This study was designed to examine the cellular distribution of the angiotensin II type-1 (AT1) and type-2 (AT2) receptors in the normal human and pathological human lung. Riboprobes were prepared against specific portions of each receptor DNA and labelled with FITC for detection using an anti-FITC antibody in combination with the alkaline phosphatase-anti-alkaline phosphatase technique and new Fuchsin. These were used to detect the presence of receptor mRNA in the lung. Specific antibodies were used to detect receptor protein in cells by immunocytochemistry. Image analysis was used in order to semi-quantify receptor density. AT1 receptor mRNA and protein were localised on vascular smooth muscle cells, macrophages and in the stroma underlying the airways epithelium probably relating to underlying fibroblasts. The AT1 receptor protein was not expressed in the epithelium although there was a low level of mRNA. In contrast, AT2 receptor RNA and protein was observed in the epithelium, with strong staining on the bronchial epithelial cell brush border and also on many of the underlying mucous glands. The AT2 receptor was also present on some endothelial cells. These findings were supported by the presence of mRNA in each case. In patients with chronic obstructive pulmonary disease, there was a five- to sixfold increase in the ratio of AT1 to AT2 receptors in the regions of marked fibrosis surrounding the bronchioles. This correlated well with the reduced lung function as expressed by the forced expiratory volume.
Highlights pH-sensitive PCL and PCL/chitosan nanofibres are successfully electrospun. pH-sensitive PCL and PCL/chitosan nanofibres show a clear halochromic response. Chitosan addition results in a significantly increased water sorption. Chitosan addition is indispensable for a sensitive and rapid response. Theoretical modelling on the dye-polymer interactions underpins the experimental findings. Highlights (for review)Polycaprolactone and polycaprolactone/chitosan nanofibres functionalised with pH- Polycaprolactone (PCL) is an aliphatic polyester, often used in (bio)medical applications 56 because of its biocompatibility, slow biodegradability, low-cost, non-toxicity and good 57 mechanical properties (Moghe et al., 2009; Van der Schueren et al., 2011). However, PCL is Prabhakaran et al., 2008;Yang et al., 2009; Bhattarai et al., 2009; Hong & Kim, 2011; 63 Cooper et al., 2011). Contact angle measurements were carried out with the drop-shape analysis system DSA 10- 168Mk2, coupled to a control unit G120 Mk1/G140-Mk1 and with the drop-shape analysis 169 software DSA1 (v1.80, Krüss). 171Dynamic Vapour Sorption (DVS) measurements were conducted in a Q-5000SA instrument 172(TA-instruments, Zellik, Belgium). All measurements were performed at 23 °C ± 0.1 °C. 173Deliquescent salts (sodium bromide and potassium chloride) were used to verify the humidity 174 of the instrument. 4 mg of nanofibres were placed in the quartz sample pans. At the start of 175 each moisture sorption cycle, the fibres were dried at 0 % relative humidity (RH) until the 176 weight change was stabilised to be less than 0.05 % for a period of 15 minutes. After the 177 stabilisation, the moisture sorption cycle was started and the humidity was increased hydroxide were used to adjust the pH. 196The UV-Vis spectra were recorded with a Perkin-Elmer Lambda 900 spectrophotometer. For suggests an increased interaction with water when chitosan blend nanofibres are used. 287As a final step prior to the halochromic study, the dye leaching of the samples is 288 characterised ( The nanofibrous samples were all yellow just after the electrospinning process, in agreement 306 with the acidic conditions during their production (acetic acid-formic acid solvent system). compared to the sharp transition of NY in aqueous solutions, which occurs between pH 6 and 346 8 (Fig. 3a), the response of PCL nanofibres is less sensitive (response between pH 4 and 10, observed. All PCL/chitosan samples showed a sharp transition between pH 4 and 6 (Fig. 3c). 362Also the wavelength maxima did not alter and remained constant at 474 nm and 605 nm in proposed, which will then be validated by theoretical results. After electrospinning pure PCL (Fig. 5b) with NY, no halochromic behaviour is observed, structures. The chitosan model (Fig. 5e) has a PA of 908 kJ/mol, which is much higher than 429 the value of 841 kJ/mol obtained for the PCL model (Fig. 5d). This suggests that the chitosan ( Fig. 7) is much higher, -132.3 kJ/mol. The value for dye leaching was, however, much larger...
Halochromic polyamide6-based fabrics with drastically reduced dye-leaching through blend electrospinning of PA6 with dye-functionalized copolymer.
Colorimetric sensors for monitoring and visual reporting of acidic environments both in water and air are highly valuable in various fields, such as safety and technical textiles. Until now solgel based colorimetric sensors are usually non-flexible bulk glass or thin film sensors. Large area, flexible sensors usable in strong acidic environments are not available. Therefore, in this study organically modified silicon oxide nanofibrous membranes are produced by combining electrospinning and sol-gel technology. Two pH-indicator dyes are immobilized in the nanofibrous membranes: Methyl Yellow via doping, Methyl Red via both doping and covalent bonding. This resulted in sensor materials with a fast response time and high sensitivity for pHchange in water. The covalent bond between dye and the sol-gel network showed to be essential to obtain a reusable pH-sensor in aqueous environment. Also a high sensitivity was obtained for sensing of HCl and NH3 vapors, including a memory function allowing visual read-out up to 20 minutes after exposure. These fast and reversible, large area flexible nanofibrous colorimetric sensors are highly interesting for use in multiple applications such as protective clothing and equipment. Moreover, the sensitivity to biogenic amines was demonstrated, offering potential for control and monitoring of food quality.
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