Poly(methacryloyloxy ethyltrimethylammonium chloride) (PMETAC), poly(sulfopropylmethacrylate potassium salt), or poly(N‐isopropyl acrylamide) (PNIPAM) brushes are synthesized by means of the atom transfer radical polymerization technique from gold surfaces coated with a monolayer of the initiator ω‐mercaptoundecyl bromo isobutyrate. The brush growth is followed in situ and in real time by the combination of quartz crystal microbalance with dissipation technique (QCM‐D) and spectroscopic ellipsometry in a single device. The combination of QCM‐D and ellipsometry allows for the simultaneous determination of both the acoustic mass, macous, comprising the mass of the polymer and the solvent, and the optical mass, mopt, which corresponds to the polymer mass alone. Brush hydration is calculated from the difference between the values obtained for macous and mopt for each polymer synthesized. Brush hydration is then used to quantify the percentage of water released in the brush during collapse; a 30–40% release of water for PMETAC and PSPM brushes in 1 M NaCl and 80% for PNIPAM brushes when the temperature is increased to values above the lower critical solution temperature is observed. 相似文献
We fabricated a two-dimensional (2D) molecularly imprinted sol-gel thin film-coated quartz crystal microbalance (QCM) for the rapid detection of staphylococcal enterotoxin B (SEB) by combining organosilanes and the template protein SEB on the surface of piezoelectric quartz crystal (PQC) Au-electrode by in-situ immobilization. The detection process was monitored by the QCM's frequency shift (Δf). The working range of this method was 1.0 × 10?1–1.0 × 103 µg/mL. The detection limit was 6.1 ng/mL, which was lower than that of the PQC immunosensor, and the detection period was within 0.5 h. The reproducibility of the imprinted film-coated QCM was satisfactory due to no significant statistical difference (P > 0.05) in the rapid detection of SEB between intra- and inter-batch. The selectivity of the imprinted sol-gel film showed that it could discriminate the template molecule from its analogues and other guest molecules. Compared with immunochip, the imprinted film-coated QCM is more advantageous in terms of simplicity, rapidity, low cost, and sensitivity. Moreover, in real sample analysis, the recoveries of this method were 89.4–106.63%, which can be considered a favorable and applicable method for the rapid determination of SEB in real samples. 相似文献
This paper describes a novel batch-type quartz crystal microbalance immunosensor that incorporates a commercially available stainless-steel holder. The sensor was coated with a hydrophilic polymer interface containing phosphatidylcholine analogs that attract water and amino groups for the covalent attachment of receptors. The hydrophilic polymer on a gold substrate captured antibodies and reduced nonspecific adsorption. Operation of the immunosensor required only one sample injection. A clear response triggered by antigen-antibody binding was observed and allowed measurement of the IgG antibody concentration with a superior signal-to-noise ratio using only commercially available components. We thus demonstrate an inexpensive and readily available sensor. 相似文献
The formation of Q-state PbS particle in lead arachidate (PbAr) Langmuir-Blodgett films has been monitored using the quartz crystal microbalance (QCM) measurement. The study showed that the mass uptake of PbAr films with different thicknesses on exposure to hydrogen sulfide was consistent with that expected for the quantitative conversion of Pb2+ in the films to PbS and the corresponding conversion of PbAr to arachidic acid. Mass uptake measurement on PbAr films extensively exposed to H2S gas showed the arachidic acid molecules left after Q-state particle formation could be quantitatively converted to PbAr by immersing the film in a stirred aqueous solution containing lead ions. Subsequent reexposure of the film to H2S increases the mole fraction of PbS in the film. 相似文献
Abstract Sulfur dioxide was detected and determined in air by a piezoelectric quartz crystal sensor coated with 4-aminoantipyrine 1-hydroxyetil-2-heptadecenyl imidazol (amine 220) solution (1:1 v/v in chloroform). The analytical response curve is linear over the concentration range from 0.70 to 5.0 ppm of SO2. Good linearities (r = 0.9990, 0.9995 and 0.9968) and sensitivities (18.0, 33.4 and 50.7 Hz/ppm) were found, respectively for exposure times of 30, 60 and 90 seconds. The sensor can be used for more than six months without loss in sensitivity and presented good reversibility and reproducibility. Among some possible interferents tested, only nitrogen dioxide and moisture caused major frequency changes. 相似文献
The effect of salt concentration on layer-by-layer deposition of poly(sodium 4-styrene sulfonate) (PSSS)/poly(vinylbenzyl trimethylammonium chloride) (PVTC) was investigated by use of quartz crystal microbalance with dissipation (QCM-D). The changes in frequency and dissipation demonstrate that the addition of NaCl leads the thickness of PSSS/PVTC multilayer to increase. The deposition of PSSS/PVTC is dominated by surface charge overcompensation level at lower salt concentrations. However, it is mainly determined by the interpenetration of polyelectrolytes at a higher salt concentration, as reflected in the oscillation of dissipation change. 相似文献
Summary: The growth of surface‐initiated poly([2‐(methacryloyloxy)ethyl]trimethylammonium chloride) (pMETAC) brushes by ATRP was monitored by the quartz crystal microbalance technique with dissipation (QCM‐D). The change in mass of the quartz crystals starting from the adsorption of a thiol initiator monolayer through to the growth of the polymer brushes was determined. The use of QCM‐D allowed determination of the kinetics of polymerization from the surface. The technique can be applied to other polymers synthesised from surfaces and allows the study of varying conditions on the polymerization kinetics.
Changes in frequency of a quartz crystal during polymerization. 相似文献