Presence Of Hydrophilic Polymer Research Articles

Live membrane filters with immobilized quorum quenching bacterial strains for anti-biofouling

Membrane filters are core materials for water treatment, reuse, and desalination. However, their fouling caused by biofilm growth is a major challenge, needing resolution. Here, we report the new strategies and efficacy of anti-biofouling membranes fabricated through the immobilization of quorum quenching (QQ) bacterial strains (Rhodococcus sp. BH4). The QQ cells are not attached to the membrane by direct phase inversion. However, they anchor to the membrane with its incubation in the presence of hydrophilic polymers (polyvinyl alcohol and alginate) as evidenced in the spectroscopic and morphological observations. Membrane filters with live QQ bacteria can degrade a signal molecule (N-octanoyl-l-homoserine lactone) with the first-order rate constant of 0.58–0.82 h−1 and inhibit the growth of a biofilm-forming bacterium (PAO1) and its secretion of biopolymers. The QQ membrane demonstrates its significant anti-biofouling effect in bioreactors for treating synthetic wastewater (i.e., membrane fouling was delayed by 57–67% compared to the naked membrane), although the initial water permeabilities are reduced with surface modification by 34–47% compared to pristine condition. The findings of this work bring the broad potential for material fabrication requiring biofouling control, encountered in our daily lives and mechanical, marine, and medical industries in addition to membrane filters.

Mechanistic investigation on the performance of Huperzine A loaded microparticles based on ultra-fine particle processing system

Ultra-fine particle processing system (UPPS) was more advantageous in producing microparticles (MPs) than the conventional technologies since it was applicable for a wide range of drugs and the MPs could be manufactured in a successive and controllable way under mild conditions. The MPs based on this technology showed small uniform particle size, proper surface roughness, and dense structure, which were anticipated to benefit tablet compaction. Therefore, ethyl cellulose (EC) was selected as the matrix material to confirm the superiorities of UPPS produced MPs for compaction due to its rigidity and inflexibility. To improve the encapsulation efficiency (EE%) of EC based MPs, hydrophilic/hydrophobic plasticizers and polymers were added, and the effect was mechanistically investigated regarding to the polymer properties and particle size of MPs. The results revealed that the EE% of MPs was significantly improved in the presence of hydrophilic polymers, which was mainly related to the reduced drug leakage as a result of modified polymer properties and decreased particle size of MPs. The forming mechanism of MPs determined by X-ray photoelectron spectroscopy (XPS) revealed that the MPs were enriched with low molecular weight polymers on the surface due to the unevenly migration driven by the centrifugal force. The topography of MPs determined by atomic force microscopy showed that the MPs had considerable rough surface to the commercial excipient, which benefited for further compaction. Consequently, the dissolution profile of MPs after compaction was approachable to that of original MPs and the tablets showed optimal content uniformity.

Enhancement in Elastic Bending Rigidity of Polymer Loaded Reverse Microemulsions.

Elastic bending rigidity of the surfactant shell is a crucial parameter which determines the phase behavior and stability of microemulsion droplets. For water-in-oil reverse microemulsions stabilized by AOT (sodium 1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate) surfactant, the elastic bending rigidity is close to thermal energy at room temperature (kBT) and can be modified by the presence of hydrophilic polymers. Here, we explore the influence of two polymers polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP), both having nearly same size (radius of gyration, Rg) but different dipole moment, on elastic bending rigidity of water-AOT-n-decane reverse microemulsions via estimating the percolation temperatures (TP) and droplet radii using dielectric relaxation spectroscopy (DRS) and small-angle neutron scattering (SANS) techniques. Notably, an increase in TP is observed on introducing PEG and PVP polymers and is attributed to the adsorption of polymer chains onto the surfactant monolayer. The stability of the droplet phase of microemulsion after the incorporation of PEG and PVP polymers is confirmed by contrast matching SANS experiments. An enhancement in elastic bending rigidity of AOT surfactant shell amounting to ∼46% is observed upon incorporation of PVP into the droplet core, whereas for PEG addition, a smaller increase of about 17% is recorded. We conjecture that the considerable increase in elastic bending rigidity of the surfactant monolayer upon introducing PVP is because of the strong ion-dipole interaction between anionic AOT and dipoles present along the PVP polymer chains. Scaling exponents extracted from the temperature dependent electrical conductivity measurements and the frequency dependent scaling of conductivity at percolation indicate the dynamic nature of percolation for both pure and polymer loaded reverse microemulsions. The decrease in activation energy of percolation upon incorporating PEG and PVP polymer molecules also reflects the increased stability of microemulsion droplets against thermal fluctuations.

Influence of hydrophilic polymers addition into cinnarizine–β-cyclodextrin complexes on drug solubility, drug liberation behaviour and drug permeability

The aims of this study were (1) to prepare cinnarizine (CNZ)–β-cyclodextrin (β-CD) complexes by the kneading, co-precipitation and co-evaporation methods with (ternary system) or without (binary system) the addition of two different hydrophilic polymers [hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP)] in their two different grades (HPMC E5-LV or K4M and PVP K-25 or K-30) and (2) to determine the polymers influence on enhancing the CNZ solubility and the in vitro CNZ liberation behaviour or drug permeation characteristics via artificial membrane from the prepared CNZ–β-CD binary and ternary complexes in 0.1 N HCl (pH 1.2). The presence of hydrophilic polymers in ternary complex system did produce irregular-shaped but smooth-surfaced particles while binary complex system (with no polymer addition) did not. The ternary complexes prepared with HPMC K4M, β-CD and CNZ showed higher solubility efficiency value compared to other tested hydrophilic polymers to make ternary complex systems. Consequently, irrespective of the three preparation methods, the ternary complex systems exhibited higher drug libration behaviour in comparison to the binary complex system, physical mixtures and CNZ powder. But because of the possible presence of a solubility and permeability interplay or tradeoff particularly in the binary and ternary complex systems, the CNZ permeation amount in 0.1 N HCl (pH 1.2) via artificial membrane was established to a minimum compared to the CNZ powder. Therefore, the CNZ–β-CD complexes with or without the HPMC and PVP should unequivocally be used with great care by considering the solubility–permeability interplay or tradeoff into account.

TRANSDERMAL DELIVERY OF CALCIUM CHANNEL BLOCKER: DEVELOPMENT AND CHARACTERIZATION

Objective: Felodipine, a BCS class II calcium channel blocker, is used in the management of hypertension and angina pectoris. Due to the poor solubility and low bioavailability of the drug, there is a necessity to design an alternative route to achieve a constant plasma concentration of felodipine for its maximum therapeutic utility and can be achieved by transdermal route.Methods: In this study, matrix type transdermal patches were prepared using different combinations of hydrophilic polymer, namely, polyvinylpyrrolidone (PVP) and hydrophobic polymer, namely, ethyl cellulose (EC) by solvent evaporation technique and were subjected for characterization.Results: The Fourier transform infrared studies confirmed the compatibility between drug and polymers. Hydrophilic nature of the polymers greatly influenced physical characteristics and dissolution rate. Equal percentage of PVP and EC yielded patches with good folding endurance. The concentration of plasticizer present in the patches gave them desired folding endurance, and it increased with the presence of hydrophilic polymer. The formulation with highest PVP concentration, F3, exhibited a maximum drug release of 96.23% for 24 hrs. While the formulation with highest EC concentration, F5, exhibited only 74.45% drug release for 24 hrs.Conclusion: From the data, formulation F2 (PVP/EC, 2:1) can be concluded as best formulation due to its desired physical characteristics, good initial drug release, sustained release behavior, and good in vitro permeation. This formulation can be further studied in a clinical scenario.

Controlled precipitation for enhanced dissolution rate of flurbiprofen: development of rapidly disintegrating tablets

Objective: The aim of this work was to investigate the potential of controlled precipitation of flurbiprofen on solid surface, in the presence or absence of hydrophilic polymers, as a tool for enhanced dissolution rate of the drug. The work was extended to develop rapidly disintegrated tablets.Significance: This strategy provides simple technique for dissolution enhancement of slowly dissolving drugs with high scaling up potential.Methods: Aerosil was dispersed in ethanolic solution of flurbiprofen in the presence and absence of hydrophilic polymers. Acidified water was added as antisolvent to produce controlled precipitation. The resultant particles were centrifuged and dried at ambient temperature before monitoring the dissolution pattern. The particles were also subjected to FTIR spectroscopic, X-ray diffraction and thermal analyses.Results: The FTIR spectroscopy excluded any interaction between flurbiprofen and excipients. The thermal analysis reflected possible change in the crystalline structure and or crystal size of the drug after controlled precipitation in the presence of hydrophilic polymers. This was further confirmed by X-ray diffraction. The modulation in the crystalline structure and size was associated with a significant enhancement in the dissolution rate of flurbiprofen. Optimum formulations were successfully formulated as rapidly disintegrating tablet with subsequent fast dissolution.Conclusions: Precipitation on a large solid surface area is a promising strategy for enhanced dissolution rate with the presence of hydrophilic polymers during precipitation process improving the efficiency.

Materials based on X-ray contrast octahedral metal cluster complexes and hydrophilic polymers

Herein we report the comparative study of cytotoxicity of a series of hexarhenium cluster complexes of general formula [{Re6Q8}L6]n (Q = S, Se, Te; L = P(CH2CH2COO–)3, SO32–, OH–, CN–) in the presence of hydrophilic polymers: dextran-70 (Mw ∼70 kDa) and polyethylene glycol (Mw ∼40 kDa) and their oxidised derivatives. It was demonstrated that cluster complexes in the presence of dextran polymers are generally more cytotoxic than non-coated cluster complexes, while PEG-coated cluster complexes are vice versa less cytotoxic.

Preparation of Polymer‐Functionalized Iron Oxide Nanoparticles and Their Biomedical Properties

AbstractSuperparamagnetic iron oxide nanoparticles with narrow size distributions were successfully prepared in large scale by a facile one‐pot synthetic method in the presence of hydrophilic polymers, such as polyethylene glycol diacid (HOOC‐PEG‐COOH) and poly(acrylic acid) (PAA). The as‐prepared products were investigated in detail by powder X‐ray diffraction (XRD), thermogravimetric analyses (TGA), transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), and vibrating sample magnetometer (VSM). The interaction between polymers and iron oxide nanoparticles was investigated using Fourier transform infrared spectrometry (FT‐IR). The results show that polymers can be attached onto the surface of iron oxide nanoparticle by bridging coordination and monodentate fashion, respectively. The interaction affects iron oxide nanoparticle properties significantly, such as XRD diffraction intensity, hydrodynamic diameter, isoelectric point, and saturation magnetization. Furthermore, the results of in vitro experiments indicated that iron oxide‐PEG‐COOH nanoparticle is more cytotoxic than iron oxide‐PAA nanoparticle due to different coordinating modes.

Role of cyclodextrin complexation in felodipine-sustained release matrix tablets intended for oral transmucosal delivery: In vitro and ex vivo characterization

The objective of the present research was two-fold: To characterize the produced inclusion complex of felodipine (FDP)-hydroxypropyl-β-cyclodextrin (HPβCD) utilizing lyophilization, and to develop and characterize a complexed sustained-release polymeric matrix tablets intended for buccal delivery. The phase-solubility diagram suggested an AL type system with 1:1 stoichiometry. Solid complexes prepared by physical mixing and lyophilization were characterized by thermal and non-thermal analytical techniques to corroborate the fact of complex formation. The sustained-release FDP tablets were produced by direct compression, and these drug or complex-loaded hydrophilic matrices were assessed for in vitro bioadhesion and release modulation, ex vivo permeation, and in vivo residence time. The in vitro drug release and ex vivo permeation across the porcine buccal membrane demonstrated that the matrix tablets containing FDP-HPβCD (FH5) solid complex exhibited a complete and sustained drug release pattern, and a significantly higher drug permeation (p < 0.05) compared to all of the other formulations tested. This could be attributed to both, the FDP-HPβCD complexation phenomenon, and the presence of hydrophilic polymer in the formulation. All of the formulations tested, demonstrated good stability in human saliva. Additionally, in vivo mucoadhesive behavior of the optimized formulations was studied in healthy human volunteers and subjective parameters were evaluated.

Synthesis of water dispersible magnetite nanoparticles in the presence of hydrophilic polymers

Water dispersible magnetite nanoparticles (Fe3O4) were synthesized by thermal decomposition of iron (III) acetylacetonate (Fe(acac)3) in the presence of carboxylic acid-terminated poly(ethylene glycol) (mPEG acid), poly(vinyl alcohol) and NH2-containing polyether. Crystal structure was investigated using X-ray diffractometry (XRD) and it showed that the as-synthesized particles had high crystallinity with distinct lattices. Particle size of the nanoparticles was investigated using XRD (15.32 nm), transmission electron microscopy (18.8 nm) and photo correlation spectroscopy (32 nm) techniques. Vibrating sample magnetometry indicated that magnetite nanoparticles exhibited superparamagnetic behavior at room temperature. Influence of each functional group on magnetic properties of the particles was also examined. These magnetite nanoparticles remained dispersible in aqueous dispersions with only 5% particles aggregating after 1 month of preparing.

Crystallization of titania ultra-fine particles from peroxotitanic acid in aqueous solution in the present of polymer and incorporation into poly(methyl methacylate) via dispersion in organic solvent

We report a novel strategy for incorporation of titanium dioxide (TiO2) particles, which were crystallized from peroxotitanic acid in the presence of hydrophilic polymer by hydrothermal treatment in aqueous solution, into poly(methyl methacrylate) (PMMA) via dispersion into chloroform. Dispersion of TiO2 particles into chloroform was achieved by solvent change from water to chloroform in aid of amphiphilic polymer dispersant, poly(N-vinyl pyrrolidone) (PVP), poly(N-vinyl pyrrolidone-co-methyl methacrylate) (PVP-co-PMMA), poly(N-vinyl pyrrolidone-block-methyl methacrylate) (PVP-b-PMMA) through azeotropical removal of water. Incorporation of TiO2 particles into PMMA was carried out by a casting process of a mixture of TiO2 particles dispersed with PVP154-b-PMMA156 in chloroform and PMMA on a glass substrate. Resultant hybrid film containing TiO2 less than 10 wt.% showed high transparency in visible region attributable to homogeneous dispersion into PMMA matrix. The refractive index of the hybrid films increased with TiO2 content and agreed with the calculated values.

The expulsion of lipophilic drugs from the cores of solid lipid microspheres in diluted suspensions and in concentrates

The aim of the study was to compare incorporation of bupivacaine base, bupivacaine stearate and indomethacin in diluted suspensions of lipospheres (10%, w/w of lipid) and in concentrates (50%, w/w of lipid). The lipid cores were composed of a mixture of solid and liquid triglycerides (Precirol and Miglyol 4:1). The lipospheres sizing between 0.5–10 μm (suspensions) and 0.5–20 μm (concentrates) were prepared using a hot emulsification with high-shear mixing and cold resolidification method. None of the studied drugs was successfully incorporated in the lipid core. The increased incorporation of drugs determined in the concentrated lipospheres was only apparent, since in fact all the dose was only attached to the surface of the lipid particles and was transferred to the aqueous phase in the course of an intensive agitation. The presence of hydrophilic polymers in the aqueous phase did not prevent the expulsion effect although drug precipitation was retarded. The expulsion effect did not correlate with the solubility of drugs determined in the bulk lipids.

A novel powder coating process for attaining taste masking and moisture protective films applied to tablets

A novel powder coating process was developed for the application of taste masking and moisture protective films on tablets while avoiding the use of solvents or water. The coalescence of particles to form a polymeric film was investigated through studies of dry powder layering of micronized acrylic polymer (E PO) to produce free films. Theophylline containing tablets were coated with the same acrylic polymer in a laboratory scale spheronizer using a powder coating technique. The dry powder layer delayed the onset of drug release in pH 6.8 medium, depending on the coating level, while no delay was observed in pH 1.0 medium. The presence of hydrophilic polymers in the acrylic coating layer decreased the lag time for drug release in pH 6.8 medium, while only the presence of HPMC in the film slowed the drug release rate in acidic medium. The dry coating process was demonstrated to be a reliable alternative to solvent or aqueous film coating technologies for applying taste masking and moisture protective film coats onto compressed tablets. A controlled drug release profile was achieved in pH 6.8 media.

Solubilization of tropicamide by hydroxypropyl-β-cyclodextrin and water-soluble polymers: in vitro/in vivo studies

1% (w/v) aqueous solutions of tropicamide (TR), a poorly water-soluble mydriatic-cycloplegic drug, are usually obtained by adjusting the pH to ∼5.0, at the expense, however, of ocular tolerance and bioavailability. The capacity of hydroxypropyl-β-cyclodextrin (HP-β-CD) to solubilize TR in pH 7.4 0.02 M phosphate buffer was investigated in the absence and presence of hydrophilic polymers (PVP, CMC and HPMC). Approximately 3.5% (w/v) HP-β-CD was required to solubilize 1% (w/v) TR in pH 7.4 buffer at room temperature. The required amount was reduced to 0.9% (w/v) by heating at 120°C in the presence of 0.1% (w/v) HPMC. Mydriatic activity tests in rabbits showed an improved bioavailability and maximal mydriatic response for two CD formulations, with and without HPMC, when compared to standard 1% (w/v) TR eyedrops, buffered at pH 5.0. The improved in vivo behaviour of the CD formulations are likely due to their physiological pH, resulting in a reduced irritant effect, although an effect of HP-β-CD on corneal permeability cannot be dismissed a priori.

Sterically Stabilized Vesicles

AbstractAfter significant developments in liquid crystal and polymer research, scientists became interested in lyotropic systems containing polymers. These studies investigated, for instance, phase behavior and stability characteristics of suspensions of colloidal particles containing water‐soluble or surface‐adsorbed polymers or block copolymers. The most frequently studied were micelles, latex prticles, and lipid vesicles (liposomes). Liposomes aggregate and fuse in the presence of hydrophilic polymers but their properties were difficult to explain when block copolymers were adsorbed or surfactants with larger polymeric polar heads were inserted into the liposome membrane, because such systems are inherently ill defined. Liposomes containing diacyl surfactants with covalently linked, longer polymer chains display many new properties with very important consequences for both basic and applied research. They stimulate fundamental studies on phase behavior and polymer conformation, scaling laws, colloidal and surface properties, and cell function: applications deal predominantly with liposomes as drug delivery systems. While in basic research theory is currently more advanced than experiment, in medical applications theoretical understanding lags behind experimental achievements. It was discovered only relatively late that liposomes with an appropriate polymer coating are significantly more stable in a biological milieu, a necessary condition for their utility as drug carriers. In particular in medical applications, this practice has rejuvenated the field of anticancer therapy and targeted drug deliviery. All these advances were made possible by an effective and synergistic overlap of many different disciplines.