Amine functionalization of cholecyst-derived extracellular matrix with generation 1 PAMAM dendrimer

This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Biomacromolecules, copyright © American Chemical Society after peer review. To access the final edited and published work, see http://pubs.acs.org/doi/pdf/10.1021/bm701055k.A method to functionalize cholecyst-derived extracellular matrix (CEM) with free amine groups was established in an attempt to improve its potential for tethering of bioactive molecules. CEM was incorporated with Generation-1 polyamidoamine (G1 PAMAM) dendrimer by using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide and N-hydroxysuccinimide cross-linking system. The nature of incorporation of PAMAM dendrimer was evaluated using shrink temperature measurements, Fourier transform infrared (FTIR) assessment, ninhydrin assay, and swellability. The effects of PAMAM incorporation on mechanical and degradation properties of CEM were evaluated using a uniaxial mechanical test and collagenase degradation assay, respectively. Ninhydrin assay and FTIR assessment confirmed the presence of increasing free amine groups with increasing quantity of PAMAM in dendrimer-incorporated CEM (DENCEM) scaffolds. The amount of dendrimer used was found to be critical in controlling scaffold degradation, shrink temperature, and free amine content. Cell culture studies showed that fibroblasts seeded on DENCEM maintained their metabolic activity and ability to proliferate in vitro. In addition, fluorescence cell staining and scanning electron microscopy analysis of cell-seeded DENCEM showed preservation of normal fibroblast morphology and phenotype

Carrageenan-based hydrogels for the controlled delivery of PDGF-BB in bone tissue engineering applications

One of the major drawbacks found in most bone tissue engineering approaches developed so far consists in the lack of strategies to promote vascularisation. Some studies have addressed different issues that may enhance vascularisation in tissue engineered constructs, most of them involving the use of growth factors (GFs) that are involved in the restitution of the vascularity in a damaged zone. The use of sustained delivery systems might also play an important role in the re-establishment of angiogenesis. In this study, !-carrageenan, a naturally occurring polymer, was used to develop hydrogel beads with the ability to incorporate GFs with the purpose of establishing an effective angiogenesis mechanism. Some processing parameters were studied and their influence on the final bead properties was evaluated. Platelet derived growth factor (PDGF-BB) was selected as the angiogenic factor to incorporate in the developed beads, and the results demonstrate the achievement of an efficient encapsulation and controlled release profile matching those usually required for the development of a fully functional vascular network. In general, the obtained results demonstrate the potential of these systems for bone tissue engineering applications.This work was supported by the European NoE EXPERTISSUES (NMP3-CT-2004-500283), the European STREP HIPPOCRATES (NMP3-CT-2003-505758), and by the Portuguese Foundation for Science and Technology (FCT) through the project PTDC/FIS/68517/2006 and through the V. Espirito Santo's Ph.D. grant (SFRH/BD/39486/2007)

Supercapacitance from cellulose and carbon nanotube nanocomposite fibers

Copyright © 2013 American Chemical SocietyACS AuthorChoice open access articleMultiwalled carbon nanotube (MWNT)/cellulose composite nanofibers have been prepared by electrospinning a MWNT/cellulose acetate blend solution followed by deacetylation. These composite nanofibers were then used as precursors for carbon nanofibers (CNFs). The effect of nanotubes on the stabilization of the precursor and microstructure of the resultant CNFs were investigated using thermogravimetric analysis, transmission electron microscopy and Raman spectroscopy. It is demonstrated that the incorporated MWNTs reduce the activation energy of the oxidative stabilization of cellulose nanofibers from 230 to 180 kJ mol–1. They also increase the crystallite size, structural order, and electrical conductivity of the activated CNFs (ACNFs). The surface area of the ACNFs increased upon addition of nanotubes which protrude from the fiber leading to a rougher surface. The ACNFs were used as the electrodes of a supercapacitor. The electrochemical capacitance of the ACNF derived from pure cellulose nanofibers is demonstrated to be 105 F g–1 at a current density of 10 A g–1, which increases to 145 F g–1 upon the addition of 6% of MWNTs.The authors would like to thank the [Engineering and Physical Sciences Research Council] EPSRC (EP/F036914/1 and EP/I023879/1), Guangdong and Shenzhen Innovative Research Team Program (No. 2011D052,KYPT20121228160843692), National Natural Science Foundation of China (Grant No. 21201175), R&D Funds for basic Research Program of Shenzhen (Grant No. JCYJ20120615140007998), and the Universities of Exeter and Manchester for funding this research

Designing Bioactive Delivery Systems for Tissue Regeneration

The direct infusion of macromolecules into defect sites generally does not impart adequate physiological responses. Without the protection of delivery systems, inductive molecules may likely redistribute away from their desired locale and are vulnerable to degradation. In order to achieve efficacy, large doses supplied at interval time periods are necessary, often at great expense and ensuing detrimental side effects. The selection of a delivery system plays an important role in the rate of re-growth and functionality of regenerating tissue: not only do the release kinetics of inductive molecules and their consequent bioactivities need to be considered, but also how the delivery system interacts and integrates with its surrounding host environment. In the current review, we describe the means of release of macromolecules from hydrogels, polymeric microspheres, and porous scaffolds along with the selection and utilization of bioactive delivery systems in a variety of tissue-engineering strategies

Using mechanisms of object-oriented programming for the unification of procedures of work with the monthly plan and for manufacture and shipment of the main production

This article describes a version of the modernization of the software (SOFTWARE), which allows to create monthly production plans and shipping program for shops of the main production, which used some of the mechanisms of object-oriented programming. The result of this work was the unification of the same actions in the formation of monthly plans for different shops within the framework of this SOFTWARE, the use of the same objects in different parts of the SOFTWARE with rapid adaptation to specific requirements in this place, the possibility of using the obtained objects in the newly developed provision by various departments of development