Tunable Properties of Poly-DL-Lactide-Monomethoxypolyethylene Glycol Porous Microparticles for Sustained Release of Polyethylenimine-DNA Polyplexes

Tuning the Emulsion Properties Influences the Size of Poly(Caprolactone) Particles for Drug Delivery Applications

Advances in drug delivery have been accelerated with the addition of polymeric drug carriers. Direct delivery to a target site is a promising step in developing effective drug and gene therapies to treat disease. The efficacy of these drug carriers heavily relies on cell uptake without compromising critical cellular processes that promote cell viability. Drug release from biodegradable polymers is mediated largely by polymer degradation, and therefore the rate of polymer degradation dictates the feasibility of drug delivery applications. Traditionally, poly(caprolactone) (PCL) has only been used in long-term biomedical applications because the degradation time is much slower than other polymers. However, the biocompatibility of this polymer and the potential for longer delivery windows renders it a promising polymer candidate for drug delivery. In this work, we outline sixteen emulsion solvent evaporation preparation methods for PCL nanoparticles and microparticles to develop particles between 300 nm and 1.7 μm and with zeta potentials of -1.8 mV. We further investigated particles in a size range suitable for systemic tumor delivery and inhaled aerosol delivery to determine cell biocompatibility with the polymer in lung adenocarcinoma, endometrial adenocarcinoma, and human embryonic kidney cells. We determined these particles aren't detrimental to cell viability below particle monolayer coverage atop cells and therefore these formulations hold promise for the next stage of development as sustained-release drug delivery carriers.

Inhalable microparticles as drug delivery systems to the lungs in a dry powder formulations

Inhalation-administrated drugs remain an interesting possibility of addressing pulmonary diseases. Direct drug delivery to the lungs allows one to obtain high concentration in the site of action with limited systemic distribution, leading to a more effective therapy with reduced required doses and side effects. On the other hand, there are several difficulties in obtaining a formulation that would meet all the criteria related to physicochemical, aerodynamic and biological properties, which is the reason why only very few of the investigated systems can reach the clinical trial phase and proceed to everyday use as a result. Therefore, we focused on powders consisting of polysaccharides, lipids, proteins or natural and synthetic polymers in the form of microparticles that are delivered by inhalation to the lungs as drug carriers. We summarized the most common trends in research today to provide the best dry powders in the right fraction for inhalation that would be able to release the drug before being removed by natural mechanisms. This review article addresses the most common manufacturing methods with novel modifications, pros and cons of different materials, drug loading capacities with release profiles, and biological properties such as cytocompatibility, bactericidal or anticancer properties.

Preparation of Protein Aerogel Particles for the Development of Innovative Drug Delivery Systems

The research was oriented towards the preparation of aerogel particles based on egg white and whey protein isolate using various dispersion methods: dripping, spraying, and homogenization. Based on the results of analytical studies, the most appropriate samples were selected to obtain aerogels loaded with the drug. The results of the experimental research were used to study methods for obtaining nasal drug delivery systems based on aerogels. Protein aerogels were obtained by thermal gelation followed by supercritical drying. The obtained particles of protein aerogels have a specific surface area of up to 350 m²/g with a pore volume of up to 2.9 cm³/g, as well as a porosity of up to 95%. The results of experimental studies have shown that changing the dispersion method makes it possible to control the structural characteristics of protein aerogel particles. The results of the studies were applied to obtain innovative nasal drug delivery systems for the treatment of socially significant diseases. Analytical studies were conducted to determine the amount and state of adsorbed drugs in protein aerogel particles, as well as in vivo experiments on the distribution of clomipramine in blood plasma and brain tissue of rats to study the pharmacokinetics and bioavailability of the resulting drug-loaded protein aerogel.

Glass Transition Temperature of PLGA Particles and the Influence on Drug Delivery Applications

Over recent decades, poly(lactic-co-glycolic acid) (PLGA) based nano- and micro- drug delivery vehicles have been rapidly developed since PLGA was approved by the Food and Drug Administration (FDA). Common factors that influence PLGA particle properties have been extensively studied by researchers, such as particle size, polydispersity index (PDI), surface morphology, zeta potential, and drug loading efficiency. These properties have all been found to be key factors for determining the drug release kinetics of the drug delivery particles. For drug delivery applications the drug release behavior is a critical property, and PLGA drug delivery systems are still plagued with the issue of burst release when a large portion of the drug is suddenly released from the particle rather than the controlled release the particles are designed for. Other properties of the particles can play a role in the drug release behavior, such as the glass transition temperature (T_g). The T_g, however, is an underreported property of current PLGA based drug delivery systems. This review summarizes the basic knowledge of the glass transition temperature in PLGA particles, the factors that influence the T_g, the effect of T_g on drug release behavior, and presents the recent awareness of the influence of T_g on drug delivery applications.

PLGA-based biodegradable microspheres in drug delivery: recent advances in research and application

Biodegradable microspheres have been widely used in the field of medicine due to their ability to deliver drug molecules of various properties through multiple pathways and their advantages of low dose and low side effects. Poly (lactic-co-glycolic acid) copolymer (PLGA) is one of the most widely used biodegradable material currently and has good biocompatibility. In application, PLGA with a specific monomer ratio (lactic acid and glycolic acid) can be selected according to the properties of drug molecules and the requirements of the drug release rate. PLGA-based biodegradable microspheres have been studied in the field of drug delivery, including the delivery of various anticancer drugs, protein or peptide drugs, bacterial or viral DNA, etc. This review describes the basic knowledge and current situation of PLGA biodegradable microspheres and discusses the selection of PLGA polymer materials. Then, the preparation methods of PLGA microspheres are introduced, including emulsification, microfluidic technology, electrospray, and spray drying. Finally, this review summarizes the application of PLGA microspheres in drug delivery and the treatment of pulmonary and ocular-related diseases.

Precise Control of the Surface and Internal Morphologies of Porous Particles Prepared Using a Spontaneous Emulsification Method

Porous particles with controllable surface and internal morphologies were successfully prepared by a "one-step mechanical emulsification" technique via the control of spontaneous emulsification where self-emulsification is followed by mechanical emulsification. The morphological changes in the porous particles were determined not by the preparation conditions of the water-in-oil-in-water (w/o/w) emulsion but by the proportion of solvents that favors the stabilization of the spontaneously prepared water-in-oil (w/o) emulsion droplets acting as porogens. The proposed method for controlling the morphology of the porous particles could be applied to all particle-preparation systems based on emulsion-solvent evaporation using organic solvents. The methodology for the morphological control of porous particles independent of the concentration or composition of the polymer is considered valuable for future investigations into the aerodynamic performance and drug-release behavior of biomedical porous particles with complex shapes.

Encapsulating Polyethyleneimine-DNA Nanoplexes into PEGylated Biodegradable Microparticles Increases Transgene Expression In Vitro and Reduces Inflammatory Responses In Vivo

Encapsulating genetic material into biocompatible polymeric microparticles is a means to improving gene transfection while simultaneously decreasing the tendency for inflammatory responses; and can be advantageous in terms of delivering material directly to the lungs via aerosolization for applications such as vaccinations. In this study, we investigated the advantages of using polymeric microparticles carrying the luciferase reporter gene in increasing transfection efficiency in the readily transfectable HEK293 cell line and the difficult to transfect RAW264.7 cell line. The results indicated that there was a limit to the ratio of nitrogen in polyethylenimine (PEI) to phosphate in DNA (N/P ratio) beyond which further increases in transgene expression no longer, or only marginally, occurred. Microparticles encapsulating PEI:DNA nanoplexes induced cellular toxicity in a dose-dependent manner. PEGylation increased transgene expression, likely related to enhanced degradation of particles. Furthermore, intra-tracheal instillation in rats allowed us to investigate the inflammatory response in the lung as a function of PEGylation, porosity, and size. Porosity did not influence cell counts in bronchoalveolar lavage fluid in the absence of PEG, but in particles containing PEG, non-porous particles recruited fewer inflammatory cells than their porous counterparts. Finally, both 1 μm and 10 μm porous PLA-PEG particles recruited more neutrophils than 4 μm particles. Thus, we have shown that PEGylation and lack of porosity are advantageous for faster release of genetic cargo from microparticles and a reduced inflammatory response, respectively.

Ectopic chondrogenesis of nude mouse induced by nano gene delivery enhanced tissue engineering technology

Background: Many techniques and methods have been used clinically to relieve pain from cartilage repair, but the long-term effect is still unsatisfactory. Purpose: The objective of this study was to form an artificial chondroid tissue gene enhanced tissue engineering system to repair cartilage defects via nanosized liposomes. Methods: Cationic nanosized liposomes were prepared and characterized using transmission electron microscope (TEM) and dynamic laser light scattering (DLS). The rat mesenchymal stem cells (rMSCs) were isolated, cultivated, and induced by SRY (Sex-Determining Region Y)-Box 9 (Sox9) via cationic nanosized liposomes. The induced rMSCs were mixed with a thermo-sensitive chitosan hydrogel and subcutaneously injected into the nude mice. Finally, the newly-formed chondroid tissue obtained in the injection parts, and the transparent parts were detected by HE, collagen II, and safranin O. Results: It was found that the presently prepared cationic nanosized liposomes had the diameter of 85.76±3.48 nm and the zeta potential of 15.76±2.1 mV. The isolated rMSCs proliferation was fibroblast-like, with a cultivated confluence of 90% confluence in 5-8 days, and stained positive for CD29 and CD44 while negative for CD34 and CD45. After transfection with cationic nanosized liposomes, we observed changes of cellular morphology and a higher expression of SOX9 compared with control groups, which indicated that rMSCs could differentiate into chondrocyte in vitro. By mixing transfected rMSCs with the thermo-sensitive hydrogel of chitosan in nude mice, chondroid tissue was successfully obtained, demonstrating that rMSCs can differentiate into chondrogenic cells in vivo. Conclusion: This study explored new ways to improve the quality of tissue engineered cartilage, thus accelerating clinical transformation and reducing patient pain.