Polymeric controlled release formulations of niclosamide for control of Biomphalaria alexandrina, the vector snail of schistosomiasis

Schistosomiasis is one of the most important public health problems in many developing countries. The present study was conducted to investigate the effect of the polymeric niclosamide formulations against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni in Egypt. Three new polymeric formulations were prepared for the molluscicide niclosamide. The formulations were prepared either by the chemical modifications of poly(glycidyl methacrylate) or by physical entrapment of the niclosamide in calcium alginate beads. The release of the niclosamide from the polymeric formulations was investigated. The activity of the prepared formulations against Biomphalaria alexandrina was investigated. The results obtained revealed higher potency for polymerized niclosamide B3 than B1; the lowest potency was revealed for B2. After an exposure period of 24 hours, LC(50) values were 0.073, 0.098 and 1.09 ppm for B3, B1 and B2, respectively. In addition, the molluscicidal potency of the test polymeric niclosamide was age-dependent, where old snails were more tolerant to the test solutions than young and newly hatched snails. The results also indicated that the molluscicidal activity of B3 was extended for 21 days and 17 days for B1, compared with 5 days for free niclosamide. However, the molluscicidal potency of the polymerized niclosamide was increased after boiling for one hour, and was increased with increasing the pH of the medium to pH 9. In addition, their potency was increased with decreasing the water hardness concentrations (CaCO(3)).Molluscicidal activity of free niclosamide and its polymeric formulations vs. exposure time.     

Stabilizing action of polymeric plasticisers in PVC

Polymeric plasticisers gained considerable success in PVC formulations in the early eighties and there are now several manufacturers of plasticising additives based on polymeric compositions in the USA. The good performance of these additives has been considered in the technical literature. For epoxy polymeric plasticisers, an improvement of heat and U.V. stability was also observed as a function of the oxirane oxygen content in formulations. In this paper we refer to some experimental tests on thermal and U.V. light stabilising action of linear low molecular polyesters, based on glycols and dibasic aliphatic acids, which possess a good plasticising effect and low toxicity. Creep tests and calculations of isochronous creep modulii were used to evaluate the stability of PVC formulations.     

Polymeric Formulations Based on Iron and Cobalt Molybdophosphates and Polyacrylates

The possibility of using synthesized iron(III) and cobalt(II) molybdophosphates as dyes in dyeing of copolymers and polymeric formulations based on methacrylic acid and methyl methacrylate and also as pigments deposited onto natural and inorganic supports for heterogeneous dyeing of polymeric materials was studied.     

Polymers for the enhancement of solubility of pharmaceutical substances in solid drug formulations

This review presents the survey of basic properties of polymers. As potential solubilizers for pharmaceutical formulations with low solubility in water, diverse polymeric excipients containing various functional groups are considered.     

An overview of polymeric nanomicelles in clinical trials and on the market

Polymeric nanomedicine is a promising and rapidly evolving field.Among the different polymeric carriers,polymeric micelle(PM) with nanoscale size exhibit potent physical and biological advantages including excellent solubility and pharmacokinetics,enhanced efficacy and lower toxicity.PM has garnered increasing intere st in research and in the clinic.This review will highlight the clinical outcomes of several PM-based formulations,and further summarized their preparation methods,strengths and challenges.     

Comparative study of the behavior of ammonium phosphate in fireproofing intumescent formulations

A comparative study of the behavior of ammonium dihydrogen phosphate and partially substituted ammonium polyphosphates in fireproofing formulations based on organic solutions of polymers was made. Differences in the interaction of monomeric and polymeric acidic salts with the surface of a metal being protected were revealed.     

Influence of chemical shell structure on the thermal properties of microcapsules containing a flame retardant agent

Microcapsules containing ammonium phosphate as the acid source for an intumescent system were prepared by various processes. The microcapsules have different morphologies, load content and various types of polymeric shell. The polymers for our microcapsule shell are polymers considered as carbon source for intumescent formulations. In this paper we discuss the influence of polymeric shell and phosphate content of the microcapsules on the capacity to produce a thermally stable residue at high temperature, one of the characteristics for an intumescent formulation.     

Brazilian clays as synergistic agents in an ethylenic polymer matrix containing an intumescent formulation

The effect of two different Brazilian montmorillonitic clays in intumescent ammonium polyphosphate and pentaerythritol formulations was evaluated. Ethylene and butyl acrylate copolymer was used as polymeric matrix. The clays were added both to the pure polymer and to the polymer containing intumescent mixture. The influence of these mineral fillers on flame retardancy was investigated by thermogravimeric analysis (TG). The results show that these inorganic additives have a synergist effect in the polymeric composite containing the intumescent formulation.     

Synthesis of photoactive single‐chain folded polymeric nanoparticles via combination of radical polymerization techniques and Menschutkin click chemistry

This contribution reports that synthesis of polystyrene based photoactive polymeric nanoparticles by radical copolymerization and Menschutkin Chemistry methodology. In the first step, poly(styrene‐co‐chloromethyl styrene) was achieved by thermally initiated radical copolymerizations and subsequently copolymers were reacted to commercially available Type II photoiniator (Michler's ketone) in dilute condition in order to achieve intramolecular crosslinked polymeric nanoparticles. After the characterization studies, polymeric nanoparticles were used for free radical photopolymerization of methacrylic formulations to determine the initiation efficiency. Upon UV irradiation, resulting polymeric nanoparticle lost its globular structure by releasing benzophenone part and transformed into linear copolymer analogue. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1998–2003     

New approach to the measurement of polymer photooxidation

In an attempt to eradicate many of the problems associated with outdoor and accelerated testing of polymeric formulations, an apparatus was constructed for the sensitive measurement of oxygen uptake into a polymer during its incipient stages of photooxidation. The photooxidation curves of certain HDPE and LDPE formulations demonstrate a first order asymptotic approach to a limiting value which corresponds to the initial number of reactive centers that are available in the material for oxygen attack. An equation for oxygen uptake as a function of time is derived which incorporates the asymptotic value together with a constant whose value reflects the rate at which the asymptote is approached. These parameters are used to calculate the value of the initial quantum yield for oxygen uptake, a quantity which is indicative of the relative photostability of a given formulation. The kinetics parameters obtained from analyses of certain photooxidative curves confirm that the initial rate of photooxidation is proportional to the concentration of polymer hydroperoxide species which are present in the material as a result of oxidation during processing. The removal of these by thermal treatment of the material in an inert atmosphere results in the appearance of an induction period in the photooxidative profile. The experimental results suggest that this method of determining and interpreting photooxidative curves has certain potential for assessing the relative photostabilities of polymeric formulations.     

Polymeric dressing formulations containing water-soluble fullerene derivatives

The effect of small additions of water-soluble fullerene C₆₀ derivatives on the strength properties of polyvinyl alcohol films was examined. Solutions of polyvinyl alcohol and fullerenol were tested as polymeric dressing formulations for glass-reinforced plastics based on a thermoplastic polyethylene or polyamide matrix.     

A Light-Triggerable Nanoparticle Library for the Controlled Release of Non-Coding RNAs

RNA-based therapies offer a wide range of therapeutic interventions including the treatment of skin diseases; however, the strategies to efficiently deliver these biomolecules are still limited due to obstacles related to the cellular uptake and cytoplasmic delivery. Herein, we report the synthesis of a triggerable polymeric nanoparticle (NP) library composed of 160 formulations, presenting physico-chemical diversity and differential responsiveness to light. Six formulations were more efficient (up to 500 %) than commercially available lipofectamine in gene-knockdown activity. These formulations showed differential internalization by skin cells and the endosomal escape was rapid (minutes range). The NPs were effective in the release of siRNA and miRNA. Acute skin wounds treated with the top hit NP complexed with miRNA-150-5p healed faster than wounds treated with scrambled miRNA. Light-activatable NPs offer a new strategy to topically deliver non-coding RNAs.     

A Light‐Triggerable Nanoparticle Library for the Controlled Release of Non‐Coding RNAs

RNA‐based therapies offer a wide range of therapeutic interventions including the treatment of skin diseases; however, the strategies to efficiently deliver these biomolecules are still limited due to obstacles related to the cellular uptake and cytoplasmic delivery. Herein, we report the synthesis of a triggerable polymeric nanoparticle (NP) library composed of 160 formulations, presenting physico‐chemical diversity and differential responsiveness to light. Six formulations were more efficient (up to 500 %) than commercially available lipofectamine in gene‐knockdown activity. These formulations showed differential internalization by skin cells and the endosomal escape was rapid (minutes range). The NPs were effective in the release of siRNA and miRNA. Acute skin wounds treated with the top hit NP complexed with miRNA‐150‐5p healed faster than wounds treated with scrambled miRNA. Light‐activatable NPs offer a new strategy to topically deliver non‐coding RNAs.     

Design and characterization of bi-soft segmented polyurethane microparticles for biomedical application

Bi-soft segmented poly(ester urethane urea) microparticles were prepared and characterized aiming a biomedical application. Two different formulations were developed, using poly(propylene glycol), tolylene 2,4-diisocyanate terminated pre-polymer (TDI) and poly(propylene oxide)-based tri-isocyanated terminated pre-polymer (TI). A second soft segment was included due to poly(?-caprolactone) diol (PCL). Infrared spectroscopy, used to study the polymeric structure, namely its H-bonding properties, revealed a slightly higher degree of phase separation in TDI-microparticles. TI-microparticles presented slower rate of hydrolytic degradation, and, accordingly, fairly low toxic effect against macrophages. These new formulations are good candidates as non-biodegradable biomedical systems.     

Evaluation of drug-polymer interaction in polymeric microspheres containing diltiazem hydrochloride

The aim of this study was to evaluate the drug-polymer interaction in polymeric microsphere formulations containing diltiazem hydrochloride (DH). The microspheres were successfully prepared by solvent evaporation technique using two different polymer types, Eudragit®RS 100 and ethylcellulose. The existence of a possible interaction between DH and the polymers was investigated by using DSC and XRD. The DSC curves and XRD patterns indicated that there was no interaction between DH and the polymers. The peak area calculations in the DSC curves of F1- and F2-coded microsphere formulations showed that DH was dispersed, not dissolved, in the ethylcellulose polymer matrix, while it partly dissolved in the Eudragit®RS 100 polymer matrix.     

3D Printing of Drug Nanocrystals for Film Formulations

The aim of the study was to prepare indomethacin nanocrystal-loaded, 3D-printed, fast-dissolving oral polymeric film formulations. Nanocrystals were produced by the wet pearl milling technique, and 3D printing was performed by the semi-solid extrusion method. Hydroxypropyl methyl cellulose (HPMC) was the film-forming polymer, and glycerol the plasticizer. In-depth physicochemical characterization was made, including solid-state determination, particle size and size deviation analysis, film appearance evaluation, determination of weight variation, thickness, folding endurance, drug content uniformity, and disintegration time, and drug release testing. In drug nanocrystal studies, three different stabilizers were tested. Poloxamer F68 produced the smallest and most homogeneous particles, with particle size values of 230 nm and PI values below 0.20, and was selected as a stabilizer for the drug-loaded film studies. In printing studies, the polymer concentration was first optimized with drug-free formulations. The best mechanical film properties were achieved for the films with HPMC concentrations of 2.85% (w/w) and 3.5% (w/w), and these two HPMC levels were selected for further drug-loaded film studies. Besides, in the drug-loaded film printing studies, three different drug levels were tested. With the optimum concentration, films were flexible and homogeneous, disintegrated in 1 to 2.5 min, and released the drug in 2–3 min. Drug nanocrystals remained in the nano size range in the polymer films, particle sizes being in all film formulations from 300 to 500 nm. When the 3D-printed polymer films were compared to traditional film-casted polymer films, the physicochemical behavior and pharmaceutical performance of the films were very similar. As a conclusion, 3D printing of drug nanocrystals in oral polymeric film formulations is a very promising option for the production of immediate-release improved- solubility formulations.     

Encapsulation of essential oils within a polymeric liposomal formulation for enhancement of antimicrobial efficacy

Essential oils and their constituents are known to possess antimicrobial activity; however, their inherent volatility is a limiting factor. In order to exploit the antimicrobial efficacy of essential oils, encapsulation within polymeric liposomal systems was undertaken. The liposomes were subsequently polymer-coated in order to further enhance the stability of the formulations. Essential oils distilled from Artemisia afra, Eucalyptus globulus and Melaleuca alternifolia were encapsulated into diastearoyl phosphatidylcholine and diastearoyl phosphatidylethanolamine liposomes employing a reverse phase evaporation methodology. A polyelectrolyte coating was then applied via the layer-by-layer self-deposition technique. A batch of the liposomes was polymer-coated with a 0.15%w/v chitosan solution. Using the minimum inhibitory concentration assay, the liposome-encapsulated, unencapsulated and polymer-coated liposome-encapsulated essential oils were compared in order to observe whether the antimicrobial efficacy was improved with encapsulation and polymer coating. Fractional inhibitory concentrations (FICs) were calculated in order to determine the antimicrobial interactions amongst the lipoid components, polymer coating and essential oils (synergistic, additive, indifferent and antagonistic interactions). With the exception of A. afra, microbial growth was inhibited at lower concentrations for the encapsulated formulations in comparison with the nonencapsulated oils. Synergistic to additive interactions were noted for encapsulated E. globulus (sigmaFIC values 0.25-0.45) and M alternifolia (sigmaFIC values 0.26-0.52) formulations. The addition of the polymer coating did not enhance antimicrobial activity, but owing to their positive effects on membrane stability, its presence is important as a means of extending the shelf life of these formulations. Additionally, the presence of the polymeric coating availed the essential oil at a slower rate. This investigation is a stepping stone towards the promotion of the antimicrobial use of essential oils. The added benefits are that essential oils not only provide effective antimicrobial efficacy, but also promote a "greener" consumerism. Within liposomes, they will enhance dermato-cosmetic properties and increase the marketing image of the final product.     

A thermogravimetric method for assessing the substantivity of polymer films on dentally relevant substrates

A thermogravimetric (TG) method is described for evaluating the substantivity of multi-functional polymeric materials that may be used as protective coatings for teeth. Applied to poly(butyl methacrylate) and poly(octadecyl methacrylate) film structures deposited onto model tooth surfaces from aqueous latex formulations, the method shows that while the latter polymer exhibits little substantivity, the former may be a suitable candidate material for dental-care applications.     

Ethylcellulose, polycaprolactone, and eudragit matrices for controlled release of piroxicam from tablets and microspheres

The present paper provides details of the preparation of polymeric tablets and microspheres based on piroxicam as a therapeutic active agent and the drug release study from these formulations. Tablets composed of ethylcellulose, Eudragit? or mixtures of Eudragit? and synthesised poly(oxepan-2-one) were prepared and tested. The effect of the matrix on the drug release at 37°C was studied. The drug-loaded microparticles were prepared using solvent evaporation microencapsulation. These systems were characterised by SEM and FTIR spectroscopy and the size and size distribution were also determined. The results demonstrated that the drug release could be modified by means of these formulations. Finally, piroxicam dissolution rate constants were calculated from Higuchi??s release model.     

Development of hard materials by radiation curing technology

For studying nanoglobular modification effects in radiation cured polymeric composites, we prepared polymerization active silico-organic nanoparticles. With their polymerization active ligands, these nanoparticles form crosslinks by modifying the viscoelastic properties in radiation cured polymeric nanocomposites. In this process, there was a polymerization activity imparted to the particle surfaces of nanopowders, thus applying the physico-chemical modification scheme of a heterogeneous copolymerization to novel scratch and abrasion resistant coatings. By varying the nanoparticle-monomer formulation and the curing method, additional property can be achieved. In this works, we also investigated the influence of various factors such as addition of photoinitiators and other additives into the formulations. The coating materials were applied to the substrate by using different type of coaters. These materials were cured by ultraviolet light and electron beam irradiation. Properties of coatings were characterized using Universal scratch tester and Taber abrasion tester.