Oil/water and pre-emulsified oil/water (PIT) dispersions in a stirred vessel: Implications for fermentations

This study examines dispersions of rapeseed oil (RSO) in water by mechanical agitation under conditions mimicking those found in certain antibiotic fermentations; for example, in the presence of air, antifoam, and finely divided CaCO(3) particles. A problem with residual oil has been reported for such fermentations, and it has been suggested that the use of pre-emulsified oil can reduce this problem. Hence, the dispersion of a pre-emulsified oil produced by the "phase inversion temperature (PIT) method" has been evaluated. In both cases, the volume fraction of oil was 2%. For the RSO systems, a relatively high agitation speed was required to disperse the oil, especially in the presence of the particles and, when the agitation was stopped, separation occurred rapidly. The Sauter mean drop diameters depended on the system, being at an average energy dissipation rate of approximately 0.9 W kg(-1), 180 microm for RSO/water, 130 microm for RSO/water(antifoam)/air, 580 microm for RSO/water/CaCO(3), and 850 microm for RSO/water(antifoam)/air/CaCO(3). For the same four systems, the PIT emulsion, once dispersed, was very stable and the drop size was essentially independent of the operating conditions, with a Sauter mean diameter of approximately 0.3 microm. The implications of these findings for fermentations in which oil is used as a carbon source are assessed.     

Nano-liposomal dry powder inhaler of tacrolimus: preparation, characterization, and pulmonary pharmacokinetics

The studies were undertaken to evaluate feasibility of pulmonary delivery of liposomaly encapsulated tacrolimus dry powder inhaler for prolonged drug retention in lungs as rescue therapy to prevent refractory rejection of lungs after transplantation. Tacrolimus encapsulated liposomes were prepared by thin film evaporation technique and liposomal dispersion was passed through high pressure homogenizer. Tacrolimus nano-liposomes (NLs) were separated by centrifugation and characterized. NLs were dispersed in phosphate buffer saline (PBS) pH 7.4 containing different additives like lactose, sucrose, and trehalose, and L-leucine as antiadherent. The dispersion was spray dried and spray dried powders were characterized. In vitro and in vivo pulmonary deposition was performed using Andersen Cascade Impactor and intratracheal instillation in rats respectively. NLs were found to have average size of 140 nm, 96% +/- 1.5% drug entrapment, and zeta potential of 1.107 mV. Trehalose based formulation was found to have low density, good flowability, particle size of 9.46 +/- 0.8 microm, maximum fine particle fraction (FPF) of 71.1 +/- 2.5%, mean mass aerodynamic diameter (MMAD) 2.2 +/- 0.1 microm, and geometric standard deviation (GSD) 1.7 +/- 0.2. Developed formulations were found to have in vitro prolonged drug release up to 18 hours, following Higuchi's Controlled Release model. In vivo studies revealed maximal residence of tacrolimus within lungs of 24 hours, suggesting slow clearance from the lungs. The investigation provides a practical approach for direct delivery of tacrolimus encapsulated in NLs for controlled and prolonged retention at the site of action. It may play a promising role as rescue therapy in reducing the risk of acute rejection and chronic rejection.     

An electronmicroscopic study of the distribution of myelin basic protein in multilayer dispersions of diacylphosphatidylserine

Although dispersions containing lipid and protein are widely used as model systems to explore the properties of biomembranes, the extent of mixing of the two components has generally not been determined. Here, the distribution of bovine myelin basic protein in dispersions with bovine brain L-alpha-diacylphosphatidylserine (PS) has been examined electronmicroscopically. Dispersions of PS were prepared by hydrating a known amount of dried lipid with buffer or with buffer containing an equal weight of myelin basic protein or lysozyme. The lipid-protein complexes were separated from unbound protein by centrifugation in 0-60% sucrose density gradients. In both systems only a few percent of the protein was unbound and the resultant recombinants, which gave single bands on the gradients, contained about 50% protein by weight. After removal of the sucrose by dialysis the dispersions were fixed in 2.5% glutaraldehyde and 1% osmium tetroxide, dehydrated and embedded in epoxy resin. Thin sections cut from these blocks were incubated, after removal of osmium tetroxide, with antiserum raised in rabbits against human myelin basic protein. Excess antiserum was removed and the antigen-antibody complexes on the thin sections were labelled with 13 nm diameter colloidal gold particles stabilized with protein A. The distributions of these gold particles were examined under an electronmicroscope. Comparison of the labelling patterns for PS, PS-lysozyme and PS-basic protein demonstrated specific labelling in the last, and showed the gold particles to be uniformly dispersed. It was concluded that in these dispersions the protein and lipid were intimately mixed at the molecular level.     

Human Y-chromatin : I. Dispersion and condensation

The fluorescent Y-body was observed to manifest striking variations in morphology in interphase lymphocyte and fibroblast nuclei. These variations appeared to be largely independent of the specific fixation or hypotonic treatment. The Y-chromatin body ranged from a highly condensed mass to a constellation of smaller discrete particles. Dispersion of Y-chromatin was not seen in mitotically inactive cells from buccal mucosa and hair root sheaths. Comparison of uncultured and cultured lymphocytes confirmed a higher proportion of dispersed Y-bodies in cultured cells, particularly those with a relatively large mean nuclear diameter. In serially cultured lymphocytes, the frequency of Y-body dispersion showed a direct relationship to the time in culture. Mean nuclear diameter also increased directly with time in culture. In cultured fibroblasts dispersion of the Y-body increased during the logarithmic phase of growth and declined during the post-logarithmic phase.     

Lignin-based electrospun nanofibers reinforced with cellulose nanocrystals

Lignin-based fibers were produced by electrospinning aqueous dispersions of lignin, poly(vinyl alcohol) (PVA), and cellulose nanocrystals (CNCs). Defect-free nanofibers with up to 90 wt % lignin and 15% CNCs were achieved. The properties of the aqueous dispersions, including viscosity, electrical conductivity, and surface tension, were examined and correlated to the electrospinnability and resulting morphology of the composite fibers. A ternary lignin-PVA-water phase diagram was constructed as a tool to rationalize the effect of mixing ratios on the dispersion electrospinability and morphology of the resulting fibers. The influence of reinforcing CNCs on the thermal properties of the multicomponent fibers was investigated by using thermal gravimetric analysis and differential scanning calorimetry. The thermal stability of the system was observed to increase owing to a strong interaction of the lignin-PVA matrix with the dispersed CNCs, mainly via hydrogen bonding, as observed in Fourier transform infrared spectroscopy experiments.     

Nonlamellar liquid crystalline nanostructured particles: advances in materials and structure determination

Analogous to the dispersion of lamellar phase-forming lipids to form liposomes, dispersion of lipids that form alternative liquid crystalline structures, such as cubic and hexagonal phase, forms particles termed cubosomes and hexosomes, respectively. Although these particles possess alternative structural forms and hence behavior, when compared to liposomes, they have received significantly less attention in the literature. While most studies have utilized glyceride lipids to prepare nonlamellar dispersions, recent advances in identifying new materials from which to prepare these particles has broadened the interest in this field. This review focuses on the materials used to form nonlamellar dispersions and the methods used to characterize their structure. Increased awareness of their structural characteristics and hence potential benefits in applications, such as drug delivery, is hoped to stimulate further studies that will ultimately see their uptake in commercial products.     

Development of prednisone: Polyethylene glycol 6000 fast-release tablets from solid dispersions: Solid-state characterization, dissolution behavior, and formulation parameters

The aim of the current study was to design oral fast-release polymeric tablets of prednisone and to optimize the drug dissolution profile by modifying the carrier concentration. Solid dispersions were prepared by the solvent evaporation method at different drug:polymer ratios (wt/wt). The physical state and drug:carrier interactions were analyzed by X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. The dissolution rate of prednisone from solid dispersions was markedly enhanced by increasing the polymer concentration. The tablets were prepared from solid dispersion systems using polyethylene glycol (PEG) 6000 as a carrier at low and high concentration. The results showed that PEG 6000-based tablets exhibited a significantly higher prednisone dissolution (80% within 30 minutes) than did conventional tablets prepared without PEG 6000 (<25% within 30 minutes). In addition, the good disintegration and very good dissolution performance of the developed tablets without the addition of superdisintegrant highlighted the suitability of these formulated dosage forms. The stability studies performed in normal and accelerated conditions during 12 months showed that prednisone exhibited high stability in PEG 6000 solid dispersion powders and tablets. The X-ray diffraction showed that the degree of crystallinity of prednisone in solid dispersions decreased when the ratio of the polymer increased, suggesting that the drug is present inside the samples in different physical states. The Fourier transform infrared spectroscopic studies showed the stability of prednisone and the absence of well-defined drug:polymer interactions. Scanning electron microscopy images showed a novel morphology of the dispersed systems in comparison with the pure components.     

Release of phospholipids from colloidal particles to polymeric surfaces

This study presents a small-scale polymerization of high molecular weight methyl methacrylate/n-butyl acrylate (MMA/n-BA) colloidal particles that are synthesized in an aqueous environment in the presence of phospholipid hydrogenated soybean phosphatidylcholine (HSPC) molecules that also serve as the particle stabilizing agents. When such particles coalesce to form polymeric films, they release phospholipids, which, in turn, form organized structures near the film-air (F-A) interface. Diffusion and mobility of phospholipid molecules are affected not only by their compatibility with colloidal particles but also by electrolyte environments of colloidal dispersions. When Na(+), K(+), and Ca(2+) counterions are added to MMA/n-BA aqueous colloidal dispersions stabilized with HSPC, and such films are coalesced, different degrees of diffusion of HSPC to the F-A interface exist, depending on the counterion, and conformational changes of HSPC result. For example, in the presence of Ca(2+), HSPC molecules collapse entropically to form random surface layers, as opposed to smaller Na(+) and K(+), which force amphiphilic HSPC ends to align preferentially parallel to the film surface. These studies show that it is possible to design stimuli-response colloidal systems triggered by chemical environments of active molecules on colloidal polymer particles.     

Water-stable all-biodegradable microparticles in nanofibers by electrospinning of aqueous dispersions for biotechnical plant protection

Pheromone eluting oligolactide (OLA) microcapsules immobilized in electrospun biodegradable polyester nanofibers were obtained by electrospinning of aqueous dispersions of the microcapsules. OLA was prepared by conventional melt polycondensation of lactic acid. Following the protocol of the solvent displacement method, OLA was dissolved in acetone and mixed with Brij S20 and the pheromone of the European grape vine moth, Lobesia Botrana, (E,Z)-7,9-dodecadien-l-yl acetate (DA). Up to 32 wt % of this mixture could be dispersed in water with colloidal stability of several weeks without any sedimentation. Without DA as well as OLA, no stable dispersions of OLA in water were obtained. Replacement of DA by classical hydrophobes typically used for miniemulsions did not yield stable dispersions, but the addition of octyl acetate, which shows structural similarity to DA, yielded stable dispersions in water up to 10 wt %. Dispersions of OLA/DA were successfully electrospun in combination with an aqueous dispersion of a biodegradable block copolyester resulting in water-stable nanofibers containing OLA/DA microcapsules. Release of DA from microcapsules and fibers was retarded in comparison with non-encapsulated DA, as shown by model studies.     

Co-electrospun nanofiber fabrics of poly(L-lactide-co-epsilon-caprolactone) with type I collagen or heparin

Functionally designed elastomeric nanofiber fabrics made of the equimolar copolyester, poly(L-lactide-co-epsilon-caprolactone) (PLCL), with type I collagen or the tri-n-butylamine salt of heparin (heparin-TBA) were co-electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as a solvent. The co-electrospun fabrics (mixing ratio: 0, 5, 10, 30, 50, 70, and 100 wt % of collagen to PLCL) consisted of nanoscale fibers with a mean diameter ranging from approximately 120 to 520 nm. An increase in collagen content in the solution resulted in a decrease in the mean diameter of fibers. Transmission electron microscopy (TEM) showed that collagen in a co-electrospun fiber was phase-separated to form a dispersed phase, which was localized in the interior and peripheral region in the continuous matrix phase of fibers. The tensile strength was decreased with increasing collagen content. Human umbilical vein endothelial cells (HUVECs) were highly elongated and well spread on the fibrous surfaces of fabrics made of PLCL with 5 wt % or 10 wt % collagen. Heparin-TBA (mixing ratio: 1, 5, and 10 wt % to PLCL), soluble in HFIP, was co-electrospun with PLCL to form a fabric. TEM observation showed that heparin-TBA formed as a dispersed phase in a PLCL nanofiber. The releasing rate, released amount, and surface content of heparin-TBA were increased with increasing heparin-TBA content in co-electrospun fabrics. The potential biomedical application of co-electrospun PLCL with type I collagen or heparin-TBA was discussed.     

Film formation from colloidal dispersions stabilized by sugar derivatives and their controllable release for selective protein adsorption

Although the use of sugar and sugar derivatives has been documented in polymer research for many years, there are no reports that would utilize these species as polymerization sites of colloidal polymeric particles that, later on, may be released during particle coalescence to form films with surfaces that differentiate protein adsorption. These studies show that, when n-dodecyl-beta-D-maltoside (DDM) is utilized for the synthesis and stabilization of poly[methyl methacrylate-co-(n-butyl acrylate)] (p-MMA/nBA) colloidal particles, upon particle coalescence DDM stratifies near the film-air (F-A) interface. By using attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and internal reflection infrared imaging (IRIRI), comparative adsorption studies on p-MMA/nBA surfaces exposed to globulin (Glo), fibrinogen (Fib), and bovine serum albumin (BSA) reveal that the presence of DDM selectively inhibits Glo and Fib adsorption, but does not affect BSA. The presence of DDM also enhances the rate of mobility of sodium dioctylsulfosuccinate (SDOSS) resulting from interactions between DDM and SDOSS moieties, and the surface morphologies change as a result of concentration variations of DDM in the colloidal dispersions.     

The influence of particle size distribution and operating conditions on the adsorption performance in fluidized beds

The influence of matrix properties and operating conditions on the performance in fluidized-bed adsorption has been studied using Streamline diethyl-aminoethyl (DEAE), an ion exchange matrix based on quartz-weighted agarose, and bovine serum albumin (BSA) as a model protein. Three different particle size fractions (120-160 mum, 120-300 mum, and 250-300 mum) were investigated. Dispersion in the liquid phase was reduced when particles with a wide size distribution were fluidized compared to narrow particle size distributions. When the mean particle diameter was reduced, the breakthrough capacities during frontal adsorption were enlarged due to a shorter diffusion path length within the matrix. At small particle diameters the effect of film mass transfer became more relevant to the adsorption performance in comparison to larger particles. Therefore matrices designed for fluidized-bed adsorption should have small particle diameter and increased mean particle density to ensure small diffusion path length in the particle and a high interstitial velocity to improve film mass transfer. Studies on the influence of sedimented matrix height on axial mixing showed an increased Bodenstein number with increasing bed length. Higher breakthrough capacities were also found for longer adsorbent beds due to reduced dispersion and improved fluid and particle side mass transfer. With increasing bed height the influence of flow rate on breakthrough capacity was reduced. For a settled bed height of 50 cm breakthrough capacities of 80% of the equilibrium capacity for flow rates varying from 3 to 9 cm/min could be achieved. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 54-64, 1997.     

Effect of filler content and size on transport properties of water vapor in PLA/calcium sulfate composites

Starting from calcium sulfate (gypsum) as fermentation byproduct of lactic acid production process, high-performance composites have been produced by melt-blending polylactide (PLA) and beta-anhydrite II (AII) filler, i.e., calcium sulfate hemihydrate previously dried at 500 degrees C. Characterized by attractive properties due to good filler dispersion throughout the polyester matrix and favorable interactions between components, these composites are interesting for potential use as biodegradable rigid packaging. The effect of filler content and mean particle diameter on the barrier properties such as sorption and diffusion to water vapor has been examined and compared to unfilled PLA. Even without additional treatments, the presence of the filler introduced constraints on molecular mobility in the permeable phase of amorphous PLA and the amount of solvent absorbed appears lower in the highly filled composites. Surprisingly, for PLA-30% AII compositions, by addition of filler characterized by high mean particle diameter (e.g., 43 microm) the thermodynamic diffusion parameter, D(0), decreased up to 2 orders of magnitude. The dimension of filler particles and their percentage in the continuous polymeric phase seem to be the most important parameters that determine the barrier properties of the PLA-AII composites to water vapor.     

New Nanometric Solid Dispersions of Glibenclamide in Neusilin<Superscript>®</Superscript> UFL2

To improve the poor water solubility and dissolution rate of the oral hypoglycemic drug glibenclamide, it was molecularly dispersed in Neusilin^® UFL2, an amorphous synthetic form of magnesium aluminometasilicate, at different proportions; the physicochemical and biopharmaceutical properties, as well as the stability of the four different batches recovered were characterised, and it was determined that complete dispersion of glibenclamide in the amorphous polymer was obtained at the drug to Neusilin ratio of 1 to 2.5. Completely amorphous dispersion was proven by Thermal Analysis and X-Ray Powder Diffractometry. Very small particles were obtained, ranging from approximately 200 to 400 nm. The amorphous batches were physically and chemically stable for the entire duration of experiments. The physicochemical properties of the four batches were compared to those of the starting materials and physical mixtures of Neusilin^® UFL2 and glibenclamide, the latter showing the typical behaviour of simple mixes, i.e., the additivity of properties of single components. The dissolution studies of the four solid dispersions revealed a very high dissolution rate of the completely amorphous batches (Batches 3 and 4), behaviour that was ascribed to their high Intrinsic dissolution rate due to the amorphous characteristics of the solid dispersions, to their very small particle size, and to the presence of polysorbate 80 that improved solid wettability. The technique under investigation thus proved effective for recovering stable amorphous dispersions of very small particle sizes.     

Nanostructured microspheres produced by supercritical fluid extraction of emulsions

The system poly(lactic-co-glycolic) acid/ piroxicam (PLGA/PX) was selected, as a model system, to evaluate the effectiveness of supercritical carbon dioxide (SC-CO(2)) extraction of the oily phase (ethyl acetate) from oil-in-water emulsions used in the production of polymer/drug microspheres for sustained drug release applications. The influence of process parameters like operating pressure and temperature, flow rate and contacting time between the emulsion and SC-CO(2) was studied with respect to the microsphere size, distribution and solvent residue. Different polymer concentrations in the oily phase were also tested in emulsions formulation to monitor their effects on droplets and microspheres size distribution at fixed mixing conditions. Spherical PLGA microspheres loaded with PX (10% w/w) with mean sizes ranging between 1 and 3 microm and very narrow size distributions were obtained due to the short supercritical processing time (30 min) that prevents the aggregation phenomena typically occurring during conventional solvent evaporation process. A solvent residue smaller than 40 ppm was also obtained at optimized operating conditions. DSC and SEM-EDX analyses confirmed that the produced microparticles are formed by a solid solution of PLGA and PX and that the drug is entrapped in an amorphous state into the polymeric matrix with an encapsulation efficiency in the range of 90-95%. Drug release rate studies showed very uniform drug concentration profiles, without any burst effect, confirming a good dispersion of the drug into the polymer particles.     

Polymorphic phase behavior of lysopalmitoylphosphatidylcholine in poly(ethylene glycol)-water mixtures

The polymorphic phase behavior of 1-palmitoyl-2-lyso-sn-glycero-3-phosphocholine dispersions in excess water has been studied as a function of temperature and poly(ethylene glycol) (PEG) concentration, using proton dipolar-decoupled 31P NMR spectroscopy and turbidity measurements. The phase behavior was found to depend on both lipid concentration and PEG concentration, and most of the NMR experiments were conducted at a lipid concentration of 15 mg/mL. At low PEG concentrations (0-12 wt %), a thermotropic transition occurs at 3-5 degrees C with increasing temperature, from an interdigitated lamellar gel (L beta i) phase to a normal micellar phase. At intermediate PEG concentrations (12-20 wt %), thermotropic transitions take place with increasing temperature, first from the lamellar gel phase to a fluid cubic (Q alpha) phase and then at higher temperatures from the cubic phase to the micellar phase. At intermediate PEG concentrations above the former range (20-30 wt %), thermotropic transitions take place with increasing temperature, first from the lamellar gel phase to the cubic phase, then from the cubic phase to a normal hexagonal (HI) phase, and finally from the hexagonal phase to the micellar phase. At high PEG concentrations (greater than 30 wt %), a thermotropic transition takes place with increasing temperature from the lamellar gel phase directly to the fluid hexagonal phase. At these high PEG concentrations, the micellar phase is not attained within the accessible temperature range (less than or equal to 90 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of hydrophilic swellable polymers on dissolution enhancement of carbamazepine solid dispersions studied using response surface methodology

The objective of this work was to study dissolution enhancement efficiency and solid dispersion formation ability of hydrophilic swellable polymers such as sodium carboxymethyl cellulose (Na-CMC), sodium starch glycolate (SSG), pregelatinized starch (PGS), and hydroxypropylmethyl cellulose (HPMC) with carbamazepine using 3² full factorial design for each of the polymers. Solid dispersions of carbamazepine were prepared using solvent evaporation method with around 70% solvent recovery. The independent variables were the amount of polymer and organic solvent. The dependent variables assessed were percentage drug dissolved at various time points and dispersion efficiency (ie, in terms of particle size of solid dispersion). Solid dispersions were evaluated for percentage drug dissolved, wettability, differential scanning calorimetry, scanning electron microscopy, and angle of repose. Multiple linear regression of results obtained led to equations, which generated contour plots to relate the dependent variables. Similarity factor and mean dissolution time were used to compare dissolution patterns obtained in distilled water and simulated gastric fluid United States Pharmacopeia (USP) XXVI of pH 1.2. Maximum drug dissolution was obtained with polymer order Na-CMC>SSG>PGS>HPMC. Particle size of drug was reduced ≈ 10–15, 3–5, 5–7, and 10–25 times in Na-CMC, SSG, PGS, and HPMC solid dispersions, respectively; whereas wettability of solid dispersions was found in the order of Na-CMC>HPMC>PGS>SSG. Angle of repose was found to be in the range of 29° to 35° for all solid dispersions, which shows good flowability characteristics. HPMC showed increase in drug dissolution up to an optimized level; however, furthers increase in its concentration decreased drug dissolution. Published: April 6, 2007     

Axial dispersion in plate-pulsed columns

The residence time distribution (RTD) of the phase under continuous flow and dispersed flow was measured in a plate-pulsed column under countercurrent liquid-liquid flow, and modelled using (i) the axial dispersion model and (ii) the noninteger ideal stage cascade model. The axial mixing in the continuous phase was found to be significantly higher than in the dispersed phase. The model parameters were related to the operating conditions and system variables.     

Formation of flower- or cake-shaped stereocomplex particles from the stereo multiblock copoly(rac-lactide)s

Flower- or cake-shaped particles with uniform particle size ranging from nanometers to micrometers were prepared from the stereo multiblock copoly(rac-lactide)s (smb-PLAs) by precipitating the polymer from its solution in methylene chloride/ethanol via three different methods: slowly lowering the solution temperature, slowly evaporating the solvent, and slowly adding a nonsolvent. Under the same condition, sheet-shaped crystals in 10 mum size but not particles were obtained from the pure PLLA with almost the same molecular weight. Electron diffraction and WAXD data demonstrated that the stereocomplex particles belonged to the monoclinic system. All three methods resulted in particles with identical morphology and almost the same particle size. At a given stereoregularity of 88%, as the molecular weight of the polymer increased from 8700 to 23,200 Da, the crystallinity decreased, the particle morphology changed from flower-shaped to cake-shaped, and the diameter and height of the particles increased from 0.8 and 0.45 to 3.6 microm and 2.0 microm, respectively. The initial concentration of the polymer solution influenced the particle size slightly but affected the morphology markedly. On the basis of the above experimental observations, it was proposed that the smb-PLA particles of flower- or cake-shape were formed in four steps: (1) complexation in solution of the smb-PLA chains; (2) particle nucleation; (3) particle growth in the width direction; and (4) particle growth in the height direction. The curvature of the paired smb-PLA chains and the inner stress governed the particle size, and the interconnection between the neighboring particles determined the layered structure and the package density of the particles formed.     

Particles of liquid-crystalline dispersions formed by (nucleic acid-rare earth element) complexes as a potential platform for neutron capture therapy

Microscopic size particles of the cholesteric double-stranded DNA (RNA) liquid-crystalline dispersions, containing the ions of the rare earth elements in their content, have been obtained for the first time. The properties of these particles differ from those of classical DNA cholesterics noticeably. The local concentration of the rare earth elements in a particle reaches 200 mg/ml. The particles of the liquid-crystalline dispersion of the (DNA-gadolinium) complex maintain the properties for a long time. The combination of the microscopic size of particles, high concentration of gadolinium in particles and their stability opens a way to practical application of this new biomaterial.