The mechanism of catalase loading into porous vaterite CaCO3 crystals by co-synthesis

Porous vaterite CaCO3 crystals are nowadays extensively used as high-capacity bio-friendly sacrificial templates for the fabrication of such protein-containing nano- and micro-particles as capsules and beads. The first step in the protein encapsulation is performed through loading of the protein molecules into the crystals. Co-synthesis is one of the most useful and simple methods proven to effectively load crystals with proteins; however, the loading mechanism is still unknown. To understand the mechanism, in this study, we focus on the loading of a model protein catalase into the crystals by means of adsorption into pre-formed crystals (ADS) and co-synthesis (COS). Analysis of the physico-chemical characteristics of the protein in solution and during the loading and simulation of the protein packing into the crystals are performed. COS provides more effective loading than ADS giving protein contents in the crystals of 20.3 and 3.5 w/w%, respectively. Extremely high loading for COS providing a local protein concentration of about 550 mg mL−1 is explained by intermolecular protein interactions, i.e. formation of protein aggregates induced by CaCl2 during the co-synthesis. This is supported by a lower equilibrium constant obtained for COS (5 × 105 M−1) than for ADS (23 × 105 M−1), indicating a higher affinity of single protein molecules rather than aggregates to the crystal surface. Fitting the adsorption isotherms by classical adsorption models has shown that the Langmuir and BET models describe the adsorption phenomenon better than the Freundlich model, proving the aggregation in solution followed by adsorption of the aggregates into the crystals. We believe that this study will be useful for protein encapsulation through CaCO3 crystals using the COS method

Inter-protein interactions govern protein loading into porous vaterite CaCO3 crystals

The fast development of protein therapeutics has resulted in a high demand for advanced delivery carriers that can effectively host therapeutic proteins, preserve their bioactivity and release them on demand. Accordingly, vaterite CaCO3 crystals have attracted special attention as sacrificial templates for protein encapsulation in micro- and nanoparticles (capsules and beads, respectively) under mild biofriendly conditions. This study aimed to better understand the mechanism of protein loading into crystals as a primary step for protein encapsulation. The loading of three therapeutic proteins (250 kDa catalase, 5.8 kDa insulin, and 6.5 kDa aprotinin) was investigated for crystals with different porosities. However, unexpectedly, the protein loading capacity was not consistent with the protein molecular weight. It solely depends on the inter-protein interactions in the bulk solution in the presence of crystals and that inside the crystals. The smallest protein aprotinin aggregates in the bulk (its aggregate size is about 100 nm), which prohibits its loading into the crystals. Insulin forms hexamers in the bulk, which can diffuse into the crystal pores but tend to aggregate inside the pores, suppressing protein diffusion inward. Catalase, the largest protein tested, does not form any aggregates in the bulk and diffuses freely into the crystals; however, its diffusion into small pores is sterically restricted. These findings are essential for the encapsulation of protein therapeutics by means of templating based on CaCO3 crystals and for the engineering of protein-containing microparticles having desired architectures

THE FORMATION OF COMMUNICATIVE COMPETENCE OF FUTURE TEACHERS OF FINE ARTS AT THE TIME OF TEACHING PRACTICE

The article characterizes the main competence is developed communicative qualities of the teacher, in the preparation of the bachelor of teacher education. Considers the issues of the educational and production practices as the most important types of educational practiceoriented professional training of the graduates of art-graphic faculty in the areas of education, qualification - bachelor of teacher education.В статье характеризуются основные компетенции, для которых важны развитые коммуникативные качества преподавателя, при подготовке бакалавра педагогического образования. Рассматриваются вопросы учебной и производственной педагогических практик как важнейших видов учебных занятий, ориентированных на профессиональную подготовку выпускников художественно-графического факультета по направлению подготовки – педагогическое образование, квалификации – бакалавр педагогического образования

Hybrid CaCO3-mucin crystals: effective approach for loading and controlled release of cationic drugs

Vaterite CaCO3 crystals are actively used as a biocompatible and degradable matrix for encapsulation of fragile biomacromolecules. However, the incorporation of small cationic drugs into the crystals remains awkward due to a poor binding of these drugs to the crystal surface and scarce retention inside the crystal pores. Herein, we achieve efficient drug loading and control over drug release performance via utilisation of hybrid CaCO3 crystals impregnated with mucin. The co-loading of mucin and anticancer drug doxorubicin (DOX) into CaCO3 crystals enhanced drug content in the crystals by ca 12 times giving DOX concentration of 1.3 mg g−1 CaCO3. Retention of DOX inside hybrid crystals is governed by strong electrostatic attraction to mucin matrix and significant narrowing of the crystal pores in the presence of mucin. At physiologically relevant conditions, DOX release kinetics strongly depends on the recrystallization of the porous vaterite to non-porous calcite that is regulated by mucin concentration. We believe that this study will help to design novel effective drug delivery systems able to load high amounts of drugs at mild conditions for sustained and controlled release of the drugs. This is indispensable for mucosal delivery where mucin produced by epithelial tissues is a main component

The formation of common cultural competencies in the process of professional training of the designer

In the article we consider great importance and the main principles of forming general cultural competence in the process of professional training a graphic designerВ статье рассматривается важное значение и основные принципы формирования общекультурных компетенций в процессе профессиональной подготовки графического дизайнер

Bio-friendly encapsulation of superoxide dismutase into vaterite CaCO3 crystals. Enzyme activity, release mechanism, and perspectives for ophthalmology

Mesoporous vaterite CaCO3 crystals are nowadays one of the most popular vectors for loading of fragile biomolecules like proteins due to biocompatibility, high loading capacity, cost effective and simple loading procedures. However, recent studies reported the reduction of bioactivity for protein encapsulation into the crystals in water due to rather high alkaline pH of about 10.3 caused by the crystal hydrolysis. In this study we have investigated how to retain the bioactivity and control the release rate of the enzyme superoxide dismutase (SOD) loaded into the crystals via co-synthesis. SOD is widely used as an antioxidant in ophthalmology and its formulations with high protein content and activity as well as opportunities for a sustained release are highly desirable. Here we demonstrate that SOD co-synthesis can be done at pH 8.5 in a buffer without affecting crystal morphology. The synthesis in the buffer allows reaching the high loading efficiency of 93%, high SOD content (24 versus 15 w/w % for the synthesis in water), and order of magnitude higher activity compared to the synthesis in water. The enormous SOD concentration into crystals of 10−2 M is caused by the entrapment of SOD aggregates into the crystal pores. The SOD released from crystals at physiologically relevant ionic strength fully retains its bioactivity. As found by fitting the release profiles using zero-order and Baker-Lonsdale models, the SOD release mechanism is governed by both the SOD aggregate dissolution and by the diffusion of SOD molecules thorough the crystal pores. The latest process contributes more in case of the co-synthesis in the buffer because at higher pH (co-synthesis in water) the unfolded SOD molecules aggregate stronger. The release is bi-modal with a burst (ca 30%) followed by a sustained release and a complete release due to the recrystallization of vaterite crystals to non-porous calcite crystals. The mechanism of SOD loading into and release from the crystals as well as perspectives for the use of the crystals for SOD delivery in ophthalmology are discussed. We believe that together with a fundamental understanding of the vaterite-based protein encapsulation and protein release, this study will help to establish a power platform for a mild and effective encapsulation of fragile biomolecules like proteins at bio-friendly conditions

Self-assembled mucin-containing microcarriers via hard templating on CaCO3 crystals

Porous vaterite crystals of CaCO3 are extensively used for the fabrication of self-assembled polymer-based microparticles (capsules, beads, etc.) utilized for drug delivery and controlled release. The nature of the polymer used plays a crucial role and discovery of new perspective biopolymers is essential to assemble microparticles with desired characteristics, such as biocompatibility, drug loading efficiency/capacity, release rate, and stability. Glycoprotein mucin is tested here as a good candidate to assemble the microparticles because of high charge due to sialic acids, mucoadhesive properties, and a tendency to self-assemble, forming gels. Mucin loading into the crystals via co-synthesis is twice as effective as via adsorption into preformed crystals. Desialylated mucin has weaker binding to the crystals most probably due to electrostatic interactions between sialic acids and calcium ions on the crystal surface. Improved loading of low-molecular-weight inhibitor aprotinin into the mucin-containing crystals is demonstrated. Multilayer capsules (mucin/protamine)3 have been made by the layer-by-layer self-assembly. Interestingly, the deposition of single mucin layers (mucin/water)3 has also been proven, however, the capsules were unstable, most probably due to additional (to hydrogen bonding) electrostatic interactions in the case of the two polymers used. Finally, approaches to load biologically-active compounds (BACs) into the mucin-containing microparticles are discussed

Mucin adsorption on vaterite CaCO3 microcrystals for the prediction of mucoadhesive properties

Porous vaterite CaCO3 crystals are widely used as containers for drug loading and as sacrificial templates to assemble polymer-based nano- and micro-particles at mild conditions. Special attention is paid nowadays to mucosal delivery where the glycoprotein mucin plays a crucial role as a main component of a mucous. In this work mucoadhesive properties of vaterite crystals have been tested by investigation of mucin binding to the crystals as a function of (i) time, (ii) glycoprotein concentration, (iii) adsorption conditions and (iv) degree of mucin desialization. Mucin adsorption follows Bangham equation indicating that diffusion into crystal pores is the rate-limiting step. Mucin strongly binds to the crystals (ΔG = −35 ± 4 kJ mol−1) via electrostatic and hydrophobic interactions forming a gel and thus giving the tremendous mucin mass content in the crystals of up to 16%. Despite strong intermolecular mucin-mucin interactions, pure mucin spheres formed after crystal dissolution are unstable. However, introduction of protamine, actively used for mucosal delivery, makes the spheres stable via additional electrostatic bonding. The results of this work indicate that the vaterite crystals are extremely promising carriers for mucosal drug delivery and for development of test-systems for the analysis of the mucoadhesion

Encapsulation of Insulin in Biodegradable Polymers

 Encapsulation of insulin into alginate particles was carried out by the method of ionotropic gelation. To protect against the acidic, alkaline environment of the gastrointestinal tract, alginate particles were coated with gelatin. The optimal concentration of the solution of the crosslinking agent ‒ CaCl2 was determined during the optimization of the particle preparation method. The mechanism of interaction between alginate and gelatin was investigated using FTIR spectroscopy, FTIR spectra data confirm the formation of a polyelectrolyte complex between alginate an-d gelatin. The roughness and morphology of samples were determined by atomic force microscopy. The swelling of particles under simulated pH conditions of various parts of the human gastrointestinal tract was studied. The release of insulin from the particles was evaluated using UV spectroscopy, at pH 6.86; 9.18 the release of insulin reached 50%; 83% relatively

Hybrid Mucin‐Vaterite Microspheres for Delivery of Proteolytic Enzyme Chymotrypsin

Abstract While the enteral delivery of proteolytic enzymes is widely established for combating many diseases as an alternative to antibiotic treatment, their local delivery only emerges as administration route enabling sustained release in a controlled manner on site. The latest requires the development of drug delivery systems suitable for encapsulation and preservation of enzymatic proteolytic activity. This study proposes hybrid microspheres made of mucin and biodegradable porous crystals of calcium carbonate (CC) as the carriers for chymotrypsin (CTR) delivery. CTR is impregnated into CC and hybrid CC/mucin (CCM) microspheres by means of sorption without any chemical modification. The loading of the CC with mucin enhances CTR retention on hybrid microspheres (adsorption capacity of ≈8.7 mg g−1 vs 4.7 mg g−1), recharging crystal surface due to the presence of mucin and diminishing the average pore diameter of the crystals from 25 to 8 nm. Mucin also retards recrystallization of vaterite into nonporous calcite improving stability of CCM microspheres upon storage. Proteolytic activity of CTR is preserved in both CC and CCM microspheres, being pH dependent. Temperature‐induced inactivation of CTR significantly diminishes by CTR encapsulation into CC and CCM microspheres. Altogether, these findings indicate promises of hybrid mucin‐vaterite microspheres for mucosal application of proteases