Mathilde Casetta

Remediation of Heavy Metals by Biomolecules: A Review

Some biomolecules are well known for the complexation of heavy metals from wastewater: cellulose, alginate, pectins, and starches for example. However, less used natural molecules could also be efficient to chelate heavy metals. Indeed, some cells contain polypeptides that can help detoxifying living organisms containing heavy metals. This natural detoxification process is of great interest, and particularly the molecules taking part in it. The amino acids composing these polypeptides, especially cysteine, tyrosine, and histidine, can be used for water purification. The efficiency of biomolecules containing aromatic rings on heavy metals complexation is also investigated. All these biomolecules are able to chelate heavy metals thanks to some chemical groups and atoms: the most well-known and efficient chemical groups are listed in the article. Finally, some potential environmental applications of biomolecules are suggested at the end of the article.

Anticoagulant and antimicrobial finishing of non-woven polypropylene textiles

The aim of this work is to prepare non-woven polypropylene (PP) textile functionalized with bioactive molecules in order to improve its anticoagulation and antibacterial properties. This paper describes the optimization of the grafting process of acrylic acid (AA) on low-pressure cold-plasma pre-activated PP, the characterization of the modified substrates and the effect of these modifications on the in vitro biological response towards cells. Then, the immobilization of gentamicin (aminoglycoside antibiotic) and heparin (anticoagulation agent) has been carried out on the grafted samples by either ionic interactions or covalent linkages. Their bioactivity has been investigated and related to the nature of their interactions with the substrate. For gentamicin-immobilized AA-grafted samples, an inhibition radius and a reduction of 99% of the adhesion of Escherichia coli have been observed when gentamicin was linked by ionic interactions, allowing the release of the antibiotic. By contrast, for heparin-immobilized AA-grafted PP samples, a strong increase of the anticoagulant effect up to 35 min has been highlighted when heparin was covalently bonded on the substrate, by contact with the blood drop.

One pot flame retardant and weathering resistant coatings for plastics: a novel approach

The self-stratifying approach is a one step process allowing the formation of a complex laminated coating structure at the surface of plastics or other substrates, combining optimized surface and adhesion properties. These coatings have already been developed for various application fields but have never been considered for fire retardant purposes, whatever the substrate involved. In this work, the self-layering concept has been used to make polycarbonate fire retardant, using a mixture of epoxy and fluoropolymer resins, and iron oxide as flame retardant additive (10 wt%). Self-stratification was evidenced by microscopic analyses. The flame retardant properties were evaluated according to Limiting Oxygen Index (LOI), UL-94 and Mass Loss Calorimetry (MLC). Weathering resistance by accelerated UV, thermal and humidity exposure was also considered. In the first part, the effect of solvent on the self-layering process was investigated. It was shown that the system diluted in a blend of butylacetate : xylene (1 : 1 ratio) exhibits a perfect stratification and excellent adhesion onto polycarbonate. In such a system, an outstanding improvement of the fire retardant properties (V0 rating at UL-94 and 32 vol% at LOI), unaffected by weathering (both UV and temperature/humidity exposure), was observed when a 200 μm wet thick coating was applied. The coating allows the formation of a protective barrier and the presence of metal particles avoids dripping and promotes a charring effect.