Degradable mesoporous semimetal antimony nanospheres for near-infrared II multimodal theranostics

Metallic and semimetallic mesoporous frameworks are of great importance owing to their unique properties and broad applications. However, semimetallic mesoporous structures cannot be obtained by the traditional template-mediated strategies due to the inevitable hydrolytic reaction of semimetal compounds. Therefore, it is yet challenging to fabricate mesoporous semimetal nanostructures, not even mention controlling their pore sizes. Thus, we have developed a facile and robust selective etching route to synthesize monodispersed mesoporous antimony nanospheres (MSbNSs). This is the first report of semimetallic mesoporous structure to the best of our knowledge. The pore sizes of MSbNSs are tunable by carefully controlling the partial oxidation of Sb nuclei and the selective etching of the as-formed Sb2O3. MSbNSs showed a wide absorption from visible to second near-infrared (NIR-II) region. Moreover, PEGylated MSbNSs were degradable and the degradation mechanism was further explained. The NIR-II photothermal performance of MSbNSs was excellent with a high photothermal conversion efficiency of ~44% and intensive NIR-II photoacoustic signal. MSbNSs showed great potential as multifunctional nanomedicines for NIR-II photoacoustic imaging guided synergistic photothermal/chemo therapy in vivo. Our novel selective etching process would contribute to the development of various semimetallic mesoporous structures and efficient multimodal nanoplatforms for theranostics.

The Influence of Sodium Benzoate on the Alkaline Hydrolysis of Fuchsin: Inhibition Study

Kinetics of alkaline hydrolysis of Fuchsin in the absence and presence of sodium benzoate was investigated at 546.5 nm by pseudo first order kinetics. The reaction was found to be first order each in [Fuchsin] and [NaOH] in the presence and absence of sodium benzoate. Double reciprocal plot indicates the presence of an intermediate complex in the course of the reaction. Activation parameters were obtained from Erying’s equation as ΔH# 24.70 kJmol-1, ΔS# -0.193 kJK-1mol-1 and ΔG# 82.21 kJ mol-1 in the absence of sodium benzoate and ΔH# 27.59 kJmol-1, ΔS# -0.185 kJ K-1mol-1 and ΔG# 82.72 kJ mol-1in the presence of sodium benzoate. Sodium benzoate plays an inhibitory role in the hydrolysis reaction. The values of the change in Gibb’s free energy of activation shows same mechanism for the hydrolytic reaction in the presence and absence of sodium benzoate. A plausible mechanism is proposed. Keywords: Sodium benzoate, Fuchsin, NaOH, rate law, mechanism

Novel Insights into the Thioesterolytic Activity of N-Substituted Pyridinium-4-oximes

The pyridinium oximes are known esterolytic agents, usually classified in the literature as catalysts, which mimic the catalytic mode of hydrolases. Herein, we combined kinetic and computational studies of the pyridinium-4-oxime-mediated acetylthiocholine (AcSCh+) hydrolysis to provide novel insights into their potential catalytic activity. The N-methyl- and N-benzylpyridinium-4-oximes have been tested as oximolytic agents toward the AcSCh+, while the newly synthesized O-acetyl-N-methylpyridinium-4-oxime iodide was employed for studying the consecutive hydrolytic reaction. The relevance of the AcSCh+ hydrolysis as a competitive reaction to AcSCh+ oximolysis was also investigated. The reactions were independently studied spectrophotometrically and rate constants, koxime, kw and kOH, were evaluated over a convenient pH-range at I = 0.1 M and 25 °C. The catalytic action of pyridinium-4-oximes comprises two successive stages, acetylation (oximolysis) and deacetylation stage (pyridinium-4-oxime-ester hydrolysis), the latter being crucial for understanding the whole catalytic cycle. The complete mechanism is presented by the free energy reaction profiles obtained with (CPCM)/M06–2X/6–311++G(2df,2pd)//(CPCM)/M06–2X/6–31+G(d) computational model. The comparison of the observed rates of AcSCh+ oximolytic cleavage and both competitive AcSCh+ and consecutive pyridinium-4-oxime-ester hydrolytic cleavage revealed that the pyridinium-4-oximes cannot be classified as non-enzyme catalyst of the AcSCh+ hydrolysis but as the very effective esterolytic agents.

A one-pot route to N-acyl ureas: a formal four-component hydrolytic reaction involving aminonitrones and isocyanide dibromides

A one-pot route to N-acyl ureas proceeds via generation of electrophilically activated 2-substituted 1,2,4-oxadiazolium salts. The conformation of the N-acyl ureas is stabilized via moderate strength (6.2–7.8 kcal mol−1) resonance-assisted hydrogen bonds.

PENGARUH PERLAKUAN AWAL DIC PADA PENGERINGAN DAUN SALAM (Eugenia polyanta Wight, Walp) TERHADAP EFISIENSI EKSTRAKSI DAN KECUKUPAN KANDUNGAN SENYAWA FENOL TOTAL (Phenol Content).

The development of science in every field and the finding of new medicines are growing very fast, as well as the use of herbal medicines. One of the many herbal plants is Salam (Eugenia polyanta (Wight), Walp). Judging by the great prospectiveness of the Salam leaves, the government through the Indonesian FDA has included the Salam plant as one of the nine excellent plant, so that it can be developed as a Phytopharmaceutical. The phytopharmaceutical has to follow certain prerequisites, one of them is it has to be in the form of standardized extract or powder. In order to produce extract, the raw material is preferred in a dry state, because the water content can be reduced, so that it can minimized the enzymatic and hydrolytic reaction. In this study, the effect of pre drying by Détente Instantanée Contrôlée (DIC/Instantaneous Controlled Pressure-Drop) method is carried out, as it will opened up the pores of the plant cells, so that the vaporization will be accelerated and the the thermal degradation can be minimized. Eleven parameters have been studied. It can be concluded that based on the drying times and the Total Phenol Content, the parameter 1,9 bar and 10,86 second is the optimum parameter of the DIC.

Nano-magnesium oxide as hard template synthesis of lignin carbonbased solid acids and its application for cellulose hydrolysis

In comparison with templates of zeolites and silica, a template of nano-magnesium oxide (nano-MgO) has some unique advantages. Namely, it is easily removed by dilute noncorrosive acid solution, is recyclable for nano-MgO precursors, and has tunable pore size by selecting various nano-MgO precursors. In this study, the nano-MgO as a hard template synthesis of lignin carbon-based solid acids catalyst was characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). After using nano-MgO as a hard template, the resulting nano-MgO mesoporous carbon-based solid acids (MLCSAs) presented a uniform porous morphology and the smooth surface became rough. When the carbonization temperature was 400°C, the catalytic activity of MLCSAs for the hydrolytic reaction of cellulose was greater than lignin carbon-based solid acids (LCSAs) without nano-MgO as a hard template.

Influence of Ethylene Oxide Content in Nonionic Surfactant to the Hydrolysis of Reactive Dye in Silicone Non-Aqueous Dyeing System

Silicone reverse dyeing technology provides an important means of saving water and salts-free in the textile dyeing industry. The interactions between dyes and surfactants may influence the hydrolysis of dye during dyeing. In this investigation, the effect of ethylene oxide content in nonionic surfactant on the hydrolytic reaction of reactive dye was firstly investigated in a siloxane reverse emulsion dyeing system. Compared with no surfactants, the hydrolytic reaction of vinyl sulfone reactive dye was a slowdown when some nonionic surfactants were used during dyeing. Usually, the hydrophobic groups in nonionic surfactants were dodecyl chains but their polar head groups were different. The hydrolytic reaction of vinyl sulfone dye showed that the longer of EO (ethylene oxide) chains, the faster the hydrolytic reaction of vinyl sulfone dye. From the absorption spectrum of dye, it could be concluded that more of dyes would be solubilized into the formed micelles, and dye-surfactant complexes were adhered to the surface of micelles if the molecular structure of surfactant had a shorter EO chains. Furthermore, the intramolecular or intermolecular hydrogen bond could be formed between dye and surfactant, which would further influence the hydrolytic reaction of vinyl sulfone dye. However, the solubility of surfactant in siloxane non-aqueous media would decrease with the increase of EO chains. Meanwhile, the dispersion of dye was enhanced as well as the hydrolytic reaction of dye. From this investigation, some surfactant can be used to improve the fixation of reactive dye during dyeing. Furthermore, washing times after dyeing and the ecological problems can be decreased.

Synthesis of diamido-bridged bis-pillar[5]arenes and tris-pillar[5]arenes for construction of unique [1]rotaxanes and bis-[1]rotaxanes

The pillar[5]arene mono- and di(oxyalkoxy)benzoic acids were successfully prepared in high yields by sequential alkylation of ω-bromoalkoxy-substituted pillar[5]arenes with methyl or ethyl p-hydroxybenzoate followed by a hydrolytic reaction under basic conditions. Under catalysis of HOBt/EDCl, the amidation reaction of pillar[5]arene mono(oxybutoxy)benzoic acid with monoamido-functionalized pillar[5]arenes afforded diamido-bridged bis-pillar[5]arenes. 1H NMR and 2D NOESY spectra clearly indicated that [1]rotaxanes were formed by insertion of longer diaminoalkylene unit into the cavity of one pillar[5]arene with another pillar[5]arene acting as a stopper. The similar catalysed amidation reaction of pillar[5]arene di(oxybutoxy)benzoic acid with monoamido-functionalized pillar[5]arenes resulted in the diamido-bridged tris-pillar[5]arenes, which successfully form the unique bis-[1]rotaxanes bearing longer than diaminopropylene diamido bridges.