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In this study porous gelatin scaffolds were prepared using in-situ gas foaming, and four crosslinking agents were used to determine a biocompatible and effective crosslinker that is suitable for such a method. Crosslinkers used in this study included: hexamethylene diisocyanate (HMDI), poly(ethylene glycol) diglycidyl ether (epoxy), glutaraldehyde (GTA), and genipin. The prepared porous structures were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), thermal and mechanical analysis as well as water absorption analysis. The microstructures of the prepared samples were analyzed using Scanning Electron Microscopy (SEM). The effects of the crosslinking agents were studied on the cytotoxicity of the porous structure indirectly using MTT analysis. The affinity of L929 mouse fibroblast cells for attachment on the scaffold surfaces was investigated by direct cell seeding and DAPI-staining technique. It was shown that while all of the studied crosslinking agents were capable of stabilizing prepared gelatin scaffolds, there are noticeable differences among physical and mechanical properties of samples based on the crosslinker type. Epoxy-crosslinked scaffolds showed a higher capacity for water absorption and more uniform microstructures than the rest of crosslinked samples, whereas genipin and GTA-crosslinked scaffolds demonstrated higher mechanical strength. Cytotoxicity analysis showed the superior biocompatibility of the naturally occurring genipin in comparison with other synthetic crosslinking agents, in particular relative to GTA-crosslinked samples.

The current study presents an effective and simple strategy to obtain stable porous scaffolds from gelatin via gas foaming method. The technique exploits the intrinsic foaming ability of gelatin in the presence of CO2 to obtain a porous structure stabilised with glutaraldehyde. The produced scaffolds were characterised using physical and mechanical characterisation methods. The results showed that gas foaming may allow the tailoring of the 3-dimensional structure of the scaffolds with an interconnected porous structure. To assess the effectiveness of preparation method in mitigating the potential cytotoxicity risk of using glutaraldehyde as a crosslinker, direct and indirect cytotoxicity assays were performed at different concentrations of glutaraldehyde. The results indicate the potential of the gas foaming method, in the preparation of viable tissue engineering scaffolds.

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ArticleTitle: The dynamics of sedimentassociated contaminants over a transition from drought to multiple flood events in a lowland UK catchment It is advisable to refer to the publisher's version if you intend to cite from this work. Version: Accepted version Abstract:Fine sediment in suspended form, recently deposited overbank and in temporary storage on or in channel beds was collected in the Nene basin during a period of drought through to a period of four high flows. The sediment was analysed for arsenic, copper, lead, phosphorus and zinc concentrations with the aim of investigating their sources, movement, temporary storage and potential for environmental harm.Copper, lead and zinc probably originated from urban street dusts, phosphorus (originally in dissolved form) from sewage effluent and arsenic from natural soils developed over ironstone. There was little difference in the metal or arsenic concentrations in the sediment under different flow conditions; instead proximity to pollutant sources appeared to control their concentrations. Phosphorus in tributary sub-catchments probably adsorbed to sediment during periods of low flow but these sediments were flushed away during high flows and replaced by sediment with lower concentrations. However, concentrations of all pollutants in overbank sediments along the Nene's main channel were not reduced in successive flood events, suggesting no first flush effect. Only phosphorus accumulated on sediment at concentrations exceeding those of its catchment -based sources (e.g. street dusts, channel banks, catchment soils). This scavenging of aqueous phosphate by sediment explained the difference in behaviour between phosphorus, arsenic and heavy metals. The surface area and organic matter content were shown to have a small effect on contaminant concentrations.Street dust contaminants only exceeded predicted effect levels (PELs) in close proximity to urban areas, suggesting a small potential for harm to the aquatic environment. Arsenic concentrations exceeded PELs in most sediment samples. However, it has been shown to be largely non-bioavailable in previously published research on the Nene, limiting its potential for significant environmental harm. Phosphorus concentrations in river sediments are high in comparison to the soils in the catchment and in comparison with sediment-P concentrations in other published lowland catchment studies, indicating a large potential for eutrophication should the Phosphorus be, or become, bioavailable.2