Preparation of a Carrier to Achieve In Vivo Delivery of siRNA: The Example of Chitosan-Coated Poly(isobutylcyanoacrylate) Nanoparticles.

This chapter describes the preparation of chitosan-coated poly(isobutylcyanoacrylate) nanoparticles as a suitable carrier to deliver siRNAs to two types of xenograft tumor models of mice. The nanoparticles are prepared by a method of emulsion polymerization that includes steps of polymerization and purification. The polymerization method is carried out in a single pot in an aqueous medium. siRNAs are coupled with the nanoparticles at the end of the preparation by adsorption. The protocol also explains how to determine optimum yield/the titer of association of siRNA with the nanoparticles. It is described for a preparation scale at 4 mL of nanoparticle dispersion at a concentration of 42-46 mg nanoparticles/mL. Optimal loading capacity of the nanoparticles with the siRNA can be achieved by performing an association yield above 90% using a mass ratio of 1 mg siRNA/50 mg of nanoparticles (20 µg siRNA/mg nanoparticles, 1 nmol siRNA (Mw 14 kDa)/mg nanoparticles).

Functionalized polymer microbubbles as new molecular ultrasound contrast agent to target P-selectin in thrombus.

Thrombotic diseases rarely cause symptoms until advanced stage and sudden death. Thus, early detection of thrombus by a widely spread imaging modality can improve the prognosis and reduce mortality. Here, polymer microbubbles (MBs) made of degradable poly(IsoButylCyanoAcrylate) and functionalized with fucoidan (Fucoidan-MBs) were designed as a new targeted ultrasound contrast agent to image venous thrombus. The physicochemical characterizations demonstrate that the MBs with fucoidan surface exhibit a size of 2-6 µm and stability in suspension at 4 °C up to 2 months. MBs exhibit high echogenicity and could be completely burst under high destructive pulse. Flow chamber experiments on activated human platelets show a higher affinity of Fucoidan-MBs than control anionic MBs (CM-Dextran-MBs) under shear stress conditions. In vivo analysis by ultrasound and histological results demonstrate that Fucoidan-MBs are localized in rat venous thrombotic wall, whereas few CM-Dextran-MBs are present. In addition, the binding of Fucoidan-MBs in healthy vein is not observed. Collectively, Fucoidan-MBs appear as a promising functionalized carrier for ultrasound molecular imaging in thrombotic diseases.

Critical analysis of cyanoacrylate in intestinal and colorectal anastomosis.

BACKGROUND: Although cyanoacrylate glue (CA) has been widely used in various kinds of medical applications, its application in gastrointestinal anastomosis remains limited, and outcomes of experimental studies have not been satisfactory. This systematic review summarizes research regarding CA application in intestinal and colorectal anastomosis, and correlates methodological aspects to experimental outcomes. METHODS: A systematic literature search was performed using Medline, Embase, Cochrane, and Web-of-Science libraries. Articles were selected if CA was applied to intestinal or colorectal anastomoses. Included articles were categorized according to CA molecular structure; the method details in each study were extracted and analyzed. RESULTS: Twenty-two articles were included. More than half of the inclusions reported positive outcomes (seven articles) or neutral outcomes (eight articles). Analysis of the methods revealed that methodological details such as CA dosage, time of polymerization were not consistently reported. Porcine studies, inverted anastomosis, and n-butyl-cyanoacrylate studies showed more positive outcomes; everted anastomosis, and oversized sutures might negatively influence the outcomes. CONCLUSIONS: Owing to the positive outcome from the porcine studies, application of CA in gastrointestinal (GI) anastomosis still seems promising. To achieve a better consistency, more methodological details need to be provided in future studies. Optimizing the dosage of CA, choice of animal model, inverted anastomosis construction, and other method details may improve intestinal and colorectal anastomoses with CA application in future studies.

The counterbalanced effect of size and surface properties of chitosan-coated poly(isobutylcyanoacrylate) nanoparticles on mucoadhesion due to pluronic F68 addition.

PURPOSE: To evaluate of the effect of size and surface characteristics of poly(isobutylcyanoacrylate) nanoparticles coated with pluronic F68 and thiolated chitosan on mucoadhesion. METHODS: Nanoparticles were obtained by radical emulsion polymerization in presence of different amounts of F68 (0-4%w/v). Mucoadhesion was ex vivo evaluated by applying nanoparticle suspension on rat intestinal mucosa and quantifying the amount of attached nanoparticles after incubation. RESULTS: F68 unimers added in the polymerization medium allowed decreasing nanoparticle size from 251 to 83 nm, but resulted in nanoparticle surface modification. The amount of thiolated chitosan onto nanoparticle surface was decreased resulting in lower thiol groups and zeta potential. Consequently, the decrease of nanoparticle hydrodynamic diameter resulted in eight-fold-increase of the number of nanoparticles attached to the mucosa but a significant decrease of the weight of attached nanoparticles was observed. This unexpected result was due to a decrease of the amount of chitosan and thiolated chitosan available to interact with mucus upon addition of F68 in the polymerization medium. CONCLUSIONS: Addition of F68 should not be recommended to improve the amount of mucoadherent nanoparticles. Further studies could allow understanding if the low amount of small size nanoparticles could be able to improve oral bioavailability.

siRNA nanoformulation against the ret/PTC1 junction oncogene is efficient in an in vivo model of papillary thyroid carcinoma.

Delivery is a very important concern for therapeutic applications of siRNA. In this study, we have used chitosan-coated poly(isobutylcyanoacrylate) nanoparticles to deliver siRNA with a complementary sequence to the fusion oncogene ret/PTC1. By screening the mRNA junction we have selected a potent siRNA sequence able to inhibit this oncogene in a model of Papillary Thyroid Carcinoma cells. This siRNA sequence has then been validated by a shRNA approach using the same sequence. Furthermore, the high ret/PTC1 inhibition has triggered a phenotypic reversion of the transformed cells. We have designed well-defined chitosan decorated nanoparticles and succeeded to reduce their size. They have allowed to protect ret/PTC1 siRNA from in vivo degradation and leading to significant tumour growth inhibition after intratumoral administration.

In vitro evaluation of calcium binding capacity of chitosan and thiolated chitosan poly(isobutyl cyanoacrylate) core-shell nanoparticles.

The ability of chitosan and its derivatives to bind cations is well known. Chitosan and thiolated chitosan were recently associated with poly(isobutyl cyanoacrylate) (PIBCA) nanoparticles leading to very promising results in terms of bioadhesion and permeation enhancement properties. Taking into account the influence that cations concentration have in the maintenance of both the permeation and the enzymatic barrier of the oral route, the possible cation binding capacity of these colloidal systems might be interesting in the use of these nanocarriers for the oral administration of pharmacologically active peptides. The aim of the present work was to in vitro evaluate the capacity of these colloidal systems to bind calcium, a model cation of physiological interest in the intestinal tract. The presence of chitosan on the nanoparticle surface importantly increased the calcium binding ability, in comparison to non-coated PIBCA nanoparticles. In addition, its presentation in the gel layer surrounding the nanoparticles, also beneficiated its binding capacity, obtaining 2-3 folds higher values when the polymer coated the nanoparticles than when it was in solution. The cross-linked structure observed for thiolated chitosan, due to the formation of inter- and intra-chain disulphide bonds, diminished the accessibility of cation to active sites of the polymer, decreasing the binding capacity of the calcium ion. However, when the amount of free thiol groups on the nanoparticle surface was high enough, the binding behaviour observed was higher than for nanoparticles elaborated with non-modified polymer.

Tuning of shell and core characteristics of chitosan-decorated acrylic nanoparticles.

The aim of the work was to develop a new family of chitosan-coated acrylic nanoparticles to increase the specificity of absorption of drugs associated given by the mucosal route. To achieve this goal, techniques of radical and anionic emulsion polymerisation of isobutylcyanoacrylate (IBCA) were used. Changes in the shell composition were made by using chitosan of different molecular weight and thiolated chitosan to modify the particle surface properties in order to vary the mucosae-nanoparticle interactions. The core was also modified by the inclusion of methyl methacrylate (MMA) as second monomer potentially able to improve the control of drug release. Finally, the labelling of nanoparticles core with a fluorophore, methacryloxyethyl thiocarbamoyl rhodamine B (Polyfluor), was successfully achieved, necessary for the in vitro and in vivo evaluation of the systems created. Results showed that nanoparticle size varied from 200 to 500 nm, depending on the molecular weight of chitosan used. Positive surface charge values were obtained in all cases. In addition, evidences of the presence of thiol groups were obtained (0.03-0.16 x 10(-3)micromol/cm(2) of nanoparticle).

Preparation and characterization of carbonyl iron/poly(butylcyanoacrylate) core/shell nanoparticles.

In this article a method is described to prepare composite colloidal nanoparticles, consisting of a magnetic core (carbonyl iron) and a biodegradable polymeric shell [poly(butylcyanoacrylate) or PBCA]. The method is based on the so-called anionic polymerization procedure, often used in the synthesis of poly(alkylcyanoacrylate) nanospheres designed for drug delivery. Interest of this investigation is based upon the fact that the heterogeneous structure of the particles can confer them both the possibility to respond to external magnetic fields and to be used as drug carriers. In order to investigate to what extent do the particles participate of this mixed properties, we compare in this work the physical characteristics (structure, chemical composition, specific surface area and surface electrical and thermodynamic properties) of the core/shell particles with those of both the nucleus and the coating material. This preliminary study shows that the mixed particles display an intermediate behavior between that of carbonyl iron and PBCA spheres. Electrophoretic mobility measurements as a function of pH and as a function of KNO3 concentration, show a great similarity between the core/shell and pure polymer nanoparticles. Similarly, a surface thermodynamic study performed on the three types of particles demonstrated that the electron-donor component of the surface free energy of the solids is very sensitive to the surface composition. In fact, a measurable decrease of such component is found for core/shell particles as compared to carbonyl iron. We also analyzed the influence of the relative amounts of polymer and carbonyl iron on the characteristics of the composite particles: data on the coating thickness, the amount of polymer bound to the magnetic nuclei, the redispersibility characteristics of the suspensions and the surface electrical and thermodynamic properties, suggest that the optimal synthesis conditions are obtained for a 4/3 initial monomer/carbonyl iron weight ratio.

Physical and biological properties of a novel siloxane adhesive for soft tissue applications.

The aim of this study was to investigate the adhesive properties of an in-house aminopropyltrimethoxysilane-methylenebisacrylamide (APTMS-MBA) siloxane system and compare them with a commercially available adhesive, n-butyl cyanoacrylate (nBCA). The ability of the material to perform as a soft tissue adhesive was established by measuring the physical (bond strength, curing time) and biological (cytotoxicity) properties of the adhesives on cartilage. Complementary physical techniques, X-ray photoelectron spectroscopy, Raman and infrared imaging, enabled the mode of action of the adhesive to the cartilage surface to be determined. Adhesion strength to cartilage was measured using a simple butt joint test after storage in phosphate-buffered saline solution at 37 degrees C for periods up to 1 month. The adhesives were also characterised using two in vitro biological techniques. A live/dead stain assay enabled a measure of the viability of chondrocytes attached to the two adhesives to be made. A water-soluble tetrazolium assay was carried out using two different cell types, human dermal fibroblasts and ovine meniscal chondrocytes, in order to measure material cytotoxicity as a function of both supernatant concentration and time. IR imaging of the surface of cartilage treated with APTMS-MBA siloxane adhesive indicated that the adhesive penetrated the tissue surface marginally compared to nBCA which showed a greater depth of penetration. The curing time and adhesion strength values for APTMS-MBA siloxane and nBCA adhesives were measured to be 60 s/0.23 MPa and 38 min/0.62 MPa, respectively. These materials were found to be significantly stronger than either commercially available fibrin (0.02 MPa) or gelatin resorcinol formaldehyde (GRF) adhesives (0.1 MPa) (P < 0.01). Cell culture experiments revealed that APTMS-MBA siloxane adhesive induced 2% cell death compared to 95% for the nBCA adhesive, which extended to a depth of approximately 100-150 microm into the cartilage surface. The WST-1 assay demonstrated that APTMS-MBA siloxane was significantly less cytotoxic than nBCA adhesive as an undiluted conditioned supernatant (P < 0.001). These results suggest that the APTMS-MBA siloxane may be a useful adhesive for medical applications.

Scaffold-enhanced albumin and n-butyl-cyanoacrylate adhesives for tissue repair: ex vivo evaluation in a porcine model.

An ex vivo study was conducted in a porcine model to compare the tensile strength of tissue samples repaired by three different repair methods: (i) scaffold-enhanced light-activated albumin protein solder, (ii) scaffold-enhanced n-butyl-cyanoacrylate adhesive, and (iii) conventional sutures. Biodegradable polymer scaffolds of controlled porosity were fabricated with poly(L-lactic-co-glycolic acid) (PLGA) and salt particles using a solvent-casting and particulate-leaching technique. Repairs were conducted on seventeen different tissues including the carotid, femoral, splenic, coronary, and pulmonary arteries, aorta, small intestine, ureter, sciatic nerve, spleen, atrium, kidney, muscle, skin, lung, liver and pancreas. Acute breaking strengths were measured and the data were analyzed by Student's T-test. The resultant repairs using the scaffold-enhanced light-activated adhesive (Group I) were found to yield equivalent tensile strengths to conventional sutures (Group III), with significantly smaller mean standard deviations (8% vs. 25%). The cyanoacrylate-doped scaffold (Group II) repairs performed extremely well with tensile strengths approximately 30% higher for organ tissue and approximately 20% higher for vascular tissue than with the other two repair techniques evaluated in this study. The addition of the polymer scaffold assists in tissue alignment and reduces problems associated with adhesive runaway from the repair site. With appropriate packaging, scaffold-enhanced adhesives offer the potential for quick application in the field by less skilled professionals, paraprofessionals and bystanders in emergency situations--both military and civilian--outside a hospital or clinic setting.

Aislamiento absoluto: una técnica alternativa y atraumática / Absolute isolation: an alternative and atraumatic technique

Es una alternativa al método convencional de aislamiento absoluto que se comenzó a utilizar hace aproximadamente 8 años. Técnica totalmente atraumática, fácil y económica. Consideraciones: el isobutil cianoacrilato permite suturar heridas de labio que involucren epidermis, mucosa y músculos. Es bicompatible, ayuda a la hemostasia, polimeriza en presencia de sangre, carece de toxicidad, tiene bajo costo y es de fácil aplicación. La utilización del producto sebre tejidos duros y blandos debe realizarse sobre campo seco y sin aplicar calor a la zona. Es irritante para la mucosa conjuntival. El Isobutil Cianoacrilato no necesita calor para su polimerización y lo hace en presencia de oxígeno, por el contrario, los isobutiles comunes requieren altas temperaturas para polimerizar. Requerimientos: Goma dique, porta goma, perforador de goma, aplicador Microbrush o similar, adhesivo instantáneo. Técnica: se selecciona el elemento a tratar y se comienza con la perforación de la goma siempre con el orificio de menor diámetro para que la goma entre a presión sobre la superficie a tratar. Se seca el campo y se aplica el adhesivo con el microbrush contactando el adhesivo en parte con la goma y en parte con el elemento dentario, de esta forma el adhesivo polimeriza produciendo una exotermia suave que funde el látex de la goma sobre el diente brindando aislamiento absoluto. Se retira luego la goma hacia el exterior de la cavidad bucal, y si existieran rastros de adhesivo los mismos se retiran con una cureta o explorador. En conclusión esta técnica permite realizar tratamientos en elementos dentarios permanentes que no se puedan aislar con la técnica convencional

Aislamiento absoluto: una técnica alternativa y atraumática / Absolute isolation: an alternative and atraumatic technique

Es una alternativa al método convencional de aislamiento absoluto que se comenzó a utilizar hace aproximadamente 8 años. Técnica totalmente atraumática, fácil y económica. Consideraciones: el isobutil cianoacrilato permite suturar heridas de labio que involucren epidermis, mucosa y músculos. Es bicompatible, ayuda a la hemostasia, polimeriza en presencia de sangre, carece de toxicidad, tiene bajo costo y es de fácil aplicación. La utilización del producto sebre tejidos duros y blandos debe realizarse sobre campo seco y sin aplicar calor a la zona. Es irritante para la mucosa conjuntival. El Isobutil Cianoacrilato no necesita calor para su polimerización y lo hace en presencia de oxígeno, por el contrario, los isobutiles comunes requieren altas temperaturas para polimerizar. Requerimientos: Goma dique, porta goma, perforador de goma, aplicador Microbrush o similar, adhesivo instantáneo. Técnica: se selecciona el elemento a tratar y se comienza con la perforación de la goma siempre con el orificio de menor diámetro para que la goma entre a presión sobre la superficie a tratar. Se seca el campo y se aplica el adhesivo con el microbrush contactando el adhesivo en parte con la goma y en parte con el elemento dentario, de esta forma el adhesivo polimeriza produciendo una exotermia suave que funde el látex de la goma sobre el diente brindando aislamiento absoluto. Se retira luego la goma hacia el exterior de la cavidad bucal, y si existieran rastros de adhesivo los mismos se retiran con una cureta o explorador. En conclusión esta técnica permite realizar tratamientos en elementos dentarios permanentes que no se puedan aislar con la técnica convencional (AU)

Aislamiento absoluto: una técnica alternativa y atraumática / Absolute isolation: an alternative and atraumatic technique

Es una alternativa al método convencional de aislamiento absoluto que se comenzó a utilizar hace aproximadamente 8 años. Técnica totalmente atraumática, fácil y económica. Consideraciones: El Isobutil Cianoacrilato permite suturar heridas de labio que involucren epidermis, mucosa y músculos. Es biocompatible, ayuda a la hemostasia, polimeriza en presencia de sangre, carece de toxicidad, tiene bajo costo y es de fácil aplicación. La utilización del producto sobre tejidos duros y blandos debe realizarse sobre campo seco y sin aplicar calor a la zona. Es irritante para la mucosa conjuntival. El Isobutil Cianoacrilato no necesita calor para su polimerización y lo hace en presencia de oxígeno, por el contrario, los isobutiles comunes requieren altas temperaturas para polimerizar. Requerimientos: goma dique, porta goma, perforador de goma, aplicador Microbrush o similar, Adhesivo instantáneo. Técnica: Se selecciona el elemento a tratar y se comienza con la perforación de la goma siempre con el orificio de menor diámetro para que la goma entre a presión sobre la superficie a tratar. Se seca el campo y se aplica el adhesivo con el microbrush contactando el adhesivo en parte con la goma y en parte con el elemento dentario, de esta forma el adhesivo polimeriza produciendo una exotermia suave que funde el látex de la goma sobre el diente brindando aislamiento absoluto. Se retira luego la goma hacia el exterior de la cavidad bucal, y si existieran rastros de adhesivo los mismos se retiran con una cureta o explorador. En conclusión esta técnica permite realizar tratamientos en elementos dentarios permanentes que no se puedan aislar con la técnica convnecional

Aislamiento absoluto: una técnica alternativa y atraumática / Absolute isolation: an alternative and atraumatic technique

Es una alternativa al método convencional de aislamiento absoluto que se comenzó a utilizar hace aproximadamente 8 años. Técnica totalmente atraumática, fácil y económica. Consideraciones: El Isobutil Cianoacrilato permite suturar heridas de labio que involucren epidermis, mucosa y músculos. Es biocompatible, ayuda a la hemostasia, polimeriza en presencia de sangre, carece de toxicidad, tiene bajo costo y es de fácil aplicación. La utilización del producto sobre tejidos duros y blandos debe realizarse sobre campo seco y sin aplicar calor a la zona. Es irritante para la mucosa conjuntival. El Isobutil Cianoacrilato no necesita calor para su polimerización y lo hace en presencia de oxígeno, por el contrario, los isobutiles comunes requieren altas temperaturas para polimerizar. Requerimientos: goma dique, porta goma, perforador de goma, aplicador Microbrush o similar, Adhesivo instantáneo. Técnica: Se selecciona el elemento a tratar y se comienza con la perforación de la goma siempre con el orificio de menor diámetro para que la goma entre a presión sobre la superficie a tratar. Se seca el campo y se aplica el adhesivo con el microbrush contactando el adhesivo en parte con la goma y en parte con el elemento dentario, de esta forma el adhesivo polimeriza produciendo una exotermia suave que funde el látex de la goma sobre el diente brindando aislamiento absoluto. Se retira luego la goma hacia el exterior de la cavidad bucal, y si existieran rastros de adhesivo los mismos se retiran con una cureta o explorador. En conclusión esta técnica permite realizar tratamientos en elementos dentarios permanentes que no se puedan aislar con la técnica convnecional (AU)

Algunos problemas de los dientes con pérdidas de sustancias subgingivales / Some problems of teeth with loss of subgingival substances

Se intenta llamar la atención sobre un problema frecuente en odontología, que no suele estudiarse de modo sistemático: las causas, efectos y posibles soluciones de las pérdidas de sustancia dentaria que se extienden hasta la zona subgingival. Dado que la mayoría de los colegas pueden hallarse ante esta situación, se les pide también que comuniquen sus opiniones sobre ella y su experiencia en la materia

Algunos problemas de los dientes con pérdidas de sustancias subgingivales / Some problems of teeth with loss of subgingival substances

Se intenta llamar la atención sobre un problema frecuente en odontología, que no suele estudiarse de modo sistemático: las causas, efectos y posibles soluciones de las pérdidas de sustancia dentaria que se extienden hasta la zona subgingival. Dado que la mayoría de los colegas pueden hallarse ante esta situación, se les pide también que comuniquen sus opiniones sobre ella y su experiencia en la materia (AU)

Response surface methodology as a predictive tool for determining the effects of preparation conditions on the physicochemical properties of poly(isobutylcyanoacrylate) nanoparticles.

Preparation conditions of nanoparticles greatly influence their physicochemical characteristics. A factorial design was used to evaluate the influence of these conditions on the particle diameter, zeta potential, polydispersity, percentage recovery, and molecular weight of poly(isobutylcyanoacrylate) nanoparticles. The relationship between these responses and the effects of simultaneously varying three preparation factors (monomer concentration, surfactant concentration, pH of the polymerization medium) were modelled by response-surface methodology. Three levels were chosen for each factor, giving 27 trials. The responses obtained in the experimental design were found to be modelled by either a reduced quadratic or second-order model. Particle diameter was found to be a function of the pH, whereas zeta potential depended on pH and to a lesser extent of the monomer concentration. Polydispersity depended on the pH and an interaction term between pH and the surfactant concentration. The particle recovery was significantly influenced by all three factors, whereas the pH was the primary influence on the molecular weight. Thus, response surface methodology gave detailed information on the predicted physicochemical characteristics found on poly(isobutylcyanoacrylate) nanoparticles prepared using a wide range of experimental conditions.

Cyclodextrins and carrier systems.

This paper describes two new possibilities of using cyclodextrins to increase water solubility and bioavailability of poorly water-soluble drugs intended for targeting delivery by the oral or the parenteral route. They use either amphiphilic cyclodextrin nanoparticles or polymeric nanoparticles containing cyclodextrins. Amphiphilic skirt-shaped cyclodextrins, resulting from the esterification of primary hydroxyl groups by hydrocarbon chains varying from C6 to C14, are capable of forming spontaneously nanoparticles which have been loaded with a series of steroid drugs. The drug in the amphiphilic cyclodextrin nanoparticles is molecularly dispersed and can be released very rapidly. Poly(isobutylcyanoacrylate) nanoparticles can be loaded with natural or hydroxypropyl cyclodextrins. This technique results in a significant increase in the loading capacity of nanoparticles with a series of steroids and in a very rapid release of the drug. Both methods are described as well as their potential interest for water-insoluble drugs.

Combined poly(isobutylcyanoacrylate) and cyclodextrins nanoparticles for enhancing the encapsulation of lipophilic drugs.

PURPOSE: The aim of this study was to prepare and characterize nanoparticulate systems constituted of poly(isobutylcyanoacrylate) and cyclodextrins and intended for increasing the loading of the particles with lipophilic substances. Progesterone was used as a model substance. METHODS: Nanoparticles were prepared by polymerization of isobutylcyanoacrylate in presence of cyclodextrins or progesterone/ hydroxypropyl-beta-cyclodextrin complex. Particle size, zeta potential, cyclodextrin and progesterone loading of the particles were determined. RESULTS: Nanoparticles could be easily prepared in presence of cyclodextrins. An increase in hydroxypropyl-beta-cyclodextrin concentration resulted in small nanoparticles (less than 50 nm). It was found that large amounts of cyclodextrins remained associated to the particles, resulting in a 50 fold increase in progesterone loading compared to nanoparticles prepared in absence of cyclodextrins. CONCLUSIONS: The poly(isobutylcyanoacrylate)cyclodextrin nanoparticles were characterized by the presence of many lipophilic sites belonging to the cyclodextrins which were firmly anchored to the structure of the particles. Therefore, this new type of nanoparticles offers probably an opportunity for increasing the loading of nanoparticles with various lipophilic drugs.