One Unique 1D Silver(I)-Bromide-Thiol Coordination Polymer Used for Highly Efficient Chemiresistive Sensing of Ammonia and Amines in Water.

Reaction of AgBr with TabHPF6 (TabH = 4-(trimethylammonio)benzenethiol) readily produces a unique one-dimensional coordination polymer [(TabH)(AgBr2)]n (1), consisting of anionic chains [AgBr2]n(n-) with hydrogen bonds to TabH(+) cations. By examining its electrical resistance and stability upon exposure to ammonia and seven common organic amines in water under ambient conditions, compound 1 is found to exhibit good stability and reproducibly high sensitivity toward these analytes at low concentrations. Especially, it can selectively detect NH3 in water with the detection limit as low as 0.05 ppm. This chemiresistive sensing system has the potential for highly efficient monitoring of ammonia and amines responsible for water pollution, eutrophication, food contamination, and industrial hazards.

[Determination of ochratoxin A in human urine by HPLC-FLD after cleaned-up by molecularly imprinted polymer solid phase extraction column].

A method was developed for the determination of ochratoxin A (OTA) in human urine by HPLC-FLD after molecularly imprinted polymer solid phase extraction (MIP-SPE) column. After the pH being adjusted to 2.5 with 0.1 mol x L(-1) HC1, sample was cleaned up with MIP-SPE column for ochratoxin A, the analyte was analyzed by high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD), and finally all the positive results were confirmed by LC-MS/MS. Recoveries from urine samples spiked with OTA at levels ranging from 2 to 20 ng x mL(-1) were 90.6%-101.9%, and RSDs were 0.1%-1.6%. Sixty-five volunteers living in Beijing took part in the study, of which 5 were found containing OTA in their urine and the highest value was 0.091 ng x mL(-1). The MIP-SPE column was firstly applied to purify and concentrate OTA in human urine, this method is simple, rapid and reliable and can be used to determine the contents of OTA in human urine.

[Technical study of vinpocetine micelles prepared by thin-film hydration method].

OBJECTIVE: To prepare PEG-PLA polymeric micelles loaded with vinpocetine (VP). METHODS: VP micelles were prepared by thin-film hydration method, single factors affecting drug loading content, encapsulation efficiency, productivity, particle size and polydispersity index (PDI) such as dosage, type of organic solvent, quantity of organic solvent, hydration temperature, hydration speed, amount of hydration water, hydration time were investigated, and the optimum technology was obtained. The mean particle size and PDI were determined by DLS. The drug loading content, encapsulation efficiency, productivity of VP micelles were investigated by UV. RESULTS: The drug loading content and particle size of VP micelles were 20.35% and 118.3 nm, respectively. CONCLUSION: The technology of VP micelles prepared by thin-film hydration method is practical and simple. It's valuable to be further studied.

[Three-dimensional analysis of the mandible with impacted mandibular second molar].

OBJECTIVE: To study the developmental and morphological characteristics of the mandible in patients with impacted mandibular second molar and to predict the possible trend of mandibular development via three-dimensional (3D) measurement and analysis. METHODS: A total of 88 cases of impacted group and 88 cases of control group were screened out. 3D measurements were performed by using Mimics software. A total of 23 landmark points and 17 measurements were determined. The measurements were analyzed by t-test. RESULTS: The mandible length, the space between the first molars, the space between mandibular angles, and the width between the first molars in the impacted group were lower than those in the control group (P<0.05). Moreover, the value of the submandibular angle was higher than that in the control group (P<0.05). CONCLUSIONS: The impacted mandible of patients with mandibular second molar showed lack of sagittal and width development, and the impacted mandibular second molar was a manifestation of its degeneration.

PEGylation-based strategy to identify pathways involved in the activation of apoptotic BAX protein.

BACKGROUND: BAX activation is a crucial step for commitment to apoptosis. Several activators, such as BimBH3-based therapeutic peptides and cleaved Bid (cBid) protein, can trigger BAX-mediated apoptosis, but it is unclear whether they proceed through the same pathway. METHODS: Here we utilize PEGylation-based approach, which is shown to efficiently shield individual binding grooves in BAX from activators, to investigate and reveal that the activators take different routes to induce BAX-mediated apoptosis. Various spectroscopic/biochemical tools, including electron spin resonance, circular dichroism, fluorescence recovery after photobleaching, and label-transfer assay, were employed to reveal details in the processes. RESULTS: We observe a key mutant BAX 164-PEG that acts differently in response to cBid and BimBH3 stimuli. While BimBH3 directly interacts with the trigger groove (TG) to induce the conformational changes in BAX that includes the release of α9 from the canonical groove (CG) and oligomerization, cBid engages with CG and works with mitochondrial lipids to fully activate BAX. CONCLUSION: PEGylation-based approach is proven useful to shield individual binding grooves of BAX from apoptotic stimuli. Groove engagement in CG of BAX is required for a full cBid-induced BAX activation. This study has identified differences in the pathways involved during the initiation of BAX activation by full-length cBid protein versus synthetic BimBH3-based peptides. GENERAL SIGNIFICANCE: Our finding is potentially valuable for therapeutic application as the pore-forming activity of 164-PEG is independent from the cBid-mediated apoptotic pathways, but can be administrated by the synthetic short peptides.

Characterization of a Chitosanase from Jelly Fig (Ficus awkeotsang Makino) Latex and Its Application in the Production of Water-Soluble Low Molecular Weight Chitosans.

A chitosanase was purified from jelly fig latex by ammonium sulfate fractionation (50-80% saturation) and three successive column chromatography steps. The purified enzyme was almost homogeneous, as determined by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and gel activity staining. The molecular mass of the enzyme was 20.5 kDa. The isoelectric point (pI) was <3.5, as estimated by isoelectric focusing electrophoresis on PhastGel IEF 3-9. Using chitosan as the substrate, the optimal pH for the enzyme reaction was 4.5; the kinetic parameters Km and Vmax were 0.089 mg mL-1 and 0.69 µmol min-1 mg-1, respectively. The enzyme showed activity toward chitosan polymers which exhibited various degrees of deacetylation (21-94%). The enzyme hydrolyzed 70-84% deacetylated chitosan polymers most effectively. Substrate specificity analysis indicated that the enzyme catalyzed the hydrolysis of chitin and chitosan polymers and their derivatives. The products of the hydrolysis of chitosan polymer derivatives, ethylene glycol (EG) chitosan, carboxymethyl (CM) chitosan and aminoethyl (AE) chitosan, were low molecular weight chitosans (LMWCs); these products were referred to as EG-LMWC, CM-LMWC and AE-LMWC, respectively. The average molecular weights of EG-LMWC, CM-LMWC and AE-LMWC were 11.2, 11.2 and 8.89 kDa, respectively. All of the LMWC products exhibited free radical scavenging activities toward ABTS•+, superoxide and peroxyl radicals.