Comparison between novel star-like redox-sensitive amphiphilic block copolymer and its linear counterpart copolymer as nanocarriers for doxorubicin.

Linear and star-like redox-sensitive amphiphilic block copolymers have been studied as anticancer drug delivery systems. However, few reports directly compared the properties of those two structures especially when they are used as nanocarriers for antitumor drugs. To address this, a novel star-like copolymer and its linear counterpart were synthesized with a hydrophobic/redox-responsive/hydrophilic structure. The overall molecular weight of the star-shaped copolymer was nearly equal to that of the linear counterpart. The star-like micelles exhibit size of 90 nm, which was smaller than that of linear copolymers (151.6 nm) and critical micelle concentration of 1 mg/L, which was lower than that of the linear micelles (8.9 mg/L). The disassembly behaviors and the redox-sensitivity of the nanoparticles to reductive stimuli of glutathione was evaluated from the changes of the micellar size and morphology. Furthermore, doxorubicin was physically loaded into the hydrophobic part of the copolymers. The drug-loading capacities in the star-like and linear micelles were 15.94 and 7.53 wt%, respectively. Drug release studies carried out at two different glutathione concentrations. A cytotoxicity study of the micelles was performed by MTT assay. The prepared star copolymer showed no significant toxicity against HDF cells while enhanced cytotoxicity of the DOX-loaded micelles against MCF-7 cells was observed. Therefore, developing sucrose-PCL-SS-PEG copolymer reported in this paper as an effective reduction-responsive carrier with excellent properties and cell biocompatibility is promising for the efficient intracellular delivery of hydrophobic chemotherapeutic drugs. This work also indicates that modification of the nanocarrier structure is a potential strategy for optimizing drug delivery.

Synthesis and evaluation of injectable thermosensitive penta-block copolymer hydrogel (PNIPAAm-PCL-PEG-PCL-PNIPAAm) and star-shaped poly(CL─CO─LA)-b-PEG for wound healing applications.

BACKGROUND: Loss of skin integrity due to injury, burning, or illness makes the development of new treatment options necessary. Skin tissue engineering provides some solutions for these problems. OBJECTIVE: The potential of a biodegradable star-shaped copolymer [Poly(CL─CO─LA)-b-PEG] and penta-block copolymer hydrogel (PNIPAAm-PCL-PEG-PCL-PNIPAAm) was assessed for skin tissue engineering applications. METHODS: Two copolymers were synthesized for cellular culture scaffolds and their mechanical properties were compared. The resulting star-shaped copolymer and thermosensitive penta-block copolymer were characterized using Fourier transform infrared and nuclear magnetic resonance spectroscopy. The crystallizability of the two copolymers was analyzed using X-ray diffraction. The resulting thermosensitive penta-block copolymer was evaluated by differential thermal analysis, differential scanning calorimetry and thermogravimetric analysis. Scanning electron microscopy and in vitro degradation of the polymer network in phosphate buffer solutions (pH 7.4) at 37°C were also examined. The pore size of the gels was calculated with Image Analyzer software. Finally, the cytotoxic, morphological, and gene expression effects of copolymers on the skin fibroblast were evaluated. RESULTS: The experiments showed that the PNIPAAm-PCL-PEG-PCL-PNIPAAm polymer with the right composition and the expected molecular weight was achieved. The hydrogel had less crystallizability compared with its precursors. The resulting thermosensitive hydrogel had a three-dimensional structure with interconnected pores that mimicked the extracellular matrix. The control of the degradability rate can be possible by weight percent changes. The pore size correlated with the polymer concentration in aqueous solution and the pore sizes of the 20 wt% hydrogel were better for fibroblast cultivation than those of the 10 wt% hydrogel. Cell proliferation on the 20% gel was more than that of the 10% gel. The hydrogel not only preserved the viability and phenotypical morphology of the entrapped cells but also stimulated the initial cell-cell interactions and proliferation of fibroblasts. The hydrogel did not influence cell conformation and this property of the polymer underlined its safety. Cells seeded on this copolymer showed a normal and spear shape and formed a focal adhesion with the hydrogel surface. Notably, the hydrogel increased collagen I α1 and collagen III mRNAs expression. CONCLUSION: Due to the low molecular weight and poor mechanical strength of the star-shaped copolymer, it was not considered for fabrication of the scaffolds for wound healing. The biodegradable, biocompatible, injectable and thermosensitive PNIPAAm-PCL-PEG-PCL-PNIPAAm hydrogel in 20 wt% demonstrated a desirable potential for future application as a cell scaffold in skin tissue engineering and wound healing.

Application of poly 1,8-diaminonaphthalene/multiwalled carbon nanotubes-COOH hybrid material as an efficient sorbent for trace determination of cadmium and lead ions in water samples.

Poly 1,8-diaminonaphthalene/multiwalled carbon nanotubes-COOH hybrid material as an effective sorbents in solid phase extraction has been developed for the separation and preconcentration of Cd(II) and Pb(II) at trace levels in environmental water samples. The results indicate that the novel nanocomposite show a high affinity for these heavy metals due to the presence of several good extractive sites, which are introduced to the synthesized nanocomposite The maximum adsorption capacity of the synthesized sorbent for cadmium and lead ions was found to be 101.2 and 175.2 mg g(-1) , respectively. The detection limits of this method were 0.09 and 0.7 ng ml(-1) for Cd(II) and Pb(II), respectively.

Highly selective and sensitive recognition of multi-ions in aqueous solution based on polymer-grafted nanoparticle as visual colorimetric sensor.

A novel, selective and sensitive colorimetric sensor for naked-eye detection and adsorption of multi-ions in aqueous solution was synthesized using hybridization of organic-inorganic phase. The polymer-grafted nanoparticles (PGNPs) was synthesized via atom transfer radical polymerization (ATRP) of monomers on modified TiO2 NPs and applied under optimized conditions for naked-eye detection: sensor mass: 15 mg; response time: 30 s with limits of detection (LODs) as small as 10, 1, 0.5, and 1 ppb Hg (II), Cd (II), Cu (II), and UO2 (II) at pH = 8, 9, 6, and 7, respectively. The efficient selectivity of the naked eye sensor to multi-ions in the presence of various ions was affirmed wherein the color of the chemosensor in the presence of Hg (II), Cd (II), Cu (II), and UO2 (II) shifted from gray to violet, orange, green and yellow, respectively. The salient advantages of this method comprise expeditious, selectable, high reproducibility, with reasonable adsorption capacity (133 mg g-1) and inexpensive nature for rapid detection of heavy metal ions contamination in aqueous solution in an inexpensive manner. The adsorption mechanism was studied via adsorption kinetics and adsorption isotherm models and the accuracy of the chemosensor has been confirmed and supported by XRD, FT-IR, TGA, 1H-NMR, SEM, TEM, EDX mapping, DLS, BET, and EDS analysis.

HVHC-ESD-Induced Oxygen Vacancies: An Insight into the Phenomena of Interfacial Interactions of Nanostructure Oxygen Vacancy Sites with Oxygen Ion-Containing Organic Compounds.

The challenging environmental chemical and microbial pollution has always caused issues for human life. This article investigates the detailed mechanism of photodegradation and antimicrobial activity of oxide semiconductors and realizes the interface phenomena of nanostructures with toxins and bacteria. We demonstrate how oxygen vacancies in nanostructures affect photodegradation and antimicrobial behavior. Additionally, a novel method with a simple, tunable, and cost-effective synthesis of nanostructures for such applications is introduced to resolve environmental issues. The high-voltage, high-current electrical switching discharge (HVHC-ESD) system is a novel method that allows on-the-spot sub-second synthesis of nanostructures on top and in the water for wastewater decontamination. Experiments are done on rhodamine B as a common dye in wastewater to understand its photocatalytic degradation mechanism. Moreover, the antimicrobial mechanism of oxide semiconductors synthesized by the HVHC-ESD method with oxygen vacancies is realized on methicillin- and vancomycin-resistant Staphylococcus aureus strains. The results yield new insights into how oxygen ions in dyes and bacterial walls interact with the surface of ZnO with high oxygen vacancy, which results in breaking of the chemical structure of dyes and bacterial walls. This interaction leads to degradation of organic dyes and bacterial inactivation.

Multilayered mucoadhesive hydrogel films based on Ocimum basilicum seed mucilage/thiolated alginate/dopamine-modified hyaluronic acid and PDA coating for sublingual administration of nystatin.

The present study establishes an experimental design for the preparation of new bi and tri-layer mucoadhesive sublingual films based on basil (Ocimum basilicum L.) seed mucilage (OBM) as novel plant-polysaccharide for oromucosal administration of nystatin (Nys). The films formulation consists of a drug reservoir-mucoadhesive layer cross-linked via CaCl2, with protective mucoadhesive layers based on thiolated alginate (TA) and polydopamine (PDA). OBM served as a new mucoadhesive polysaccharide in second layers, where the dopamine-modified-hyaluronic acid (DHA) improved the mucoadhesive strength and swelling rate properties. The drug-loaded formulations of trilayer film with PDA coating, and bilayer film with DHA/OBM (1:1) in the second layer, showed the desired mucoadhesion properties (about 69 and 75.3% respectively). The obtained results revealed that the bilayer film containing DHA had a superior swelling degree in the range of 15-19 (g/g). While the PDA coating sample showed the highest resistance to water uptake and erosion. The bilayer film (DHA/OBM with 1:1 ratio) provided a maximum drug release of 86% after 4 h. The selected formulations indicated good mechanical properties with no cytotoxicity.

Dual Redox/pH-Sensitive Micelles Self-Assembled From Star-Like Amphiphilic Copolymers Based On Sucrose For Controlled Doxorubicin Delivery.

Novel dual redox/pH-sensitive star-like amphiphilic sucrose-oligo(butyl fumarate) (thioglycolic acid conjugate)-SS-poly(ethylene glycol) (Suc-OBF(TGA)-SS-PEG) copolymers and their self-assembled micelles were prepared and utilized for intracellular doxorubicin delivery. Importance of changing the hydrophobic chain length on micelles properties was investigated. Results showed that the micelles with longer hydrophobic chain exhibited smaller size and were more stable in aqueous solution. The redox and pH sensitivity of the micelles was confirmed by the change of micelle diameter/diameter distribution measured by dynamic light scattering and the change of micellar morphology observed by scanning electron microscope. The micelles display a decent doxorubicin loading capacity. In vitro release studies showed that only 14.3% doxorubicin was released from doxorubicin-loaded micelles under physiological conditions in 30 h. The release of doxorubicin was accelerated at pH 5.5 or in the presence of 10 mM glutathione at pH 7.4 (46.9% and 76.9% of doxorubicin was released, respectively, in 30 h). The doxorubicin release was further expedited under pH 5.5 and 10 mM GSH conditions (91.4%). Suc-OBF(TGA)-SS-PEG micelles displayed no cytotoxicity toward HDF cells. MTT assays indicated that doxorubicin-loaded micelles had good cytotoxicity against MCF-7 cells. This work suggested that star-like amphiphilic Suc-OBF(TGA)-SS-PEG copolymer micelles may provide a promising platform for delivering doxorubicin and other hydrophobic anticancer drugs.

Synthesis of chemically cross-linked hydrogel films based on basil seed (Ocimum basilicum L.) mucilage for wound dressing drug delivery applications.

The present study aims toward the preparation of pH-sensitive hydrogel films based on basil seed mucilage (OBM) biopolymer as a novel drug delivery system for wound dressing. Various contents of polyvinyl alcohol (PVA), glutaraldehyde (GA) as cross-linker, and glycerol as a plasticizer were incorporated to have an optimal combination of softness and resilience. OBM hydrogel films characterized by FT-IR, thermogravimetric analysis (TGA), morphological analysis by scanning electron microscope (SEM) and their physical properties were discussed on the reportage of the results of several tests: rheology, mechanical tests (stress at maximum load and Young's modulus), O2 permeability and water vapor permeability, gel fraction, water retention capacity and swelling degree measurements. The best results for this work were Mu-Gly2, which has the acceptable swelling degree and gel fraction leading to functional water retention capacity, as well as the selected formulations, which were non-toxic and biocompatible according to the result of cytotoxicity test. The optimized formulations of films were used for loading of Tetracycline hydrochloride (TH) as a model drug, and the release studies showed better results at pH = 8.5 and pH = 7.4 rather than acidic pH.

1'-Methyl-2-oxo-5'-phenyl-spiro-[indoline-3,3'-pyrrolidine]-4',4'-dicarbo-nitrile.

The title spiro-compound, C(20)H(16)N(4)O, crystallizes with four independent mol-ecules in the asymmetric unit. In all of them, the oxindole unit is planar, the r.m.s. deviations ranging from 0.07 to 0.08 Å, while the pyrrolinyl ring adopts an envelope conformation (with the N atom representing the flap). In the crystal, adjacent mol-ecules are linked by N-H⋯N and N-H⋯O hydrogen bonds.

Sustained delivery of olanzapine from sunflower oil-based polyol-urethane nanoparticles synthesised through a cyclic carbonate ring-opening reaction.

The forefront horizon of biomedical investigations in recent decades is parcelling-up and delivery of drugs to achieve controlled/targeted release. In this regard, developing green-based delivery systems for a spatiotemporal controlling therapeutic agent have drawn a lot of attention. A facile route based on cyclic carbonate ring-opening reaction has been utilised to synthesise a bio-based polyol-containing urethane bond [polyol-urethane (POU)] as a nanoparticulate drug delivery system of olanzapine in order to enhance its bioavailability. After characterisation, the nanoparticles were also estimated for in vitro release, toxicity, and pharmacokinetic studies. As olanzapine has shown poor bioavailability and permeability in the brain, the sustained release of olanzapine from the designed carriers could enhance pharmacokinetic effectiveness. POU in the aqueous solution formed micelles with a hydrophobic core and embedded olanzapine under the influence of its hydrophobic nature. Drug release from the nanoparticles (90 ± 0.43 nm in diameter) indicated a specific pattern with initial burst release, and then a sustained release behaviour (82 ± 3% after 168 h), by the Higuchi-based release mechanism. Pharmacokinetics assessments of POU-olanzapine nanoparticles were carried in male Wistar rats through intravenous administration. The obtained results paved a way to introduce the POU as an efficient platform to enhance the bioavailability of olanzapine in therapeutic methods.

Preconcentration and extraction of lead ions in vegetable and water samples by N-doped carbon quantum dot conjugated with Fe3O4 as a green and facial adsorbent.

Magnetically N-doped Carbon quantum dots has been synthesized via a simple chemical method and applied as a sorbent for the preconcentration and extraction of trace amounts of Pb2+ from water and vegetable samples followed by flame atomic absorption spectrometric detection. The nanoparticles were characterized by X-ray diffraction, UV-vis spectra, Fourier transform infrared spectroscopy, vibrating sample magnetometer analysis and transmission electron microscopy. A central-composite design was used to find the optimum conditions for the preconcentration procedure through response surface methodology. The effects of various parameters such as the pH value, adsorption time, amount of adsorbent, desorption conditions (type, concentration and volume of the eluent and desorption time), sample volume and interfering ions have been studied. Under the optimized conditions, the calibration graph was linear in the range of 0.3-300µgL-1 (R2=9992). The detection limit and pre-concentration factor were found to be 0.082µgL-1 and 265, respectively.

In situ formation of interpenetrating polymer network using sequential thermal and click crosslinking for enhanced retention of transplanted cells.

Injectable hydrogels, which are used as scaffolds in cell therapy, provide a minimally invasive strategy to enhance cell retention and survival at injection site. However, till now, slow in situ gelation, undesired mechanical properties, and weak cell adhesion characteristics of reported hydrogels, have led to improper results. Here, we developed an injectable fully-interpenetrated polymer network (f-IPN) by integration of Diels-Alder (DA) crosslinked network and thermosensitive injectable hydrogel. The proposed DA hydrogels were formed in a slow manner showing robust mechanical properties. Interpenetration of thermosensitive network into DA hydrogel accelerated in situ gel-formation and masked the slow reaction rate of DA crosslinking while keeping its unique features. Two networks were formed by simple syringe injection without the need of any initiator, catalyst, or double barrel syringe. The DA and f-IPN hydrogels showed comparable viscoelastic properties along with outstanding load-bearing and shape-recovery even under high levels of compression. The subcutaneous administration of cardiomyocytes-laden f-IPN hydrogel into nude mice revealed high cell retention and survival after two weeks. Additionally, the cardiomyocyte's identity of retained cells was confirmed by detection of human and cardiac-related markers. Our results indicate that the thermosensitive-covalent networks can open a new horizon within the injection-based cell therapy applications.

Design, characterization and in vitro evaluation of novel amphiphilic block sunflower oil-based polyol nanocarrier as a potential delivery system: Raloxifene-hydrochloride as a model.

Presently, modern pharmaceuticals, are almost exclusively derived from the arduous refining of petroleum whose supply is inherently unsustainable. In order to address this issue bio-based materials are increasingly being used for chemical synthesis, particularly in drug delivery systems. Biodegradable and biocompatible hyper-branched polyol (an alcohol containing three or more hydroxyl groups) was synthesized via a facile method through the ring-opening and thiol-ene click reactions at room temperature. Due to the bio-based content of the polyol backbone, the synthesized polyol had both excellent biodegradability and low cytotoxicity. Raloxifene hydrochloride, an oral selective estrogen receptor modulator, was used as a hydrophobic drug model to test the potential of polyol as a drug delivery system carrier. Polyol showed an amphiphilic character and could be prepared as a nanoparticle for the sustained delivery of raloxifene hydrochloride, a drug with poor bioavailability in aqueous solution. Raloxifene hydrochloride was readily encapsulated in the lipophilic core of polyol whose branched hydroxyls were on the external part of the prepared nanoparticles. The diameter of the nanoparticles was 94±0.43nm, their drug entrapment efficiency was 93±0.5% and they showed a sustained release profile (17±1.5% after 4weeks). The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay showed low toxicity towards human osteoblast MG-63 cells. Based on its good biodegradability and low cytotoxicity, polyol provides a bio-based source for the design new drug delivery systems.

Fully glutathione degradable waterborne polyurethane nanocarriers: Preparation, redox-sensitivity, and triggered intracellular drug release.

Polyurethanes are important class of biomaterials that are extensively used in medical devices. In spite of their easy synthesis, polyurethanes that are fully degradable in response to the intracellular reducing environment are less explored for controlled drug delivery. Herein, a novel glutathione degradable waterborne polyurethane (WPU) nanocarrier for redox triggered intracellular delivery of a model lipophilic anticancer drug, doxorubicin (DOX) is reported. The WPU was prepared from polyaddition reaction of isophorone diisocyanate (IPDI) and a novel linear polyester polyol involving disulfide linkage, disulfide labeled chain extender, dimethylolpropionic acid (DMPA) using dibutyltin dilaurate (DBTDL) as a catalyst. The resulting polyurethane self-assembles into nanocarrier in water. The dynamic light scattering (DLS) measurements and scanning electron microscope (SEM) revealed fast swelling and disruption of nanocarriers under an intracellular reduction-mimicking environment. The in vitro release studies showed that DOX was released in a controlled and redox-dependent manner. MTT assays showed that DOX-loaded WPU had a high in vitro antitumor activity in both HDF noncancer cells and MCF- 7 cancer cells. In addition, it is found that the blank WPU nanocarriers are nontoxic to HDF and MCF-7 cells even at a high concentration of 2mg/mL. Hence, nanocarriers based on disulfide labeled WPU have appeared as a new class of biocompatible and redox-degradable nanovehicle for efficient intracellular drug delivery.

Synthesis and Characterization of Biodegradable Semi-Interpenetrating Polymer Networks Based on Star-Shaped Copolymers of ɛ-Caprolactone and Lactide.

In this paper, the focus is on a new kind of biodegradable semi-interpenetrating polymer networks, which is derived from ɛ-caprolactone, lactide, 1,4-butane diisocyanate and ethylenediamine and also its potential has been investigated in soft tissue engineering applications. The polymers were characterized by nuclear magnetic resonance (NMR) spectrometry, Fourier transform infrared spectroscopy (FT-IR), differential thermal analysis (DTA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). These experiments show that the polymers with the right composition and the expected molecular weight were achieved. Also, the in-vitro degradation of polymer network was examined in phosphate buffer solutions (pH 7.4) at 37 °C. Moreover, cell viability and adhesion tests were carried out with fibroblast cells by the MTT assay, which confirmed biocompatibility. Polyurethane materials have superior mechanical properties, so these biodegradable and biocompatible films demonstrate potential for future application as cell scaffolds in soft tissue engineering applications.

Facile preparation of pH-responsive polyurethane nanocarrier for oral delivery.

This study reports a novel one pot synthesis of pH-responsive nanocarrier for oral delivery of hydrophobic drug under gastrointestinal tract. Triblock copolymer MPEG-HTPB-MPEG was synthesized coupling of MPEG and HTPB using hexamethylene diisocyanate(HDI) and pH-responsive carboxylic acid group was attached to polybuthadiene backbone by thiol-ene click reaction in a facile and convenient procedure. The MPEG-HTPB (g-COOH)-MPEG block copolymers were self-organized into micelle assemblies in the water. The size and shape of the micelle assemblies were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The nanocarriers have high drug loading ability for poorly water-soluble drug. The pH-responsive profile was demonstrated by pH-dependent swelling and in vitro drug release. <10.0% IBU was released under artificial gastric fluid after 2h, whereas an immediate release was observed under artificial intestinal fluid. The XTT assay indicated that the micelle obtained from PEG-HTPB (g-COOH)-PEG triblock copolymer are safe in a wide range of concentrations. The results show that pH-responsive PEG-HTPB (g-COOH)-PEG triblock copolymers are promising nanocarriers for the oral administration of hydrophobic drugs.

pH-responsive unimolecular micelles self-assembled from amphiphilic hyperbranched block copolymer for efficient intracellular release of poorly water-soluble anticancer drugs.

Novel unimolecular micelles from amphiphilic hyperbranched block copolymer H40-poly(ε-caprolactone)-b-poly(acrylic acid)-b'-methoxy poly(ethylene glycol)/poly(ethylene glycol)-folate (i.e., H40-PCL-b-PAA-b'-MPEG/PEG-FA (HCAE-FA)) as new multifunctional nanocarriers to pH-induced accelerated release and tumor-targeted delivery of poorly water-soluble anticancer drugs were developed. The hydrophobic core of the unimolecular micelle was hyperbranched polyester (H40-poly(ε-caprolactone) (H40-PCL)). The inner hydrophilic layer was composed of PAA segments, while the outer hydrophilic shell was composed of PEG segments. This copolymer formed unimolecular micelles in the aqueous solution with a mean particle size of 33 nm, as determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). To study the feasibility of micelles as a potential nanocarrier for targeted drug delivery, we encapsulated a hydrophobic anticancer drug, paclitaxel (PTX), in the hydrophobic core, and the loading content was determined by UV-vis analysis to be 10.35 wt.%. In vitro release studies demonstrated that the drug-loaded delivery system is relatively stable at physiologic conditions but susceptible to acidic environments which would trigger the release of encapsulated drugs. Flow cytometry and fluorescent microscope studies revealed that the cellular binding of the FA-conjugated micelles against HeLa cells was higher than that of the neat micelles (without FA). The in vitro cytotoxicity studies showed that the PTX transported by these micelles was higher than that by the commercial PTX formulation Tarvexol®. All of these results show that these unique unimolecular micelles may offer a very promising approach for targeted cancer therapy.

The use of tetragonal star-like polyaniline nanostructures for efficient solid phase extraction and trace detection of Pb(II) and Cu(II) in agricultural products, sea foods, and water samples.

Due to importance of trace analysis of lead and copper ions because of their toxicity, in this paper, for the first time a unique tetragonal star-like morphology of polyaniline was applied as a efficient solid phase for selective trace separation of copper and lead at optimum experimental conditions in shrimp, fish and water samples. Due to the unique star like nanostructure of synthesized sorbent, the tendency of the sorbent toward selective extraction of lead and copper ion in the optimised pH is very interesting. The prepared polymeric resin displayed good figures of merits with analytical calibration curve ranging from 1 to 120 µg L(-1) for copper and 2 to 100 µg L(-1) for lead ions with limits of detection of 0.4 µg L(-1) for copper and 0.9 µg L(-1) for lead, adsorption capacities of 84 and 110 mg g(-1) for copper and lead ions, respectively, extraction efficiency of greater than 96%, and relative standard deviation (RSD) of less than 4% for eight separate column experiments in determination of 5.0 µg of lead and copper. The obtained data for adsorption capacity of the sorbent shows the high tendency of the sorbent toward the mentioned ions in this nanostructure form. Finally, this sorbent can be used as a simple, rapid, reliable, selective and sensitive method for determination of trace levels of Cu(II) and Pb(II).

Preparation of new magnetic nanocatalysts based on TiO2 and ZnO and their application in improved photocatalytic degradation of dye pollutant under visible light.

Photocatalytic degradation of methyl orange (MO) as a model of an organic pollution was accomplished with magnetic and porous TiO(2)/ZnO/Fe(3)O(4)/PANI and ZnO/Fe(3)O(4)/PANI nanocomposites under visible light irradiation. The structures of nanocomposites were characterized by various techniques including UV-Vis absorption spectroscopy, XRD, SEM, EDS, BET and TGA. Optical absorption investigations show two λ(max) at 450 and 590 nm for TiO(2)/ZnO/Fe(3)O(4)/PANI nanocomposites respectively possessing optical band gaps about 2.75 and 2.1 eV smaller than that of the neat TiO(2) and ZnO nanoparticles. Due to these optical absorptions, the nanocomposites can be considered promising candidates as visible light photocatalysts to produce more electron-hole pairs. The degradation of MO, extremely increased using polymeric photocatalysts and decolorization in the presence of visible light achieved up to 90% in less than 20 min in comparison with the neat nanoparticles (about 10%). All these advantages promise a bright future for these composites as useful photocatalysts. The degradation efficiency of MO using stable nanocomposites was still over 70% after ten times reusing. The highest decolorizing efficiencies were achieved with 0.75 g L(-1) of catalyst and 10 mg L(-1) of MO at natural pH under visible light irradiation in less than 20 min.

Divergent synthesis of dendrimer-like pH-responsive macromolecules through a combination of ATRP and ROP for controlled release of anti-cancer drug.

This work is focused on the synthesis and controlled drug release behavior of 8-arm and 12-arm amphiphilic pH-responsive dendrimer-like block copolymers. To study the role of architecture and the number of arms at the critical micelle concentration (CMC) value, differential scanning calorimetry (DSC), micelle size and in vitro controlled release of drug, we investigated a series of 8-arm and 12-arm block copolymers. The poly(acrylic acid) (PAA)-carrying dendrimer-like block copolymers were synthesized in two main steps. First, a second-generation dendrimer-like poly(ε-caprolactone) (PCL) was obtained by ring-opening polymerization (ROP) of ε-caprolactone (CL) from a bis and tris-hydroxylated core. For this goal, a conventional selective AB2-type branching agent for the PCL chain ends was designed: the latter includes a carboxyl (A) group for its attachment to the PCL arm ends and two geminal hydroxyls (B2) for the reiteration of the PCL growth as second generation using ROP. Subsequently, the hydroxyl-end groups quantitatively converted into bromoester groups as atom transfer radical polymerization (ATRP) initiating sites. The second step is the ATRP which thus served to grow poly(tBA) chains. After the hydrolysis of the t-butyl ester groups, amphiphilic, pH-responsive dendrimer-like block copolymers were obtained. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) demonstrated that the micelles exhibit a spherical shape with a size range of 43-64 nm in diameter. As a model drug, quercetin was loaded into the obtained 2G3(PAA)8 and 3G3(PAA)12 micelles via a dialysis method for in vitro release studies and their response to pH variation was investigated. The in vitro cytotoxicity evaluation of the polymers clearly showed that both compounds are safe in a wide range of concentrations (several times above the CMC value).