Spherulitic morphologies of nylon 6 9 as an example of an even-odd nylon were studied by optical microscopy. A well-defined dependence on crystallization temperature was found. In particular, positively birefringent spherulites were characteristic for temperatures higher than 232 ºC, low birefringence spherulites developed between 232 and 225 ºC, positive ringed spherulites were found between 225 and 220 ºC, and finally negative fibrillar spherulites were formed at temperatures lower than 220 ºC. These optical properties were clearly different from those observed with even-even nylons (e.g., negative and positive birefringence for high and low temperatures, respectively), and may derive from the peculiar crystalline structures determined for even-odd nylons.Furthermore, low birefringence spherulites were characterized by a flat-on lamellar disposition and reversibility of the birefringence sign in the 80-120 ºC temperature interval (positive and negative values at high and low temperatures, respectively).Real time WAXD profiles taken during heating and cooling processes demonstrated that different crystalline structures (named I, II and III) developed depending on the temperature and crystallization procedure of samples (e.g., from solution or from the melt state). Crystalline structures were characterized by the formation of hydrogen bonds along two crystalline directions in all cases, a peculiar arrangement that may account for the development of positive and negative spherulites in a more simple way than formulated for conventional polyamides having a single hydrogen bonding direction. DSC and FTIR data also showed a complex structural behavior with structural transitions in the 80-120 ºC range, a region that corresponds to birefringence sign reversibility.

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FF-PLA, respectively) have been synthesized by the ring-opening polymerization of L-lactide using the peptide fragment as an initiator. The structure of the conjugates was confirmed by 1 H NMR, FT-IR, GPC, UV-Vis and CD. Molecular dynamics simulations have been used to identify both the conformational preferences of the FF-PLA conjugate in solution and the potential intramolecular interactions between the peptide and polymer blocks, while TD-DFT calculations have been applied to model the electronic transitions observed by the UV-Vis absorption spectroscopy. Results show that the polymer fragment prefers a random coil or a mix of helix/strand while the peptide fragment tends to have folded and helical conformations. Although the degree of interaction between the two fragments is slightly higher than that reported for other peptide-polymer conjugates, it is small enough to suggest that FF-PLA is a potential candidate to aggregate forming peptide-guided organizations via self-assembly. On the other hand, quantum mechanical calculations have allowed us to identify the p / p* transition, which is typically observed in helical peptides and proteins, as well as the n / p* transition along the N-C-O backbone.

Electrospraying of poly(butylene succinate) and its mixture with different indole derivatives was successfully performed using chloroform as solvent and relatively low flow rates and concentrations. Morphology of particles (size, diameter distribution and surface texture) and encapsulation efficiency were dependent on the loaded drug and specifically on the type of substituent (methyl or phenyl) and its position in the indole core. In general, particles showed a raisin-like morphology caused by the shell collapsing of the resulting structurally weak microspheres. Accumulation of electrosprayed particles gave rise to consistent mats and they had a more hydrophobic surface than that determined for smooth films. The increase of hydrophobicity was mainly dependent on the porosity and the hydrophobic nature of the incorporated drugs. Indole derivatives were hardly delivered in a standard phosphate saline buffer due to their scarce solubility in aqueous media but the addition of ethanol caused a drastic change in the release behavior. This was generally characterized by a fast burst effect and followed by the establishment of an equilibrium condition that was dependent on the indole derivative. However, a clearly different behavior was found when the indole was unable to form hydrogen bonds (e.g. 1-methylindole) since in this case a slow and sustained release was characteristic. Microspheres loaded with indole derivatives showed a high antiproliferative activity that was dependent on encapsulation efficiency and the type of loaded drug. The best results were specifically attained for the indole with an aromatic substituent. Interestingly significant differences were found between cancer and immortalized cells, a feature that points out the potential use of such systems for cancer prevention and treatment. (C) 2015 Elsevier Ltd. All rights reserved.Postprint (author's final draft

Novel enzyme loaded scaffolds with enzyme-responsive degradable properties for drug delivery are prepared by an original inverse-miniemulsion electrospinning method. Miniemulsions with aqueous nanodroplets containing different enzymes, i.e. lipase or alpha-chymotrypsin, and a fluorophore are electrospun with a solution of poly(ester amide) and polycaprolactone to fabricate multicompartment nanofibers. The poly(ester amide) contains the two essential amino acids phenylalanine and leucine that promote low cytotoxicity degradation products and makes them suitable for the preparation of drug delivery devices for the biomedical field. The activity of the loaded enzymes in different conditions and a sustained degradation of fibers mechanism with an approximate 20% weight loss within one month are observed. Locating enzymes in degradation medium accelerated the degradation until complete scaffold destruction in less than 5 days. In all cases, a nearly complete release of the loaded fluorophore (from 80% and upwards) was achieved before the complete degradation of fibers occurred, suggesting that the nanofibers are suitable as self-triggered drug release systems with sustained mechanical integrity and a flexible range of degradation rates.Postprint (published version