Xiangtao Wang

Nanomaterials as Sorbents to Remove Heavy Metal Ions in Wastewater Treatment

Wastewater containing heavy metal ions is considered as the serious environmental problem in human society. Adsorption as the widely used method plays an important role in wastewater treatment, which is based on the physical interaction between metal ions and sorbents. With the development of nanotechnology, nanomaterials are used as the sorbents in wastewater treatment; several researches have proved that nanomaterials are the effective sorbents for the removal of heavy metal ions from wastewater due to their unique structure properties. Three kinds of nanomaterials are presented in this paper, including nanocarbon materials, nanometal particles, and polymer-supported nanoparticles.For heavy metal ions, all these nanomaterials show high selectivities and adsorption capacities. Besides, the adsorption isotherm model and adsorption kinetics are introduced briefly to understand the adsorption procedure.

Honokiol nanosuspensions: Preparation, increased oral bioavailability and dramatically enhanced biodistribution in the cardio-cerebro-vascular system

Honokiol is a phytochemical component with multiple pharmacological activities, but Honokiols wider use has been restricted by its poor solubility. Using bovine serum albumin and polyvinylpyrrolidone as stabilisers in a solvent precipitation-ultrasonication method, Honokiol nanosuspensions were prepared with a mean particle size of 116.2 nm (±2 nm), a zeta potential of -44.7 mV (±1.7 mV) and a high drug payload of 50.4 ± 0.6% (w/w). X-ray powder diffraction and differential scanning calorimetry indicated that Honokiol was in an amorphous state in the nanosuspensions, in contrast with bulk Honokiol powder. Honokiol was released faster in vitro from nanosuspensions with no burst release, and the highest 98% cumulative release was after 60 h. Honokiol nanosuspensions improved the oral bioavailability of Honokiol in in vivo studies in rats with a 3.94-fold Cmax and a 2.2-fold AUC(0-t). Remarkably, in contrast to oral administration, intraperitoneal administration of Honokiol nanosuspensions could dramatically alter the biodistribution of Honokiol, resulting in a much higher drug level and tissue bioavailability in the blood, heart and brain, benefitting the treatment of cardio-cerebro-vascular diseases.

The Application and Reaction Mechanism of Catalytic Ozonation in Water Treatment

Pharmaceuticals and personal care products (PPCPs) are considered as the emerging environmental problem in the recent years. The elimination of PPCPs during water treatment are investigated at lab through different advanced oxidation processes (AOPs), which are the technologies based on the intermediacy of hydroxyl and other radicals to oxidize pollutants. Catalytic ozonation is proved as an effective technology for the removal of organics from wastewater. The paper presents a short review about the introduction of the ozonation catalysts and the reaction mechanism of the catalytic ozonation. The main aim is to provide a new and effective method in the removal of PPCPs in the aqueous solution.

Preparation, characterization, biodistribution and antitumor efficacy of hydroxycamptothecin nanosuspensions.

Hydroxycamptothecin (HCPT) has shown activity against a broad spectrum of cancers, but its therapeutic efficacy is impaired by its poor solubility and delivery challenges. In this study, HCPT nanosuspensions were prepared with precipitation-combined ultrasonication and characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The HCPT nanosuspensions were spherical with a smooth surface and a small size of 150-200 nm. The lyophilized powders for the HCPT nanosuspensions were amorphous and displayed sustained release in vitro. Compared to commercial HCPT injection, in vivo experiments with HCPT nanosuspensions showed significantly increased HCPT concentrations in the blood and all tissues of the tested as well as improved tumor targetability and liver targetability. Meanwhile, nanosuspensions displayed better anticancer efficacy than injection on H22 bearing mice (81.20% vs. 56.39%, in tumor inhibition rate). Therefore, HCPT nanosuspensions seem very promising for the treatment of hepatic cancer.

Methotrexate Nanoparticles Prepared with Codendrimer from Polyamidoamine (PAMAM) and Oligoethylene Glycols (OEG) Dendrons: Antitumor Efficacy in Vitro and in Vivo

The novel methotrexate-loaded nanoparticles (MTX/PGD NPs) prepared with amphiphilic codendrimer PGD from polyamidoamine and oligothylene glycol dendrons were obtained via antisolvent precipitation method augmented by ultrasonication. Based on the excellent hydrophility of PGD, the drug-loaded nanoparticles could be investigated easily with the high drug-loading content (~85.2%, w/w). The MTX/PGD NPs possessed spherical morphology, nanoscaled particle size (approximately 182.4 nm), and narrow particle size distribution. Release of MTX from MTX/PGD NPs showed a sustained release manner and completed within 48 h. Hemolytic evaluation indicated MTX/PGD NPs presented good blood compatibility, and the cytotoxicity of nanoparticles against breast cancer cells in vitro, biodistribution in tumor tissue, and antitumor efficacy in vivo were enhanced significantly compared to MTX injection. According to the higher drug-loading content, enhanced antitumor efficacy, and appropriate particle size, MTX/PGD NPs as the drug delivery systems could have potential application for cancer chemotherapy in clinic.

A nanoparticulate drug-delivery system for 20(S)-protopanaxadiol: formulation, characterization, increased oral bioavailability and anti-tumor efficacy

Abstract As with many other hydrophobic anticancer agents, 20(S)-protopanaxadiol (PPD) has a very low oral bioavailability. In this study, a precipitation-combined ultrasonication technique was used to prepare PPD nanosuspensions. The mean particle size of the nanosuspensions was approximately 222 ± 12 nm, the drug payload achieved 50% after lyophilization and the maximum PPD concentration can reach 100 mg/ml, which is over 30 000 times the solubility of PPD in aqueous solution (3 μg/ml). After oral administration, the Cmax and AUClast values of PPD nanosuspensions were approximately 3.66-fold and 3.48-fold as those of PPD coarse suspensions, respectively. In contrast to the free drug solution, PPD nanosuspensions showed higher in vitro anti-tumor activity against HepG-2 cells (an IC50 value of 1.40 versus 5.83 μg/ml at 24 h, p < 0.01). The in vivo study in H22-tumor-bearing mice demonstrated that PPD nanosuspensions showed good anti-tumor efficacy with an inhibition rate of 79.47% at 100 mg/kg, while 50 mg/kg of cyclophosphamide was displayed as positive control, and the inhibition rate was 87.81%. Considering the highest drug payload, oral bioavailability reported so far, significant anti-tumor efficacy and excellent safety of encapsulated drugs, PPD nanosuspensions could be used in potential effective strategies for anticancer therapy; further investigation is ongoing.

High drug payload curcumin nanosuspensions stabilized by mPEG-DSPE and SPC: in vitro and in vivo evaluation

Abstract Context: Curcumin (CUR) is a promising drug candidate based on its broad bioactivities and good antitumor effect, but the application of CUR is potentially restricted because of its poor solubility and bioavailability. Objective: This study aims at developing a simple and effective drug delivery system for CUR to enhance its solubility and bioavailability thus to improve its antitumor efficacy. Materials and methods: Curcumin nanosuspensions (CUR-NSps) were prepared by precipitation-ultrasonication method using mPEG2000-DSPE and soybean lecithin as a combined stabilizer. Results: CUR-NSps with a high drug payload of 67.07% were successfully prepared. The resultant CUR-NSps had a mean particle size of 186.33 ± 2.73 nm with a zeta potential of −19.00 ± 1.31 mV. In vitro cytotoxicity assay showed that CUR-NSps exhibited enhanced cytotoxicity compared to CUR solution. The pharmacokinetics results demonstrated that CUR-NSps exhibited a significantly greater AUC0–24 and prolonged MRT compared to CUR injections after intravenous administration. In the biodistribution study, CUR-NSps demonstrated enhanced biodistribution compared with CUR injections in liver, spleen, kidney, brain, and tumor. The CUR-NSps also showed improved antitumor therapeutic efficacy over the injections (70.34% versus 40.03%, p < 0.01). Conclusions: These results suggest that CUR-NSps might represent a promising drug formulation for intravenous administration of CUR for the treatment of cancer.

Codendrimer (PAG) from polyamidoamine (PAMAM) and oligoethylene glycols (OEG) dendron: evaluation as drug carrier

Based on the successful synthesis of codendrimer PAMAM-co-OEG (PAG) from polyamidoamine (PAMAM) and oligoethylene glycols (OEG) dendron, the aim of this paper was to prepare drug-loaded aggregates and evaluate the ability of PAG as the drug carrier. A series of hydrophobic drugs with different functional groups were selected as model drugs. The drug-loading procedures were optimized by single factor exploration with resveratrol. From the results of drug-loading content (DLC) and entrapment efficiency (EE), MTX was proved to be the most suitable drug. Moreover, higher loading capacity and slower in vitro release of MTX were observed, which was due to the hydrophobic interactions and electrostatic interactions between MTX and PAG. In summary, PAG exhibited great potential for modifications in the stability, drug solubilization, and release properties of drug-loaded aggregates.

Well-defined podophyllotoxin polyprodrug brushes: preparation via RAFT polymerization and evaluation as drug carriers

Novel poly(triethylene glycol methacrylate)-b-poly(podophyllotoxin methacrylate) copolymers (PTP) with a well-defined structure were designed and synthesized by direct RAFT polymerization with the hydrophobic monomer derivative from the anticancer drug podophyllotoxin. After optimizing the hydrophilic/hydrophobic ratio, the polyprodrug brush PT45P14 was utilized as a carrier to prepare polyprodrug nanoparticles (PT45P14 NPs) via the dialysis method. The polyprodrug nanoparticles presented a drug-loading content of approximately 40% and excellent storage and medium stabilities. The release of POD from PT45P14 NPs showed a sustained and pH-dependent release manner within 72 h; the release rate was increased under acidic conditions because ester bonds cleaved faster in a low pH environment. PT45P14 NPs presented higher cytotoxicity against Hela cells compared with free POD, the antitumor efficacy in vitro was enhanced 5-fold, and the cellular uptake mechanism was proven to be sucrose-blocking clathrin-mediated endocytosis. According to their great drug-loading content, moderate hydrophilicity, appropriate particle size, pH-sensitive release, and enhanced antitumor efficacy, PT45P14 NPs as efficient drug delivery systems could have potential application in pH-sensitive cancer therapy.

Honokiol nanoparticles stabilized by oligoethylene glycols codendrimer: in vitro and in vivo investigations

Nanoparticles based on dendrimers were explored as excellent candidates for nanoscale drug delivery system. In this study, the fluorescently labeled amphiphilic codendrimer PGC from PAMAM G4.0 and oligoethylene glycol dendron was utilized as a carrier to prepare honokiol-loaded nanoparticles (HK NPs) via an evaporation method augmented by ultrasonication with an optimized drug-loading content (∼60%, wt%). The release of HK NPs showed a sustained release manner and was completed within 120 h. The HK NPs presented higher cytotoxicity against 4T1 cells, and the cellular uptake mechanism was proven to be caveolae-mediated endocytosis and clathrin-mediated endocytosis. Importantly, the HK NPs resulted in a strong antitumor efficacy on the 4T1 breast tumor model in vivo, and no significant adverse effects were observed. In addition, in vivo studies also showed that the HK NPs possessed better tumor accumulation over HCPT injection. According to the higher drug-loading content, enhanced antitumor efficacy, and appropriate particle size, HK NPs were shown to be safe and efficient drug delivery systems and could have potential application in cancer chemotherapy.