyl protecting groups reported in the literature,^11,12 we chose the methyldiphenylsilyl group because it was a hybrid of the aforementioned groups, the kinetics of phenyl-containing silyl groups had not been reported, and the lone methyl group provided a basis for larger aliphatic groups, which are discussed in subsequent paragraphs.Open in a separate windowScheme 1Products and proposed mechanism of disassembly for reaction of silyl-terminated carbonates and carbamates with TBAF.Rate constants of disassembly and percentage of silyl-terminated carbonates and carbamates remaining once treated with TBAF under non-stirred conditions

用新底物DCAP-P检测酸性磷酸酶方法的建立

目的　合成酸性磷酸酶 (ACP)的底物 2 ,6 二氯 4 乙酰基苯基磷酸 (DCAP P) ,并建立以DCAP P为底物的一种新的ACP测定方法。方法　在BTS 310型半自动分析仪和TBA 4 0FR型全自动生化分析仪上研究连续监测法 ,建立试验参数。结果　本法测定DCAP吸收峰为 32 6nm ;ACP的Km=0 139mmol/L ;340nm时DCAP的摩尔消光系数为 14 4 4 0L·mol 1·cm 1,缓冲液浓度 0 1mol/L ,最适pH5 .4 ,底物浓度 2 0mmol/L ,延滞期 6 0s,线性反应期 15min ;线性范围为 0～ 1188U/L ;血红蛋白 <115 6 2mg/L及胆红素对测定结果无影响 ;本法总ACP与PAP(前列腺酸性磷酸酶 )的参考值范围分别为 12 5 8～ 19 4 2U/L和 2 5 2～9 0 4U/L。结论　此方法重复性好 ,线性反应期长 ,线性范围广 ,干扰因素少 ,适用于自动化分析仪。     

Assessment of SYBR Green I Dye-Based Fluorescence Assay for Screening Antimalarial Activity of Cationic Peptides and DNA Intercalating Agents

The SYBR green I (SG) dye-based fluorescence assay for screening antimalarial compounds is based on direct quantitation of parasite DNA. We show that DNA-interacting cationic cell-penetrating peptides (CPPs) and intercalating agents compete with SG dye to bind to DNA. Therefore, readouts of this assay, unlike those of the [³H]hypoxanthine incorporation assay, for the antimalarial activity of the above DNA binding agents may be erroneous. In the case of CPPs, false readouts can be improved by the removal of excess peptides.     

Synthesis and Evaluation of Ga-68-Labeled Rhein for Early Assessment of Treatment-Induced Tumor Necrosis

Molecular Imaging and Biology - This study aimed to synthesize a necrosis-avid agent using rhein as a precursor and labeled with gallium-68 (Ga-68) for positron emission tomography/computed...     

Green synthesis of nitrogen-doped multiporous carbons for oxygen reduction reaction using water-caltrop shells and eggshell waste

A green synthesis method is proposed for the preparation of nitrogen-doped multiporous carbons (denoted as N-MPCs) from water-caltrop shell (WCS) using eggshell waste as both a nitrogen-dopant and an activating agent. It is shown that the surface area, porosity, yield and nitrogen content of the as-prepared N-MPCs can be easily controlled by adjusting the activation temperature. Moreover, in oxygen reduction reaction (ORR) tests performed in O₂-saturated 0.1 M KOH_(aq) electrolyte containing 1.0 M methanol, the N-MPC catalysts show a high ORR stability and good resistance to methanol corrosion. In addition, as a cathode material in Al–air battery tests, the N-MPCs achieve a power density of 16 mW g⁻¹ in a saturated NaCl_(aq) electrolyte. Overall, the results show that the N-MPCs have a promising potential as a green and sustainable material for ORR catalysis applications.

A green synthetic method is proposed for the preparation of nitrogen-doped multiporous carbons (denoted as N-MPCs) from water-caltrop-shell (WCS) biochar by using eggshell waste as both a nitrogen-dopant and an activating agent.     

速度向量成像技术定量评价阵发性房颤患者左房功能的研究

[目的]采用超声速度向量成像技术(VVI)定量评价阵发性房颤(PAF)患者左房功能,探讨其可行性及临床应用价值.[方法]选择窦性心律健康者30例(对照组),PAF 患者30例(PAF组),均采用常规二维及多普勒超声获取左房功能参数,采用VVI检测左心房收缩期峰值应变(Ss)及峰值应变率(SRs),左心房舒张早期峰值应变(Se)及峰值应变率(SRe)和左心房舒张晚期峰值应变(Sa)及峰值应变率(SRa),并与左房常规参数:E(脉冲多普勒超声二尖瓣舒张早期血流速度峰值),A(脉冲多普勒超声二尖瓣舒张晚期血流速度峰值),E/A比值,E′(组织多普勒超声二尖瓣环舒张早期运动速度峰值),A′(组织多普勒超声二尖瓣环舒张晚期运动速度峰值)比较.[结果]对照组左房径(LAD)、左房容积(LAV)、E、A、E/A、E′ 、A′与PAF组比较差异无显著性(P>0.05);PAF组Ss、SRs、Se,SRe较对照组显著降低,其差异有统计学意义(P<0.01).[结论]VVI能够准确评价PAF患者的左房功能,并且在左房大小变化之前定量评价其机械功能.     

Real-time PCR using SYBR Green for the detection of Shigella spp. in food and stool samples

Shigella spp are exquisitely fastidious Gram negative organisms that frequently get missed in the detection by traditional culture methods. For this reason, this work has adapted a classical PCR for detection of Shigella in food and stool specimens to real-time PCR using the SYBR Green format. This method follows a melting curve analysis to be more rapid and provide both qualitative and quantitative data about the targeted pathogen.A total of 117 stool samples with diarrhea and 102 food samples were analyzed in Public Health Regional Laboratory of Nabeul by traditional culture methods and real-time PCR. To validate the real-time PCR assay, an experiment was conducted with both spiked and naturally contaminated stool samples. All Shigella strains tested were ipaH positive and all non-Shigella strains yielded no amplification products. The melting temperature (T_m = 81.5 ± 0.5 °C) was consistently specific for the amplicon. Correlation coefficients of standard curves constructed using the quantification cycle (C_q) versus copy numbers of Shigella showed good linearity (R² = 0.995; slope = 2.952) and the minimum level of detection was 1.5 × 10³ CFU/g feces. All food samples analyzed were negative for Shigella by standard culture methods, whereas ipaH was detected in 8.8% culture negative food products. Moreover, the ipaH specific PCR system increased the detection rate over that by culture alone from 1.7% to 11.1% among patients with diarrhea.The data presented here shows that the SYBR Green I was suitable for use in the real-time PCR assay, which provided a specific, sensitive and efficient method for the detection and quantification of Shigella spp in food and stool samples.     

Correction: Green synthesis of nitrogen-doped multiporous carbons for oxygen reduction reaction using water-caltrop shells and eggshell waste

Correction for ‘Green synthesis of nitrogen-doped multiporous carbons for oxygen reduction reaction using water-caltrop shells and eggshell waste’ by Chun-Han Hsu et al., RSC Adv., 2021, 11, 15738–15747. DOI: 10.1039/D1RA02100A.

The authors regret that there was an error in the funding information in the original article. The grant number was given as 108-D0111 in the original article, where it should have read 110-D0111.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.