PDMS-based films containing surface-active amphiphilic block copolymers to combat fouling from barnacles B. amphitrite and B. improvisus

Surface-active amphiphilic diblock copolymers, Si-EFS14 and Si-EFS71, consisting of a poly(dimethyl siloxane) block (degree of polymerisation 11) and a poly(4-(triethyleneglycol monomethyl ether)-2,3,5,6-tetrafluorostyrene) block (average degree of polymerisation 14 and 71) were synthesised by ATRP. Films were prepared by incorporating each copolymer (4 wt%) into a PDMS matrix, which was then condensation cured. Bioassays were performed on the films using two barnacle species, Balanus amphitrite and Balanus improvisus, at different stages of their life cycles. The cyprids of B. improvisus settled on all test surfaces in higher numbers than those of B. amphitrite. However, the juveniles of B. improvisus were more easily removed from the films containing the copolymer Si-EFS14 than from those containing the copolymer Si-EFS71. An XPS analysis revealed that the near-surface region of copolymer Si-EFS71 was enriched in oxyethylenic chains and became even more populated by these hydrophilic chains after the films were immersed in water

Dynamics and relaxation in new florinated side-chain polymers: an ESR investigation

Fluorinated azobenzene liquid crystalline polymers appear promising materials as optical data storage substrates, especially in holographic recording, for their ability of suppressing surface relief (1). Their applicative importance also arises from the excellent water repellency (2) and the possibility of modulating wettability by the change in the dipole moment of the cis-trans photochromic species (3). The comprehension of the mechanism by which the internal structure and molecular architecture of these materials affect their microscopic relaxation phenomena will address an ever improved design for technological applications and a fundamental understanding, enlightening the presence of cooperative mechanisms or/and dynamic heterogeneity. A new series of fluorinated homopolymers and random copolymers were investigated. They share the same main chain, and differentiate from a previous series (4, 5) for the substitution of the −(2)43 group with the −3 one in the terminal part of the azobenzene-containing side chain. The study was carried out by electron spin resonance to investigate the dynamics and matrix heterogeneity of the new series of copolymers, also in comparison with the previous non-fluorinated series. The structural relaxation of the polymers was also investigated by rheological measurements. Different molecular architectures result in modulation of the relaxation properties at nanoscale level. Dynamics and matrix heterogeneity is discussed, highlighting how the different molecular architecture affects different dynamic responses and matrix heterogeneity over different length and time scales. Information on cooperativity of the dynamics is also provided. References 1. F. You, M.Y.Paik, M. Häckel, L. Kador, D. Kropp, H.W. Schmidt, and C.K.Ober. Adv. Funct. Mater., 16: 1577, 2006. 2. S.D. Xiong, X.L. Guo, L. Li, S.l. Wu, P.K. Chu, and Z.S. Xu. J. Fluorine Chem., 131: 417, 2010. 3. K.Ichimura, S.K.Oh, and M.Nakagawa. Science, 288 (5471): 1624, 2000. ; S.Abbott, J.Ralston, G.Reynold, and R.Hayes. Langmuir, 15: 8923, 1999; L. M. Siewierski, W. J.Brittain, S.Petrash, and M.D.Foster. Langmuir, 12: 5838, 1996. 4. L. Andreozzi, M. Faetti, M. Giordano, D. Palazzuoli, and G. Galli. Macromolecules, 34: 7325, 2001. 5. L. Andreozzi, G. Galli, M. Giordano, E. Martinelli, and F. Zulli Macromolecules, 48: 6541, 201

Strong coupling between excitons in organic semiconductors and Bloch Surface Waves

We report on the strong coupling between the Bloch surface wave supported by an inorganic multilayer structure and $J$-aggregate excitons in an organic semiconductor. The dispersion curves of the resulting polariton modes are investigated by means of angle-resolved attenuated total reflection as well as photoluminescence experiments. The measured Rabi splitting is 290 meV. These results are in good agreement with those obtained from our theoretical model

Julolidine fluorescent molecular rotors as vapour sensing probes in polystyrene films

We introduce a new sensing polymer system for detection of volatile organic compounds (VOCs) based on the optical response of polystyrene (PS) films doped with julolidine fluorescent molecular rotors (FMRs). The julolidine FMRs exhibited viscosity-dependent changes in the fluorescence intensity, that was enhanced when glycerol was added to ethanol solutions and when they were dispersed in PS films. Thus, reduction in medium mobility slowed down internal motions and allowed for a major radiative decay pathway. The FMR/PS films were exposed to several VOCs, and showed a significant decrease in fluorescence emission when exposed to chloroform, whereas a negligible variation in their emission occurred when methanol was utilized. This vapour sensing behaviour was much more evident when a perfluorodecyl chain was linked to the julolidine core being the molecule segregated at the film surface. This responsive behaviour was affected by solvent composition and its reproducible response was easily determined by luminescence experiments

Ab initio Study of Misfit Dislocations at the SiC/Si(001) Interface

The high lattice mismatched SiC/Si(001) interface was investigated by means of combined classical and ab initio molecular dynamics. Among the several configurations analyzed, a dislocation network pinned at the interface was found to be the most efficient mechanism for strain relief. A detailed description of the dislocation core is given, and the related electronic properties are discussed for the most stable geometry: we found interface states localized in the gap that may be a source of failure of electronic devices

Synthesis of liquid crystalline graft and block copolymers by sequential cationic and free-radical polymerizations

Abstraet-New graft and block copolymers were synthesized by two procedures, each consisting of a sequence of cationic and free-radical polymerization reactions. One polymer component was a liquid crystalline side-group polymer, with the other polymer component being incorporated in crystalline grafts or in amorphous blocks. The copolymers were microphase-separated and underwent thermal transitions (glass, melting, isotropization) of each individual component

Handling of Doubtful WBC Scintigraphies in Patients with Suspected Prosthetic Joint Infections

Abstract: Despite the application of EANM recommendations for radiolabelled white-blood-cells (WBC) scintigraphy, some cases still remain doubtful based only on visual analysis. The aim of this study was to investigate the role of semi-quantitative analysis and bone marrow scan (BMS) in solving doubtful cases. We retrospectively evaluated all [99mTc]HMPAO-WBC scintigraphies performed, in the last 7 years, for a suspected monolateral prosthetic joint infection (PJI). In doubtful cases, we used five different thresholds of increase of target-to-background (T/B) ratio, between delayed and late images, as criteria of positivity (5%, 10%, 15%, 20% and 30%). BMS were also analysed and sensitivity, specificity and accuracy of different methods were calculated according to final diagnosis. The sensitivity, specificity and accuracy were, respectively, 77.8%, 43.8% and 53.0% for the cut-off at 5%; 72.2%, 66.7% and 68.2% for the cut-off at 10%; 66.7%, 75.0% and 72.7% for the cut-off at 15%; 66.7%, 85.4% and 80.3% for the cut-off at 20%; 33.3%, 93.8% and 77.3% for the cut-off at 30%. BMS provided a significantly higher diagnostic performance than 5%, 10% and 15% thresholds. Conversely, we did not observe any statistically significant difference between BMS and the cut-off of more than 20%. Therefore, doubtful cases should be analysed semi-quantitatively. An increase in T/B ratio of more than 20% between delayed and late images, should be considered as a criterion of positivity, thus avoiding BMS

Amphiphilic modified-styrene copolymer films: Antifouling/fouling release properties against the green alga Ulva linza

Surface-active copolymers of a styrene carrying a polysiloxane side chain (SSi) and a triethyleneglycol monomethyl ether-modified pentafluorostyrene (EFS) (39 and 77 mol% EFS) were prepared and incorporated (8 wt% loading) into a polydimethyl siloxane (PDMS) matrix to produce crosslinked blend films. The wettability of the surface-active copolymer films and PDMS-blend films was investigated by contact angle measurements. An angle-resolved X-ray photoelectron spectroscopy (XPS) of the surface chemical composition before and after immersion in water for 7 days enabled location of the hydrophilic oxyethylenic segments of EFS within the top 10 nm from the film surface. Laboratory bioassays on the blend films against the marine green alga Ulva linza evidenced that the films containing the copolymer with the larger EFS content showed greater resistance to settlement of zoospores of U. linza, whereas both films had superior fouling-release properties of sporelings (young plants) compared to the PDMS standard films

Pre-clinical evaluation of eight DOTA coupled gastrin-releasing peptide receptor (GRP-R) ligands for in vivo targeting of receptor-expressing tumors.

BACKGROUND: Overexpression of the gastrin-releasing peptide receptor (GRP-R) has been documented in several human neoplasms such as breast, prostate, and ovarian cancer. There is growing interest in developing radiolabeled peptide-based ligands toward these receptors for the purpose of in vivo imaging and radionuclide therapy of GRP-R-overexpressing tumors. A number of different peptide sequences, isotopes, and labeling methods have been proposed for this purpose. The aim of this work is to perform a direct side-by-side comparison of different GRP-R binding peptides utilizing a single labeling strategy to identify the most suitable peptide sequence. METHODS: Solid-phase synthesis of eight derivatives (BN1-8) designed based on literature analysis was carried out. Peptides were coupled to the DOTA chelator through a PEG4 spacer at the N-terminus. Derivatives were characterized for serum stability, binding affinity on PC-3 human prostate cancer cells, biodistribution in tumor-bearing mice, and gamma camera imaging at 1, 6, and 24 h after injection. RESULTS: Serum stability was quite variable among the different compounds with half-lives ranging from 16 to 400 min at 37 °C. All compounds tested showed K d values in the nanomolar range with the exception of BN3 that showed no binding. Biodistribution and imaging studies carried out for compounds BN1, BN4, BN7, and BN8 showed targeting of the GRP-R-positive tumors and the pancreas. The BN8 compound (DOTA-PEG-DPhe-Gln-Trp-Ala-Val-NMeGly-His-Sta-Leu-NH2) showed high affinity, the longest serum stability, and the highest target-to-background ratios in biodistribution and imaging experiments among the compounds tested. CONCLUSIONS: Our results indicate that the NMeGly for Gly substitution and the Sta-Leu substitution at the C-terminus confer high serum stability while maintaining high receptor affinity, resulting in biodistribution properties that outperform those of the other peptides