Biologically active Camellia oleifera protein nanoparticles for improving the tumor microenvironment and drug delivery.

It is important for antitumor drugs to accumulate at the tumor site and penetrate deeply to play a role in treatment. However, it is difficult for the drugs to reach the destination on account of the complex tumor microenvironment such as elevated tumor interstitial fluid pressure (IFP) and solid stress. Here, we report a type of nanocarrier composed entirely of Camellia oleifera protein (COP), which could lower tumor IFP and solid stress. Its physicochemical properties, cellular uptake, in vitro cytotoxicity and tumor perfusion, biodistribution, and in vivo antitumor efficiency were evaluated. It was found that COP NPs had good cellular uptake ability and cytocompatibility. When loading doxorubicin, COP NPs showed an in vitro concentration-dependent cytotoxicity. Importantly, the tumor IFP and solid stress were greatly reduced after injecting COP NPs into tumor-bearing mice, leading to more drug accumulating in the tumor and a longer survival time for tumor-bearing mice. Therefore, our study provided a new strategy to improve the tumor microenvironment and to achieve better antitumor efficiency.

Targeting and microenvironment-improving of phenylboronic acid-decorated soy protein nanoparticles with different sizes to tumor.

It is essential for nanoparticles to delivery drugs accurately and penetrate deeply to tumor. However, complicated tumor microenvironment such as elevated tumor interstitial fluid pressure (IFP) and solid stress reduces the transport efficiency of nanomedicines in tumor. Methods: We herein report a drug delivery system of phenylboronic acid-decorated soy protein nanoparticles with the size of 30 nm, 50 nm and 150 nm. In vitro examinations including cytotoxicity, cellular uptake and penetration in multicellular tumor spheroids and in vivo observations including IFP and tumor solid stress measurements and antitumor activity were performed. Results: It was found that phenylboronic acid moiety could endow the nanoparticles actively targeting affinity to sialic acid (SA) which overexpressed in tumor cells. Simultaneously soy protein could improve tumor microenvironment such as reduction of IFP and tumor stress. Among the soy protein nanoparticles with different sizes, 30 nm-sized nanoparticles showed the best cellular uptake and highest cytotoxicity in vitro after loading doxorubicin (DOX). In vivo, 30 nm-sized nanoparticles showed the best tumor microenvironment improvement efficiency, leading to the enhanced drug accumulation and antitumor efficiency when combination with DOX. Conclusion: Our study introduces a bioactive nanoparticulate design strategy to actively target and significantly improve tumor microenvironment for enhanced cancer therapy.

Influence of the surface structure of graphene oxide on the adsorption of aromatic organic compounds from water.

In this work, graphene oxide (GO) has been employed as an efficient adsorbent for the removal of three aromatic organic compounds (AOCs), namely, aniline, nitrobenzene, and chlorobenzene, from water under various initial AOC concentrations and pH levels. Based on the characteristics of surface structures of GO, a simple semiquantitative model has been provided to describe the intrinsic adsorption behavior of GO to AOCs. Accordingly, the adsorption mechanism has been discussed in detail at molecular levels. The contribution coefficients derived from the proposed model indicate that the most preferential interactions between GO and AOCs are hydrophobic interactions (π-π stacking and hydrophobic effect) that occur on graphitic zones of GO (unoxidized region). In the oxidized region, there also exist the hydrophobic interactions on sp(2) clusters, although they may be hindered by surrounding sp(3) zones which are the most unfavorable and are only accessible to AOCs through hydrogen bonding or electrostatic effects. More interestingly, aniline exhibits the highest contribution coefficients in both hydrophobic and hydrophilic zones of GO among the three measured AOCs due to its good water solubility and facile formation of hydrogen bonds. Furthermore, the analytical results of the adsorption isotherms are also fully consistent with those from the proposed model.

Broad hexagonal columnar mesophases formation in bioinspired transition-metal complexes of simple fatty acid meta-octaester derivatives of meso-tetraphenyl porphyrins.

A series of meta-substituted fatty acid octaester derivatives and their transition-metal complexes of meso- tetraphenyl porphyrins (TPP-8OOCR, with R = C(n-1)H(2n-1), n = 8, 12, or 16) have been prepared through very simple synthesis protocols. The thermotropic phase behavior and the liquid crystalline (LC) organization structures of the synthesized porphyrin derivatives were systematically investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and variable-temperature small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) techniques. The shorter octanoic acid ester substituted porphyrin (C8-TPP) did not show liquid crystallinity and its metal porphyrins exhibited an uncommon columnar mesophase. The lauric acid octaester (C12-TPP) and the palmitic acid octaester (C16-TPP) series porphyrins generated hexagonal columnar mesophase Colh. Moreover, the metal porphyrins C12-TPPM and C16-TPPM with M = Zn, Cu, or Ni, exhibited well-organized Colh mesophases of broad LC temperature ranges increasing in the order of TPPNi

Evaluation of a novel chitosan-based flocculant with high flocculation performance, low toxicity and good floc properties.

In this work, a novel chitosan-based flocculant, carboxymethyl chitosan-graft-poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride] (CMC-g-PDMC), was designed and prepared successfully. Flocculation performance of CMC-g-PDMC was systematically evaluated using kaolin suspension, humic acid (HA) solution and kaolin-HA mixed suspension as synthetic wastewater under acidic, neutral and alkaline conditions, respectively. The experimental results demonstrated that CMC-g-PDMC exhibited lower optimal dosage, higher contaminant removal efficiency, wider applicable pH range, lower effluent toxicity and better floc properties for handling and disposal, in comparison with polyaluminum chloride. The high flocculation performance of CMC-g-PDMC was ascribed to two structural advantages of improved both positive charges and molecular weight. In addition, flocs characteristics including flocs formation, breakage, regrowth and fractal structure, were studied by an in-situ light scattering system during the flocculation process. Detailed analysis clearly illuminated the differences and relationship among floc size, fractal dimension and floc strength. Based on analysis of floc properties in combination with zeta potential measurements, flocculation mechanisms in different synthetic wastewater at various pHs were deeply discussed: charge neutralization or patching played the key role under different conditions, and the relationship between flocculation mechanisms and floc properties has been built. The effective and environment-friendly flocculant bear significant application potentials in water treatment fields.

Flocculation of Escherichia coli using a quaternary ammonium salt grafted carboxymethyl chitosan flocculant.

Only few studies are available on bacteria removal efficiencies and antibacterial properties of flocculants, which is one of the important requirements in water treatment work. Escherichia coli (E. coli) was selected as an example of a Gram-negative bacteria for testing the flocculating properties of a quaternary ammonium salt grafted chitosan (carboxymethyl chitosan-graft-poly[(2-methacryloyloxyethyl) trimethylammonium chloride] copolymer; i.e., CMC-g-PDMC). The effect of various flocculation parameters, including flocculant dosage, initial bacterial density, nutrient medium content, and pH were successively investigated. The experimental results indicated that, besides flocculation effects, CMC-g-PDMC also exhibited a bactericidal effect (not requiring additional treatment facilities). Moreover, the flocculation mechanisms were investigated via zeta potential measurements, floc observation, and three-dimensional excitation-emission matrix spectra analysis. Apart from its flocculating and settling effect, this chitosan-based material has bactericidal action through the breaking of bacterial cell walls by grafted quaternary ammonium salt.

Rapid removal and separation of iron(II) and manganese(II) from micropolluted water using magnetic graphene oxide.

A novel two-dimensional carbon-based magnetic nanomaterial, magnetic graphene oxide (MGO), was prepared and then used as an efficient adsorbent. MGO showed rapid and complete removal of iron(II) (Fe) and manganese(II) (Mn) from micropolluted water bodies over a wide pH range. After saturated adsorption, MGO could be rapidly separated from water under an external magnetic field. Results of the adsorption equilibrium study indicated that the adsorption of Fe and Mn by MGO took place via monolayer heterogeneous and spontaneous processes resulting from the heterogeneity of the MGO surface as well as from the electrostatic interactions between surface acidic groups of MGO and metal ions. In addition, both the Fe and Mn uptake of MGO was very slightly affected by NaCl, although it decreased with increased humic acid in solutions. In an Fe/Mn binary aqueous system, both metal ions can be efficiently removed at low concentrations, but MGO showed preferential adsorption of Fe in a concentrated aqueous mixture. The adsorption behavior in the binary system was due to different affinities of surface oxygen-containing functional groups on MGO to Fe and Mn. Finally, unlike traditional approaches in recycling and reusing an adsorbent, the Fe- and Mn-loaded MGO can be directly applied as a new adsorbent to achieve the efficient removal of fluoride from aqueous solutions.

Effects of the oxidation degree of graphene oxide on the adsorption of methylene blue.

In this current work, a series of graphene oxides (GO) with different oxidation degrees (OD) was prepared using Hummer method. Fundamental adsorption behavior of the GO series for removal of methylene blue (MB) from aqueous solutions has been studied. The GO series shows an overall fast and pH-independent MB adsorption, which is even capable of removing trace levels of dye completely from very dilute solutions. Furthermore, the effects of the oxidation degree (OD) on MB adsorption behavior have been investigated systematically, indicating that the dye uptakes of GO exponentially increase with the increase of OD. Further study on the adsorption mechanism shows that adsorption behavior of GO would change from a Freundlich-type to a Langmuir-type adsorption as the OD increases. It may be due to both the enhanced exfoliation degree of the carbon planes in graphite caused by oxidation and the production of more active adsorption sites. The binding features of the MB loaded GO gradually change from MB molecule parallel stacking on graphite plane through hydrophobic π-π interaction to vertical standing via electrostatic interaction with increasing OD, resulting in a significant improvement of MB uptakes. In addition, the adsorption capacity of the regenerated GO has little loss until four cycles.

Flocculation performance and mechanism of graphene oxide for removal of various contaminants from water.

The application of nanomaterials in water treatment plants has attracted significant attention recently. This study investigates the possibility of using graphene oxide (GO) as a novel flocculant to remove contaminants with different surface charges from water, including two particulate ones (kaolin and hematite) and two soluble ones (humic acid (HA) and cationic light yellow 7GL dye (7GL)). The flocculation performances of traditional polyaluminum chloride (PAC) and original graphite were also tested for comparison. Fractal theory was applied to evaluate the floc properties and explore the flocculation mechanism in combination with zeta potential measurements. For negatively charged contaminants, kaolin and HA, GO was observed to remove these contaminants successfully via the sweeping flocculation effect under acidic and neutral conditions. However, GO was less efficient than PAC. For positively charged contaminants, hematite and 7GL, the flocculation performances of GO were significantly improved than those of PAC via patching effect for hematite suspension and charge neutralization effect for 7GL solution. The results highlighted the extensive potential applicability of GO as a suitable flocculant in water treatment.

Flocculation of both anionic and cationic dyes in aqueous solutions by the amphoteric grafting flocculant carboxymethyl chitosan-graft-polyacrylamide.

In the current work, a series of amphoteric grafting chitosan-based flocculants (carboxymethyl chitosan-graft-polyacrylamide, denoted as CMC-g-PAM) was designed and prepared successfully. The flocculants were applied to eliminate various dyes from aqueous solutions. Among different graft copolymers, CMC-g-PAM11 with a PAM grafting ratio of 74% demonstrated the most efficient performance for removal of both the anionic dye (Methyl Orange, MO) and the cationic dye (Basic Bright Yellow, 7GL) under the corresponding favored conditions (80 mg/L of the flocculant at pH 4.0, and 160 mg/L at pH 11.0). In comparison with its precursors, chitosan and carboxymethyl chitosan, CMC-g-PAM11 showed higher removal efficiencies and wider flocculation windows. More importantly, the graft copolymer produced notably more compacted flocs based on image analysis in combination with fractal theory, which was of great significance in practical water treatment. Furthermore, the flocculation mechanism was discussed in detail. The grafted polyacrylamide chains were found to contribute much to the improved bridging and sweeping flocculation effects, but reduced charge neutralization flocculation for the effect of charge screening.

Preparation of chitosan/poly(acrylic acid) magnetic composite microspheres and applications in the removal of copper(II) ions from aqueous solutions.

In this current work, the magnetic composite microspheres (MCM), consisting of Fe(3)O(4) nanoparticles and poly(acrylic acid) (PAA) blended chitosan (CS), were prepared successfully by a simple method, co-precipitation of the compounds in alkaline solution. SEM, FTIR and TG techniques have been applied to investigate the structures of the MCM materials. The vibrating-sample magnetometer (VSM) measurement illustrated a paramagnetic property as well as a fast magnetic response, which indicated the significant separability of the MCM in the aqueous suspensions. Then, the MCM materials were employed as absorbents for removal of copper(II) (Cu(II)) ions from aqueous solutions. The fundamental adsorption behaviors of MCM were studied also. Experimental results revealed that the CS/PAA-MCM had greater adsorption capacity than CS-MCM, and PAA played an important role for the adsorption of Cu(II) ions. Moreover, the adsorption isotherms were all well described by the Langmuir model, while the adsorption kinetics followed the pseudo-second order equation. Furthermore, the adsorbent could be easily regenerated at lower pH and reused almost without any loss of adsorption capacity. On the contrary, the Cu(II) ions loaded CS-MCM and CS/PAA-MCM were stable enough at pH higher than 4.0, and both exhibited efficient phosphate removal with maximal uptakes around 63.0 and 108.0 mg Pg(-1), respectively.

Efficient removal of both cationic and anionic dyes from aqueous solutions using a novel amphoteric straw-based adsorbent.

In the current paper, a novel amphoteric straw-based adsorbent was prepared and applied to adsorb various dyes from aqueous solutions. The amphoteric adsorbent was proven effective in eliminating both cationic and anionic dyes (methylene blue and acid green 25), especially at corresponding favored pH conditions. The fundamental adsorption behavior of the adsorbent on removing various dyes was also investigated at different temperatures. The adsorption isotherms were all best-fitted by the Langmuir equation, whereas the adsorption kinetics was well-described by both the pseudo-second order model and the Elovich model. The experimental result revealed that the adsorption mechanism followed the monolayer chemical adsorption with an ion-exchange process.

Adsorption of anionic dyes from aqueous solutions using chemically modified straw.

The effective disposal of redundant straw is a significant work for environmental protection and full utilization of resource. In this work, the wheat straw has been modified by etherification to prepare a kind of quaternary ammonium straw adsorbents. The adsorption behaviors of the modified straw for methyl orange (MO) and acid green 25(AG25) were studied in both batch and column systems. The adsorption capacity of the straw for both dyes improved evidently after modification. The maximal MO and AG25 uptakes were more than 300 and 950 mg g(-1), respectively. Furthermore, the adsorption equilibrium, kinetics and column studies all indicated that the adsorption behavior was a monolayer chemical adsorption with an ion-exchange process. In addition, after adsorption of anionic dyes, the used adsorbents were successfully applied to adsorb a cationic dye directly at suitable conditions in the secondary adsorption. This was due to the altered surface structures of the used adsorbents.

Evaluation of the flocculation performance of carboxymethyl chitosan-graft-polyacrylamide, a novel amphoteric chemically bonded composite flocculant.

In the present work, a novel amphoteric chemically bonded composite flocculant (carboxymethyl chitosan-graft-polyacrylamide, denoted as CMC-g-PAM) was successfully prepared and used to flocculate the kaolin suspension. The flocculation performance of CMC-g-PAM in acidic, neutral, and alkaline conditions was systematically evaluated by light scattering in combination with fractal theory, as well as by traditional turbidity and zeta potential measurements. Based on the experimental facts from in situ size and fractal dimension measurements, different flocculation mechanisms play key roles at various pH levels, resulting in substantially varied flocculation kinetic processes under three pH conditions. In acidic condition, patching was the main mechanism involved in the opposite zeta potential between CMC-g-PAM and the kaolin suspension. A flat configuration was favored when the polymeric flocculant was adsorbed onto the particle surface, leading to a slower initial floc growth rate but larger and denser flocs. Bridging was the dominant mechanism in neutral and alkaline conditions. A faster initial rate of bridging resulted in smaller and more open floc structures. A rearrangement process in neutral pH subsequently led to more compact flocs, whereas no restructuration of flocs occurred in alkaline conditions because of the electrostatic repulsion of the same negative charges on the flocculant and particles.

Cationic content effects of biodegradable amphoteric chitosan-based flocculants on the flocculation properties.

A series of biodegradable amphoteric chitosan-based flocculants (3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CTA) modified carboxymethyl chitosan, denoted as CMC-CTA) with different substitution degrees of CTA were prepared successfully. The content of carboxymethyl groups in each CMC-CTA sample was kept almost constant. The solubility of the various flocculants showed that, higher cationic content of flocculants caused a better solubility. The flocculation experiments using kaolin suspension as synthetic water at the laboratory scale indicated that the substitution degree of CTA was one of the key factors for the flocculation properties. With the increase of cationic content, the flocculants were demonstrated better flocculation performance and lower dosage requirement. Flocculation kinetics model of particles collisions combining zeta potential and turbidity measurements was employed to investigate the effects of the cationic content of the flocculants on the flocculation properties from the viewpoint of flocculation mechanism in detail. Furthermore, flocculation performance using raw water from Zhenjiang part of Yangtze River at the pilot scale showed the similar effects to those at the laboratory scale.

Solvation behaviors of N-isopropylacrylamide in water/methanol mixtures revealed by molecular dynamics simulations.

Solvation behaviors of N-isopropylacrylamide (NIPAM) in water/methanol mixtures are investigated by molecular dynamics simulations. The results indicate that NIPAM-solvent interactions are weakened with the increase of methanol mole fractions (x(methanol)) from 0.25 to 0.80, rationalizing the reentrant coil-to-globule-to-coil transition behaviors of poly(N-isopropylacrylamide) in the mixed solvents. Interestingly, hydrogen-bonded water/methanol clusters are abundant in binary mixed solvents, leading to the decrement of NIPAM-solvent interactions. To better understand the intermolecular interactions in the water/methanol complex clusters, the structures of pure water and methanol clusters are also studied for a comparison. Although the amount of water clusters decreases with an increase in x(methanol), the structure of water clusters stays stable, and hydrogen-bonded networks are not essentially disrupted. As for methanol molecules, they prefer to form short nonbranched chainlike hydrogen-bonded clusters. However, most of the chainlike hydrogen-bonded methanol clusters are broken in water-rich solutions, leaving the little probability for the formation of dimeric and trimeric methanol clusters.

[Identification of concentration and brand for products using differential gel permeation chromatography].

In differential gel permeation chromatographic method (D-GPC), a standard solution and an analyzed solution are used as the eluent and injected solution, respectively. It can determine the minute differences between them. When the analyzed solution and the standard solution are identical, a null signal is given, otherwise the nonzero signal tells the detailed differences between them. Two examples, the concentration identification of five polyethylene glycol 200 (PEG200) solutions and the brand identification of three brands of beers, are given to show the application of the D-GPC method. The potential applications of the D-GPC method in quality control and the identification of counterfeit products are also discussed.

Preparation and liquid crystalline properties of spherical cellulose nanocrystals.

A novel kind of spherical cellulose nanocrystal (SCNC) suspension was prepared by hydrolysis of microcrystalline cellulose with a mixture of sulfuric acid and hydrochloric acid under ultrasonic treatment. The mechanism of SCNC formation and the liquid crystalline properties of their suspensions were investigated. A suspension of spherical particles was usually inclined to form crystallization colloids rather than liquid crystals at high concentration. However, a SCNC suspension with high polydispersity (49%) was observed to form the liquid crystalline phase, and the liquid crystalline textures changed with increasing concentration. This observation offers an approach to the liquid crystal formation of highly polydisperse spherical nanoparticles.

Glass transition of the two distinct single-chain particles of poly(N-isopropylacrylamide).

Two distinct single-chain particles of poly(N-isopropylacrylamide) (PNIPAM) in the state of loose coil and compact globule, have been prepared successfully below and above the lower critical solution temperature (LCST) in extreme dilute aqueous solution by the freeze-drying method, respectively. During the preparation of the compact globular single-chain sample, the surfactant of sodium n-dodecyl sulfate (SDS) was added into the system to prevent aggregation of globular single chains formed at a temperature above the LCST. After all the coil has been transformed into the compact globular particle, the SDS molecules were removed by dialysis. The glass transition temperature (T(g)) of the two single-chain samples has been measured by differential scanning calorimetery (DSC) in comparison with that of bulk polymer. It was found that the T(g) of the single-chain sample in compact-globule state was very near to that of the bulk polymer, whereas the T(g) of the single-chain sample in loose-coil state was approximately 6 K lower than that of the bulk polymer. After treating the sample with repeated DSC cycles, the T(g) of the single-chain sample in loose-coil state rose up successively near to that of the bulk polymer. These results have been explained in terms of the effect of entanglement on the mobility of the polymer segments in the two distinct single-chain samples.

Analysis of interfacial phenomena of aqueous solutions of polyethylene oxide and polyethylene glycol flowing in hydrophilic and hydrophobic capillary viscometers.

Viscosities of aqueous solutions of five polyethylene oxide (PEO) samples with molar masses from 1.5 x 10(5) to 1.0 x 10(6) were carefully measured in a polytetrafluoroethylene (PTFE) capillary Ubbelohde viscometer in the concentration range from dilute down to extremely dilute concentration regions and compared with those of the same sample obtained from a glass capillary viscometer. At the same time, viscosities of aqueous solutions of three PEG samples in glass and paraffin-coated capillary viscosity were measured. The wall effects occurred in viscosity measurements for PEO and PEG aqueous solutions in different capillary viscometers were theoretically analyzed and discussed. It was found that different interfacial behaviors occurred in both hydrophobic and hydrophilic capillary viscometers respectively and the interfacial behaviors also exhibit molar mass dependence.