•Scientific questions: Expanding the Global Polio Eradication Initiative (GPEI) and establishing environmental surveillance systems in countries at risk of poliovirus transmission warrants the ...development of additional virus enrichment methods with reduced costs and shorter turnaround times.•Evidence before this study: The acute flaccid paralysis (AFP) case surveillance system is the gold standard for poliovirus surveillance; however, the “silent” transmission of poliovirus in the population makes environmental surveillance a crucial auxiliary tool for poliovirus surveillance.•New findings: The filtration method using a mixed cellulose ester (MCE) membrane is more sensitive than two-phase separation and can be used as a robust, sensitive, and cost-effective method to isolate enteroviruses from sewage.•Significance of the study: The filtration method using a mixed cellulose ester (MCE) membrane allows sensitive monitoring of the dynamic changes of enteroviruses in the environment. Additionally, this method enables researchers to track the actual dynamics of enterovirus transmission in human communities and provide early warnings for diseases in the population.
This study aimed to compare the sensitivity of two-phase separation and the filtration method using a mixed cellulose ester (MCE) membrane to detect enteroviruses in sewage samples. From December 2015 to July 2016, four domestic sewage samples (1 L/sample) were collected monthly from the Guangzhou Liede Sewage Treatment Plant, and each sewage sample was divided into two aliquots (500 mL). The sewage sample was concentrated using the two-phase separation and the filtration method using an MCE membrane, and the treated solutions were inoculated into cells for enterovirus isolation. Polymerase chain reaction amplification, VP1 sequencing, and enterovirus molecular typing were performed on the positive isolates. The detection rates of poliovirus (PV) and non-polio enterovirus (NPEV) obtained using the filtration method using an MCE membrane were higher than those using the two-phase separation method. McNemar's test showed that the detection rates of PV, NPEV, type 1 Sabin-like (SL1), type 2 Sabin-like (SL2), and type 3 Sabin-like (SL3) strain were not statistically significant (P > 0.05). In Guangdong Province, China, the detection rates for PV and NPEV were 53.13% and 62.50% (20/32), respectively. Twenty-seven PVs were isolated, three highly variable strains of the type 1 vaccine, with seven nucleotide substitutions in the VP1 region, compared with the type 1 Sabin strains. Eighty-seven strains of NPEV were isolated and nine serotypes were identified, among which coxsackievirus B3 (CVB3), echovirus 6(E6), and echovirus 11(E11) were the dominant strains. The filtration method using an MCE membrane is more sensitive than two-phase separation and can be used as a robust, sensitive, and cost-effective method to isolate enteroviruses from sewage.
Long/short chain mixed cellulose esters (MCE) are practical, promising polymers with interesting properties. In the molecular design of MCE, using long acyl chains made from renewable resources is ...important and enhances the value of MCE as sustainable materials. In this study, we focused on two types of renewable long acyl chains for MCE: the aromatic 3-pentadecylphenoxy acetyl (PA) group derived from cardanol extracted from cashew nutshells and the aliphatic stearoyl (St) group made from vegetable oils. Using these long acyl chains and the acetyl (Ac) group as a short acyl chain, we synthesized PA/Ac MCE (P-series) and St/Ac MCE (S-series) in LiCl/DMAc medium. The thermal and mechanical analyses revealed that a mixed substitution of long and short acyl chains prevented the crystallization of the long acyl chain moieties in MCE. The P-series had slightly higher bending strength and glass transition temperature than those of the S-series but showed low impact strength because of the existence of the aromatic ring in the PA group, which caused an increase in the stiffness of the cellulose backbone and the extra intermolecular interaction. However, the S-series without aromatic rings showed remarkably improved impact strength with sufficient balanced mechanical properties for use in durable products due to its composition of low crystalline long acyl chain moieties.
A facile, catalyst-free synthesis of a norbornylated cellulosic material (NC) with a high degree of substitution (2.9) is presented by direct reaction of trimethylsilyl cellulose with norbornene acid ...chloride. The resulting NC is highly soluble in organic solvents and its reactive double bonds were exploited for the copper-free inverse-electron demand Diels-Alder (iEDDA) "click" reaction with 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine. Reaction kinetics are comparable to the well-known Huisgen type 1,3-dipolar cycloaddition of azide with alkynes, while avoiding toxic catalysts.
Long chain cellulose esters are internally plasticized bio-based materials, which have good future potential in several applications such as coatings, films and plastics. The long chain cellulose ...esters with different side chain lengths were synthesized using different esterification methods. When homogeneous esterification was used, the acyl chloride method was the most effective esterification method and cellulose esters prepared using this method have the highest degree of substitution values (DS). In this case, the long chain cellulose esters showed DS values from 0.3 to 1.3 depending on the side chain length of cellulose esters. CDI activation, vinyl transesterification and anhydride routes resulted in somewhat lower DS values. The cellulose was also pretreated with ozone, which decreased cellulose molar mass, and resulted in synthesized cellulose esters having higher DS and better reaction efficiency than untreated cellulose. When heterogeneous esterifications were used, only acyl chloride method seemed to work.
Materials chemistry; Cellulose; Esterification; Long chain cellulose ester
An efficient path to prepare cellulose acetoacetates is reviewed in detail. The biopolymer dissolved in
N
,
N
-dimethylacetamide-LiCl is allowed to react with 2,2,6-trimethyl-4
H
-1,3-dioxin-4-one at ...elevated temperatures without any catalyst. The procedure, which is briefly described in the literature (Marson and El Seoud in J Appl Polym Sci 74:1355–1360,
1999
), utilizes simple to handle, commercially available compounds and requires only a short reaction time to obtain pure products that are promising starting materials for the design of advanced cellulose-based materials. Cellulose acetoacetates with degree of substitution of up to 1.84 can be obtained. A side reaction forming comb-like polymer structures was realized applying high molar ratio of cellulose to reagent (above 2 mol per mol) that was not known up to now. The hydrophobic cellulose acetoacetates can be transferred easily into nanoparticles with particle sizes ranging from 120 to 300 nm.
Polymer foams are widely used in several fields such as thermal insulation, acoustics, automotive, and packaging. The most widely used polymer foams are made of polyurethane, polystyrene, and ...polyethylene but environmental awareness is boosting interest towards alternative bio-based materials. In this study, the suitability of bio-based thermoplastic cellulose palmitate for extrusion foaming was studied. Isobutane, carbon dioxide (CO2), and nitrogen (N2) were tested as blowing agents in different concentrations. Each of them enabled cellulose palmitate foam formation. Isobutane foams exhibited the lowest density with the largest average cell size and nitrogen foams indicated most uniform cell morphology. The effect of die temperature on foamability was further studied with isobutane (3 wt%) as a blowing agent. Die temperature had a relatively low impact on foam density and the differences were mainly encountered with regard to surface quality and cell size distribution. This study demonstrates that cellulose palmitate can be foamed but to produce foams with greater quality, the material homogeneity needs to be improved and researched further.
Clarithromycin (CLA) is an aminomacrolide antibiotic whose physical properties are fascinating and challenging. It has very poor solubility at neutral intestinal pH, but much better solubility under ...acidic conditions due to amine protonation. The improved solubility in an acid environment is confounded by the poor chemical stability of clarithromycin that is quite labile toward acid-catalyzed degradation. This creates a complex system under gastrointestinal (GI) conditions: dissolution in the stomach, degradation, potential for precipitation in the small intestine, and interplay with the formulation components. We report herein a study of amorphous solid dispersion (ASD) of CLA with carboxyl-containing cellulose derivatives, which have recently been shown to be excellent ASD matrices for maximizing oral bioavailability. This approach was intended to improve CLA solubility in neutral media while minimizing release in an acid environment, and thereby increase its uptake from the small intestine. Amorphous polymer/CLA nanoparticles were also prepared by high-shear mixing in a multi-inlet vortex mixer (MIVM). Different extents of release were observed at low pH from the various formulations. Thus the solubility increase from nanosizing was deleterious to the concentration of intact CLA obtained upon reaching small intestine conditions; the high extent of release at gastric pH led to complete degradation of CLA. Using pH-switch experiments, it was possible to separate the effects of loss of CLA from solution by crystallization vs. that from chemical degradation. It was found that the hydrophobic cellulose derivative cellulose acetate adipate propionate (CAAdP) was effective at protecting CLA from dissolution in the stomach, and preventing CLA decomposition at low pH; 54% of CLA in CAADP ASD was released intact, vs. 0% and 6% from HPMCAS and CMCAB ASDs, respectively. We conclude that protection against degradation is central to enhancing overall release of intact CLA from ASD formulations; the formulations studied herein have great promise for simultaneous CLA solubility enhancement and protection from loss to chemical degradation, thereby reducing dose requirements and potentially decreasing colonic exposure to CLA (reduced colonic exposure is expected to minimize killing of beneficial colonic bacteria by CLA).
•Novel ω-hydroxy-substituted cellulose esters synthesized by hydroboration–oxidation.•Standard hydroboration conditions gave undesired ester saponification or reduction.•9-BBN hydroboration reagent ...and NaOAc oxidation catalyst successfully suppressed ester loss.•Hydroboration–oxidation compliments olefin cross-metathesis, transforms ω-unsaturated- to novel ω-hydroxy-cellulose esters.
We describe the first synthesis of hydroxy-functionalized polysaccharide esters via chemoselective olefin hydroboration–oxidation in the presence of ester groups. Cellulose esters with terminally olefinic side chains were first synthesized by esterification of commercially available cellulose esters (e.g., cellulose acetate) with undec-10-enoyl chloride or pent-4-enoyl chloride. Subsequent two-step, one-pot hydroboration–oxidation reactions of the cellulose esters were performed, using 9-borabicyclo3.3.1nonane as hydroboration agent, followed by oxidizing the intermediate borane to a hydroxyl group using mildly alkaline H2O2. Sodium acetate was used as a weak base to catalyze the oxidation, thereby minimizing undesired ester hydrolysis. Characterization methods including FTIR, 1H, and 13C NMR proved the selectivity of the hydroboration–oxidation pathway, providing a family of novel cellulose ω-hydroxyalkanoyl esters that were previously difficult to access.
Fundamental transport properties including salt and water partition coefficients, permeability and diffusivity of various newly synthesized cellulose esters were evaluated in this study in order to ...investigate the relationship among them as a function of molecular structure. Dense flat cellulose ester films were prepared and studied so that the influence of membrane fabrication, morphology and processing history on transport properties can be minimized. Positron annihilation lifetime spectroscopy (PALS) was employed to characterize the free volume of these cellulose esters. It was found that the transport and free volume properties can be correlated with the functional groups and their content in cellulose esters. High hydroxyl content leads to a high hydrophilicity hence resulting in a high water and salt partition coefficient. Hydrophilic cellulose esters suffer from low water/salt selectivity. On the other hand, an increase in bulky and hydrophobic propionyl or butyryl groups generally enhances cellulose esters' selectivity but brings down the permeability. However, a very high content of bulky functional group causes a drop in selectivity due to poor chain packing and the enlarged free volume as confirmed by PALS. Experimental results suggest that cellulose esters with moderate content of both hydroxyl and bulky side groups have the best diffusivity selectivity and may be suitable as membrane materials for salty water separation. An upper bound relationship between solubility selectivity and water partition coefficient was also observed in these cellulose esters as suggested in previous literature for other polymers.
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