Ecaterina Andronescu

Hybrid magnetite nanoparticles/Rosmarinus officinalis essential oil nanobiosystem with antibiofilm activity

Biofilms formed by fungal organisms are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence of the fungi despite antifungal therapy. The purpose of this study is to combine the unique properties of nanoparticles with the antimicrobial activity of the Rosmarinus officinalis essential oil in order to obtain a nanobiosystem that could be pelliculised on the surface of catheter pieces, in order to obtain an improved resistance to microbial colonization and biofilm development by Candida albicans and C. tropicalis clinical strains. The R. officinalis essential oils were extracted in a Neo-Clevenger type apparatus, and its chemical composition was settled by GC-MS analysis. Functionalized magnetite nanoparticles of up to 20 nm size had been synthesized by precipitation method adapted for microwave conditions, with oleic acid as surfactant. The catheter pieces were coated with suspended core/shell nanoparticles (Fe3O4/oleic acid:CHCl3), by applying a magnetic field on nanofluid, while the CHCl3 diluted essential oil was applied by adsorption in a secondary covering treatment. The fungal adherence ability was investigated in six multiwell plates, in which there have been placed catheters pieces with and without hybrid nanoparticles/essential oil nanobiosystem pellicle, by using culture-based methods and confocal laser scanning microscopy (CLSM). The R. officinalis essential oil coated nanoparticles strongly inhibited the adherence ability and biofilm development of the C. albicans and C. tropicalis tested strains to the catheter surface, as shown by viable cell counts and CLSM examination. Due to the important implications of Candida spp. in human pathogenesis, especially in prosthetic devices related infections and the emergence of antifungal tolerance/resistance, using the new core/shell/coated shell based on essential oil of R. officinalis to inhibit the fungal adherence could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with antibiofilm properties.

Collagen-hydroxyapatite/Cisplatin Drug Delivery Systems for Locoregional Treatment of Bone Cancer

In this paper, the synthesis and characterization of novel cisplatin-loaded collagen (COLL)/hydroxyapatite (HA) composite materials are presented. The composite materials were designed to obtain a COLL: HA weight ratio close to the bone composition. The content of embedded cisplatin was chosen to assure a concentration of cisplatin of 6 and 10 μM, respectively, into the culture media used in cell culture experiments. These cisplatin delivery systems were characterized by determining the physico-chemical properties of the composite material, the drug release process as well as their biological activity. Based on the in vitro data that showed the cytotoxic, anti-proliferative and anti-invasive activities of these multifunctional systems on G292 osteosarcoma cells in dependence on the cisplatin concentration released in culture medium, we conclude that the newly developed COLL/HA-cisplatin drug delivery system could be a feasible approach for locoregional chemotherapy of bone cancer.

Advances in Collagen/Hydroxyapatite Composite Materials

The annually necessary human bone grafts are in continuous grown due to the increasing of fractals, congenital and non-congenital diseases. Based on statistical reports (Murugan and Ramakrishna 2005), only in USA about 6.3 million fractures occur every year and about 550.000 of these require bone grafting. The most frequently fractures occur at the level of hip, ankle, tibia and fibula. Due to the higher physical effort, the men are more exposed to fracture than women (2.8% in the case of men comparing to 2.0% in the case of women). The number of fractures increases year by year and consequently many researchers from different research fields co-operate in order to develop new bone graft materials. Also, it is important to mention that, in the present, the bone diseases are overlapped only by hearth diseases. The history of bone grafting is starting in 1913 when Dr. D.E. Robertson assays a piece of cat’s bone and a piece of human bone for bone grafting into dogs (Gallie and Toronto 1914). The microscopic analysis of implanted graft after 20 days shows that the space between graft and living bone is filled with new cancellous bone. These early works made the premises for the development of the bone grafts. Due to the increasing of the necessarily bone grafts, autografts and allografts can not cover the overall need of bone grafts. For compensate this gap, artificial (synthetic) grafts are necessary and, consequently used. The use of synthetic grafts has some advantages versus allografts, autografts and xenografts: the possibility to obtain unlimited number/quantity of synthetic grafts, more safety use of artificial bone grafts without disease transmission risk, pain limitation by elimination of some secondary surgical intervention. The need of bone grafts materials lead to the synthesis of many kind of materials with different properties. Function of the nature of these materials and the relation between these grafts and the host tissue, these materials can be divided into 4 generations (Fig. 1). The components of the first generation of bone grafting biomaterials have remarkable mechanical properties but they are neither bioresorbable nor bioactive. More than, the use of these kind of bone grafts have limited lifetime (usually less than 10-15 years) and need to be extracted and replaced surgically. Some of the most representative biomaterials from the first generation of bone grafting biomaterials are: the iron, cobalt, chromium, titan or their alloys: steel (especially 316 L), cobalt or titan based alloys (Corces 2002; Corces and Garcia 2007) etc.

Nanotechnology: a challenge in hard tissue engineering with emphasis on bone cancer therapy

Abstract The increasing need for bone grafting materials, as well as the increasing incidence of bone cancer has led to an increasing interest of researchers and clinicians in developing new materials and strategies for bone tissue reconstruction and repair, as well as for the treatment of different specific diseases of the bone tissue: cancer, infections, osteoporosis, and so forth. At this moment, the most intense activity is focused in developing ceramic and composite materials for bone tissue engineering even if the use of metals is still required for the engineering of the long bones. When using metals, the main improvements are obtained by modifying their surface with adequate, active layers/coatings. The use of ceramic-polymer composite materials seems to be the most adequate alternatives. Collagen and hydroxyapatite, being the main components of the bone, are expected to be the most adequate materials for developing composite materials or bone tissue engineering, but many other materials, natural or derived from natural materials (chitosan, chitin, cellulose and especially biocellulose, alginate, etc.), as well as synthetic materials [poly- l -lactic acid, carbon-based materials, calcium phosphates (CaPs), bioglasses, etc.] can be used. Depending on the disease causing the bone defects, along with the aforementioned biomaterials, other components can be added: various nanoparticles (magnetite, silver, or gold nanoparticles, zinc or titanium oxides, etc.), active agents, such as antibiotics, cytostatics, analgesics, and so forth, and targeting agents used in cancer treatment. The present work was intended to gather some information about the role of nanotechnology in developing materials for hard tissue engineering with a special emphasis on bone cancer therapy. Based on the recent advances in the field of materials, the most promising materials for bone tissue regeneration seem to be the tissue-engineered nanocomposites, which can be designed for achieve specific functionalities.

Advances in Cancer Treatment: Role of Nanoparticles

This chapter is devoted to the advances in the field of nanoparticles-mediated cancer treatment. A special attention is devoted to the use of magnetite and silver nanopar‐ ticles. The synthesis and properties of Fe3O4 and Ag nanoparticles as contrast or antitumoral agents as monolith or component of more complex systems such as polymer matrix composite materials based on: polymers (chitosan, collagen, poly‐ ethylene glycol, polyacrylates, and polymethacrylates, polylactic acid, etc.) and various antitumoral agents (cytostatics, natural agents and even nanoparticlesmagnetite, silver, or gold) are discussed. Special attention is paid for the benefits and risks of using silver and magnetite nanoparticles. In both cases, the discussion focuses on aspects related to diagnosis and treatment of cancer. The influence of size and shape [1-3] is important from the materials characteristics as well as from the biological points of view. The role of magnetite is also analyzed from the point of view of its influence on the delivery of different components of interests (antitumoral compo‐ nents, analgesics/anti-inflammatory agents, etc.). The potentiating effect of the nanoparticles over the cytostatics and natural components is highlighted.

Nanoalumina obtained by pyrosol method

Ceramic materials are interesting due to their properties such as chemical and thermal stability, corrosion resistance, biocompatibility, piezoelectricity, high dielectricity. Also, nano-sized materials may have properties different from the micro scale materials. Pyrosol method is an alternative method to obtain nanoscale particles. In this study alumina particles were prepared by pyrosol method using AlCl3 (0.1 M and 0.05 M) as precursor solutions. The particles were obtained by maintaining the temperature of 400 °C in the pyrolysis furnace. Then, the powders were heat treated at 1000 °C for 2 hours. The X-ray diffraction analyses indicated that the obtained nanoparticles were identified as a mixture of a and g crystalline alumina. Scanning electron microscopy images showed that the prepared Al2O3 nanoparticles obtained from the concentration of 0.05 M had smaller dimensions than those obtained from the concentration of 0.1 M. Images of transmission electron microscopy showed spherical particles with the median diameter approximately of 150 nm, using as precursor AlCl3 solution (0.05 M).