Francesca Signori

Bis(benzoxazolyl)stilbene excimers as temperature and deformation sensors for biodegradable poly(1,4-butylene succinate) films

In this work, new and innovative polymeric film sensors based on excimer luminescence and responsive to both mechanical and temperature stress were obtained through the dispersion of moderate amounts (0.02–0.2 wt%) of the food-grade dye bis(benzoxazolyl)stilbene (BBS) into a thermoplastic aliphatic biodegradable polyester [poly(1,4-butylene succinate), PBS]. Emission from BBS excimers emerged with dye concentrations higher than 0.05 wt% conferring to the film a green luminescence (λexc. = 366 nm). On applying mechanical stress at rt, the PBS reorganization efficiently breaks the BBS arrangements leading to the prevalence of blue emission from the excited isolated chromophores. Moreover, the optical behaviour of PBS–BBS quenched blends was thermally affected in the range 50–80 °C, providing composite films characterized by a very sensitive temperature dependent luminescence response. The easy modulation of the luminescent properties of polyester films by varying the supramolecular organization of BBS dispersed molecules by thermal or mechanical perturbations suggests various applications in the field of smart and intelligent films from thermoplastic materials.

Ageing and oxidative stress: A role for dolichol in the antioxidant machinery of cell membranes?

Dolichol is a polyprenol compound broadly distributed in membranes, biosynthetized by the general isoprenoid pathway from acetate via mevalonate and farnesyl pyrophosphate. Dolichol lays inside the membrane between the two leaflets of the lipid bilayer very close to the tail of phospholipid fatty acids. No definite catabolic pathways for this molecule have yet been identified. Evidence is produced that dolichol levels increase dramatically with increasing age; that anti-ageing caloric restriction retards this age-associated change; that dolichol may act as a radical scavenger of peroxidized lipids belonging to the cell membranes. In view of the polyunsaturated fatty acids (PUFA), dolichol and Vitamin E location and stechiometry, it is proposed that molecules might interact each-other to form a highly matched free-radical-transfer chain, whose malfunctioning might be involved in statin toxicity and neurodegenerative diseases.

New perspectives for (S)-dolichol and (S)-nordolichol synthesis and biological functions

A procedure is described for the preparation of (S)-dolichol and (S)-nordolichol starting from the polyprenyl fraction extracted fromGingko biloba integer or exhausted leaves. The procedure appears extremely valuable in obtaining the two chiral isoprenoid compounds in good chemical yields and retention of a high degree of enantiomeric excess. Also, the (S)-nordolichol represents a good chiral precursor for the preparation of 14C-labelled (S)-dolichol to be used in biological investigations into the (S)-dolichol catabolism in the functional living cell. Furthermore, the possible role of (S)-dolichol as a free radical scavenger in the cell membrane was preliminarily evaluated by means of a 1H-NMR analytical method. Apparently, experimental results substantiate this hypothesis.

Threshold temperature luminescent indicators from biodegradable poly(lactic acid)/poly(butylene succinate) blends

In this work, a new thermal stimuli sensitive multiphase polymer system consisting of a bio-related mixture of poly(lactic acid) (PLA, 85 wt%) and poly(1,4-butylene succinate) (PBS, 15 wt%) was prepared by the controlled incorporation of moderate amounts ( 60 to 70 °C) leading to a clear change of the emission properties due to the occurrence of dye aggregation. Thermal analysis by DSC showed an evident connection between blend morphology features and luminescence response. The results are here discussed with reference to the transition temperatures of the two polymer phases and their effect on aggregation/disaggregation of dispersed BBS.

Nanoparticle Systems for the Targeted Release of Active Principles of Proteic Nature

The preparation and characterization of nanoparticles based on biodegradable/bioerodible polymers is reported. They have been designed for the controlled-targeted release of proteic drugs such as α-interferon and for the release of active principles in tissue engineering. The amenability of some of the prepared polymeric matrices to be used in the fabrication of micro and nano patterned scaffolds is also described.

Development of new PLA-based biodegradable compounds

New biodegradable compounds having high renewable resources starting materials content were developed and formulated at Lab, pilot and industrial level. Pipes were prepared using the here developed compounds, and perfectly mimic the mechanical behavior as well as the chemical resistance of the currently used polyethylene based materials. This work is currently developed within the EC founded HYDRUS project.

Segmented Polyetheresters Containing Hydrogen Bonding Units

In recent years, the growing interest in the delivery of protein and peptide drugs stimulated the development of new materials with tailored properties. Requisites to be fulfilled are the non-denaturation of the incorporated protein as well as the loaded drug and the possibility of controlling both the mechanism and kinetics of polymer degradation and drug release1.