Hydrophilic-hydrophobic Balance Research Articles

Hydrophobic poly(3,4-ethylenedioxythiophene) particles synthesized by aqueous oxidative coupling polymerization and their use as near-infrared-responsive liquid marble stabilizer

The aqueous oxidative coupling polymerization of 3,4-ethylenedioxythiophene was conducted in the presence of heptadecafluorooctane sulfonic acid, which was used as a perfluoroalkyl dopant to synthesize hydrophobic poly(3,4-ethylenedioxythiophene) particles. The poly(3,4-ethylenedioxythiophene) particles were characterized in terms of their size, morphology, surface and bulk chemical compositions, conductivity, hydrophilic–hydrophobic balance and (photo)thermal properties. The electron microscopy studies confirmed that poly(3,4-ethylenedioxythiophene) consisted of aggregates of primary atypical particles of a submicrometer size. X-ray photoelectron spectroscopy and the contact angle measurement indicated that the perfluoroalkyl dopants were present on the surface of the poly(3,4-ethylenedioxythiophene) particles, which caused them to have a hydrophobic character. The electrical conductivity of the pressed pellet was 15.5 S cm−1, which was one order of magnitude higher than that of the poly(3,4-ethylenedioxythiophene) that was synthesized in the absence of the perfluoroalkyl dopant. The dried poly(3,4-ethylenedioxythiophene) particles could be used as a near-infrared-responsive liquid marble stabilizer exhibiting light-to-heat conversion properties. The movement of the poly(3,4-ethylenedioxythiophene) particle-coated liquid marbles on a planar water surface was driven by near-infrared laser-induced Marangoni propulsion. The inner liquid could be released by the disruption of the liquid marbles via an application of an external stimulus. The aqueous oxidative coupling polymerization of 3,4-ethylenedioxythiophene was conducted in the presence of heptadecafluorooctane sulfonic acid, which was used as a perfluoroalkyl dopant to synthesize hydrophobic poly(3,4-ethylenedioxythiophene) particles. The dried poly(3,4-ethylenedioxythiophene) particles could be used as a near-infrared-responsive liquid marble stabilizer exhibiting light-to-heat conversion properties. The movement of the poly(3,4-ethylenedioxythiophene) particle-coated liquid marbles on a planar water surface was driven by near-infrared laser-induced Marangoni propulsion.

First report of antioxidative 2H-chromenyl derivatives from the intertidal red seaweed Gracilaria salicornia as potential anti-inflammatory agents

Phytochemical investigation on biologically active compounds of an intertidal red seaweed Gracilaria salicornia (family Gracilariaceae) guided to the separation of two previously undisclosed 2H-chromenyl derivatives. The compounds were characterised as 4′-[10′-[7-hydroxy-2,8-dimethyl-6-(pentyloxy)-2H-chromen-2-yl]ethyl]-3′,4′-dimethyl-cyclohexanone (1) and 3′-[10′-(8-hydroxy-5-methoxy-2,6,7-trimethyl-2H-chromen-2-yl)ethyl]-3′-methyl-2′-methylene cyclohexyl butyrate (2) by extensive spectroscopic experiments. The studied metabolites recorded prospective bioactivities against 5-lipoxygenase (IC50 < 2.50 mM), whereas their selectivity indices were significantly greater (∼1) than ibuprofen (0.89) (p < 0.05), which attributed higher anti-inflammatory selectivity of 2H-chromenyl compounds against inducible cyclooxygenase-2 than its constitutive pro-inflammatory isoform of cyclooxygenase-1. The radical scavenging potential of 2 against oxidants, 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis-3 ethylbenzothiozoline-6-sulfonic acid were higher (IC50 < 1.35 mM) than standard antioxidant, α-tocopherol (IC50 1.42-1.79 mM). The greater hydrogen bond interactions and binding affinity of 2 (−7.35 kcal mol−1) bearing 2H-chromenyl ethyl-3′-methyl-4′-methylenecyclohexyl butyrate moiety with 5-lipoxygenase, along with higher electronic properties and permissible hydrophobic-hydrophilic balance, manifested towards its greater anti-inflammatory activity than 1.

Third Generation Cyclodextrin Graft with Polyurethane Embedded in Hydrogel for a Sustained Drug Release: Complete Shrinkage of Melanoma.

An injectable hydrogel-based drug delivery carrier has been developed for long-term drug release by assembling various generations of cyclodextrin (CD) followed by hydrophobic layers to control the drug release for effective cancer treatment. Three generations of CD are designed through urethane linkages using small spacers to create a large hydrophilic core, which is covered with hydrophobic layers of polyurethane through grafting to maintain the hydrophilic hydrophobic balance of the whole superstructure. Drug release becomes sustained from the intricate superstructure following the non-Fickian diffusion process, resulting in massive cancer cell killing as compared to the low killing rate from the pure drug/material arising from its burst release. The superstructure is found to be a good biomaterial, and its drug-loaded conjugate as a carrier is applied to albino mice to treat their tumors, generated through a melanoma cell line. A drug-embedded superstructure is inoculated in an injectable hydrogel and is placed subcutaneously, below the tumor site, which completely healed the melanoma. No side effect was observed, as opposed to the conventional/control system, due to a sustained drug release from the superstructure as evident from histopathological studies of sensitive body organs and biochemical parameters. Thus, a new design of the vehicle heals the melanoma tumor by enhancing the bioavailability of drug and specific interaction without having any side effects as opposed to conventional chemotherapeutic treatment.

Effect of Pluronic F127 on porous and dense membrane structure formation via non-solvent induced and evaporation induced phase separation

Novel porous and dense membranes based on polysulfone (PSF) modified by poly(ethylene glycol)–b–poly(propylene glycol)–b– poly(ethylene glycol) (Pluronic F127) were developed. The influence of Pluronic F127 introduction to the casting solution on different types of polymer membrane formation via two different phase inversion techniques—non-solvent induced phase separation (NIPS) for porous membranes and evaporation induced phase separation (EIPS) for dense membranes—was investigated. According to the triangular phase diagram obtained, PSF-Pluronic F127-N,N-dimethylacetamide (DMAc) systems feature lower critical solution temperature and have a tendency to micelle formation due to Pluronic F127 self-assembly. The structure, hydrophilic-hydrophobic balance and physicochemical properties of PSF-Pluronic F127 membranes were characterized by water contact angle measurements, scanning electron microscopy, nuclear magnetic resonance, small-angle X-ray scattering, and atomic force microscopy. The performance of dense membranes in pervaporation separation of water-ethyl acetate mixtures was investigated to reveal the effect of Pluronic F127 on the structure and free volume of the PSF-Pluronic F127 membranes. It was shown that Pluronic F127 introduction to the casting solution during membrane formation via two different techniques (NIPS and EIPS) leads to the increase in the pore size of the porous membranes and free volume of the dense membranes, as well as the increase in flux and surface hydrophilicity for both membrane types. Pluronic F127 was found to improve the antifouling performance of porous PSF-Pluronic F127 membranes in the BSA solution ultrafiltration. The introduction of 3 wt% Pluronic F127 into dense PSF membrane improved permeation flux in 1.7 and 2.7 times (15.1 and 27.3 g/(m2h)) at high selectivity level (100 wt% water in the permeate) during the separation of ethyl acetate-water mixtures (2 and 4 wt% ethyl acetate) compared to pristine PSF membrane.

First report of chromenyl derivatives from spineless marine cuttlefish Sepiella inermis: Prospective antihyperglycemic agents attenuate serine protease dipeptidyl peptidase-IV.

Spineless marine cuttlefish Sepiella inermis has been considered as a popular dietary cephalopod species in Asian and Mediterranean coasts. Bioassay-directed purification of organic extract of S. inermis ensued in the characterization of two chromenyl derivatives. The studied compounds exhibited significantly greater antioxidant potencies (IC50 ≤0.5mg/ml) when compared with α-tocopherol. The substituted 1H-isochromenyloxy-11-hydroxyethyl pentanoate isoform (compound 1) efficiently inhibited the carbolytic enzymes along with key regulator of insulin secretion dipeptidyl peptidase-IV (IC50 0.16mg/ml). The molecular docking simulations displayed optimum binding affinity of the compound 1 (-10.01kcal/mol) with dipeptidyl peptidase-IV and lesser inhibition constant (Ki 46.41nM), which along with its permissible hydrophobic-hydrophilic balance (log Pow ~2) appeared to play significant roles in its greater antihyperglycemic activity compared to other studied chromenyl isoform. The greater antioxidant and antidiabetic properties of compound 1 could be utilized as an important natural lead against hyperglycemic-related disorders. PRACTICAL APPLICATIONS: The edible spineless marine cuttlefish Sepiella inermis are ubiquitously available in Asian and Mediterranean coasts. The sequential chromatographic purification of the organic extract of S. inermis led to the identification of two pure chromenyl chemotypes. The metabolites with substituted 1H-isochromenyloxy-11-hydroxyethyl pentanoate isoform (compound 1) displayed potential antioxidative and antihyperglycemic activities compared to the chemotype (2) bearing 3H-isochromen-5-yl moiety. The attenuating potential of chromenyl chemotype 1 against carbohydrate hydrolyzing enzymes and insulin secretion regulator attributed towards its efficiency as an important natural lead against postprandial hyperglycemia and incretin hormone regulation to maintain glucose homeostasis in the biological system. The chromenyl metabolites isolated from S. inermis could be utilized as a functional food ingredient in the nutraceutical formulations against hyperglycemic-related disorders.

Drug delivery systems using pullulan, a biocompatible polysaccharide produced by fungal fermentation of starch

Advanced drug delivery systems are now designed with biodegradable, biocompatible and non-toxic materials such as polysaccharides. Pullulan is a polysaccharide consisting of maltotriose units. Pullulan is produced from starch by the fungus Aureobasidium pullulans. Pullulan and derivatives are able to conjugate or complex with hydrophobic drugs. Scientists are optimizing the physical interactions and hydrophilic–hydrophobic balance to create systems with controlled loading and targeted delivery of the drugs to cancer cells or liver cell receptors. This article reviews pullulan-based systems of various therapeutic properties. Pullulan structure can be easily modified to transfer various drugs. Pullulan can form microparticles, nanoparticles, micelles, films and hydrogels. Therapeutic properties include antibacterial, antifungal, antitumor, anti-inflammatory, immunomodulatory, antioxidant, antiglycemic, antilipidemic, bone regenerator and systemic protective role. The medical suitability of pullulan-based drug carriers is confirmed by profiles of drug release and cytotoxicity tests carried out in vivo or in vitro.

Insights on the influence of the precursors on the sol–gel synthesis of hybrid organic–inorganic saponite-like materials

Abstract Lamellar organic–inorganic hybrid materials, especially talc- and saponite-like structures, have been broadly investigated over the past decades because of the combination of the thermal and mechanical properties of the inorganic part with the possibility to finely tune hydrophilic–hydrophobic balance, ion exchange capacity, and properties through the choice of the silicon source. These compounds are generally produced by coprecipitation or hydrothermal synthesis methods, allowing the formation of well-crystallized particles but it is time and energy consuming. Recently, hybrid organic–inorganic lamellar materials have been synthesized using sol–gel method, which is attractive as it is a one-step method performed under mild conditions, with low energy consumption and short formation times. The originality of this research stands in the study of the influence of the reactants on the formation of saponite-like hybrids and especially on the role of the aluminum source in the sol–gel synthesis of hybrid organic–inorganic lamellar materials. The obtained materials have been characterized by X-ray diffraction, Fourier transform infrared, and solid-state nuclear magnetic resonance spectroscopies and thermogravimetric analysis, and it was shown that hydrotalcite-like compounds can be obtained beside saponite-like compounds depending on the aluminum source.

Poly(3-ethylglycolide): a well-defined polyester matching the hydrophilic hydrophobic balance of PLA

The novel lactide isomer 3-ethyl-1,4-dioxane-2,5-dione (3-ethylglycolide, EtGly) represented the basis for the development of polyesters varying crystallinity.

Predominant Factor Determining Thermal Conductivity Behavior of Nanofluid: Effect of Cluster Structures with Various Nanoparticles

Despite several research efforts, the detailed mechanism that dominates the thermal conductivity of nanofluids has not been explained. We investigated the effect of the chemical surface design of NPs (hydrophobic–hydrophilic balance of the NPs containing Janus surface) and verified the influence of their self–assembled structures on the thermal conductivity of a nanofluid using molecular simulation. When hydrophobic (HO) NPs are added to a nanofluid, they only form one large cluster because they do not prefer to be in contact with water molecules. Hence, an increment in the thermal conductivity of the nanofluid added with HO NPs was observed. On the contrary, the mean cluster size of Janus NPs was limited because of their limited HO superficial areas (attractive domains). Hence, an increment in the enhancement ratio of thermal conductivity was not observed even when the volume fraction of the NPs (ϕNP) was increased. Thus, our results demonstrate that the mean cluster size of NPs is the key factor for thermal conductivity enhancement. In addition, this study reveals that it is possible to control the thermal conductivity of nanofluids (or the mean cluster size of Janus NPs) using Janus NPs with surfaces designed using anisotropic chemical interactions.

Hypoxia-responsive micelles self-assembled from amphiphilic block copolymers for the controlled release of anticancer drugs.

Amphiphilic block copolymers poly(ethylene glycol)-block-poly(methacrylic acid-co-2-nitroimidazole methacrylate) (PEG-b-P(MAA-co-NIMA)) were synthesized by the combination of atom transfer radical polymerization (ATRP), hydrolysis and EDC reactions. These copolymers could self-assemble into spherical micelles in water. 2-Nitroimidazole (NI) groups presented hypoxia-responsive properties under hypoxia conditions. The hydrophobic NI groups could be converted into hydrophilic aminoimidazole (AI) groups, which would lead to the expansion of micelles. Moreover, the content of NI groups in the copolymers would affect the hydrophilic-hydrophobic balance and therefore influence the self-assembly behaviour of the copolymer and the morphologies of the micelles. The copolymer micelles were used as a drug delivery system for controlled release of anticancer drug doxorubicin (DOX). The in vitro cytotoxicity investigation revealed that the DOX-loaded micelles showed higher toxicity to hypoxic cells than to normoxic cells. As a result, the block copolymers are expected to be used as an intelligent carrier for hydrophobic drugs to treat hypoxia-associated diseases.

In English

Active promotion of enterosorbents to the market outruns thorough study of the mechanisms of their therapeutic effect. The consumers and even many specialists have a simplified view of the only role of the enterosorbents to fix and remove toxins, that is, act as a "cleaner" of the body. The aim of this paper is to reveal the importance of physicochemical factors for the therapeutic action of enterosorbents. These factors include: (i) electrostatic charge of sorbent surface; (ii) pore size; (iii) accessible area of surface; (iv) hydrophilic-hydrophobic balance of surface; (v) ion exchange properties; (vi) capability to structure water. Mentioned factors can be estimated quantitatively using such methods as electrophoresis, gas chromatography, photon correlation and 1 Н NMR spectroscopy, volumetric analysis, etc. However, in pharmaceutical practice, it is more convenient to characterize the enterosorbent by its capability to adsorb some test substances. To examine the above factors, we use oppositely charged dyes methylene blue and congo red, ions of Zn 2+ , gelatin, phenol and amino acid tryptophan. By the help of this approach we have characterized various types of charcoal, nanosized fumed silica (Atoxil), porous Syloid ® 244FP, hydrophobic Aerosil ® R972, silica gel, Enterosgel, fumed alumina, Smecta ® , zeolites, kaolin, any derivatives of cellulose, lignin and other materials. To study the interaction of enterosorbents with the intestinal mucosa, a gel of eye vitreous humor was used as a model. As a result, we concluded that nanosized silica might be considered first of all as enveloping agent, the main mechanism of action of which is interaction with glycoproteins of the intestinal mucosa. Consequently, two therapeutic effects are realized: (1) difficulty forms for diffusion of pathogenic substances through the mucosa that leads to decrease in their absorption; (2) antidiarrheal effect due to protecting mucosal receptors from the adhesion of microorganisms and impact of microbial toxins. Taking into account that the intestinal mucosa throughout its extent, in the pH range from 6.0 to 9.0, is negatively charged, this interaction for silica occurs with the overcoming of electrostatic repulsion. Therefore, the enveloping power of silica is less than that of alumina containing preparations which in the intestine have a positive charge. Generally speaking, the absorbing mechanism of healing action can only be applied to highly porous sorbents such as charcoal, zeolites, silica gel, Syloid ® 244FP, etc.

Optimizing the Coverage Density of Functional Groups over SiO2 Nanoparticles: Toward High-Resistant and Low-Friction Hybrid Powder Coatings.

Hybrid powder coatings (HPC) with low friction and high hardness enhance the sliding speed and allow interlocking or meshing products to slide effortlessly within each other, saving energy. In automobiles, they decrease fuel consumption and greenhouse gas emission. In the present work, a new insight of the key role played by the coverage density of triethoxyphenylsilane (TPS) grafted to SiO2 nanoparticles over the friction coefficient, hardness, elastic modulus, and roughness of HPC is presented for the first time. In all cases, a very low amount (0.1 wt %) of functionalized or unfunctionalized SiO2 nanoparticles were added to a powder-coating formulation based on polyester resin. HPC formulated with functionalized nanoparticles at a suitable coverage density (HPC–TPS3) exhibited significantly low friction coefficient (μ = 0.12), strong wear resistance (under dry sliding conditions at 1 and 5 N of load), low roughness (Rq = 3.5 nm), and high hardness and elastic modulus on the surface. We demonstrated that it is possible to tune the macroscopic properties by varying only the coverage density of TPS that is chemically attached to SiO2 nanoparticles. Also, a physicochemical explanation was disclosed, wherein a hydrophilic–hydrophobic balance between −OH and phenyl groups was proposed. In all cases, the phenyl group allows the migration of functionalized nanoparticles through the polyester matrix, enhancing the hardness and elastic modulus on the surface. Thus, the functional nanomaterial design with tunable coverage density is a powerful tool to improve the physical and superficial properties of powder coatings using low amounts of nanomaterial.

Grafted cyclodextrin as carrier for control drug delivery and efficient cell killing.

The presence of hydroxyl groups in cyclodextrin (CD) makes it highly hydrophilic and simultaneously allows its chemical modification to graft polyurethane to control the drug release for longer period of time by maintaining the hydrophobic-hydrophilic balance through varying extent of grafting. Grafting of polyurethane on CD is confirmed through 1 H NMR and molecular weight measurement while FTIR and UV visible studies further support grafting and emphasize the interaction among polymer chains as a whole. Degree of grafting is evaluated from the integrated peak area in NMR spectra. Thermal and mechanical measurements show improved stability and strength of the graft polymers with respect to pure CD. The conversion of particle nature of CD to strip-like morphology in graft copolymers is evident from atomic force microscopy. Sustained drug release has been achieved using graft copolymer against burst release from pure CD and specific interactions, as observed through spectroscopy and thermal measurements, are responsible for sustained release of drug. Biocompatibility of graft copolymers has been checked using cellular studies through MTT assay and cell adhesion. Importantly, the cell killing efficiency has been demonstrated by embedding anticancer drug in polymer matrices causing mortality rate of 75% using graft copolymer against scanty 25% using pure drug or drug embedded in CD and the result is understood from the sustained release of drug from the graft copolymer vis-à-vis burst release in other systems. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 434-444, 2019.

Macrocyclic lactones from seafood Amphioctopus neglectus: Newly described natural leads to attenuate angiotensin-II induced cardiac hypertrophy

Amphioctopus neglectus (Family: Octopodidae) is recognised as culinary delicacy in many cultures and a common sea food item on the Mediterranean and Asian coasts. Bioassay-directed fractionation of ethyl acetate/methanol extract of A. neglectus ensued in the characterisation of four previously undescribed macrocyclic lactones (1-4). These compounds exhibited potential radical-scavenging capacities (IC50 0.95–1.73 mM) along with anti-hypertensive activities (IC50 1.12–2.34 mM) against angiotensin converting enzyme (ACE). The optimum binding affinity of compound 2 (−9.84 kcal mol−1) bearing furo[1,4,8]trioxacyclohexadecine-12,19-dione moiety with ACE, along with its permissible hydrophobic-hydrophilic balance, manifested towards its greater anti-hypertensive activity compared to other analogues. The compound 2, with lesser values of the inhibitory constant (Ki = 1.0 mM) towards ACE, was found to bind more effectively to the enzyme in a non-competitive manner, and could describe the greater inhibitory ramifications than those displayed by other compounds (Ki >1.1 mM). The ex-vivo studies revealed that compound 2 imparted protective effects against angiotensin-II induced cardiac hypertrophy at 25 μg mL−1 on H9C2 cell lines, wherein about 34 percent decrease in cell area with increase in viability could be attributed to anti-hypertrophic effects of the compound administrated. These results confirmed that the protective effect of the isolated macrocyclic lactones is mediated by enhancement of anti-oxidant defense systems, which subsequently attenuates the hypertensive related disorders.

Synthesis and Antifungal Activities of Amphiphilic PDMS-b-QPDMAEMA Copolymers on Rhizoctonia solani

Cationic polymers are prospective fungicidal agents for inhibiting plant diseases because of the controllability of their structure and properties. This study investigates the effect of the hydrophobic-hydrophilic balance on the antifungal activities of antimicrobial polymers against phytopathogenic fungi (Rhizoctonia solani Kühn AG-1(IA)), the pathogen of rice sheath blight (RShB). A series of polydimethylsiloxane-polymethacrylate block copolymers containing quaternary ammonium salts (PDMS-b-QPDMAEMA, labeled as SnQm; n and m represent 1000th of the molecular weight of the PDMS and QPDMAEMA chain, respectively) were synthesized via anionic ring-opening polymerization and atom transfer radical polymerization (ATRP). The abilities of the quaternary ammonium salts to adsorb onto the surface of R. solani sclerotia and permeate the R. solani sclerotia were investigated on the basis of static water contact angles and fluorescence labeling. The results indicated that the moderately hydrophobic PDMS chain helped stabilize the attachment of the hydrophilic QPDMAEMA chain and then help it penetrate the R. solani sclerotia. Its antifungal properties toward R. solani were characterized by determining its minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) and the inhibition rate of R. solani sclerotia germination. The hydrophobic PDMS chains had a significant influence on the antifungal activities of amphiphilic SnQm against R. solani sclerotia. This work highlights the prospective application of amphiphilic antimicrobial polymers as antifungal agents for inhibiting plant diseases.

A New Strategy for Intestinal Drug Delivery via pH-Responsive and Membrane-Active Nanogels.

Oral administration of hydrophobic and poorly intestinal epithelium-permeable drugs is a significant challenge. Herein, we report a new strategy to overcome this problem by using novel, pH-responsive, and membrane-active nanogels as drug carriers. Prepared by simple physical cross-linking of amphiphilic pseudopeptidic polymers with pH-controlled membrane-activity, the size and hydrophobicity-hydrophilicity balance of the nanogels could be well-tuned. Furthermore, the amphiphilic nanogels could release hydrophobic payloads and destabilize cell membranes at duodenum and jejunum pH 5.0-6.0, which suggests their great potential for intestinal drug delivery.

Well‐Defined Thermoresponsive Polymethacrylamide Copolymers with Ester Pendent Groups through One‐Pot Statistical Postpolymerization Modification of Poly(2‐Isopropenyl‐2‐Oxazoline) with Multiple Carboxylic Acids

ABSTRACTThermoresponsive polymers that undergo a solubility phase transition in water are important as basis for the development for a wide variety of responsive and smart materials. In this study, the synthesis of thermoresponsive copolymers is demonstrated by the straightforward one‐pot statistical postpolymerization modification of well‐defined poly(2‐isopropenyl‐2‐oxazoline) (PiPOx) by ring‐opening reaction with multiple carboxylic acids. The reactions are carried out using dual, triple, and quadruple mixtures of up to four different aliphatic carboxylic acids. The cloud point temperatures of the resulting polymethacrylamide copolymers with ester pendent groups can be finely tuned by adjusting the feed ratio and the hydrophilic–hydrophobic balance of the acids that are used for the ring‐opening modification of PiPOx. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 360–366

In Ukrainian

The purpose of this research article is to study the influence of additives of cationic surfactant - benzethonium chloride and the pH of the initial solutions from which suspensions were prepared on the electro-surface properties of titanium dioxide of rutile modification in its aqueous suspensions as well as to detect changes in the ratio between positively charged and negatively charged surface hydroxyl groups due to adsorption of surfactant molecules. In this study, we used powdered rutile-form titanium dioxide (average particle diameter 0.23 µm and specific surface area 14.6 m 2 /g), the surface of which was modified with inorganic oxides (Al 2 O 3 , 4 %, and SiO 2 , 2 %) and graft hydrocarbon chains in order to impart required optical properties and regulate of hydrophobic–hydrophilic balance. Benzethonium chloride is an industrial surfactant that is widely used to regulate the colloidal and chemical properties of many disperse systems. According to the results of the research, it has been found that additives of benzethonium chloride to aqueous suspensions of titanium dioxide have a significant effect upon its electro-surface properties. By using the 2-pK model of a double electric layer and a multistage model of surfactant adsorption on a solid surface, it has been found that the adsorption of benzethonium chloride molecules results in a decrease in the number of surface neutral hydroxyl groups and in the redistribution of superficial positive and negatively charged hydroxyl groups. The character of the redistribution of these groups depends on the pH of the aqueous solutions on the basis of which the suspensions of titanium dioxide were prepared. By evaluating the effect of adsorption of benzethonium molecules on the electro-surface properties of titanium dioxide in its aqueous suspensions, three sites of their dependence on the pH of the initial solutions can be distinguished: the first in the range from pH ≈ 2 to pH ≈ 5, the second in the range from pH ≈ 5 to pH ≈ 9 and the third in the range from pH ≈ 9 to pH ≈ 12. The dependence analysis of the adsorption of benzethonium chloride molecules on the pH of the initial solutions shows that adsorption increases slightly in the first section, does not show any significant fluctuations in the second one, and increases significantly in the third one due to an increase in the pH of the output solutions. The adsorption quantities of benzethonium chloride on titanium dioxide which have been theoretically predicted according to the proposed model, are in good agreement with the experimental results. An increase in the concentration of benzethonium chloride in suspensions involves the displacement of the isoelectric point of the investigated suspensions of titanium dioxide into the alkaline region. The obtained results are in good agreement with the experimental results of the study of the dependence of the zeta potential of titanium dioxide suspensions on the concentration of benzethonium chloride. The found dependencies allow to purposefully regulate properties of aqueous suspensions of titanium dioxide for production of necessary technological compositions.

Efficacy of polyurethane graft on cyclodextrin to control drug release for tumor treatment

Hydrophilicity of cyclodextrin is controlled through grafting of polyurethane of varying graft density, thereby maintain the hydrophilic-hydrophobic balance, to sustain the drug delivery rate for better tumor treatment. Grafting is verified through nuclear magnetic resonance (1H NMR) and other spectroscopic techniques along with the hydrodynamic volume measurement of grafted species and the degree of substitution has been calculated from the integrated peak areas. Thermal and mechanical stability of the graft copolymers have improved significantly with respect to cyclodextrin and the formation of smaller blobs having larger in number has been obtained from small angle neutron scattering, atomic force microscopy and optical images. Sustained drug delivery has been achieved using graft copolymer as opposed to burst release in pure cyclodextrin and polyurethane and the phenomenon is understood from the specific interactions, as observed though spectroscopic and thermal measurement, between graft copolymer and drug followed by this novel architecture of the graft copolymers. Biocompatibility of graft copolymers has been checked using cellular studies through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell adhesion. Importantly, the cell killing efficiency has been demonstrated by embedding anti-cancer drug in polymer matrices causing mortality rate of 80% using graft copolymer against meagre 20% using pure drug or drug embedded in cyclodextrin and the result is realised from the sustained release of drug from the graft copolymer vis-à-vis burst release in other systems. Cellular studies have been translated into an animal model showing the efficacy of newly developed patch, made of drug embedded in copolymer, towards the significant suppression of tumors in mice as compared to control. Histopathological images and biochemical parameters indicate the normal body organ/blood in copolymer treated mice against severely damaged organ especially liver/blood in the mice treated with pure drug or drug embedded in cyclodextrin arising from burst release. Thus, graft copolymer with unique architecture is found to be an effective drug delivery vehicle for melanoma cancer treatment without side effect.

Surface-Functionalized Polystyrene Latexes Using Itaconate-Based Surfmers

Itaconic acid was readily transformed to a series of amphiphilic diesters via stepwise esterification of itaconic anhydride; the diesters carry one alkyl (cetyl or octyl) group and either a PEG, glyceryl, or dopamine segment. These diesters were used as surfmers for the preparation of polystyrene (PS) emulsions, with the expectation that the surface of the emulsion particles would carry PEG, glyceryl or dopamine units. NMR spectroscopic studies revealed that the surfmers were covalently incorporated into the polystyrene chains; furthermore, NMR tube polymerization experiments also confirmed that when the PEG surfmer was used, the PEG segments are indeed present on the surface of the emulsion particles. The size of the PEGlyated PS emulsions was readily varied from 35 to 140 nm by changing the mole fraction of surfmer used. In the case of the glyceryl and dopamine carrying surfmers, anoctyl unit was used as the hydrophobic segment to ensure appropriate hydrophobic-hydrophilic balance; it was noticed that significantly larger mole fractions of the surfmers were required (15-20 mol %) to generate stable emulsions with particle sizes of about 150 nm. The PS emulsions carrying dopamine units on the surface were found to adhere to glass surfaces; thus suggesting that such "sticky" emulsion particles could be used to functionalize different types of surfaces. Finally, itaconate diesters bearing cetyl and perfluorooctyl segments were also prepared and shown to copolymerize with styrene to generate fluoroalkyl-enriched PS copolymers; these were used to generate hydrophobic coatings, with water contact angles of over 120°. Thus, itaconate-based surfmers are readily accessible alternatives for the preparation of emulsions with tailored size and surface functionality.