Sixty-seven surface marine sediment samples in the <63 μm fraction collected from the coast of Sfax (Tunisia) were analyzed by inductively coupled plasma-atomic emission spectrometry for seven heavy metals (Pb, Ni, Cu, Cr, Zn, Cd, and Fe). Metal concentrations were compared with natural values, marine sediment quality standards, and also with other results concerning sediments from several Mediterranean coasts. The study of their spatial distributions refined by complementary approaches including principal component analysis, enrichment factors, and geoaccumulation index showed a significant impact of multiple anthropogenic sources. These included industrial sources and municipal discharges of the urban Sfax and also non-controlled discharges in rural zones close to the coastline. Moderate pollution of sediments, especially by Pb, Zn, and Ni, was shown to exist in localized sites. Besides, it was shown that other sites, slightly to highly enriched in terms of Cu, Cr, and Cd, are characterized by a quality of sediments varying from unpolluted to moderately polluted.

The urbanized coastal zones are frequently faced to various pollutant discharges mainly in the shoreline. The quantification of the pollution level was mainly based on sea-water analysis. However, in this environment, the sediment characterization, using quality indicators, may constitute an accurate approach. The latter can be particularly appropriate to define heavy metals pollution degree. Chemical analyses of Cd, Cu, Zn, and Fe were undertaken for a total of 45 surface marine sediment samples of Gabes city coast. There is a significant extension of pollution, strongly influenced by the dominant longshore current. The studied sediments were found usually enriched with Cu, Cd, and Zn. These anthropogenic heavy metals have identical behavior and similar distribution. These metals did not show any correlations with Fe chosen as natural tracer. The multi-element indices used permitted to conclude that 70% of sampling sites are highly affected by heavy metal contamination and associated with very high ecological risk. These indices use a simple contamination factor, which, however, would not take account of the sedimentary inputs and the complex sediment behavior. Consequently, modified indices, employing enrichment factor, were used and demonstrated better to assess pollution and ecological risk.

In the context of cancer treatment, gold nanoparticles (AuNPs) are considered as very promising radiosensitizers. Here, well-defined polymer-grafted AuNPs were synthesized and studied under gamma irradiation to better understand the involved radiosensitizing mechanisms. First, various water-soluble and well-defined thiol-functionalized homopolymers and copolymers were obtained through Atom Transfer Radical Polymerization. They were then used as ligands in the one-step synthesis of AuNPs, resulting in stable hybrid metalpolymer nanoparticles. Second, these nano-objects were irradiated in solution by gamma rays at different doses. Structures were fully characterized through SEC, SAXS and SANS measurements, prior and after irradiation. We were thus able to quantify and to localize radiation impacts onto the grafted polymers, revealing the production sites of reactive species around AuNPs. Both external and near-surface scissions were observed. Interestingly, the ratio between these two effects was found to vary according to the nature of polymer ligands. Medium-range and long-distance dose enhancements could not be identified from the calculated scission yields, but several mechanisms were considered to explain high yields found for near-surface scissions. Then, cytotoxicity was shown to be equivalent for both nonirradiated and irradiated polymer-grafted NPs, suggesting that released polymer fragments were non-toxic. Finally, the potential to add bioactive molecules such as anticancer drugs has been explored by grafting doxorubicin (DOX) onto the polymer corona. This may lead to nano-objects combining both radiosensitization and chemotherapy effects. This work is the first one to study in details the impact of radiation on radiosensitizing nano-objects combining physical, chemical and biological analyses.