Cysteamine-Modified Silver Nanoparticle Aggregates for Quantitative SERS Sensing of Pentachlorophenol with a Portable Raman Spectrometer

Cysteamine-modified silver nanoparticle aggregates has been fabricated for pentachlorophenol (PCP) sensing by surface-enhanced Raman spectroscopy (SERS) using a portable Raman spectrometer. The cysteamine monolayers could preconcentrate PCP close to the substrate surface through the electrostatic interaction, which makes the SERS detection of PCP possible. Moreover, the Raman bands of cysteamine could be used as the internal spectral reference in the quantitative analysis. Qualitative detection of PCP was carried out by SERS without any sample pretreatment. Quantitative analysis of PCP was further realized based on the prepared substrate, as the log–log plot of normalized SERS intensity of PCP versus its concentrations exhibits a good linear relationship. The SERS signals collected on 20 randomly selected points show that the relative standard deviation of the normalized Raman intensity is 5.8%, which indicates the substrate had good uniformity. The PCP sensor also shows good long-term stability in the analyte solution. The substrate was cyclic immersed into PCP and methanol solution; after several cycles, the sensor still had good adsorption to PCP, which revealed the sensor has good reusability. Coupling with a portable Raman spectrometer, the cysteamine-modified silver nanoparticle aggregates have the potential to be used for in situ and routine SERS analysis of PCP in environmental samples

Flow cytometry images.

<p>Flow cytometry images.</p

Lung histopathology.

<p>Lung histopathology was examined by hematoxylin and eosin (HE) staining and periodic acid-Schiff (PAS) staining in (A1 and A2) mice in the normal control group, (B1 and B2) mice in the asthma control group, and (C1 and C2) mice in the <i>M</i>. <i>vaccae</i> prevention group. The normal control group showed complete airway epithelium mucosa, ordered cilia, thin basilar membranes and smooth muscle, a smooth and glossy lung small vascular endothelium, no inflammatory cell infiltration, few goblet cells (A1), and no mucus secretion (A2). The asthma control group showed cellular swelling of the airway epithelia, increased plicae mucosae, disordered cilia, broken bronchial mucous membranes, infiltration of inflammatory cells, a thickened alveolar wall and basilar membrane, hyperplasia of the smooth muscle (B1), proliferation and hypertrophy of the airway epithelia and goblet cells, generous mucus and mucus plugs, and desquamation of the epithelia (B2). The <i>M</i>. <i>vaccae</i> group showed no obstruction of the airway lumen and ordered epithelia (C1), and no goblet cells or mucus secretion (C2).</p

Airway hyperresponsiveness.

<p>^#<i>P</i> < 0.05, <i>M</i>. <i>vaccae</i> group vs. normal control group.</p

Flow cytometry results.

<p>#<i>P</i> < 0.001, compared with the normal control; ##<i>P</i> < 0.001, compared with the asthma control; *<i>P</i> < 0.05, compared with the normal control; **<i>P</i> < 0.01, compared with the asthma control.</p

Experimental protocol.

<p><i>M</i>. <i>vaccae</i>: <i>Mycobacterium vaccae</i>; Neb.: nebulization.</p

High Glucose-induced VSMC proliferation and migration is associated with decreased PGC-1α expression.

<p>Cultured rat VSMCs were incubated for 48 h in 5.5 mM, 11 mM, 15 mM and 25 mM glucose respectively, Cell growth was determined by counting the number of cells (A) and VSMC migration was determined by a standard wound healing assay (B), PGC-1α expression was determined by real-time RT-PCR by using primers specific for rat PGC-1α and β-actin (C). The bars represent means±S.E.M (n = 6). *P<0.05, **P<0.01, #P<0.001 vs. cells incubated in 5.5 mM glucose. Arterial samples were obtained from the normal and STZ injected rats, the intima and outer and inner tissue layers were removed from arteries. PGC-1α expression was determined by real-time RT-PCR. Data (n = 10) were expressed as means±S.E.M. *P<0.05 vs. normal rats (D).</p

Suppression of PGC-1α abolishes the inhibitory effect of palmitic acid on high glucose-induced VSMC growth and movement.

<p>VSMCs were transfected with siRNA (SI) or the negative control (N), then left stimulated with 15 mM gluoose (HG) in the presence of 0.4 mM palmitic acid (PA) for 48 h. Cell growth was determined by counting the number of cells (A). Migration distance was determined by a standard wound healing assay (B) and by transwell analysis (C). The bars represent means±S.E.M (n = 6). *P<0.05, **P<0.01, #P<0.001 compared with the N+PA+HG group.</p

Increase of PGC-1α either exogenously by adenovirus or endogenously by palmitic acid abolished high glucose induced phosphorylation of ERK1/2 in VSMCs.

<p>VSMCs were infected with adenovirus for 24 h, then made quiescent by serum-starvation for 6 h, and then stimulated with HG for 4 h. Total protein were harvested and used to detect ERK1/2 activity (A). Cultured VSMCs in 5.5 mM glucose were made quiescent by serum-starvation for 6 h, then cells were either left untreated or stimulated with 15 mM glucose (HG) in the absence and presence of 0.4 mM palmitic acid (PA) for 12 h. ERK activity were determined by Western blotting with ERK1/2 (pT202/pY204) Phospho-Specific antibodies compared with b-tubulin antibody and densitometric analysis of ERK1/2 activity are showed. Representative blots of three similar results are showed. #P<0.001 compared with control.</p

Knock-down of PGC-1α accelerated high glucose-induced VSMC proliferation and migration.

<p>VSMCs transfected with siRNA (SI) or the negative control (N), were either left untreated or stimulated with 15 mM gluoose (HG). The interference effect was assessed by quantitative PCR analysis and data were shown as the ratio of PGC-1α/β-actin (A), **P<0.01compared with the negative control group (N). 120 µg total proteins from VSMCs were assayed for Western blot with PGC-1 antibody to confirm the interference effiency (B). Effects of decreased PGC-1α on high glucose-induced VSMC proliferation were determined by cell counting (C). VSMC migration was determined by wound healing (D) and transwell analysis (E). Individual data points in this figure represents the mean±S.E.M (n = 6). *P<0.05, #P<0.001 compared with the control group (N+HG).</p