Poly(ethylene glycol)‐poly(lactide) (PEG‐PLA) block copolymers are processed to solvent cast films and solution electrospun meshes. The effect of polymer composition, architecture, and number of anchoring points for the plasticizer on swelling, degradation, and mechanical properties of these films and meshes is investigated as potential barrier device for the prevention of peritoneal adhesions. As a result, adequate properties are achieved for the massive films with a longer retention of the plasticizer PEG for star‐shaped block copolymers than for the linear triblock copolymers and consequently more endurable mechanical properties during degradation. For electrospun meshes fabricated using the same polymers, similar trends are observed, but with an earlier start of fragmentation and lower tensile strengths. To overcome the poor mechanical strengths and an occurring shrinkage during incubation, which may impair the coverage of the wound, further adaptions of the meshes and the fabrication process are necessary.
This work describes the application of several analytical techniques to characterize the development of Bordetella pertussis biofilms and to examine, in particular, the contribution of virulence factors in this development. Growth of surface-attached
virulent and avirulent B. pertussis strains was monitored in continuous-flow chambers by techniques such as the crystal violet method, and nondestructive methodologies
like fluorescence microscopy and Fourier transform (FT) IR spectroscopy. Additionally, B. pertussis virulent and avirulent strains expressing green fluorescent protein were grown adhered to the base of a glass chamber of
1-μm thickness. Three-dimensional images of mature biofilms, acquired by confocal laser scanning microscopy, were quantitatively
analysed by means of the computer program COMSTAT. Our results indicate that only the virulent (Bvg+) phase of B. pertussis is able to attach to surfaces and develop a mature biofilm. In the virulent phase these bacteria are capable of producing
a biofilm consisting of microcolonies of approximately 200 μm in diameter and 24 μm in depth. FTIR spectroscopy allowed us
not only to follow the dynamics of biofilm growth through specific biomass and biofilm marker absorption bands, but also to
monitor the maturation of the biofilm by means of the increase of the carbohydrate-to-protein ratio. 相似文献
We have investigated the application of near-infrared spectroscopy for detection of human primary pancreatic and colorectal
cancers. Spectra from cancerous and normal tissue were collected from a total of 37 surgically resected pancreatic and colorectal
patient tissue specimens using a fibre-optic probe. Major spectral differences were observed in the CH-stretching first (6,000–5,400 cm−1) and second overtone (9,000–7,900 cm−1) regions. By use of artificial neural networks, linear discriminant analysis, and cluster analysis as pattern-recognition
methods the spectra were classified into cancerous and normal tissue groups with accuracy up to 89%. We also explored differences
between the spectra obtained from colorectal and pancreatic tissue. Spectral data from cancerous and normal tissue were classified
organ-specifically into four groups with accuracy between 80 and 83%. Our results indicate that CH-overtone regions, besides
serving as diagnostic markers for NIR spectroscopic diagnosis of primary human pancreas and colorectal cancers, are also useful
for elucidating differences between the spectra obtained from colorectal and pancreatic cancerous tissue. 相似文献
We develop an atomic-scale model for an ordered incommensurate gold sulfide (AuS) adlayer which has previously been demonstrated to exist on the Au(111) surface, following sulfur deposition and annealing to 450 K. Our model reproduces experimental scanning tunneling microscopy images. Using state-of-the-art Wannier-function-based techniques, we analyze the nature of bonding in this structure and provide an interpretation of the unusual stoichiometry of the gold sulfide layer. The proposed structure and its chemistry have implications for related S-Au interfaces, as in those involved in self-assembled monolayers of thiols on Au substrates. 相似文献
The analysis of acylated proteins by mass spectrometry (MS) has largely been overshadowed in proteomics by the analysis of glycosylated and phosphorylated proteins; however, lipid modifications on proteins are proving to be of increasing importance in biomedical research. In order to identify the marker ions and/or neutral loss fragments that are produced upon collision-induced dissociation, providing a means to identify the common lipid modifications on proteins, peptides containing an N-terminally myristoylated glycine, a palmitoylated cysteine and a farnesylated cysteine were chemically synthesized. Matrix-assisted laser desorption/ionization time-of-flight time-of-flight (MALDI-TOF-TOF), electrospray ionization quadrupole time-of-flight (ESI Q-TOF), and electrospray ionization hybrid triple-quadrupole/linear ion trap (ESI QqQ(LIT)) mass spectrometers were used for the analysis. The peptide containing the N-terminally myristoylated glycine, upon CID, produced the characteristic fragments a1 (240.4 Th) and b1 (268.4 Th) ions as well as a low-intensity neutral loss of 210 Da (C14H26O). The peptides containing a farnesylated cysteine residue fragmented to produce a marker ion at a m/z of 205 Th (C15H25) as well as other intense farnesyl fragment ions, and a neutral loss of 204 Da (C15H24). The peptides containing a palmitoylated cysteine moiety generated neutral losses of 238 Da (C16H30O) and 272 Da (C16H32OS); however, no marker ions were produced. The neutral losses were more prominent in the MALDI-TOF-TOF spectra, whereas the marker ions were more abundant in the ESI QqQ(LIT) and Q-TOF mass spectra. 相似文献