The use of polymeric microcarriers loaded with anti-inflammatory substances in the therapy of experimental skin wounds

USE OF SORPTION PROCESSES IN THE TECHNOLOGY OF DRUG DELIVERY SYSTEMS

The aimof this research is the review of scientific and technical literature regarding possibility of using sorption processes in the technology of drug delivery systems.

Materials and methods. The materials are the following electronic resources: eLIBRARY, CyberLeninka, PubMed. The methods of review are analysis and synthesis. The study covers the scientific literature from 1996 up to the present time.

Results.Sorbents are used as carriers for various medicinal peroral substances, they are also dispensers of various compounds in the form of polymeric eye films and stents in the human body. The delivery of medicinal substances occurs with the help of sorption processes of mass transfer. Currently, the following medical substances are used as carriers for medicinal substances: activated carbon, mineral sorbents (medical clays, synthetic sorbents), polymers and their biosimilars. 6 groups of pharmaceutical substances are registered for the production of enterosorbents in Russia and they can be used as sorbent carriers in the sorption drug system. They are: activated carbon, colloidal silicon dioxide, polyvinylpyrrolidone, dioctahedral smectite, polymethylsiloxane polyhydrate. As a result of the study, the model of the sorption drug system has been developed. It consists of sorbent carrier, active pharmaceutical ingredient and excipients that provide the desorption. Desorption of the active pharmaceutical ingredient may contribute to its modified release. The technology for obtaining sorption medicinal systems requires further study and development of modeling methods, searching for experimental pharmacological models and technological methods, which make it possible to obtain sorption dosage form with modified release.

Conclusion.The review of the sorption processes used in the technology of drug delivery systems has been carried out. The model of the sorption drug system has been developed.

Tunable Volumetric Density and Porous Structure of Spherical Poly-ε-caprolactone Microcarriers, as Applied in Human Mesenchymal Stem Cell Expansion

Polymeric microspheres may serve as microcarrier (MC) matrices, for the expansion of anchorage-dependent stem cells. They require surface properties that promote both initial cell adhesion and the subsequent spreading of cells, which is a prerequisite for successful expansion. When implemented in a three-dimensional culture environment, under agitation, their suspension under low shear rates depends on the MCs having a modest negative buoyancy, with a density of 1.02-1.05 g/cm³. Bioresorbable poly-ε-caprolactone (PCL), with a density of 1.14 g/cm³, requires a reduction in volumetric density, for the microspheres to achieve high cell viability and yields. Uniform-sized droplets, from solutions of PCL dissolved in dichloromethane (DCM), were generated by coaxial microfluidic geometry. Subsequent exposure to ethanol rapidly extracted the DCM solvent, solidifying the droplets and yielding monodisperse microspheres with a porous structure, which was demonstrated to have tunable porosity and a hollow inner core. The variation in process parameters, including the molecular weight of PCL, its concentration in DCM, and the ethanol concentration, served to effectively alter the diffusion flux between ethanol and DCM, resulting in a broad spectrum of volumetric densities of 1.04-1.11 g/cm³. The solidified microspheres are generally covered by a smooth thin skin, which provides a uniform cell culture surface and masks their internal porous structure. When coated with a cationic polyelectrolyte and extracellular matrix protein, monodisperse microspheres with a diameter of approximately 150 μm and densities ranging from 1.05-1.11 g/cm³ are capable of supporting the expansion of human mesenchymal stem cells (hMSCs). Validation of hMSC expansion was carried out with a positive control of commercial Cytodex 3 MCs and a negative control of uncoated low-density PCL MCs. Static culture conditions generated more than 70% cell attachment and similar yields of sixfold cell expansion on all coated MCs, with poor cell attachment and growth on the negative control. Under agitation, coated porous microspheres, with a low density of 1.05 g/cm³, achieved robust cell attachment and resulted in high cell yields of ninefold cell expansion, comparable with those generated by commercial Cytodex 3 MCs.

Fabrication of uniform-sized poly-ɛ-caprolactone microspheres and their applications in human embryonic stem cell culture

The generation of liquefied poly-ɛ-caprolactone (PCL) droplets by means of a microfluidic device results in uniform-sized microspheres, which are validated as microcarriers for human embryonic stem cell culture. Formed droplet size and size distribution, as well as the resulting PCL microsphere size, are correlated with the viscosity and flow rate ratio of the dispersed (Q d) and continuous (Q c) phases. PCL in dichloromethane increases its viscosity with concentration and molecular weight. Higher viscosity and Q d/Q c lead to the formation of larger droplets, within two observed formation modes: dripping and jetting. At low viscosity of dispersed phase and Q d/Q c, the microfluidic device is operated in dripping mode, which generates droplets and microspheres with greater size uniformity. Solutions with lower molecular weight PCL have lower viscosity, resulting in a wider concentration range for the dripping mode. When coated with extracellular matrix (ECM) proteins, the fabricated PCL microspheres are demonstrated capable of supporting the expansion of human embryonic stem cells.

Smart polyhydroxyalkanoate nanobeads by protein based functionalization

The development of innovative medicines and personalized biomedical approaches calls for new generation easily tunable biomaterials that can be manufactured applying straightforward and low-priced technologies. Production of functionalized bacterial polyhydroxyalkanoate (PHA) nanobeads by harnessing their natural carbon-storage granule production system is a thrilling recent development. This branch of nanobiotechnology employs proteins intrinsically binding the PHA granules as tags to immobilize recombinant proteins of interest and design functional nanocarriers for wide range of applications. Additionally, the implementation of new methodological platforms regarding production of endotoxin free PHA nanobeads using Gram-positive bacteria opened new avenues for biomedical applications. This prompts serious considerations of possible exploitation of bacterial cell factories as alternatives to traditional chemical synthesis and sources of novel bioproducts that could dramatically expand possible applications of biopolymers.

From the Clinical Editor

In the 21st century, we are coming into the age of personalized medicine. There is a growing use of biomaterials in the clinical setting. In this review article, the authors describe the use of natural polyhydroxyalkanoate (PHA) nanoparticulates, which are formed within bacterial cells and can be easily functionalized. The potential uses would include high-affinity bioseparation, enzyme immobilization, protein delivery, diagnostics etc. The challenges of this approach remain the possible toxicity from endotoxin and the high cost of production.