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

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

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

OBJECTIVETo analyze the push-out bond strength of fiber post and the durability of interface between dentin and composite resin during over drying and re-wetting of root canal.

METHODSThirty-six extracted human maxillary central incisors were randomly divided into three groups: Group A for the process of over drying, Group B for re-wetting, Group C for control. All teeth were sliced into several thin discs with thickness of 1.0 mm for micro push-out test and scanning electron microscope(SEM) observation.

RESULTSPush-out shear strengths of fiber post immediately after bonding in group A, B and C were (5.97 ± 1.97), (7.67 ± 2.19) and (8.46 ± 2.35) MPa. Push-out strengths of fiber post two months after water storage were (2.08 ± 1.67), (2.99 ± 1.48) and (3.22 ± 1.43) MPa. There was significantly difference in push-out strength between Group A and Group B (P < 0.05). Significantly difference in push-out strength was also found between Group A and Group C. In the condition of immediate testing, there was also significantly difference between push-out strength of cervical slice and middle slice, and between cervical slice and apical slice (P < 0.05). The water storage time has significant effect on the push-out bond strength of fiber posts (P < 0.05).

CONCLUSIONSInappropriate condensation air blowing operation can cause extracted teeth root canal dentin over dry. Dehydration can destroy the formation of general structure of interface between composite resin and dentin. The over dry dentin can be turned back to wetting stage by water pouring, which can help fiber-reinforced composite post regain its normal retention strength and original adhesive durability.

Dental Bonding ; methods ; Dental Pulp Cavity ; Dental Stress Analysis ; Dentin ; ultrastructure ; Dentin-Bonding Agents ; chemistry ; Humans ; Incisor ; Microscopy, Electrochemical, Scanning ; Post and Core Technique ; instrumentation ; Random Allocation ; Water ; chemistry

OBJECTIVETo develop novel self- healing and antibacterial resin composite containing microcapsules filled with polymerizable healing monomer, and to measure its properties for further clinical application.

METHODSMicrocapsules filled with healing monomer of triethylene glycol dimethacrylate were synthesized according to methods introduced in the previous research. Microcapsules were added into novel resin composite containing nano-antibacterial silica fillers grafted with long chain alkyl quaternary ammonium at mass fractions of 0, 2.5%, 5.0%, 7.5% or 10.0%. A commercial resin composite (Tetric N-Ceram) was used as control. Flexural test was used to measure resin composite flexural strength and elastic modulus. The single edge V-notched beam method was used to measure fracture toughness and self-healing efficiency. Scanning electron microscope (SEM) was used to examine the fractured surface of selected specimen for investigation of fracture mechanisms.

RESULTSThe flexural strength and elastic modulus of the resin composite were (96.4 ± 14.3) MPa and (6.2 ± 1.1) GPa respectively after incorporation of microcapsules up to 7.5%, and no significant difference was found between the experimental group and the control group [(99.1 ± 11.9) MPa and (6.1 ± 1.1) GPa] (P>0.05). The self-healing efficiency of (66.8 ± 7.0)% and (79.3 ± 9.7)% were achieved for resin composite with microcapsule mass fractions at 7.5% and 10.0%. SEM image showed that irregular films covered the fractured surface. Conclusions This novel self-healing and antibacterial resin composite containing microcapsules filled with polymerizable healing monomer exhibited a promising self- healing ability, which enabled itself well up for combating bulk fracture and secondary caries in clinical application.

Anti-Bacterial Agents ; Bisphenol A-Glycidyl Methacrylate ; chemical synthesis ; Capsules ; Composite Resins ; chemistry ; Drug Compounding ; methods ; Elastic Modulus ; Humans ; Microscopy, Electrochemical, Scanning ; Polyethylene Glycols ; chemistry ; Polymerization ; Polymethacrylic Acids ; chemistry ; Silicon Dioxide

OBJECTIVETo evaluate the types and compositions of oxide films formed during porcelain-fused-to-metal (PFM) firing on three kinds of dental casting alloys, and to investigate the corrosion property of these alloys in Dulbecco's modification of Eagle's medium (DMEM) cell culture fluid, before and after PFM firing.

METHODSSpecimens of three dental casting alloys (Ni-Cr, Co-Cr and Ni-Ti) before and after PFM firing were prepared, and were immersed in DMEM cell culture fluid. After 30 days, the type and concentration of released metal ions were measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES). X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used for analysis of oxide film on the alloys. One way-ANOVA was adopted in data analysis.

RESULTSThe total amount of metal ions released from the three dental alloys was found to be highest in Ni-Cr alloy [(2.829 ± 0.694) mg/L], followed by Co-Cr [(2.120 ± 0.418) mg/L] and Ni-Ti alloy [(1.211 ± 0.101) mg/L]. The amount of Ni ions released from Ni-Cr alloys [(1.531 ± 0.392) mg/L] was higher than that from Ni-Ti alloys [(0.830 ± 0.052) mg/L]. The amount of Cr, Mo ions released from Co-Cr alloy [Cr: (0.048 ± 0.011) mg/L, Mo: (1.562 ± 0.333) mg/L] was higher than that from Ni-Cr alloy [Cr: (0.034 ± 0.002) mg/L, Mo: (1.264 ± 0.302) mg/L] and Ni-Ti alloy [Cr: (0.013 ± 0.006) mg/L, Mo: (0.151 ± 0.026) mg/L] (P < 0.05). After PFM firing, the total amount of metal irons released from the three dental alloys decreased [Ni-Cr: (0.861 ± 0.054) mg/L, Co-Cr: (0.695 ± 0.327) mg/L, Ni-Ti: (0.892 ± 0.115) mg/L] (P < 0.05). In addition, XPS showed increase of Cr(2)O(3) and Mo-Ni oxide on the surface of all the alloys after PFM firing.

CONCLUSIONSThe amount of ions released from Ni-Cr alloy was the highest among the three dental casting alloys, this means Ni-Cr alloy is prone to corrode. The PFM firing process changed the alloys' surface composition. Increased Ni, Cr and Mo were found in oxide film, and the increase in Cr(2)O(3) can improve the corrosion-resistance of alloys.

Chromium Alloys ; chemistry ; Corrosion ; Dental Alloys ; chemistry ; Dental Casting Technique ; Dental Porcelain ; chemistry ; Dental Stress Analysis ; Ions ; Materials Testing ; Microscopy, Electrochemical, Scanning ; Molybdenum ; chemistry ; Nickel ; chemistry ; Oxides ; Photoelectron Spectroscopy ; Surface Properties ; Titanium ; chemistry

OBJECTIVETo evaluate the dentin and enamel bonding strength and resin-dentin interfaces of four resin cements.

METHODSTwenty-four sound freshly extracted molars were sectioned with low-speed saw under running water. Two mesial-distal enamel disc and two buccal-lingual dentin discs were sectioned from each molar. Four resin cements (A group: Panavia(TM) F; B group: RelyX(TM) ARC; C group: RelyX(TM) Unicem; D group: Clearfil(TM) SA Cement) were applied to the surface of these enamel and dentin discs according to manufacturers' guidance. The bonded specimen were prepared for shear bond strength test and sectioned occluso-gingivally into two slabs for scanning electron microscopy (SEM) observation.

RESULTSThe bonding strength between resin and enamel in B group [(29.38 ± 6.28) MPa] was higher than that in D group [(27.25 ± 7.03) MPa], and both of them were significantly higher than those in A [(22.92 ± 7.13) MPa] and C group [(10.92 ± 3.41) MPa] (P < 0.05). The highest dentin bonding strength was shown in B group [(27.28 ± 6.79) MPa], followed by A [(14.23 ± 6.39) MPa], D [(10.09 ± 3.26) MPa] and C group [(6.43 ± 1.60) MPa, P < 0.05].

CONCLUSIONSThe four resin cements have different enamel or dentin bonding properties.

Bisphenol A-Glycidyl Methacrylate ; chemistry ; Dental Bonding ; Dental Enamel ; ultrastructure ; Dental Stress Analysis ; Dentin ; ultrastructure ; Dentin-Bonding Agents ; chemistry ; Humans ; Microscopy, Electrochemical, Scanning ; Molar ; Polyethylene Glycols ; chemistry ; Polymethacrylic Acids ; chemistry ; Resin Cements ; chemistry ; Shear Strength