16-mercaptohexadecanoic-acid and 11-mercaptoundecanoic-acid

A series of quantum dots (QDs) fluorescent probes for the in situ identification of Microthrix parvicella (M. parvicella) in bulking sludge were designed and prepared. In the preparation of CdTe/CdS QDs, the 11-mercaptoundecanoic acid (11-acid) and 16-mercaptohexadecanoic acid (16-acid) were used as the stabilizer. The prepared QDs probes were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM), and the results showed that the CdTe/CdS QDs formed a core-shell structure and the long carbon chain was successfully grafted onto its surface. And the three QDs probes had different crystallinity and particle size, which was due to the inhibition effect of long carbon chain. The optical properties test results showed that although the formed core-shell structure and long carbon chain affected the fluorescent intensity, adsorption, and emission spectra of the QDs probes, the probes B and C had a large stokes-shift of 82 and 101 nm, which was a benefit for their fluorescent labeling property. In the fluorescent identification of M. parvicella, the probes B and C effectively adsorbed onto the surface of M. parvicella through a hydrophobic bond, and then identified M. parvicella by their unique fluorescence. In addition, it was found that a better hydrophobic property resulted in better identification efficiency.

Topics: Actinobacteria; Crystallization; Fatty Acids; Fluorescent Dyes; Hydrophobic and Hydrophilic Interactions; In Situ Hybridization, Fluorescence; Microscopy, Electron, Transmission; Palmitic Acids; Particle Size; Quantum Dots; Sewage; Spectroscopy, Fourier Transform Infrared; Sulfhydryl Compounds; Tellurium; X-Ray Diffraction

A series of nanoscale chemical patterning methods based on soft and hybrid nanolithographies have been characterized using scanning electron microscopy with corroborating evidence from scanning tunneling microscopy and lateral force microscopy. We demonstrate and discuss the unique advantages of the scanning electron microscope as an analytical tool to image chemical patterns of molecules highly diluted within a host self-assembled monolayer and to distinguish regions of differential mass coverage in patterned self-assembled monolayers. We show that the relative contrast of self-assembled monolayer patterns in scanning electron micrographs depends on the operating primary electron beam voltage, monolayer composition, and monolayer order, suggesting that secondary electron emission and scattering can be used to elucidate chemical patterns.

Topics: Adamantane; Fatty Acids; Microscopy, Electron, Scanning; Microscopy, Scanning Tunneling; Nanotechnology; Palmitic Acids; Reproducibility of Results; Sulfhydryl Compounds

Because the active remodeling of biointerfaces is a paramount feature of nature, it is very likely that future, advanced biomaterials will be required to mimic at least certain aspects of the dynamic properties of natural interfaces. This need has fueled a quest for model surfaces that can undergo reversible switching upon application of external stimuli. Herein, we report the synthesis and characterization of a model system for studying reversibly switching surfaces based on low-density monolayers of mercaptohexadecanoic acid and mercaptoundecanoic acid. These monolayers were assembled on both gold and silver electrodes. When conducting electrochemical impedance spectroscopy under physiological conditions, these monolayers exhibit significant changes in their electrochemical barrier properties upon application of electrical DC potentials below +400 mV with respect to a standard calomel electrode. We further found the impedance switching to be reversible under physiological conditions. Moreover, the impedance can be fine-tuned by changing the magnitude of the applied electrical potential. Before and during impedance switching at pH 7.4 in aqueous buffer solutions, the low-density monolayers showed good stability according to grazing angle infrared spectroscopy data. We anticipate low-density monolayers to be potentially useful model surfaces when designing active biointerfaces for cell-based studies or rechargeable biosensors.

Topics: Biosensing Techniques; Electric Impedance; Electrochemistry; Electrodes; Fatty Acids; Membranes, Artificial; Palmitic Acids; Sulfhydryl Compounds

The detection of antisperm antibody (AsAb) by electrochemical method based on Au nanoparticles with a mixed monolayer for eliminating nonspecific binding is presented. Impedance spectroscopy is used to characterize the modified procedures, the immobilization of sperm antigen (SpAg) and binding of AsAb in the presence of [Fe (CN)(6)](3-/4-). In addition, piezoelectric quartz crystal, PQC, was used to analyze the immobilization quantity of Au nanoparticles as well as to optimize experimental conditions. The change of electron-transfer resistance was correlated with the concentration of AsAb in a range from 25 to 600 mU/ml with the detection limit of 10 mU/ml. The analytical results of several human serum samples using the developed technique are in satisfactory agreement with those given by the enzyme-linked immunosorbent assay (ELISA) method.

Topics: Adsorption; Antibodies; Antigens, Surface; Complement C3; Electrochemistry; Enzyme-Linked Immunosorbent Assay; Fatty Acids; Gold; Gold Colloid; Humans; Male; Nanostructures; Palmitic Acids; Particle Size; Quartz; Serum Albumin; Spermatozoa; Sulfhydryl Compounds