Synthesis of stimuli-responsive microgels for in vitro release of diclofenac diethyl ammonium.
ABSTRACT Thermal and dual stimuli-responsive microspheres (pH and temperature) were prepared by free radical polymerization of methacrylate bovine serum albumin (BSA-MA) as cross-linker and sodium methacrylate (NaMA) and/or N-isopropylacrylamide (NIPAAm), as hydrophilic/pH-sensitive and thermo-responsive monomers, respectively. Microgels were characterized by infrared spectroscopy, morphological analysis, particle size distribution and determination of swelling properties. The network density and the shape of the microgels were found to depend on the concentration of the reactive species in the polymerization feed. Thermal analyses were performed to determine lower critical solution temperature values, which become close to the body temperature by increasing the content of the hydrophilic moieties in the network. In order to test the preformed materials as drug carriers, in vitro release studies of Diclofenac diethyl ammonium salt were performed. For all the co-polymers, a predominant drug release in the collapsed state was observed, while below the microgel transition temperature, a drug release through the swollen network occurs. The data recorded during the release tests demonstrated that the pH of the surrounding environment influences the drug release more than the temperature of the imbibing medium.
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ABSTRACT: The use of biologics, polymers, silicon materials, carbon materials, and metals has been proposed for the preparation of innovative drug delivery devices. One of the most promising materials in this field are the carbon-nanotubes composites and hybrid materials coupling the advantages of polymers (biocompatibility and biodegradability) with those of carbon nanotubes (cellular uptake, stability, electromagnatic, and magnetic behavior). The applicability of polymer-carbon nanotubes composites in drug delivery, with particular attention to the controlled release by composites hydrogel, is being extensively investigated in the present review.BioMed research international. 01/2014; 2014:825017.
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ABSTRACT: The osteointegration of the orthopaedic implants could improve the biocompatibility and the life span of the implants. The ideal implants should be made by materials easily colonized by bone-forming cells (osteoblasts), which can synthesize new bone matrix. Some implant materials are not often compatible with osteoblasts, but rather they promote the formation of soft connective tissue. There are a number of important reasons to explore the potential for the application of nanomaterials in orthopedic surgery. The use of nanotechnology has been tested on a wide range of materials (such as metals, ceramics, polymers, and composites), where either nanostructured surface features or constituent nanomaterials (including grains, fibers, or particles with at least one dimension from 1 to 100 nm) have been utilized. These nanomaterials have demonstrated superior properties compared with their conventional (or micron structured) counterparts, due to their distinctive nanoscale features and the novel physical properties that ensue. Aim of this paper is to explore how nanotechnology can really improve the future of orthopedic implants and scaffolds for bone and cartilage defects. Here we are showing the most relevant works about the use of nanotechnologies for the treatment of osteocondral defects.Journal of Nanomedicine & Biotherapeutic Discovery. 08/2013; 3(2):114.
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ABSTRACT: Aims. As shown in literature, the future strategies are based on the synergic combination of different methodologies: use of biomimetic scaffold in order to support bone regeneration, use of mesenchymal stromal cells (MSCs) and growth factors. Successful regeneration necessitates the development of tissue-inducing scaffolds that mimic the hierarchical architecture of native tissue extracellular matrix (ECM). Cells in nature recognize and interact with the surface topography they are exposed to via ECM proteins. Aim of this paper is to explore how nanotechnology can really improve the future of orthopedic implants and scaffolds for bone and cartilage defects. Aim of this paper is to explore how nanotechnology can really improve the future of orthopedic implants and scaffolds for bone defects. Here we are going to show the guidelines recently published for the design and development of nanostructured scaffolds for the bone regeneration, and the morphofunctional changing of MSCs interacting with nanogratings. Methods. Aim of this study is to design, develop and preclinical test PET nanostructured scaffolds for the transplantation and differentiation of MSCs in the treatment of bone defects. The first step of our study was the extraction of patient’s bone marrow and the isolation of MSCs. After characterizing (demonstrating the typical cell surface markers) and isolating the MSCs were cultivated on the PET substrates. The PET nanosubstrates were obtained by a low temperature embossing lithography (HEL) achieving low-damage nanotopographic surface modifications. After MSC cultivation on PET substrates we made a cytotoxicity evaluation, an optic and confocal microscopic evaluation (cells adhesion, cells polarization...) and tests to optimize cell differentiation towards osteogenic fate. Results. PET is a highly suitable thermo-plastic material, able to sustain the necessary methods to obtain nanostructured substrates. MSCs cultivated on nanostructured PET rapidly align with the direction of the nanostructure itself without any cytotoxic effects. After the cultivation on the nanostructures, MSCs sustained cytoskeleton changes suggesting the activation of intracellular signaling (mechanotrasduction) promoting osteogenesis. Conclusions. The mechanisms by which nanotopographic cues influence stem cell proliferation and differentiation appear to involve changes in cytoskeletal organization and structure, potentially in response to the geometry and size of the underlying features of the ECM by a process called mechanotrasduction. Integrating nanotopographical cues is especially important in engineering complex tissues that have multiple cell types and require precisely defined cell-cell and cell-matrix interactions at the nanoscale. Thus, in the next-generation regenerative engineering approaches, nanoscale materials/scaffolds are expected to play a parimary role in controlling MSC fate and the consequent regenerative capacity.6th China Medicinal Biotech Forum CMBF 2013, Shenzhen, China; 09/2013