p-Nitrophenylphosphate (PNPP) is usually employed as the substrate for enzyme-linked immunosorbent assays. p-Nitrophenol (PNP), the product of PNPP, with the catalyst alkaline phosphatase (ALP), will passivate an electrode, which limits applications in electrochemical analysis. A novel anti-passivation ink used in the preparation of a graphene/ionic liquid/chitosan composited (rGO/IL/Chi) electrode is proposed to solve the problem. The anti-passivation electrode was fabricated by directly writing the graphene-ionic liquid-chitosan composite on a single-side conductive gold strip. A glassy carbon electrode, a screen-printed electrode, and a graphene-chitosan composite-modified screen-printed electrode were investigated for comparison. Scanning electron microscopy was used to characterize the surface structure of the four different electrodes and cyclic voltammetry was carried out to compare their performance. The results showed that the rGO/IL/Chi electrode had the best performance according to its low peak potential and large peak current. Amperometric responses of the different electrodes to PNP proved that only the rGO/IL/Chi electrode was capable of anti-passivation. The detection of cardiac troponin I was used as a test example for electrochemical immunoassay. Differential pulse voltammetry was performed to detect cardiac troponin I and obtain a calibration curve. The limit of detection was 0.05 ng/ml.
Electrochemical Techniques/methods* ; Electrodes ; Graphite ; Immunoassay/methods* ; Ink ; Microscopy, Electron, Scanning ; Troponin I/blood*

OBJECTIVETo observe the effect of matrix metalloproteinase-1 (MMP-1) from human host on degradation of dentin organic matrix of root dentin.

METHODSThe freshly extracted caries-free impacted teeth were selected. Teeth were cut transversely under the enamel-cementum junction into dentin sections with a thickness of about 5 mm. Then all sections with removal of cementum, pulp and predentin were randomly divided into four groups. In the first group, dentin sections were demineralized with acid solution for 21 days, and then incubated with MMP-1 solution for 7 days; the second group were only treated with acid solution for 21 days; the third group were only attacked by MMP-1 solution for 7 days; and the fourth group were untreated as a control. Then all sections were dehydrated in ascending strength of alcohol, critically dried, coated with platinum, and then observed under scanning electron microscope(SEM).

RESULTSThe dentin sections of root surface attacked by acid and MMP-1 showed that demineralization of dentin mineral and degradation of dentin matrix fibrae synchronously happened. The dentin matrix fibrae wasn't degradated in the groups treated with acid or MMP-1.

CONCLUSIONThe proteinases from human host may play an important role in the development of root surface caries. MMP-1 may distinctly degradate the organic matrix of demineralized dentin.

Dental Cementum ; Dental Enamel ; Dentin ; enzymology ; Humans ; Matrix Metalloproteinase 1 ; physiology ; Microscopy, Electrochemical, Scanning ; Root Caries ; enzymology ; Tooth Root ; enzymology

The improving effect of electrospun drug-loaded nanofibers on the solubility of poorly water-soluble drug was investigated in the present research. Drug-loaded nanofibers were successfully prepared using electrospinning process with helicid as the poorly water-soluble model drug and polyvinylpyrrolidone K60 (PVP K60) as the filament-forming matrix. Scanning electron microscopy observation demonstrated that the nanofibers had a three-dimensional continuous web structure, and had well smooth surface and a diameter between 400-600 nm. X-ray diffraction results suggested that helicid lost its original crystal structure but highly distributed into the nanofibers in an amorphous state, resulting from the hydrogen bonding interactions between the carboxylic group of PVP K60 and the hydroxyl groups of helicid. The drug-loaded nanofibers obviously improved helicid's solubility, and were able to completely release the whole drug in 60 s. Electrospun drug-loaded nanofibers can improve the solubility and release profiles of poorly water-soluble drug.
Benzaldehydes ; administration & dosage ; chemistry ; Drug Carriers ; Drug Compounding ; Electrochemical Techniques ; methods ; Microscopy, Electron, Scanning ; Nanofibers ; chemistry ; ultrastructure ; Pharmaceutical Preparations ; chemistry ; Povidone ; chemistry ; Solubility ; Spectrophotometry, Ultraviolet ; X-Ray Diffraction

BACKGROUNDMonilethrix is an autosomal dominant hair disorder characterized clinically by alopecia and follicular papules. In this study, we collected a Han monilethrix family to detect the mutations in patients and investigated the correlation between the genotype and phenotype of monilethrix.

METHODSIn this study, we identified a Chinese family with monilethrix through light microscopic and scanning electron microscopic (SEM) examination. Genomic DNA from peripheral blood samples was prepared. DNA samples from controls and monilethrix patients were subject to polymerase chain reaction (PCR) amplification. Two pairs of primers were used to amplify the seventh exon of KRT86. Mutation screening of the PCR products was detected using direct sequencing.

RESULTSLight microscopic examination showed a regular alternate enlargement and narrow area. SEM examination showed that part of the cuticle of the nodules shed and disappeared gradually in the narrow area with granular protrusions on the surface similar to the erosion-like structure. Parallel longitudinal ridge and groovepattern appeared, and the ridges varied in width, like dead wood. A heterozygous transversion mutation c.1204G > A (p.E402K) in the seventh exon of KRT86 was identified in both patients.

CONCLUSIONSThe mutation of extron 7 of KRT86 identified plays a major role in the pathogenesis of this pedigree with monilethrix, and is a mutation hot spot of KRT86. Further research is needed to explore the relationship between the phenotype and the mutation of the type II hair keratin gene KRT86 of monilethrix.

Asian Continental Ancestry Group ; genetics ; China ; ethnology ; Humans ; Keratins, Hair-Specific ; genetics ; Keratins, Type II ; genetics ; Microscopy, Electrochemical, Scanning ; Monilethrix ; etiology ; genetics ; pathology ; Mutation

The present paper was designed to investigate the effect of varying concentrations of ethanol in receiver solution on the in vitro transdermal permeation of drug across the rat skin. 5-fluorouracil (5-FU) was used as the model drug on account of its good hydrophility, the excised rat skins were treated with different concentration ethanol prepared with normal saline for 12 h, then replaced by normal saline and added the saturated model drug into the donor compartment to determine the transdermal parameters of the drug. Meanwhile, scanning electron microscopy (SEM) was employed to monitor the effect of the different concentration ethanol on the stratum corneum of the rat skin. The ethanol below the concentration of 15% didn't significantly affect the barrier profile of the rat skin, while significant difference of in steady-state transdermal rate and lag times were observed when the concentration of ethanol was 20% or above. The SEM studies indicated that wrinkle of the intact rat skin gradually disappeared and a number of flakes were desquamated from the skin when the concentration of ethanol was above 20%. The results showed that the low concentration of the ethanol (below 15%) didn't obviously affect the excised skin, yet the barrier profile of rat skin would significantly disrupted with the concentration of ethanol above 20%.
Animals ; Chemistry, Pharmaceutical ; methods ; Ethanol ; chemistry ; Fluorouracil ; chemistry ; metabolism ; Male ; Microscopy, Electrochemical, Scanning ; Permeability ; Rats ; Rats, Sprague-Dawley ; Skin ; metabolism ; ultrastructure