A computational and experimental approach to develop minocycline-imprinted hydrogels and determination of their drug delivery performances

In this study, minocycline-imprinted hydrogels are developed for controlled drug delivery in ocular disease treatments. An integrated computational and experimental study are conducted for investigating the relationship between design parameters and the drug loading/release performance of hydrogels. First, suitable functional monomers are determined for successful drug-imprinting by studying pre-polymerization conditions with full-atom molecular dynamics (MD) simulations. MD simulations suggest that acrylic acid and itaconic acid are suitable monomers for imprinting minocycline. Then, minocycline-imprinted hydrogels are synthesized with acrylic acid, commonly used in hydrogels, and three different amounts of cross-linker ethylene glycol dimethacrylate, 1, 2 and 3 mol%. All hydrogels are characterized and their drug loading and release performances are determined. Our computational and experimental calculations indicate an optimum cross-linker amount of 2 mol% for controlled minocycline release from imprinted hydrogels with an imprinting factor of almost 3. Finally, the drug release kinetics are determined by Korsmeyer-Peppas model.     

The effects of gums on macro and micro-structure of breads baked in different ovens

In this study, the effects of gums on macro and micro-structure of breads baked in different ovens (infrared (IR)-microwave combination and conventional) were investigated by the help of image and SEM analysis, respectively. The gums used were xanthan, guar, κ-carrageenan and xanthan-guar blend. The gums were added to the formulation at 0.5% concentration. As a control, no gum added formulations were used. Results of Image analysis demonstrated that xanthan-guar gum blend addition improved bread quality with increasing pore area fractions. It was seen that about 75% of the pores of control breads baked in infrared-microwave combination oven and about 63% of the pores of control breads baked in conventional oven had diameters of above 1000 μm. According to SEM analysis, pores in control breads baked in conventional oven were found to be smaller, and had spherical, oval-like shape as compared to the ones baked in IR-microwave combination oven. Moreover, more homogeneous closed-cell structure was observed for conventionally baked control breads. The pores of breads baked in IR-microwave combination oven were so close to each other which resulted in coalescence of the gas cells to form channels, then the pores were no longer spherical. The starch granules in conventionally baked breads were more distorted and seen as a continuous sheet of gelatinized starch. On the other hand, granular residues and continuous starch structure was observed together in IR-microwave combination heating.     

Investigation of physicochemical properties of breads baked in microwave and infrared-microwave combination ovens during storage

Staling of breads baked in different ovens (microwave, infrared-microwave combination and conventional) was investigated with the help of mechanical (compression measurements), physicochemical (DSC, X-ray, FTIR) and rheological (RVA) methods. The effect of xanthan-guar gum blend addition on bread staling was also studied. Xanthan-guar gum blend at 0.5% concentration was used in bread formulation. The gums were mixed at equal concentrations to obtain the blend. After baking, the staling parameters of breads were monitored over 5 days storage. During storage, it was seen that hardness, retrogradation enthalpies, setback viscosity, crystallinity values, and FTIR outputs related to starch retrogradation of bread samples increased, whereas FTIR outputs related to moisture content of samples decreased significantly with time. The hardness, retrogradation enthalpy, setback viscosity, and crystallinity values of microwave-baked samples were found to be highest among other heating modes. Using IR-microwave combination heating made it possible to produce breads with similar staling degrees as conventionally baked ones in terms of retrogradation enthalpy and FTIR outputs related to starch retrogradation. Addition of xanthan-guar gum blend decreased hardness, retrogradation enthalpy and total mass crystallinity values of bread samples showing that staling was delayed.     

Separation of Nanoparticles in Aqueous Multiphase Systems through Centrifugation

This paper demonstrates the use of aqueous multiphase systems (MuPSs) as media for rate-zonal centrifugation to separate nanoparticles of different shapes and sizes. The properties of MuPSs do not change with time or during centrifugation; this stability facilitates sample collection after separation. A three-phase system demonstrates the separation of the reaction products (nanorods, nanospheres, and large particles) of a synthesis of gold nanorods, and enriches the nanorods from 48 to 99% in less than ten minutes using a benchtop centrifuge.     

Kinetics and mechanism of methylene blue removal by electrosynthesized ferrate(VI)

The oxidation of methylene blue (MB) by electrosynthesized ferrate(VI) in a semi-batch reactor is investigated. The effects of pH, Fe(VI) dose and initial MB concentration on the efficiency of the degradation process were studied. The original pH of MB solution was found more effective on the degradation and colour removal as 96.82% MB removal and 40.36% colour removal were gained. Initial MB solution and Fe(VI) dose affected the removal efficiencies. Degradation of MB by Fe(VI) was the second-order reaction kinetics. The density functional theory (DFT) analysis confirmed that density is intended mostly on the phenyl rings and least of all on the bonding orbitals of the middle heterocycle of МВ.     

Synthesis of conducting polysiloxane — polypyrrole graft copolymers

Summary Polysiloxane-polypyrrole graft copolymers have been synthesized by a series of chemical reactions and subsequent electropolymerization. First, the hydrosilation of 4-vinyl aniline by dimethyl-methylhydrosiloxane copolymer gave the corresponding aminophenyl functional polydimethylsiloxane (PDMS-NH₂). The side chain pyrrole functionalized polysiloxanes were then prepared by the reaction of PDMS-NH₂ with glycidylpyrrole. Finally, the synthesis of graft copolymers of polysiloxane and pyrrole has been achieved electrochemically by using two different electrolytes, p-toluene sulfonic acid (PTSA) and tetrabutylammonium tetrafluoroborate (TBAFB). Characterization of these graft copolymers were performed by a combination of techniques consisting of scanning electron microscopy (SEM), thermal gravimetry (TGA), differential scanning calorimetry (DSC) analyses and FT-IR studies. The conductivities were measured by four-probe technique. Received: 19 September 2001/ Revised version: 4 December 2001/ Accepted: 2 December 2001     

Effects of probiotic bacteria and oils on fatty acid profiles of cultured cream

The aim of this study was to determine the effects of using various probiotic bacteria and plant oils in cultured cream on the fatty acid profiles including conjugated linoleic acids (CLA). L. acidophilus, B. bifidum, S. thermophilus and L. bulgaricus, P. thoenii (jensenii) P126, and P. jensenii B1264 and a mixed culture (blend of L. acidophilus, B. bifidum, S. thermophilus and L. bulgaricus) were used in the fermentation of cream samples at a level of 2%. Cream samples were fortified with sunflower oil, soybean oil and hazelnut oil at a level of 2%. Microbial counts and fatty acid profile analysis were performed. The microbial results demonstrated that fermented cream could be a superior product for the presence of probiotics. Even though the cream samples contained 52% milk fat, in the majority of the samples growth of probiotic bacteria was higher than 10⁶ cfu/g. Concentrations of short‐chain fatty acids such as butyric, caproic and capric acids in cultured cream samples differed depending on the cultures used, while long‐chain unsaturated fatty acids were significantly affected by the plant oil fortification. The highest CLA content was obtained in the sample produced with B. bifidum, containing 0.73 mg of CLA/g fat. The effect of different plant oils on CLA concentration was significant (p >0.05) for HO + YC, SFO + LBYC and SO + LBYC. Results of the study are important for the dairy industry since it is the first publication on fermented cream with improved functional properties. The development of functional cultured cream with plant oils and probiotic bacteria would provide an important alternative dairy product.     

A multiscale investigation on controlling bovine serum albumin adsorption onto polyurethane films

Our previous study on castor oil (CO) and poly(ethylene glycol) (PEG)‐based shape memory polyurethane (PU) films indicated that cell spreading on the polymer surface, cell morphology, and adhesion of fibroblast are closely related to the composition of the polymer that influences surface properties. This integrated experimental and computational study is designed to investigate the effect of important parameters such as surface roughness, crystallinity, hydrophilicity, distribution of hard/soft segments, and topology of the surface on protein adsorption for CO‐ and PEG‐based PUs. Analyses indicate that the crystallinity percentage highly promotes bovine serum albumin (BSA) adsorption. Roughness together with topological features determines BSA adsorption rate and concentration. Hydrophilicity and hard segment content seem to have less critical effect on adsorption. Distribution of hard segments into the soft segments emerges as another important factor for protein adsorption. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45669.     

Effect of filler content on the structure‐property behavior of poly(ethylene oxide) based polyurethaneurea‐silica nanocomposites

Poly(ethylene oxide) (PEO) based polyurethaneurea‐silica nanocomposites were prepared by solution blending and characterized by Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Differential Scanning Calorimetry and tensile testing. The colloidal silica nanoparticles with an average size of 50 nm were synthesized by modified Stöber method in isopropanol. Silica particles were incorporated into three cycloaliphatic polyurethaneurea (PUs) copolymers based on PEO oligomers with molecular weights of 2,000, 4,600, and 8,000 g/mol. Hard segment content of PUs was constant at 30% by weight. Silica content of the PU nanocomposites varied between 1 and 20% by weight. Soft segment (SS) glass transition and melting temperatures slightly increased with increasing filler content for all the copolymers. Degree of SS crystallinity first increased with 1% silica incorporation and subsequently decreased by further silica addition. Elastic modulus and tensile strengths of PU copolymers gradually increased with increasing amount of the silica filler. Elongation at break values gradually decreased in PEO‐2000 based PU copolymer with increasing silica content, whereas no significant change was observed in PUs based on PEO‐4600 and PEO‐8000. Enhancement in tensile properties of the materials was mainly attributed to the homogeneous distribution of silica filler in polymer matrices and strong polymer‐filler interactions. POLYM. ENG. SCI., 58:1097–1107, 2018. © 2017 Society of Plastics Engineers     

Synthesis of tin oxide-coated gold nanostars and evaluation of their surface-enhanced Raman scattering activities

Tin oxide-coated gold nanostar hybrid nanostructures are prepared by first synthesizing gold nanostars (ca. 400 nm), then introducing Na₂SnO₃ precursor followed by its hydrolysis and formation of a tin oxide layer on nanoparticle surface. The synthesized hybrid structures have been characterized by combination of UV–Vis spectroscopy, transmission electron microscope (TEM), energy-dispersive X-ray studies, scanning electron microscope (SEM), X-Ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The TEM and SEM analyses showed that gold nanostars have a coating with an approximate thickness of 15 nm. The tin (IV) oxide coating on the gold nanostars was identified by XRD and XPS analyses and confirmed by FTIR spectroscopy. Surface-enhanced Raman scattering (SERS) spectroscopy was performed on tin oxide-coated and uncoated gold nanostars with crystal violet as a probe molecule. The SERS studies revealed field enhancement properties of Au nanostars, thus their strong SERS activity remained after tin oxide coating.