The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

Biosorbents for heavy metals removal and their future

Heavy metal removal from water/wastewater by nanosized metal oxides: a review.

Adsorption of dyes and heavy metal ions by chitosan composites: A review

Properties of lactic acid based polymers and their correlation with composition

Heavy metal adsorbents prepared from the modification of cellulose : A review

Hyaluronic acid based scaffolds for tissue engineering--a review.

Poly n-butyl cyanoacrylate nanoparticles: a mechanistic study of polymerisation and particle formation.

In order to improve the mechanical properties and control the degradation rate of hyaluronic acid (HA) an investigation of the structural and mechanical properties of the hydrogels crosslinked using divinyl sulfone (DVS), glutaraldehyde (GTA) and freeze-thawing, or autocrosslinking has been carried out. The thermal and mechanical properties of the gels were characterised by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and compression tests. The solution degradation products of each system have been analysed using size exclusion chromatography (SEC) and the Zimm-Stockmayer theory applied. Autocrosslinked gels swell the most quickly, whereas the GTA crosslinked gels swell most slowly. The stability of the autocrosslinked gels improves with a reduction in solution pH, but is still poor. GTA and DVS crosslinked gels are robust and elastic when water swollen, with glass transition values around 20 degrees C. SEC results show that the water soluble degradation products of the gels show a reduction in the radius of gyration at any particular molecular weight and this is interpreted as indicating increased hydrophobicity arising from chemical modification.

Physical properties of crosslinked hyaluronic acid hydrogels

Received 23 October 2006; accepted 13 December 2006DOI 10.1002/app.25993Published online 5 March 2007 in Wiley InterScience (www.interscience.wiley.com).ABSTRACT: The effectiveness of four different reagents,glutaraldehyde (GTA), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), poly(ethyelene glycol) diglycidylether (EX 810), and divinyl sulfone (DVS) as crosslinkersfor cast hyaluronic acid (HA) ﬁlms has been evaluated.Films were prepared by casting from solution and exposedto solutions of the crosslinkers in acetone–water solution.Swelling in water and in phosphate buffered saline (PBS)was then used to assess the effectiveness of the cross-linkers. GTA-crosslinked ﬁlms were found to be of lowstability compared with those treated with EDC, EX 810,and DVS. Results suggest that instability in GTA-cross-linked materials arises in part from residual acid catalyst.The effects of polymer molecular weight are not uniform.With GTA-crosslinked ﬁlm produced from higher molecu-lar weight HA swells more, and this is attributed toreduced diffusion of the crosslinker, but with EDC, theopposite effect is observed, implying some additional mo-lecular weight dependent mechanism. Differential scan-ning calorimetry and dynamic mechanical thermal analysisresults suggest that there are no signiﬁcant structural dif-ference between the gels for each crosslinker system andonly the crosslink density and moisture content alters thetransitions.

Colin Birkinshaw

Papers

Heavy metal adsorbents prepared from the modification of cellulose : A review

Hyaluronic acid based scaffolds for tissue engineering--a review.

Poly n-butyl cyanoacrylate nanoparticles: a mechanistic study of polymerisation and particle formation.

Physical properties of crosslinked hyaluronic acid hydrogels

Comparison of the Effectiveness of Four Different Crosslinking Agents with Hyaluronic Acid Hydrogel Films for Tissue-Culture Applications