Ovidiu Oprea

Synthesis and characterization of a novel controlled release zinc oxide/gentamicin-chitosan composite with potential applications in wounds care.

Freshly prepared ZnO nanoparticles were incorporated into a chitosan solution in weight ratios ranging from 1:1 to 12:1. Starting from the ratio of 3:1 the chitosan solution was transformed into a gel with a high consistency, which incorporates 15mL water for only 0.1g solid substance. The powders obtained after drying the gel were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermal analysis (TG-DSC). The electronic (UV-vis), infrared (FTIR) and photoluminescence (PL) spectra were also recorded. ZnO particles were coated with gentamicin and incorporated into the chitosan matrix, to yield a ZnO/gentamicin-chitosan gel. The release rate of gentamicin was monitored photometrically. This ZnO/gentamicin-chitosan gel proved great antimicrobial properties, inhibiting Staphylococcus aureus and Pseudomonas aeruginosa growth in both planktonic and surface-attached conditions. The results indicate that the obtained composite can be used in cutaneous healing for developing improved wound dressings, which combine the antibacterial activity of all three components with the controlled release of the antibiotic. This wound dressing maintains a moist environment at the wound interface, providing a cooling sensation and soothing effect, while slowly releasing the antibiotic. The system is fully scalable to any other soluble drug, as the entire solution remains trapped in the ZnO-chitosan gel.

ZnO Applications and Challenges

Metal oxide nanoparticles represent a new class of important materials that are increasingly being developed for use in re- search and health-related applications. Although the in vitro antibacterial activity of zinc oxides and some other zinc compounds has been known for quite some time, only in the last few years nanoparticles of ZnO have been investigated for their antibacterial activity, the knowledge about it remaining deficient. The antimicrobial activity of ZnO nanoparticles is strongly influenced by some factors such as size and the presence of light. The potential applications include, but are not limited to, topic drugs, cosmetics or component for agents that control the spread of bacterial strains (antibacterial paint in hospitals, antibacterial coatings for fabrics, antibacterial packaging for food, etc). The current review aims to present the level of knowledge accumulated on the antibacterial and antifungal activity of ZnO.

Coencapsulation of Butyl-Methoxydibenzoylmethane and Octocrylene into Lipid Nanocarriers: UV Performance, Photostability and in vitro Release

The coencapsulation of two UV filters, butyl‐methoxydibenzoylmethane (BMDBM) and octocrylene (OCT), into lipid nanocarriers was explored to develop stable cosmetic formulations with broad‐spectrum photoprotection and slow release properties. Different types of nanocarriers in various concentrations of the two UV filters were tested to find the combination with the best absorption and release properties. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have been the two types of lipid nanocarriers used. The NLCs were based on either medium chain triglycerides (MCT) or squalene (Sq). The following physicochemical properties of the nanocarriers have been evaluated: particle size, morphology, zeta potential (ZP), entrapment efficiency, loading capacity, and thermal behavior. The nanocarriers have been formulated into creams containing low amounts of UV filters (2.5% BMDBM and 1% OCT). The best photoprotection results were obtained with the cream based on NLCs prepared with MCT, having a sun protection factor (SPF) of 17.2 and an erythemal UVA protection factor (EUVA–PF) of 50.8. The photostability of the encapsulated BMDBM filter was confirmed by subjecting the nanocarriers‐based creams to in vitro irradiation. The prolonged UV‐protection efficacy was coupled with a slow in vitro release of the synthetic UV filters, which followed the Higuchi release model.

Antimicrobial Chitosan based formulations with impact on different biomedical applications.

Owing to its physico-chemical characteristics, the biodegradable and biocompatible polymer derived from crustacean shells, Chitosan is one of the preferred candidates for green biomedical applications and also for several industries. Its solubility in acid solutions and ability to form complexes with anionic macromolecules to yield nanoparticles, microparticles and hydrogels, as well as the ability of chitosan based nanocomposites to remain stable at physiological pH recommend this polymer for the development of efficient drug delivery systems. This paper reviews the main utilities of chitosan as a drug delivery component and describes the most recent technologies which utilize this polymer for developing nanostructured systems with antimicrobial effect, offering a perspective of using these findings in new, ecological biomedical applications.

Magnetite: from synthesis to applications.

In this review the synthesis, functionalization and some applications of magnetite nanoparticles (MNPs) were highlighted. It is our intention to highlight the correlations between the synthesis routes, related synthesis parameters, functionalization strategies and the properties expected for the materials containing MNPs. The uses of MNPs are strongly influenced by the properties of the materials. Therefore this review is trying to discuss the applications of the magnetite and magnetite based nanomaterials by taking into account all the factors that can influence the properties of the final materials and consequently their potential applications.

Antioxidant Activity of Solid Lipid Nanoparticles Loaded with Umbelliferone

The objective of this investigation was to develop solid lipid nanoparticles (SLNs) of umbelliferone by means of a high shear homogenization technique and to evaluate the efficiency of SLN systems in preserving and enhancing antioxidant activity of the flavonoid active component. The aqueous SLN dispersions combine two structural types of lipid compounds and different types of emulsifiers including a mixture of monoalkyl polyoxyethylene sorbitan with a block copolymer and lecithin. The assessment of umbelliferone stability in aqueous SLN dispersions, the size distribution of lipid nanoparticles loaded with umbelliferone (by DLS technique), as well as the structural changes (FT-IR spectroscopy and differential scanning calorimetry) of these lipid nanomatrices have been investigated. Moreover, the influence of umbelliferone concentration onto entrapment efficiency and antioxidant properties were clearly evidenced on four kinds of lipid nanoparticles. The umbelliferone-loaded SLN prepared with polyethylene glycol sorbitan monostearate shown a mean particle size of 173.4 nm ± 3.279, as well as good entrapment efficiency (EE = 60.70%) and antioxidant properties (AA = 75%).

Lipid nanocarriers based on natural oils with high activity against oxygen free radicals and tumor cell proliferation

The development of nano-dosage forms of phytochemicals represents a significant progress of the scientific approach in the biomedical research. The aim of this study was to assess the effectiveness of lipid nanocarriers based on natural oils (grape seed oil, fish oil and laurel leaf oil) in counteracting free radicals and combating certain tumor cells. No drug was encapsulated in the nanocarriers. The cytotoxic effect exerted by bioactive nanocarriers against two tumor cells, MDA-MB 231 and HeLa cell lines, and two normal cells, L929 and B16 cell lines, was measured using the MTT assay, while oxidative damage was assessed by measuring the total antioxidant activity using chemiluminescence analysis. The best performance was obtained for nanocarriers based on an association of grape seed and laurel leaf oils, with a capacity to scavenge about 98% oxygen free radicals. A dose of nanocarriers of 5mg·mL(-1) has led to a drastic decrease in tumor cell proliferation even in the absence of an antitumor drug (e.g. about 50% viability for MDA-MB 231 cell line and 60% viability for HeLa cell line). A comparative survival profile of normal and tumor cells, which were exposed to an effective dose of 2.5mg·mL(-1) lipid nanocarriers, has revealed a death rate of 20% for normal B16 cells and of 40% death rate for MDA-MB 231 and HeLa tumor cells. The results in this study imply that lipid nanocarriers based on grape seed oil in association with laurel leaf oil could be a candidate to reduce the delivery system toxicity and may significantly improve the therapeutic efficacy of antitumor drugs in clinical applications.

Detailed characterization of functionalized magnetite and ascertained effects

The paper reports on magnetite successfully functionalized with two new molecules. The investigations, involving chemical and physical methods, provided relevant features involving cell parameters and grain sizes, or the intermingling ratio between magnetite and functionalizing molecules, as deduced from magnetic measurements. A large amount of interesting data concerning various surface and local interaction mechanisms was supplied by detailed Mössbauer measurements. The new outputs are explained in terms of material processing and intimate mixing of the involved molecules.

Phyto-mediated nanostructured carriers based on dual vegetable actives involved in the prevention of cellular damage.

The growing scientific interest in exploitation of vegetable bioactives has raised a number of questions regarding their imminent presence in pharmaceutical formulations. This study intends to demonstrate that a dual combination between vegetable oil (e.g. thistle oil, safflower oil, sea buckthorn oil) and a carrot extract represents an optimal approach to formulate safe carrier systems that manifest cell regeneration effect and promising antioxidant and anti-inflammatory activity. Inclusion of both natural actives into lipid carriers imparted a strong negative charge on the nanocarrier surface (up to -45mV) and displayed average sizes of 70nm to 140nm. The entrapment efficiency of carrot extract into nanostructured carriers ranged between 78.3 and 88.3%. The in vitro release study has demonstrated that the entrapment of the extract represents a viable way for an equilibrated release of carotenoids. Besides the excellent antioxidant properties (e.g. scavenging up to 98% of the free oxygen radicals), the results of cellular integrity (e.g. cell viability of 133%) recommend these nanocarriers based on dual carrot extract-bioactive oil as a promising trend for the treatment of certain disorders in which oxidative stress plays a prominent role. In addition, the lipid nanocarriers based on safflower oil and sea buckthorn oil demonstrated an anti-inflammatory effect on LPS induced THP-1 macrophages, by inhibiting the secretion of two pro-inflammatory cytokines, IL-6 and TNF-α.

Ivy leaves extract based – lipid nanocarriers and their bioefficacy on antioxidant and antitumor activities

In this study, two issues commonly associated with phytochemical based nanotechnology were addressed: (1) the use of active compounds from medicinal herbs as functional ingredients entrapped into lipid-based nanocarriers; (2) the safety and efficacy of phytochemical-based nanocarriers with promising antioxidant and antitumor benefits. In this context, nanostructured lipid carriers (NLC) based on raspberry seed oil (Rso), pomegranate seed oil (Pso) and rice bran oil (Rbo) were synthesized and proven to be highly effective for the entrapment of hydrophilic ivy leaves extract (Ile). The size, morphology, zeta potential, entrapment efficiency and crystallinity of the Ile-loaded NLC were characterized. The effectiveness of Ile loaded-NLC has been proved by identifying a high capacity to scavenge free oxygen radicals (i.e. between 94 and 98%). 200 μg mL−1 Ile-NLC based on Rbo showed no significant effects on cellular viability in the fibroblast L929 cell line, while the tumor B16 cell line was markedly affected. MTS, RTCA assays and apoptosis examination revealed that these nanocarriers induce cytotoxicity and apoptosis in the murine melanoma B16 cell line. This study reports the first evidence of the association of hydrophilic and lipophilic phytochemicals in the same lipid nanocarriers, which appears to be a promising antioxidant and antitumor approach deserving further investigation.