Nanostructured 3D Constructs Based on Chitosan and Chondroitin Sulphate Multilayers for Cartilage Tissue Engineering

Nanostructured three-dimensional constructs combining layer-by-layer technology (LbL) and template leaching were processed and evaluated as possible support structures for cartilage tissue engineering. Multilayered constructs were formed by depositing the polyelectrolytes chitosan (CHT) and chondroitin sulphate (CS) on either bidimensional glass surfaces or 3D packet of paraffin spheres. 2D CHT/CS multi-layered constructs proved to support the attachment and proliferation of bovine chondrocytes (BCH). The technology was transposed to 3D level and CHT/CS multi-layered hierarchical scaffolds were retrieved after paraffin leaching. The obtained nanostructured 3D constructs had a high porosity and water uptake capacity of about 300%. Dynamical mechanical analysis (DMA) showed the viscoelastic nature of the scaffolds. Cellular tests were performed with the culture of BCH and multipotent bone marrow derived stromal cells (hMSCs) up to 21 days in chondrogenic differentiation media. Together with scanning electronic microscopy analysis, viability tests and DNA quantification, our results clearly showed that cells attached, proliferated and were metabolically active over the entire scaffold. Cartilaginous extracellular matrix (ECM) formation was further assessed and results showed that GAG secretion occurred indicating the maintenance of the chondrogenic phenotype and the chondrogenic differentiation of hMSCs

Therapeutic efficacy of artemether–lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria from three highly malarious states in India

Additional file 1. Flowchart showing site-wise enrolment and follow-up profile

Liquefied capsules coated with multilayered polyelectrolyte films for cell immobilization

NMP4-SL-2009-229292Natural-derived polymers are used to coat liquid-core capsules layer by layer to encapsulate cells. Human osteoblast-like cells (SaOs-2) are encapsulated in such spherical devices using a three-step methodology: i) ionotropic gelation to produce alginate beads encapsulating the cells; ii) layer-by-layer coating using water-soluble chitosan and alginate; and iii) core liquefaction. Cells remain viable for 3 d after the encapsulation procedure, suggesting that the developed capsules possess a semipermeable, nanostructured coating. All of the capsules exhibit a spherical shape, smooth surface and liquid-core characteristics. All of the processes are conducted under mild conditions and physiological pH. We consider that the methodology employed in the development of the capsules obtained from natural-based biomaterials has potential to find applicability in the development of scaffolds or cell carriers in tissue engineering and regenerative medicine.PTDC/QUI/68804/200

Chitosan/chondroitin sulfate multilayers as supports for calcium phosphate biomineralization

"Available online 24 January 2014"We investigated the interaction of natural derived macromolecular multilayers with calcium and phosphate ions entirely processed using the layer-by-layer (LbL) technique. A nanostructured multilayer component, with 5 or 10 bilayers, was first produced using weak polyelectrolyte biopolymers, chitosan and chondroitin sulfate. This was followed by sequential passing of solutions containing Ca2+andPO43−over the multilayers. QCM-D, SEM and EDX results conferred the formation of calcium phosphate (CaP) over the polyelectrolyte multilayers. Initiation of precipitation was observed earlier in the 10 bilayers coating than in the 5 bilayers one. These results indicate the potential of multilayers to trap ions, as a biomimetic approach that can be used to induce CaP precipitation. This could enable the preparation of more performant bioactive composite biomaterials for orthopedic applications, including in bone tissue engineering.This work was supported by the Portuguese Foundation for Science and Technology (FCT), through the doctoral Grant SFRH/BD/73174/2010 of Alvaro J. Leite and postdoctoral grant SFRH/BPD/489948/2008 of Praveen Sher

Production methodologies of polymeric and hydrogel particles for drug delivery applications

Introduction: Polymeric particles are ideal vehicles for controlled delivery applications due to their ability to encapsulate a variety of substances, namely low- and high-molecular mass therapeutics, antigens or DNA. Micro and nano scale spherical materials have been developed as carriers for therapies, using appropriated methodologies, in order to achieve a prolonged and controlled drug administration. Areas covered: This paper reviews the methodologies used for the production of polymeric micro/nanoparticles. Emulsions, phase separation, spray drying, ionic gelation, polyelectrolyte complexation and supercritical fluids precipita- tion are all widely used processes for polymeric micro/nanoencapsulation. This paper also discusses the recent developments and patents reported in this field. Other less conventional methodologies are also described, such as the use of superhydrophobic substrates to produce hydrogel and polymeric particulate biomaterials. Expert opinion: Polymeric drug delivery systems have gained increased impor- tance due to the need for improving the efficiency and versatility of existing ther- apies. This allows the development of innovative concepts that could create more efficient systems, which in turn may address many healthcare needs world- wide. The existing methods to produce polymeric release systems have some critical drawbacks, which compromise the efficiency of these techniques. Improvements and development of new methodologies could be achieved by using multidisciplinary approaches and tools taken from other subjects, including nanotechnologies, biomimetics, tissue engineering, polymer science or microfluidics.The authors declare no conflict of interest. The authors are grateful for financial support from Portuguese Foundation for Science and Technology (FCT) through the grants SFRH/BD/71395/2010 and SFRH/BPD/489948/2008

Utjecaj umrežavanja na udio metronidazola u pektinskim zrncima

The purpose of this study was to improve the entrapment efficiency of the water-soluble drug metronidazole using internal cross-linking agents. Calcium pectinate beads containing metronidazole were prepared by dropping a drug-pectin solution in 1% and 5% (m/V) calcium chloride for surface crosslinked beads. For the core cross-linked beads, calcium carbonate was dispersed in the drug-pectin solution. The beads were characterized by particle size, swelling ratio, SEM, DSC, and in vitro drug release. It was found that the beads obtained by core cross linking produced more drug entrapped beads than the surface cross-linked beads. Beads obtained using 1% (m/V) calcium chloride showed more drug entrapment than those obtained using 5% calcium chloride. The core cross-linking of pectin beads reduced drug loss by about 10-20%. The water lodging capacity of beads depended upon gel strength, which is a function of the internal gelling agent and pectin concentration. Complete drug release was observed within 30-60 min in the acidic dissolution medium. This work has showed that the core cross-linking agent increases the water-soluble drug entrapment of in calcium pectinate beads.Svrha istraživanja bila je poboljšati udio vodotopljive ljekovite tvari metronidazola u pripravcima s pektinskim zrncima koristeći sredstva za umrežavnje poput kalcijevog karbonata. Površinski umrežena zrnca kalcijevog pektinata s metronidazolom pripravljena su dokapavanjem otopine lijeka i pektina u 1% i 5% (w/V) otopinu kalcijevog klorida. Zrnca s umreženom jezgrom pripravljena su dispergiranjem kalcijevog karbonata u otopinu ljekovite tvari i pektina. Zrncima su određeni sljedeći parametri: veličina čestica, sposobnost bubrenja, SEM, DSC i oslobađanje ljekovite tvari in vitro. Zrnca dobivena umrežavanjem jezgre sadržavala su veći udio lijeka (1020%) od površinski umreženih zrnaca. Zrnca dobivena s 1% (w/V) otopinom kalcijevog klorida sadržavala su veći udio lijeka od onih dobivenih s 5% otopinom. Kapacitet vezanja vode zrnaca ovisio je o jakosti gela, a jakost gela ovisila je internom agensu za geliranje i koncentraciji pektina. U kiselom mediju ljekovita tvar se u potpunosti oslobodila unutar 3060 minuta

Bioinspired methodology for preparing magnetic responsive chitosan beads to be integrated in a tubular bioreactor for biomedical applications

Magnetic responsive chitosan beads were prepared using a methodology inspired by the rolling of water droplets over lotus leaves. Liquid precursors containing chitosan and magnetic microparticles were dispensed in the form of spherical droplets and crosslinked with genipin over synthetic superhydrophobic surfaces. Scanning electronic microscopy, histology and micro-computed tomography were employed to characterize the structure of the prepared composite beads and the inner distribution of the magnetic particles. Cellular metabolic activity tests showed that fibroblasts-like (L929 cell line) can adhere and proliferate on the prepared chitosan beads. We hypothesize that such spherical biomaterials could be integrated in a new concept of tubular bioreactor. The magnetic beads can be immobilized by an external magnetic field at specific positions and may be transported along the bioreactor by the drag of the culture medium flow. The system behavior was also studied through numerical modeling, which allowed to identify the relative importance of the main parameters, and to conclude that the distance between carrier beads plays a major role on their interaction with the culture medium and, consequently, on the overall system performance. In an up-scaled version of this bioreactor, the herein presented system may comprise different chambers in serial or parallel configurations. This constitutes a simple way of preparing magnetic responsive beads combined with a new design of bioreactor, which may find application in biomedicine and biotechnology, including in cell expansion for tissue engineering or for the production of therapeutic proteins to be used in cell therapies.This work was supported by the Fundacao para a Ciencia e Tecnologia (FCT) post-doctoral grants SFRH/BPD/39290/2007 and SFRH/BPD/489948/2008. It was also supported by FEDER, via FCT, under the PEst-C/CTM/LA0025/2011 (Strategic Project-LA 25-2011-2012) and by the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement No. REGPOT-CT2012-316331-POLARIS