Stable Polyelectrolyte Complexes Research Articles

Исследование возможности получения лигносульфонатного реагента на основе комплексных соединений для регулирования параметров бурового раствора

Investigation of the possibility of obtaining a reagent for regulating the parameters of drilling mud based on complex compounds by introducing complex-forming Fe (II) cations into the composition of sodium lignosulfonate, followed by additional modification with phosphonic compounds and obtaining a polyelectrolyte complex based on anionic polyelectrolyte-sodium lignosulfonate and modified cationic starch. The presence of functional groups of the studied sodium lignosulfonate capable of complexation was established by IR spectrometry. The determination of the optimal ratios of the initial components for the production of complex compounds based on lignosulfonate, iron sulfate and phosphonic compounds was carried out.Studies of the surface activityof experimental samples were carried out by the stalagmometric method (the method of counting drops). In order to study changes in the structure of a macromolecule of sodium lignosulfonate and a polyelectrolyte complex based on sodium lignosulfonateand cationic starch, the particle size distribution method was investigated. Obtaining a stable polyelectrolyte complex, by selecting the molar ratios of anionic and cationic components, consisted in measuring the dependence of the impedance of an electrochemical cell on the frequency of alternating current. The possibility of using the obtained lignosulfonate reagent based on complex compounds as a reagent for regulating the parameters of the drilling fluid at temperatures from 20 to 160-180°C.

Self-supporting biocatalytic polyelectrolyte complex hollow fiber membranes via salt-dilution induced phase separation

The potential use of biocatalytic membranes in industries such as water treatment, pharmaceuticals, and medicine has attracted much interest in recent years. However, the use of organic solvents in traditional membrane fabrication techniques presents a challenge in the direct integration of enzymes during the membrane production. Thus, enzyme immobilization relies on consecutive modification steps (coating, binding, activation). Yet, recent progress in membrane fabrication using all-aqueous phase inversion of polyelectrolyte complexes (PEC) enables the direct incorporation of enzymes in the polymer solution. We present the fabrication of free-standing, defect-free and mechanically stable biocatalytic PEC hollow fiber membranes via the salt-dilution induced phase separation method. A polymer solution containing poly(sodium-4-styrenesulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDADMAC), KBr, and the enzyme alkaline phosphatase (ALP) was extruded through a spinneret with a mixture of water and glycerol as lumen fluid into a water coagulation bath at 0 °C. The mechanical stability of the fibers is tuned by subsequent photo-induced cross-linking using 4,4’-diazidostilbene-2,2’-difulfonate tetrahydrate (DAS) and UV light. The resulting membranes have a molecular weight cut-off of 400Da, a pure water permeance of 1.5LMH/bar, and a burst pressure of 7bar. The immobilization of ALP proves successful, as the immobilized shows similar catalytic activity to that of the free enzyme, and both storage and thermal stability are improved. Moreover, the enzymes retain 70% of their initial activity after UV cross-linking with DAS and maintain their catalytic activity after repeated wash and filtration cycles. This work highlights the versatility of the fabrication of polyelectrolyte complex hollow fiber membranes via the salt-dilution induced phase separation, serving as a platform technology for the fabrication of porous, selective, and bioactive membranes.

A Novel Family of Stable Polyelectrolyte Complexes Based on Mixed Olefins-Maleic Anhydride Copolymer.

In the present study, the copolymer of mixed olefins included in unetherified gasoline and maleic anhydride (PUGM) was prepared by self-stabilized precipitation polymerization (2SP) and employed for the synthesis of a new family of stable polyelectrolyte complexes (PECs). Polyanionic saponified PUGM partially grafted with methoxy poly(ethylene glycol) (PUGMS-g-mPEG) and polycationic quaternized PUGM (PUGMQ) were both derived from PUGM via the facile modification of anhydride groups. The particle size, zeta potential, morphology, and stability of self-assembled PEC particles were investigated thoroughly. Strikingly, the introduction of long mPEG side chains (Mn = 4000) had a remarkable effect on the self-assembled particles, which displayed a constant particle size of ∼200 nm regardless of varying n+/n-. Moreover, it also enhanced the salt tolerance and long-term stability of PEC particles significantly. Our work not only provides an effective approach to PECs from petroleum resources with low cost but also deepens the understanding of the relationship between the chain structure of polyelectrolytes and the stability of PECs.

Eco-Friendly and Facile Integrated Intumescent Polyelectrolyte Complex Coating with Universal Flame Retardancy and Smoke Suppression for Cotton and its Blending Fabrics

Cotton and its blended fabrics are widely used textile materials in daily life; however, their high flammability brings serious fire hazards. It remains a huge challenge to endow cotton and its blended fabrics through simple and universal technology. In this work, a novel water-based polyelectrolyte complex (PEC) coating was developed from chitosan and a water treatment agent (amino trimethylphosphonic acid). By controlling the degree of ion pair aggregation through pH adjustment, the intumescent and stable PEC coating can be constructed quickly via facile blading coating and curing processes. High transparency allows for the deposition of the coating with little effect on the original pattern of the coated fabric. Additionally, when the coated fabrics were exposed to flame, the PEC coating underwent a quick self-char-forming reaction in advance and formed a protective char layer covered on the fibers. Thus, the PEC coating with low adding-on (11.5–21.5 wt %) shows universally high flame retardancy for cotton, polyester/cotton blends, and polyester/poly(vinyl alcohol)/cotton blends. The coated fabrics show excellent extinguishing performances, high limiting oxygen index values of 27.5%–28.5%, and total release smoke inhibition of 42%. This work provides a promising universal technology for manufacturing fire-safety cotton and its blends in a simple and eco-friendly way.

Chitosan-xanthan gum PEC-based aerogels: A chemically stable PEC in scCO2

An innovative aerogel obtained from a chitosan/xanthan gum polyelectrolyte complex (PEC) was developed in this work from the screening of thirteen different combinations of natural polyelectrolytes: two positively-charged biopolymers (chitosan and gelatin A), six negatively-charged biopolymers (pectin, iota-carrageenan, collagen, xanthan gum, alginate and modified galactomannan), and a neutral polymer (guar gum) using the statistical design of experiments (DOE) approach. Only the chitosan-xanthan gum formed aerogels under supercritical conditions using carbon dioxide at 150 bar and 250 bar and 35 °C. The chitosan-xanthan gum-based aerogels have bone-like structures and smooth surfaces, with pore size distributions in the meso- and macropore ranges, the average pore diameter of ∼20 nm and porosity between 60 and 70%. The specific surface areas of the aerogels processed at 150 bar and 250 bar are, respectively, 5.7 and 17.5 m2 g−1, values below those commonly reported in the literature for aerogels. The aerogels are thermally stable up to ∼240 °C, while the cryogel is thermally stable up to ∼224 °C. The value of the total weight loss through thermal decomposition of the aerogels (∼25%) is smaller than that of the cryogel (∼40%). These materials have potential applications in the environmental and biomedical areas, providing solutions to the current challenges in biomedicine and social, demographic and sanitary life sciences.

Conditions of Formation of Stable Polyelectrolyte Complexes Based on N-Succinyl Chitosan and Poly-N,N-diallyl-N,N-dimethylammonium Chloride

Conditions of Formation of Stable Polyelectrolyte Complexes Based on N-Succinyl Chitosan and Poly-N,N-diallyl-N,N-dimethylammonium Chloride

Electrospun AgNPs-polylactate nanofibers and their antimicrobial applications

Silver nanoparticles (AgNPs) have been one of the most significant nanoparticles due to their interesting characteristics, such as high antimicrobial activity. Thus, they have been applicable for wound dressing, protective textiles and tissue scaffold. In the current study, novel polylactate copolymer was prepared via condensation of lactic acid (LA) and methacrylic acid (MAA) at molar ratio of 95:5, and then the produced copolymer was subjected to free radical polymerization in the presence of N, N-methylene diacrylamide (MDA) as a cross-linking agent. AgNPs were synthesized utilizing chitosan (Cs) as reductive and stabilizing agent. The generation of AgNPs was proved with UV–Vis absorbance spectra, and transmission electron microscopy (TEM) which displayed different morphologies of AgNPs relying on the heating period. The chemical formula of the polylactate sodium salt (PLS) polymer was verified with FT-IR and 1H NMR spectra. Cs-AgNPs nanohybrid was coated into an electrospun nanofibrous membrane of the cross-linked polylactate calcium salt (PLCS) to create stable polyelectrolyte complex (PEX) nanofiber-based composites with high antimicrobial activity. The produced nanohybrids were studied by X-ray diffraction (XRD), energy-dispersive X-ray analyzer (EDX), scan electron microscopy (SEM), elemental mapping and Fourier-transform infrared spectroscopy (FT-IR). AgNPs were effectively immobilized onto the PEX nanofiber-based composite, whilst there was complex generated among the electrospun PLCS and the Cs-AgNPs nanohybrid. The developed nanofibrous mats demonstrated an improved saline absorbance in the presence of AgNPs. AgNPs exhibited a homogeneous dispersion and high deposition density on the surface of nanofibers demonstrating a nanoparticle size of 7–23 nm. In addition, the silver immobilized PLCS fibers showed an improved absorbance of 0.85% (w/v) saline solution compared to blank fibers. PEX displayed high antimicrobial efficiency against gram positive and gram negative bacterial pathogens with satisfactory permeability of water vapor in the range necessary for treating wounds.

A mixed-charge polyelectrolyte complex nanofiltration membrane: Preparation, performance and stability

Ion selectivity of nanofiltration (NF) membranes is a critical factor in NF treatment of scaling-prone multi-ion effluents, such as wastewater. When removal of multivalent ions in such effluents is unnecessary or undesired, adjusting their rejection may mitigate scaling, in which case membranes combining oppositely charged electrolytes enable a tunable selectivity towards such ions. Here we report the fabrication of a new tunable and highly stable polyelectrolyte complex NF membrane prepared by successively coating an ultrafiltration membrane support with negatively charged Nafion and positively charged polyvinylamine (PVAm) layers. While Nafion thickness controls the membrane permeability, the second PVAm coating is critical for eliminating defects in the Nafion layer and readily tunes the membrane net charge and, hence, ion selectivity via PVAm concentration in the coating solution. In this manner, a membrane with good permeability, balanced charge, and, therefore, equal (“symmetric”) rejection of divalent anions and cations is obtained. The membrane performance is unaffected by exposure to 10% salt in water; such remarkable stability for a polyelectrolyte-based membrane makes it potentially attractive for the treatment of wastewater effluents and brackish water sources.

Использование пленок, обогащенных антоциановым пигментом, в качестве индикатора свежести рыбного фарша

Introduction. Smart food packaging that alerts consumers to spoilt food by changing color is based on affordable and biodegradable raw materials. The research objective was to develop films from anionic polysaccharides and anthocyanin pigment that can be used as a freshness indicator of minced fish.
 Study objects and methods. The study featured frozen black currant berries (Ríbes nígrum), polysaccharide-based anthocyanin films, and minced fish. Extracts of anthocyanin pigment and films based on agar, kappa-carrageenan, chitosan, starch, and anthocyanin pigments were analyzed by IR spectroscopy.
 Results and its discussion. Anionic polysaccharides, i.e. agar and kappa-carrageenan, demonstrated good film-forming properties. Films based on 1.5% agar and 2% kappa-carrageenan showed elasticity, resilience, plasticity, and sufficient resistance to mechanical deformation. Neutral polysaccharide starch and cationic polysaccharide chitosan appeared to have no such qualities. An IR spectral analysis revealed chemical interactions between polysaccharide and anthocyanin molecules. It indicated the electrostatic nature of the polyelectrolyte complexes of the anthocyanin pigment with anionic polysaccharides. A film based on 1.5% agar fortified with anthocyanin pigment was used as a test-system for analyzing the quality of fish. The minced fish samples were wrapped in the anthocyanin film and left for 2–7 min to register the color change of the film. When the anthocyanin film came in contact with fresh fish, the color of the film did not change even after prolonged contact. When the film came into contact with spoilt fish, the color of the film began to change after 2 min of contact. When the contact time reached 7 min, the film turned blue.
 Conclusion. The type of polysaccharide and the interaction between polysaccharides and anthocyanin pigment had a significant effect on film formation. Anionic polysaccharides demonstrated the best results. Electrostatic interactions between anionic polysaccharides and anthocyanin pigments produced stable polyelectrolyte complexes. The new smart films were able to determine the quality of minced fish.

Efficient Synthesis of Stable Polyelectrolyte Complex Nanoparticles by Electrostatic Assembly Directed Polymerization.

Polyelectrolyte complex nanoparticles with integrated advances of coacervate complexes and nanomaterials have attracted considerable attention as soft templates and functional nano-carriers. Herein, a facile and robust strategy, namely electrostatic assembly directed polymerization (EADP), for efficient and scalable preparation of stable coacervate nanoparticles is presented. With homo-polyelectrolyte PAA (polyacrylic acid) as template and out of charge stoichiometry, the cationic monomers are polymerized together with cross-linkers, which creates coacervate nanoparticles featuring high stability against salt through one-pot synthesis. The particle size can be tuned by varying the cross-linker amount and salt concentrations during the polymerization and the composition of nanoparticles, as well as the corresponding properties can be regulated by combining different charged blocks from both strong and weak ionic monomers. The strategy can tolerate both high monomer concentrations and increased volume of up to l L, which is favorable for scaled-up preparations. Moreover, the coacervate nanoparticles can be freeze-dried to produce a product in powder form, which can be redispersed without any effect on the particle size and size distribution. Finally, the obtained nanoparticles loaded with enzyme and Au nanoparticles exhibit enhanced catalytic performance, demonstrating a great potential for exploring various applications of coacervate particles as soft and functional nano-carriers.

Thermodynamic mechanism of particulation of sodium alginate and chitosan polyelectrolyte complexes as a function of charge ratio and order of addition

This study focused on mechanistic understanding of the effect of charge ratio, order of addition and resulting thermodynamics of interaction on the formation and properties of polyelectrolyte complexes (PECs) from sodium alginate and chitosan at a constant tightly controlled pH 4 where the zeta potential difference was maximum for the formation of PECs. The morphology, particle size and particle size distribution as well as the stability of PECs were investigated as a function of molar charge ratio, and the order of addition. The association binding constant Ka and the stoichiometry of interaction between the two electrolytes, evaluated using Isothermal titration calorimetry, showed that the stoichiometry and enthalpy of reactions were strongly affected by the order of addition and influenced the average particle size and zeta potential of PECs. The addition of alginate (-) into chitosan (+) gave positively charged particles and resulted in stronger interactions characterized by larger enthalpy and entropy of complexation which led to smaller particles. Reversing the order of addition gave negatively charged particles that were larger. Morphologies of complexes studied using scanning electron microscopy (SEM) showed distorted spherical particles for both orders of addition and at most charge ratios. Stability during 8 weeks was found to depend on the order of addition and charge ratio. Alginate in chitosan gave more stable PECs consistent with the thermodynamics of interaction which showed stronger interactions for this order of addition. The particle sizes and size distributions rapidly increased near electrical neutrality during storage at 4 °C where aggregation was facilitated because of electrical neutrality but particles were stable when the net charge was either strongly positive or strongly negative.

Simple fabrication of inner chitosan-coated alginate hollow microfiber with higher stability.

Sodium alginate (NaA) has been widely used as microfiber-based scaffold material. However, Ca-alginate microfiber might disintegrate in the physiological environment due to the loss of calcium ions, which will limit its long-term application in tissue engineering. In this work, to enhance the stability of Ca-alginate microfiber in the physiological environment, an inner chitosan coating was introduced to Ca-alginate hollow microfiber by one step via a microfluidic device. A more stable composite microfiber with double cross-linking layers was generated. The stability of the microfiber was studied in the PBS solution (pH 7.4) to identify the coating effect on the hollow structure. The results revealed that chitosan component bonded an NaA layer to form a stable polyelectrolyte complex membrane in the inner wall of the microfiber, which stabilized the hollow region even though the Ca-alginate shell was disintegrated by PBS solution. In addition, the introduction of chitosan coating improved the inner environment of the low affinity of alginate to cell surfaces and facilitated the cell adhesion and culture in the microfiber. HepG2 cells in the microfibers displayed favorable cell viability and proliferation ability. We believe that this work will lead to the development of innovative methodologies and materials for both cell culture and tissue engineering application. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2527-2536, 2019.

Bioinspired baroplastic glycosaminoglycan sealants for soft tissues

We describe biomimetic adhesives inspired by the marine glues fabricated by the sandcastle worm. The formation of stable polyelectrolyte complexes between poly-L-lysine (PLL) and glycosaminoglycans (GAGs) with different sulfation degree – heparin (HEP), chondroitin sulfate (CS) and hyaluronic acid (HA) – is optimized by zeta-potential titrations. These PLL/GAG complexes are transformed into compact polyelectrolyte complexes (coPECs) with controlled water contents and densities via baroplastic processing. Rotational shear tests demonstrate that coPECs containing sulfated GAGs (HEP or CS) have solid-like properties, whereas HA-based complexes form highly hydrated viscous-like networks. The adhesiveness of the generated coPECs (normalized lap shear strength) is tested in dry and wet states using polystyrene and rabbit skin, respectively. In dry state, the adhesives exhibit lap shear strengths in the order of hundreds of kPa, with coPLL/HEP and coPLL/CS being about 1.5 times stronger than coPLL/HA. In wet state, all coPECs seal rabbit skin and recover over 60% of the elongation capacity of intact skin with coPLL/HA providing the sturdiest adhesion (∼85% elongation recovery). We demonstrate that this is due to the higher water fraction that improves the bonding between the wet specimens, showcasing the potential superior mechanical recovery on injured tissues. Statement of SignificanceThe development of medical sealants with sufficient adhesive strength in the presence of water and moist remains a huge challenge. We present glycosaminoglycans (GAGs) as biomaterials for the assembly of baroplastics with strong adhesive strength to soft tissues at physiological conditions. Baroplastics with tacky properties were generated by a mild assembly process based on polyelectrolyte complexation and compaction. These materials behave as versatile sealants: their adhesiveness can be adjusted to either dry or wet specimens because of the different sulfation degree of GAGs. These sealants were noncytotoxic towards L929 cells and allowed the damaged skin to recover a great deal of its native elasticity: they preserved the J-shaped stress/strain mechanical response that is typical of biological soft tissues.

Fabrication of Scaffold based on Chitosan – Poly-2-Acrylamido- 2-Methylpropane Sulfonic Acid (PAMPS) Polyelectrolyte Complexes

Chitosan is considered as one of the best biopolymers for bone tissue engineering application due to its appealing properties such as biocompatible, non-toxic, non-immunogenic, able to accelerate growth rate of bone tissue, possess antibacterial activity and able to form porous structure. Herein, polyelectrolyte complexes (PECs) prepared by simple mixing of chitosan solution and poly-2-acrylamido-2-methylpropane sulfonic acid (PAMPS) solution were investigated. In this study, chitosan concentration were varied from 1.0 to 2.0% (w/v), while concentration of AMPS was fixed at 0.1% (w/v) to know the influence of chitosan concentration on swelling capacity and mechanical properties of obtained PECs. Swelling test and compressive test results showed that the most stable PECs in aqueous environment with highest ultimate compressive strength was PECs obtained from chitosan 2.0% (w/v) – PAMPS 0.1% (w/v) with swelling capacity 3,326% for 2 hours and ultimate compressive strength 1.22 kPa.

Electrospun alginate nanofibres impregnated with silver nanoparticles: Preparation, morphology and antibacterial properties

Silver nanoparticles are amongst the most valuable nanoparticles with interesting properties, such as a non-toxic nature and high antibacterial efficiency, making them applicable for tissue scaffold, protective clothing and wound dressing. In this study, silver nanoparticles (AgNPs) have been synthesized using chitosan as reducing and stabilizing agent. The formation of silver nanoparticles was confirmed by UV-vis, and the TEM showed that different shapes were obtained depending on the heating duration. The chitosan/AgNPs was coated onto an electrospun alginate membrane to produce stable polyelectrolyte complex (PEC) nanofibre composites with high antibacterial efficiency. These composites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). AgNPs were successfully impregnated into the PEC nanofibre composite, while there was complexation between the electrospun alginate and the chitosan/AgNPs composite. PEC demonstrated a good antibacterial activity against both gram negative and gram positive bacteria with acceptable water vapour transmission within the range required for the treatment of injuries or wounds.

New nasal nanocomplex self-assembled from charged biomacromolecules: N,N,N-Trimethyl chitosan and dextran sulfate

Although chitosan (CHT, a linear cationic polysaccharide) is biodegradable, biocompatible, non-toxic, and mucoadhesive in nature, the low solubility of CHT in aqueous and alkaline media limits its applicability in pharmaceutical and biomedical field. This necessitate the introduction of new chemically-modified derivatives of CHT those can surmount the solubility barrier. Herein, N,N,N-trimethyl chitosan (TMC), a quaternized hydrophilic derivative of CHT, was synthesized by two-step reductive methylation of CHT and characterized for 1H NMR and zeta potential measurements. Polyelectrolyte complexes (PECs) based on TMC and dextran sulfate (DS) were prepared via ionic interactions between charged functional groups of former polysaccharides at different pH conditions (pH 5, 8, 10, and 12) and characterized for physicochemical (particle size and zeta potential) and solid- state characterizations (HR-TEM, SEM, FTIR, TGA and XRD). At alkaline pH conditions, the participant polymer chains (TMC and DS) are sufficiently close to form more stable PECs. The release efficiency was assessed after loading a model drug into optimized PEC formulation. Data indicated that the PECs fabricated at alkaline pH presents a reliable formulation for pharmaceutical and biomedical applications.

Pitch-Based Carbon Fibre-Reinforced PEEK Composites: Optimization of Interphase Properties by Water-Based Treatments and Self-Assembly

This work addresses the challenging fibre-matrix compatibilization and interface adhesion improvement of poly(etheretherketone) (PEEK) composites reinforced with pitch-based carbon fibre. An innovative and environmentally friendly method, inspired both by supramolecular “layer-by-layer” (LBL) assembly and by the composition of adhesive proteins in mussels was designed to modify the carbon fibre surface and improve the composites transverse properties by supramolecular interactions. The results proved that few sensitive carbon surfaces can be selectively modified by stable polyelectrolyte complexes and catechol amine polymer partners dispersed in water in such a way that a sizing treatment can be applied by techniques as simple as immersion or spraying procedure. It was shown that the combination of these solutions self-organized to form thin deposits containing compatibilization and/or crystallization promoter partners, thought transcrystallinity, onto carbon surface. This approach is an innovative and environmentally-friendly method which improves fibre-matrix interface quality in terms of compatibilization, adhesion and mechanical properties.

A wash-durable polyelectrolyte complex that extinguishes flames on polyester–cotton fabric

Polyester–cotton (PECO) blends were rendered flame retardant by depositing a stable polyelectrolyte complex as a wash-durable coating.

Colloid solution of surfactant monomers and polyelectrolyte: Polymerization and properties of the resulting interpolyelectrolyte complexes

In the present work, we suggest a novel method for obtaining interpolyelectrolyte complex (IPEC) by free radical polymerization in water–salt dispersions of polyelectrolyte complexes (PECs) based on an anionic polyelectrolyte (sodium salt of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS-Na)) and a cationic surfactant ((11-acryloyloxy) undecyl)-trimethylammonium bromide (AUTAB), as well as on PAUTAB cationic comb-like polyelectrolyte and AMPS-Na monomer. IPEC consisting of PAMPS and PAUTAB was obtained by two ways. The first one is polymerization of surface active monomers AUTAB in the presence of PAMPS, and the second one is polymerization of AMPS monomers in the presence of PAUTAB. Molecular hydrodynamics methods were used to determine the molecular properties of initial components, polyelectrolyte complexes (PECs), and IPECs. Analysis of the dependence between translational friction coefficient of macromolecules and their molecular masses (which takes into account excluded-volume effects) allowed us to determine the Kuhn segment length of PAMPS-Na macromolecule (A=6nm). Stable polyelectrolyte complexes, PEC, (PAMPS–AUTAB and PAUTAB–AMPS) were obtained by mixing solutions of components at low concentrations in equimolar ratios; polymerization of their low molecular weight components was carried out for the purpose of preparing IPECs. Comparison between scattered light intensity distributions measured for PEC and IPEC demonstrated that in IPEC solutions, only large aggregates of complex molecules are present, while in PEC solutions, two peaks were observed (those corresponding to diffusion of individual PECs and their aggregates). When concentrations of PEC components exceed 3.4mM, polymerization results in the formation of IPEC precipitate which was studied by small angle X-ray scattering. It was found that the IPEC based on PAMPS-Na forms a film with hexagonal packing, and the PAUTAB-based IPEC forms a lamellar film.

Cast adhesive polyelectrolyte complex particle films of unmodified or maltose-modified poly(ethyleneimine) and cellulose sulphate: fabrication, film stability and retarded release of zoledronate

The bone therapeutic drug zoledronate (ZOL) was loaded at and released by polyelectrolyte complex (PEC) particle films composed of either pure poly(ethyleneimine) (PEI) or maltose-modified poly(ethyleneimine) (PEI-M) and oppositely charged cellulose sulfate attached to model germanium (Ge) substrates by solution casting. Dispersions of colloidally stable polyelectrolyte complex (PEC) particles in the size range 11-141 nm were obtained by mixing PEI or PEI-M, CS and ZOL in defined stoichiometric ratios. TRANS-FTIR spectroscopy was used to determine the stability of the PEC films against detachment, in-situ-ATR-FTIR spectroscopy for the ZOL loss in the PEC film and UV-VIS spectroscopy for the ZOL enrichment of the release medium. Films of casted ZOL/CS/PEI-M or ZOL/CS/PEI particles were stable in contact to water, while films of the pure drug (ZOL) and of the binary systems ZOL/PEI-M or ZOL/PEI were not stable against detachment. Retarded releases of ZOL from various PEC films compared to the pure drug film were observed. The molecular weight of PEI showed a considerable effect on the initial burst (IB) of ZOL. No significant effect of the maltose modification of PEI-25 K on IB could be found. Generally, after one day the ZOL release process was finished for all measured ZOL/PEC samples and residual amounts of 0-30% were obtained. Surface adhesive drug loaded PEC particles are promising drug delivery systems to supply and release a defined amount of bone therapeutics and to functionalize bone substitution materials.