Preparation of hydrogels based on poplar cellulose and their removal efficiency of Cd(II) from aqueous solutions.

Industrial heavy metal-contaminated wastewater is one of the main water pollution problems. Adsorbents are a promising method for the removal of heavy metal contaminants. Herein, polyaspartic acid/carboxymethyl poplar sawdust hydrogels (PASP/CMPP) and ascorbic acid/carboxymethyl poplar sawdust hydrogels (VC/CMPP) were prepared by aqueous polymerization using alkalized poplar sawdust (CMPP) as the substrate and PASP and vitamin C (VC) as modifiers. The effective results, provided by the characterization analysis of SEM and BET, indicate that the surface of the PASP/CMPP hydrogel has a larger number of loose pores and a larger pore volume than the VC/CMPP hydrogel. The treatment effects of the two hydrogels on simulated wastewater containing Cd(II) were investigated by a batch of experiments. The results showed that PASP/CMPP had a better adsorption effect than VC/CMPP under the same adsorption conditions. Interestingly, the solid concentration effect was found in the process of sorption kinetics and sorption isotherms. The sorption kinetic curves of Cd(II) on PASP/CMPP were well-fitted by the quasi-second-order kinetics under different adsorbent concentrations. The adsorption conforms to Langmuir and Freundlich adsorption isotherm models. More importantly, PASP/CMPP composites are expected to be used as a new kind of environmental adsorbent for wastewater treatment.

Effects of dietary fibers with different physicochemical properties on fermentation kinetics and microbial composition by fecal inoculum from lactating sows in vitro.

BACKGROUND: Efficient utilization of dietary fibers (DFs) is important for optimizing feed resource utilization and animal health. The aim of the current study was to assess the effects of DFs with varying physicochemical properties (bulky, viscous, and fermentable) on fermentation kinetics and microbial composition during in vitro fermentation by fecal inoculum from lactating sow. According to the physicochemical properties, three different DFs, lignocellulose (LC), modified cassava starch (MCS) and konjac flour (KF) were selected as bulky fiber, fermentable fiber and viscous fiber respectively. Gas production, short-chain fatty acids (SCFAs) profiles and microbial composition were monitored during the fermentation. RESULTS: Results showed that the gas production in 72 h (GP72h ) ranked as: KF > MCS > LC (P < 0.05). The halftime of asymptotic gas production ranked as: KF < MCS = LC (P < 0.001). At 36 h of fermentation, MCS group showed higher concentrations of formic acid and lactate than LC and KF groups, whereas KF group showed higher concentrations of propionate and butyrate than LC and MCS groups (P < 0.05). At 72 h of fermentation, KF group showed higher concentrations of formic acid, lactate and propionate than LC and MCS groups, whereas MCS group showed higher concentrations of acetate and butyrate than LC and KF groups (P < 0.05). At 36 h of fermentation, Anaerovibrio and Erysipelatoclostridium abundances were higher in KF group, whereas Proteiniclasticum abundance was higher in MCS group. At 72 h of fermentation, the abundance of Fibrobacter in LC group was higher than that in MCS and KF groups. In addition, we also observed that the abundances of certain specific bacteria (Anaerovibrio and Erysipelatoclostridium) were closely related to the SCFAs production (propionate and butyrate) at different fermentation times. CONCLUSION: Collectively, the present study revealed that KF is a fast fermentation fiber which could produce propionate and butyrate rapidly, whereas LC is difficult to be fermented by bacteria. In addition, the fermentation of DFs with different physicochemical properties had divergent impacts on microbial composition and SCFA production. These findings deepen our understanding of the mechanisms of interaction between DFs and intestinal microbiota, and provide new ideas for the rational use of fiber resources in lactating sows. © 2020 Society of Chemical Industry.

Fabrication of an ionic-liquid-based polymer monolithic column and its application in the fractionation of proteins from complex biosamples.

An ionic-liquid-based polymer monolithic column was synthesized by free radical polymerization within the confines of a stainless-steel column (50 mm × 4.6 mm id). In the processes, ionic liquid and stearyl methacrylate were used as dual monomers, ethylene glycol dimethacrylate as the cross-linking agent, and polyethylene glycol 200 and isopropanol as co-porogens. Effects of the prepolymerization solution components on the properties of the resulting monoliths were studied in detail. Scanning electron microscopy, nitrogen adsorption-desorption measurements, and mercury intrusion porosimetry were used to investigate the morphology and pore size distribution of the prepared monoliths, which showed that the homemade ionic-liquid-based monolith column possessed a relatively uniform macropore structure with a total macropore specific surface area of 44.72 m2 /g. Compared to a non-ionic-liquid-based monolith prepared under the same conditions, the ionic-liquid-based monolith exhibited excellent selectivity and high performance for separating proteins from complex biosamples, such as egg white, snailase, bovine serum albumin digest solution, human plasma, etc., indicating promising applications in the fractionation and analysis of proteins from the complex biosamples in proteomics research.

Magnetic molecularly imprinted polymers integrated ionic liquids for targeted detecting diamide insecticides in environmental water by HPLC-UV following MSPE.

Efficiently detecting diamide insecticides in environmental water is challenging due to their low concentrations and complex matrix interferences. In this study, we developed ionic liquids (ILs)-incorporated magnetic molecularly imprinted polymers (IL-MMIPs) for the detection of diamide insecticides, capitalizing on the advantages of ILs and quick magnetic separation through surface imprinting. Tetrachlorantraniliprole was used as the template, and a specific IL, 1-vinyl-3-ethylimidazolium hexafluorophosphate ([VEIm][PF6]), was employed as the functional monomer. Various synthesis conditions were investigated to optimize adsorption efficiency. The prepared IL-MMIPs were successfully employed as adsorbents in magnetic solid-phase extraction (MSPE) to selectively extract, separate, and quantify three types of diamide insecticides from water samples using HPLC-UV detection. Under optimal conditions, the analytical method achieved low limits of detection (0.69 ng mL-1, 0.64 ng mL-1, 0.59 ng mL-1 for cyantraniliprole, chlorantraniliprole and tetrachlorantraniliprole, respectively). The method also displayed a wide linear range (0.003-10 µg mL-1 for cyantraniliprole and chlorantraniliprole, and 0.004-10 µg mL-1 for tetrachlorantraniliprole, respectively) with satisfactory coefficients (R2≥0.9996), and low relative standard deviation (RSD≤2.55%). Additionally, extraction recoveries fell within the range of 79.4%-109%. The results clearly demonstrate that IL-MMIPs exhibit exceptional recognition and rebinding capabilities. The developed IL-MMIPs-MSPE-HPLC-UV method is straightforward and rapid, making it suitable for the detection and analysis of three kinds of diamide insecticides in environmental water.

Fabrication of magnetic hydrophilic imprinted polymers via two-step immobilization approach for targeted detecting bisphenol A.

Molecularly imprinted polymer with water-compatibility for effective separation and enrichment of targeted trace pollutants from complicated matrix has captured extensive attention in terms of their high selectivity and matrix compatibility. This study focuses on modified ß-cyclodextrin is used as a hydrophilic functional monomer to develop magnetic molecularly imprinted polymers (MMIPs). MMIPs were prepared using Fe3O4 nanoparticles as carriers and bisphenol A (BPA) as templates using a two-step fixation strategy and surface imprinting technology. The structural characteristic and binding properties of the prepared MMIPs were thoroughly studied. The MMIPs exhibited high crystallinity, high adsorption capacity, fast rebinding rate, remarkable selectivity and distinguish reusability. In addition, through magnetic solid-phase extraction separation technology and high-performance liquid chromatography ultraviolet quantitative detection technology, MMIPs are used for selective enrichment and detection of BPA in complex media such as environmental water and milk. This work provides a new route to construct the hydrophilic molecularly imprinted materials and a new sight on developing more effective sample pretreatment strategies for monitoring targeted pollution in complicated aqueous media.

Molecular Mechanisms Underlying the Effects of Small Intestinal Fermentation on Enhancement of Prebiotic Characteristics of Cellulose in the Large Intestine.

Knowledge about the prebiotic characteristics of cellulose by in vitro fermentation is not complete due to the neglect of small intestinal fermentation. This study investigated the effects of small intestinal fermentation on the prebiotic characteristics of cellulose in the large intestine and potential mechanisms through an approach of combined in vivo small intestinal fermentation and in vitro fermentation. The structural similarity between cellulose in feces and after processing by the approach of this study confirmed the validity of the approach employed. Results showed that small intestinal fermentation of cellulose increased both acetate and propionate content and enriched Corynebacterium selectively. Compared to in vitro fermentation after in vitro digestion of cellulose, the in vitro fermentation of cellulose after in vivo small intestinal fermentation produced higher contents of acetate and propionate as well as the abundance of probiotics like Ruminococcaceae_UCG-002, Blautia, and Bifidobaterium. The changes in the structural features of cellulose after in vivo small intestinal fermentation were more obvious than those after in vitro digestion, which may account for the greater production of short-chain fatty acids (SCFAs) and the abundance of probiotics. In summary, small intestinal fermentation enhanced the prebiotic characteristics of cellulose in the large intestine by predisrupting its structure.

Amylopectin Partially Substituted by Cellulose in the Hindgut Was Beneficial to Short-Chain Fatty Acid Production and Probiotic Colonization.

Undigested amylopectin fermentation in the hindguts of humans and pigs with low digestive capacity has been proven to be a low-efficiency method of energy supply. In this study, we researched the effects and mechanisms of amylopectin fermentation on hindgut microbiota and metabolite production using an in vitro fermentation trial and ileal infusion pigs model. In addition, we also researched the effects of interaction between amylopectin and cellulose during hindgut fermentation in this study. Our results showed that amylopectin had higher short-chain fatty acid (SCFA) production and dry matter digestibility (DMD) than cellulose but was not significantly different from a mixture of amylopectin and cellulose (Amycel vitro) during in vitro fermentation. The Amycel vitro group even had the highest reducing sugar content and amylase activity among all groups. The ileal infusion trial produced similar results to vitro fermentation trial: the mixture of amylopectin and cellulose infusion (Amycel vivo) significantly increased the levels of reducing sugar, acetate, and butyrate in the hindgut compared with the amylopectin infusion (Amy vivo). The mixture of amylopectin and cellulose infusion also resulted in increased Shannon index and probiotic colonization in the hindgut. The relative abundance of Romboutsia in the Amycel vivo group, which was considered a noxious bacteria in the Amycel vivo group, was also significantly lower than that in the Amy vivo group. In summary, the high level of amylopectin fermentation in the hindgut was harmful to intestinal microbiota, but amylopectin partially substituted with cellulose was beneficial to SCFA production and probiotic colonization. IMPORTANCE A high-starch (mainly amylopectin) diet is usually accompanied by the fermentation of undigested amylopectin in the hindgut of humans and pigs with low digestive capacity and might be detrimental to the intestinal microbiota. In this research, we investigated the fermentation characteristics of amylopectin through an in vitro fermentation method and used an ileal infusion pig model to verify the fermentation trial results and explore the microbiota regulatory effect. The interaction effects between amylopectin and cellulose during hindgut fermentation were also researched in this study. Our research revealed that the large amount of amylopectin fermentation in the hindgut was detrimental to the intestinal microbiota. Amylopectin partially substituted by cellulose was not only beneficial to antioxidant ability and fermentation efficiency, but also promoted SCFA production and probiotic colonization in the hindgut. These findings provide new strategies to prevent intestinal microbiota dysbiosis caused by amylopectin fermentation.

Simultaneous determination of four plant hormones in bananas by molecularly imprinted solid-phase extraction coupled with high performance liquid chromatography.

A highly selective molecularly imprinted solid-phase extraction (MISPE) combined with liquid chromatography-ultraviolet detection was developed for the simultaneous isolation and determination of four plant hormones including indole-3-acetic acid (IAA), indole-3-propionic acid (IPA), indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA) in banana samples. The new molecularly imprinted microspheres (MIMs) prepared by aqueous suspension polymerization using 3-hydroxy-2-naphthoic acid and 1-methylpiperazine as mimic templates performed with high selectivity and affinity for the four plant hormones, and applied as selective sorbents of solid-phase extraction could effectively eliminate the interferences of the banana matrix. Good linearity was obtained in a range of 0.04-4.00 µg g(-1) and the recoveries of the four plant hormones at three spiked levels ranged from 78.5 to 107.7% with the relative standard deviations (RSD) of less than 4.6%. The developed MISPE-HPLC protocol obviously improved the selectivity and eliminated the effect of template leakage on quantitative analysis, and could be applied for the determination of plant hormones in complicated biological samples.

Rapid determination of perfluorinated compounds in pork samples using a molecularly imprinted phenolic resin adsorbent in dispersive solid phase extraction-liquid chromatography tandem mass spectrometry.

Perfluorinated compounds (PFCs) that bioaccumulate enter the food chain through animals-derived foods and ultimately harm human health. However, these compounds are extensively used, and consequently, it is important to focus on the residual PFCs content in various animal-derived foods. In this work, a molecularly imprinted polymer with surface grooves and rapid mass transfer ability was prepared hydrothermally, applied as an adsorbent to a needle filter device, and combined with LC-MS/MS for the rapid extraction and determination of trace PFCs in pork. This method requires simple equipment (syringe filter), small amount of adsorbent (2 mg), and short operation time (6-8 min) and has a low detection limit (0.011-0.08 ng g-1), good recovery (89.3-116.3%), and satisfactory intra-day (≤4.0%) and inter-day (≤8.6%) precision. This study provides a new method for assessing the exposure risk of PFCs in complex samples.

Rapid and inexpensive nylon-66-filter solid-phase extraction followed by gas chromatography tandem mass spectrometry for analyzing perfluorinated carboxylic acids in milk.

In this study, a new rapid and inexpensive filter solid-phase extraction method (FSPE) was developed for the extraction and separation of five perfluorinated carboxylic acids (PFCAs) (namely, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, and perfluorododecanic acid) from milk samples. Commercial nylon 66 syringe filters were used as adsorbents without additional modification. The proposed method could achieve the fast adsorption of analytes by benefitting from the advantages of using the nylon 66 filter membrane on PFCAs with multiple adsorption interactions, namely, hydrophobic interactions and hydrogen bonds. The FSPE was designed to achieve the rapid isolation of analytes based on the rapid solid-liquid separation while using the solid-phase extraction disk. PFCAs residues in milk were extracted by first flowing the samples through a nylon 66 syringe filter from top to bottom. Double contact desorption with methanol was then accomplished by pulling and pushing the syringe, followed by derivatization with acetyl chloride-methanol. Finally, the extracted PFCAs residues were monitored using gas chromatography-tandem mass spectrometry (GC-MS/MS) quantification. Under optimal conditions, the established method presented good linearity (correlation coefficient ≥ 0.9996), precision (relative standard deviation ≤ 13%), accuracy (81-105%), sensitivity (limits of quantification: 4-18 ng kg-1) and extraction performance (10 min).

Dual Functional Eudragit® S100/L30D-55 and PLGA Colon-Targeted Nanoparticles of Iridoid Glycoside for Improved Treatment of Induced Ulcerative Colitis.

AIM: Iridoid glycosides (IG) as the major active fraction of Syringa oblata Lindl. has a proven anti-inflammatory effect for ulcerative colitis (UC). However, its current commercial formulations are hampered by low bioavailability and unable to reach inflamed colon. To overcome the limitation, dual functional IG-loaded nanoparticles (DFNPs) were prepared to increase the residence time of IG in colon. The protective mechanism of DFNPs on DSS-induced colonic injury was evaluated in rats. MATERIALS AND METHODS: We prepared DFNPs using the oil-in-water emulsion method. PLGA was selected as sustained-release polymer, and ES100 and EL30D-55 as pH-responsive polymers. The morphology and size distribution of NPs were measured by SEM and DLS technique. To evaluate colon targeting of DFNPs, DiR, was encapsulated as a fluorescent probe into NPs. Fluorescent distribution of NPs were investigated. The therapeutic potential and in vivo transportation of NPs in gastrointestinal tract were evaluated in a colitis model. RESULTS: SEM images and zeta data indicated the successful preparation of DFNPs. This formulation exhibited high loading capacity. Drug release results suggested DFNPs released less than 20% at the first 6 h in simulated gastric fluid (pH1.2) and simulated small intestine fluid (pH6.8). A high amount of 84.7% sustained release from NPs in simulated colonic fluid (pH7.4) was beyond 24 h. DiR-loaded NPs demonstrated a much higher colon accumulation, suggesting effective targeting due to functionalization with pH and time-dependent polymers. DFNPs could significantly ameliorate the colonic damage by reducing DAI, macroscopic score, histological damage and cell apoptosis. Our results also proved that the potent anti-inflammatory effect of DFNPs is contributed by decrease of NADPH, gene expression of COX-2 and MMP-9 and the production of TNF-α, IL-17, IL-23 and PGE2. CONCLUSION: We confirm that DFNPs exert protective effects through inhibiting the inflammatory response, which could be developed as a potential colon-targeted system.

Effect of pH on ·OH-induced degradation progress of syringol/syringaldehyde and health effect.

Syringol and syringaldehyde are widely present pollutants in atmosphere and wastewater due to lignin pyrolysis and draining of pulp mill effluents. The hydroxylation degradation mechanisms and kinetics and health effect assessment of them under high and low-NOx regimes in atmosphere and wastewater have been studied theoretically. The effect of pH on reaction mechanisms and rate constants in their ·OH-initiated degradation processes has been fully investigated. Results have suggested that aqueous solution played a positive role in the ·OH-initiated degradation reactions by decreasing the energy barriers of most reactions and changing the reactivity order of initial reactions. For Sy- and Sya- (anionic species of syringol and syringaldehyde), most initial reaction routes were more likely to occur than that of HSy and Hsya (neutral species of syringol and syringaldehyde). As the pH increased from 1 to 14, the overall rate constants (at 298 K) of syringol and syringaldehyde with ·OH in wastewater increased from 5.43 × 1010 to 9.87 × 1010 M-1 s-1 and from 3.70 × 1010 to 1.14 × 1011 M-1 s-1, respectively. In the NOx-rich environment, 4-nitrosyringol was the most favorable product, while ring-opening oxygenated chemicals were the most favorable products in the NOx-poor environment. On the whole, the NOx-poor environment could decrease the toxicities during the hydroxylation processes of syringol and syringaldehyde, which was the opposite in a NOx-rich environment. ·OH played an important role in the methoxyphenols degradation and its conversion into harmless compounds in the NOx-poor environment.

Attapulgite/hydrophilic molecularly imprinted monolithic resin composite for the selective recognition and sensitive determination of plant growth regulators in cucumbers.

In this study, through in-situ polymerization process, a novel composite of attapulgite/hydrophilic molecularly imprinted monolithic resin (AT/HMIMR) were prepared in pipette tips for extraction trace plant growth regulators in cucumbers. In the preparation procedure, fibrillar attapulgite nanoparticles were embedded to increase extraction capacity, polyethyleneglycol-6000 was employed as a dual-function porogen, that acted as both the structure-directing agent of the HMIMR and the attapulgite dispersant. N-(1-naphthyl) ethylenediamine dihydrochloride was used as a dummy template to accurate quantification on extraction procedures. Experimental parameters of AT/HMIMR for extracting plant growth regulators from cucumbers were optimized, and the results showed that the recoveries of ranged from 92.4% to 101.1% with relative standard deviations ≤ 6.5% (n = 3). Considering its microporous monolithic column structure, multiple adsorption mechanism, and specific selectivity, AT/HMIMR shows promise for applications that require specific recognition for the analytes in real complex samples.

SIRT1 suppresses p53-dependent apoptosis by modulation of p21 in osteoblast-like MC3T3-E1 cells exposed to fluoride.

Fluoride is very crucial for development of teeth and bones. Excessive fluoride, however, causes damage to teeth and bones resulting in serious public health problem. SIRT1 regulates physiological and pathological processes such as apoptosis and cell cycle. Although SIRT1 inhibits p53-mediated transactivation, how SIRT1 regulates p53 in fluorosis remains unclear. This study aims to investigate the involvement of SIRT1 in fluoride-induced cell cycle arrest and apoptosis in MC3T3-E1 cells and the underlying mechanism. Cell apoptosis was determined using Annexin V-FITC/PI dual staining, cell cycle detected with PI staining, intracellular ROS levels measured with DCFH-DA probe, and apoptosis-related protein expressions determined using Western blotting. Results showed that there was a promotion in apoptosis rate, intracellular ROS levels, the ratio of Bax/Bcl-2, protein expression (Cyt c, Caspase-3, p53, Ac-p53 and p21) and blockage of S phase after cells were exposed to NaF. Afterwards, the influence of SIRT1 on apoptosis was explored after SRT1720 (SIRT1 activator) and Ex-527 (SIRT1 inhibitor) was introduced. Results indicated that SRT1720 in combination with fluoride significantly decreased the intracellular ROS levels, the protein expression of Caspase-3, Ac-p53 and p21 and alleviated apoptosis, while it was reversed by Ex-527. Collectively, SIRT1 plays an essential role in protection against fluoride-induced oxidative stress and mitochondria-dependent apoptosis in MC3T3-E1 cells. The SIRT1/p53/p21 pathway may be a potential therapeutic target for fluorosis.

A novel poly (NMA-co-DEA-co-EDMA) monolithic column as a sorbent for online solid-phase extraction and its application in the determination of ß-sitosterol in plant oil samples.

A novel monolithic column was prepared by in-situ free radical polymerization using N-methylolacrylamide (NMA) and N,N-diethylacrylamide (DEA) as co-monomers. The monolith was characterized by scanning electron microscopy (SEM) and its nitrogen adsorption-desorption isotherm, and it was used as a solid phase extraction (SPE) absorbent for the online enrichment of ß-sitosterol by high performance liquid chromatography. The optimized method had good linearity, and the linear regression coefficient was 0.998. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.006 mg/mL and 0.02 mg/mL, respectively. The interday and intraday accuracies were less than 7.28%. The spiked recoveries of ß-sitosterol in the six plant oil were 90.96-103.56%. The maximum amount of ß-sitosterol adsorbed on the monolithic column was 12.69 mg/g, and the enrichment factor of ß-sitosterol was 78. The results showed that the monolith could be used as an online SPE absorbent for the determination of ß-sitosterol in plant oil samples.

Ionic Liquid-Hybrid Molecularly Imprinted Material-Filter Solid-Phase Extraction Coupled with HPLC for Determination of 6-Benzyladenine and 4-Chlorophenoxyacetic Acid in Bean Sprouts.

A new method involving ionic liquid-hybrid molecularly imprinted material-filter solid-phase extraction coupled to high-performance liquid chromatography (IL-HIM-FSPE-HPLC) was developed for the simultaneous isolation and determination of 6-benzyladenine (6-BA) and 4-chlorophenoxyacetic acid (4-CPA) in bean sprouts. Sample preconcentration was performed using a modified filter, with the new IL-HIM as the adsorbent, which shows double adsorption. The first adsorption involves special recognition of molecular imprinting, and the second involves ion exchange and electrostatic attraction caused by the ionic liquid. This method combines the advantages of ionic liquids, hybrid materials, and molecularly imprinted polymers and was successfully applied to determine 6-BA and 4-CPA in bean sprouts. The adsorption of 6-BA to IL-HIM is based on selective imprinted recognition, whereas the adsorption of 4-CPA is mainly dependent on ion-exchange interactions.

SIRT1-mediated FoxOs pathways protect against apoptosis by promoting autophagy in osteoblast-like MC3T3-E1 cells exposed to sodium fluoride.

Fluorine may result in damage to teeth, bones and other body tissues, and is a serious public health problem. SIRT1 deacetylates FOXOs, which brings about apoptosis and autophagy promotion or suppression. Fluorine may induce cell apoptosis, however, the role of autophagy in apoptosis induced by fluorine is still poorly understood, and the interaction between SIRT1 and FOXOs should be further illustrated. Therefore, this study investigated the mechanisms underlying the NaF- induced apoptosis and autophagy in osteoblast-like MC3T3-E1 cells in vitro through activating or inhibiting SIRT1. Via RT-PCR, western blot, flow cytometry assays, fluorescence and laser confocal microscopy, it was found that NaF induced both cell apoptosis and autophagy. Results also showed that NaF up-regulated SIRT1 expression in a dose-dependent manner. The autophagy of MC3T3-E1 was also up- regulated indirectly whilst apoptosis was significantly attenuated when incubated with the SIRT1 activator SRT1720. When SIRT1 inhibitor Ex-527 was used, the latter effects were reversed. Furthermore, SIRT1 increased deacetylation of FoxO1 and promoted the up-regulation of its target substrate Rab7, as well as increase of Bnip3 which was substrate of FoxO3, and we hypothesize that these pathways may cause an increase in autophagic flux and a reduction in apoptosis. In conclusion, SIRT1-induced autophagy enhancement protects against fluoride-induced apoptosis through autophagy induction in MC3T3-E1 cells, which may be associated with a SIRT1-FoxO1-Rab7 axis and a SIRT1-FoxO3-Binp3 axis. The role of SIRT1 in selecting between cell survival and death provides a potential therapeutic strategy in fluorosis.

An overview of liposome lyophilization and its future potential.

Lyophilization is a promising approach to ensure the long-term stability of liposomes. After decades of studies in this field, different lyoprotective mechanisms, such as water replacement and vitrification models, have been proposed. Much progress has been made in developing highly stable liposomes after lyophilization based on optimization of formulation and process parameters. Here, this paper reviews the lyoprotective mechanisms, the parameters affecting the lyoprotective effect and the techniques used in a large number of studies. The parameters are discussed with regard to the following two aspects: (1) the formulation factors: the choice of drug, the lipid bilayer composition, vesicle size, selection of lyoprotectants, combination of lyoprotectants and additives, dry mass ratio of lyoprotectant to lipid, distribution of lyoprotectant on the two sides of lipid bilayers and others, which are the key factors determining the lyoprotective effect of freeze-dried liposomes. (2) The technological factors: freezing protocols, drying protocols, storage conditions and others, which are the extrinsic factors affecting the stability of freeze-dried cakes. Moreover, encapsulated solute/drug retention (ESR), gel-to-liquid crystalline phase transition temperature (T(m)) and glass transition temperature (T(g)) are selected as indicators to investigate the protective effect during this process. Finally, the major areas and future potential of research on lyophilized liposomes are highlighted.

Isosorbide-5-mononitrate (5-ISMN) sustained-release pellets prepared by double layer coating for reducing 5-ISMN migration and sublimation.

The major aim of this study was to prepare isosorbide-5-mononitrate (5-ISMN) sustained-release pellets and evaluate their stability. The pellets were prepared by extrusion/spheronization, and then the core pellets were coated with ethylcellulose (EC 10cp) and Eudragit(®)NE30D. Here, EC was used as the subcoating agent while Eudragit(®)NE30D acted as the outer-coating agent. 5-ISMN sustained-release pellets as a novel drug delivery system contained the immediate-release portion in the outer-coating layer. Unexpectedly, 5-ISMN was found to migrate from the interior of the pellets to the surface forming needle crystals and exhibited the phenomenon of sublimation, which resulted in a tremendous increase in the release rate. Our research showed that the migration and sublimation of the active ingredient was related to the temperature and humidity. Polyvinylpyrrolidone (PVP K30) can affect the precipitation of 5-ISMN by forming a charge transfer complex between the drug and PVP, while hydroxypropyl methyl cellulose (HPMC E5) had no effect, and confirmed the correctness of this view through photographs and IR spectra. In the investigation of the stability, the results showed that there was no sublimation and migration while the pellets stored at 25°C/60%RH (ambient conditions) and 40°C/75% RH (stress conditions) during a 6-month period.

The freeze-thawed and freeze-dried stability of cytarabine-encapsulated multivesicular liposomes.

To investigate the stability of cytarabine-encapsulated multivesicular liposomes (MVLs) following freeze-thawing/freeze-drying, three types of phospholipids (EPC, DPPC, and DOPC) were separately employed to prepare MVLs using a double emulsification method. The cytarabine retention (CR), phase transition behavior, aggregation/rupture of vesicles and particle size were monitored using HPLC, differential scanning calorimetry (DSC), digital biological microscopy and a laser diffraction particle size analyzer. The effect of trehalose, the lipid bilayer composition and triglyceride on the drug retention was also investigated. The DPPC-MVLs and EPC-MVLs achieved the best protective effect during freeze-thawing and freeze-drying, respectively, while DOPC-MVLs produced the lowest drug retention during both procedures. Digital biological microscopy showed that most of the MVLs were divided into small irregular and regular vesicles after freeze-thawing and freeze-drying, which was in agreement with the reduction in particle size. The vesicle fragmentations may result from the splitting of triglyceride from the lipid membrane or rupture of the lipid membrane. The rehydrated EPC-MVLs still displayed a controlled-release profile in vitro, and the results presented in this work should help in stabilizing hydrophilic drug-encapsulated liposomes with a large particle size.