Synthesis of hydroxyapatite from mussel shells for effective adsorption of aqueous Cd(II).

We report the synthesis of hydroxyapatite (HAP) powder from waste mussel shells (decomposed to CaO) and phosphoric acid at room temperature without pH control. The powder synthesized was utilized for cadmium removal from aqueous solutions using the batch technique. The effects of solution pH, adsorbent dose; initial Cd2+ concentration, contact time, and temperatures were examined. Furthermore, the adsorption process revealed a pseudo-second-order reaction model and the Langmuir isotherm is the best-fit model to predict the experimental data and adsorption capacity was found to be 62.5 mg/g. Thermodynamic analysis revealed that because of the negative values of ΔGo and the positive value of ΔHo, the adsorption process was spontaneous and endothermic. Cadmium immobilization occurs through a two step mechanism: rapid ion exchange followed by partial dissolution of hydroxapatite and precipitation of cadmium containing hydroxyapatite.

Prostaglandin E2 and interleukin-8 production in human epidermal keratinocytes exposed to marine lipid-based liposomes.

In response to exogenous stimuli such as non-sensitizing contact irritants, human keratinocytes produce various types of soluble pro-inflammatory mediators including prostaglandin E2 (PGE2) and interleukin 8 (IL-8). Polyunsaturated fatty acids of the n-3 series (n-3 PUFA) are known to play a role in the prevention of the inflammatory response. In this work, n-3 PUFA were supplied to keratinocytes through Marinosomes that are liposomes based on a natural marine lipid extract. Marinosomes contributed to reduce inflammation induced by croton oil by regulating PGE2 and IL-8 production in human keratinocyte cultures. However, the preventing effect of Marinosomes was highly dependent on the lipid concentration used and the liposome mean diameter.

Marinosomes, marine lipid-based liposomes: physical characterization and potential application in cosmetics.

Marinosomes are liposomes based on a natural marine lipid extract containing a high polyunsaturated fatty acid (PUFA) ratio. They were prepared and characterized in conditions that mimic that of topical application in terms of pH, temperature and calcium. Marinosomes were stable in storage conditions for 1 month. At low pH (pH 4) or in presence of high calcium concentrations (9 mM), complex structural rearrangements, such as aggregation and size reduction, occurred which were kinetically dependant.

Stability of marine lipid based-liposomes under Acid conditions. Influence of xanthan gum.

Liposomes are potential candidates in Human nutrition to supplement diets in essential lipo- and hydro-soluble nutriments. In this context, marine lipid based-vesicles, rich in polyunsaturated fatty acids, and containing vitamin B1 (thiamine) were prepared. Two methods were envisaged for vitamin trapping, passive encapsulation and active loading through the use of a transmembrane pH gradient. These methods were compared in terms of thiamine trapping efficiency. Influence of xanthan addition was also studied. Although, the active loading yielded to higher encapsulation ratios than the passive method, encapsulation efficiency was markedly increased, in both cases, as soon as the hydrocolloid was added after the lipid hydration phase. Liposome stability was assayed by microscopy observation and membrane permeability to thiamine in a medium that mimic that faced by the structures administrated by the oral route, i.e., an acid pH medium, as in the Human stomach. Low pH value led to an instantaneous vesicle aggregation. Thiamine was totally released from liposomes prepared without xanthan after 24 h storage in a neutral medium. This time was shortened to 1 h at pH 1.5. However, thiamine retention was significantly improved when liposomes were prepared in presence of the hydrocolloid, whatever the encapsulation method used. On the whole, these results were interpreted in terms of xanthan coating around the liposome surface that would result from lipid-hydrocolloid interactions occurring during the centrifugation steps of liposome preparation.