Influence of Different Degradation Medium on Release of Ascorbic Acid from PLGA Nano ans Microspheres

Poster presented at PHYSICAL CHEMISTRY 2008. 9th International Conference on Fundamental and Applied Aspects of Physical Chemistry, Belgrade, September 24-26, 200

Poly(lactide-co-glycolide)-based Micro and Nanoparticles for the Controlled Drug Delivery of Vitamins

Controlled drug delivery systems and polymeric carriers have undergone significant development in recent years. Polymers like polylactides (PLA), polyglycolides (PGA), poly(lactide-co-glycolides) (PLGA), are approved by the World Health Organization (WHO) and Food and Drug Administration (FDA) as materials that can be used in medicine and pharmacy. Owing to their biodegradable nature, polymer materials, such as copolymer poly(DL-lactide-co-glycolide), are widely used in various medical applications; controlled release of delivering drugs, carriers in the tissue engineering, fixation of bone fractures, chirurgical strings, etc. Polymeric particles are used for the controlled delivery of several types of medicaments, including anticancer agents, antihypertensive agents, immunomodulatory drugs, hormones, vitamins and macromolecules, such as nucleic acid, proteins, peptides, antibodies, etc. Preparation of poly(lactide-co-glycolide) submicron spheres poses serious challenges. The present review attempts to address some important issues related to micro/nanoparticle-based delivery systems comprising poly(lactide-co-glycolide), with a special reference to PLGA for the controlled delivery of vitamins. A range of topics is discussed, including formulation aspects of micro- and nanoparticles, the effects of particle size and size distribution, most commonly used incorporation techniques, surface modification with stabilizers, surface functionalization, and factors affecting degradation and drug release rate.\ud \ud A post-print version of the article: Uskokovic, Dragan, and Magdalena Stevanovic. 2009. “Poly(lactide-Co-Glycolide)-Based Micro and Nanoparticles for the Controlled Drug Delivery of Vitamins.” Current Nanoscience 5 (1) (February 1): 1–14. doi:10.2174/157341309787314566

Synthesis and characterization of DLPLG nanoparticles for controlled delivery of water-soluble vitamins

Biodegradable polymers have become the materials of choice for a variety of biomaterials applications. In particular poly (DL-lactide-co-glycolide) (DLPLG) nanoparticles have been studied for controlled released drug delivery. In this paper we are describing new method of obtaining the system for targeted and controlled delivery of the folic acid in the body. Folic acid (pteroyl-L-glutamic acid, vitamin B9) is a water-soluble vitamin essential in the human diet. It is an important cofactor in the synthesis of DNA and RNA, of dividing cells, particularly during pregnancy and infancy when there is an increase in cell division and growth. The DLPLG particles were obtained by chemical solvent/non-solvent method with PVP as a surfactant. The obtained DLPLG particles are non-agglomerated, uniform and with particles size in the submicron scale. The folic acid has been encapsulated into the polymer matrix by means of homogenization of the water and organic phases. The concentration of the folic acid in the water has been varied in order to obtain nanoparticles with different ratio of DLPLG and folic acid. The samples were characterized by Infrared Spectroscopy (IR) and Scanning Electron Microscopy (SEM)

Mobile Commerce and Consumers’ Online Purchase Orientation in Poland, Croatia and Serbia

As an innovative approach to retail, mobile commerce develops rapidly during last decade. It brings new challenges and opportunities in front of retailers who have to adapt their business strategies to new generation shoppers. With a good understanding of the shoppers’ online purchase intention, retailers are able to develop effective online strategies to attract new and keep loyal web-shopping customers. The purpose of this paper is to explain the online shopping orientation in the context of country of origin. There is a limited number of such research in Central and Eastern Europe, so there is a lack of knowledge about young consumers from this region and their attitude as mobile technology users. The article is based on the research conducted in Poland, Croatia and Serbia where 454 young non randomly selected respondents answered online survey questions. The research hypotheses were tested using correlation and non-parametric statistics. Differences between observed countries suggest that there is a necessity to adapt approach concerning online retailing even at the market with similar characteristics. Therefore, creators of marketing and sales strategies of online and omnichannel companies should consider this fact when planning business strategies. This work is licensed under a&nbsp;Creative Commons Attribution-NonCommercial 4.0 International License.</p

Mobile Commerce and Consumers’ Online Purchase Orientation in Poland, Croatia and Serbia

As an innovative approach to retail, mobile commerce develops rapidly during last decade. It brings new challenges and opportunities in front of retailers who have to adapt their business strategies to new generation shoppers. With a good understanding of the shoppers’ online purchase intention, retailers are able to develop effective online strategies to attract new and keep loyal web-shopping customers. The purpose of this paper is to explain the online shopping orientation in the context of country of origin. There is a limited number of such research in Central and Eastern Europe, so there is a lack of knowledge about young consumers from this region and their attitude as mobile technology users. The article is based on the research conducted in Poland, Croatia and Serbia where 454 young non randomly selected respondents answered online survey questions. The research hypotheses were tested using correlation and non-parametric statistics. Differences between observed countries suggest that there is a necessity to adapt approach concerning online retailing even at the market with similar characteristics. Therefore, creators of marketing and sales strategies of online and omnichannel companies should consider this fact when planning business strategies. This work is licensed under a&nbsp;Creative Commons Attribution-NonCommercial 4.0 International License.</p

Tailored preparation of nano and micro composites as new controlled bone drug delivery systems

Method of homogenous sonochemical principle for obtaining controlled forms of micro/nano particles of desired shapes, size and distribution, and solvent/nonsolvent method for obtaining spherical particles of polymer or polymer/ceramics composites with the encapsulated pharmacologically active agent for the treatment of bone tissue pathology, are methods developed in our laboratory for the production of nano and micro ceramic/polymer or polymer composite systems which can be potentially used as controlled bone drug delivery system. Method of homogenous sonochemical precipitation, by designing synthesis parameters like temperature, frequency, energy and ultrasonic field regime, and by applying appropriate solvents, enables producing desired forms and particle structures. Through this method calcium phosphate systems can be obtained, but also systems where calcium phosphate particles are coated with bioresorbable polymer with immobilized antibiotic. Physicochemical synthesis procedure in solvent/non-solvent method consists of initial dissolve of desired bioresorbable polymers and its homogenization, followed by encapsulation of the desired agents. Already produced pharmaceutically active compounds (ascorbic, folic acid, peroxidase, antibiotics, autologous plasma, etc.) can be encapsulated or different calcium phosphates used as fillers for the defected bone tissue. Micro, submicro and nano sized particles in deagglomeration form, optimal for the advanced application in bone engineering, are obtained through these preparation methods

Preparation and Characterization of Poly(D,L-Lactide-co-Glycolide) Nanoparticles Containing Ascorbic Acid

This paper is covering new, simplistic method of obtaining the system for controlled delivery of the ascorbic acid. Copolymer poly (D,L-lactide-co-glycolide) (DLPLG) nanoparticles are produced using physical method with solvent/nonsolvent systems where obtained solutions were centrifuged. The encapsulation of the ascorbic acid in the polymer matrix is performed by homogenization of water and organic phases. Particles of the DLPLG with the different content of ascorbic acid have different morphological characteristics, that is, variable degree of uniformity, agglomeration, sizes, and spherical shaping. Mean sizes of nanoparticles, which contain DLPLG/ascorbic acid in the ratio 85/150%, were between 130 to 200 nm depending on which stereological parameters are considered (maximal diameters Dmax, feret X, or feret Y). By introducing up to 15% of ascorbic acid, the spherical shape, size, and uniformity of DLPLG particles are preserved. The samples were characterized by infrared spectroscopy, scanning electron microscopy, stereological analysis, and ultraviolet spectroscopy

Conditional Sox9 ablation reduces chondroitin sulfate proteoglycan levels and improves motor function following spinal cord injury

Chondroitin sulfate proteoglycans (CSPGs) found in perineuronal nets and in the glial scar after spinal cord injury have been shown to inhibit axonal growth and plasticity. Since we have previously identified SOX9 as a transcription factor that upregulates the expression of a battery of genes associated with glial scar formation in primary astrocyte cultures, we predicted that conditional Sox9 ablation would result in reduced CSPG expression after spinal cord injury and that this would lead to increased neuroplasticity and improved locomotor recovery. Control and Sox9 conditional knock-out mice were subject to a 70 kdyne contusion spinal cord injury at thoracic level 9. One week after injury, Sox9 conditional knock-out mice expressed reduced levels of CSPG biosynthetic enzymes (Xt-1 and C4st), CSPG core proteins (brevican, neurocan, and aggrecan), collagens 2a1 and 4a1, and Gfap, a marker of astrocyte activation, in the injured spinal cord compared with controls. These changes in gene expression were accompanied by improved hind limb function and locomotor recovery as evaluated by the Basso Mouse Scale (BMS) and rodent activity boxes. Histological assessments confirmed reduced CSPG deposition and collagenous scarring at the lesion of Sox9 conditional knock-out mice, and demonstrated increased neurofilament-positive fibers in the lesion penumbra and increased serotonin immunoreactivity caudal to the site of injury. These results suggest that SOX9 inhibition is a potential strategy for the treatment of SCI. © 2012 Wiley Periodicals, Inc

Nano-sized spheres of poly(DL-lactide-co-glycolide) as drug carriers for water- soluble vitamins

Poster presented at the Women in Nano Winter School; Kranjska Gora; Slovenia; February 7-9, 200

Effect of poly-α, γ, L-glutamic acid as a capping agent on morphology and oxidative stress-dependent toxicity of silver nanoparticles

Highly stable dispersions of nanosized silver particles were synthesized using a straightforward, cost-effective, and ecofriendly method. Nontoxic glucose was utilized as a reducing agent and poly-α, γ, L-glutamic acid (PGA), a naturally occurring anionic polymer, was used as a capping agent to protect the silver nanoparticles from agglomeration and render them biocompatible. Use of ammonia during synthesis was avoided. Our study clearly demonstrates how the concentration of the capping agent plays a major role in determining the dimensions, morphology, and stability, as well as toxicity of a silver colloidal solution. Hence, proper optimization is necessary to develop silver colloids of narrow size distribution. The samples were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurement. MTT assay results indicated good biocompatibility of the PGA-capped silver nanoparticles. Formation of intracellular reactive oxygen species was measured spectrophotometrically using 2,7-dichlorofluorescein diacetate as a fluorescent probe, and it was shown that the PGA-capped silver nanoparticles did not induce intracellular formation of reactive oxygen species