Micro electrochemical mechanism of baicalin-metal complexes binding with hepatoma SMMC-7721 cell DNA / 中草药

Objective: The correlation of baicalin-metal (Y3+, La3+, and Ce3+) complexes (BMC) anti-tumor activity and the interactional ability of BMC binding with hepatoma SMMC-7721 cell DNA was investigated. Methods: Hepatoma SMMC-7721 cells DNA was extracted as a target, cyclic voltammetry and AC impedance were utilized to study the interaction between BMC and DNA, and the interaction mechanism between BMC and DNA was explored. Results: BMC and hepatoma SMMC-7721 cell DNA formed a non-electroactive supramolecular compounds through mixed-mode of electrostatic interaction, binding number m = 1, binding constant βBC = 1.27 × 105 L/mol, βBC-Y = 3.46 × 105 L/mol, βBC-La = 6.24 × 105 L/mol, and βBC-Ce = 7.29 × 106 L/mol. After BC binding with metal ions, its ability of binding to DNA significantly enhanced, and the strength order: BC-Ce > BC-La > BC-Y > BC. Conclusion: The ability of BMC binding with DNA consists with its cytotoxicity. After BMC binding with SMMC-7721 cell DNA, it could inhibit the cell proliferation and lead to the cell apoptosis, which illustrates the BMC exhibits an anti-tumor activity. The relevant results have given a reference for the study on the new anti-tumor complexes of Chinese materia medica.

In Situ Investigation on Electrochemical Polymerization and Properties of Polyaniline Thin Films by Electrochemical Surface Plasmon Resonance / 分析化学

A new type of surface plasmon resonance ( SPR) spectroscopy system was designed and built. Here, a kind of dual photocell sensor was developed as a detection device to achieve a rapid measurement of SPR angle within a certain range. This SPR system was combined and integrated with electrochemical workstation to obtain a new type of electrochemistry-time-resolved SPR ( EC-TR-SPR ) instrument via instrumental technique. This EC-TR-SPR instrument was used to characterize the electrochemical polymerization process of aniline to validate the spectroscopic characteristics. Applications of transient electrochemical characterization methods, including chronoamperometry and differential pulse voltammetry, confirmed the time resolution and the applicability of this instrument system toward the steady state and transient electrochemical methods upon small molecular reactions. The experiment results showed that this EC-TR-SPR possessed the time resolution up to 10000 times per second (0. 1 ms), and could be used to real-time investigate the doping and de-doping of polymerization process of aniline monomer as well as the prepared polyaniline film, which could not be discriminated on a conventional electrochemical current-time curve. .

Microleakage of composite resin restoration according to the number of thermocycling / 대한치과보존학회지

Present tooth bonding system can be categorized into total etching bonding system (TE) and self-etching boding system (SE) based on their way of smear layer treatment. The purposes of this study were to compare the effectiveness between these two systems and to evaluate the effect of number of themocycling on microleakage of class V composite resin restorations. Total forty class V cavities were prepared on the single-rooted bovine teeth and were randomly divided into four experimental groups: two kinds of bonding system and another two kinds of thermocycling groups. Half of the cavities were filled with Z250 follwing the use of TE system, Single Bond and another twenty cavities were filled with Metafil and AQ Bond, SE system. All composite restoratives were cured using light curing unit (XL2500, 3M ESPE, St. Paul, MN, USA) for 40 seconds with a light intensity of 600 mW/cm2. Teeth were stored in distilled water for one day at room temperature and were finished and polished with Sof-Lex system. Half of teeth were thermocycled 500 times and the other half were thermocycled 5,000 times between 5degrees C and 55degrees C for 30 second at each temperature. Teeth were isolated with two layers of nail varnish except the restoration surface and 1 mm surrounding margins. Electrical conductivity (microA) was recorded in distilled water by electrochemical method. Microleakage scores were compared and analyzed using two-way ANOVA at 95% level. From this study, following results were obtained: There was no interaction between variables of bonding system and number of thermocycling (p = 0.485). Microleakage was not affected by the number of thermocycling either (p = 0.814). However, Composite restoration of Metafil and AQ Bond, SE bond system showed less microleakage than composite restoration of Z250 and Single Bond, TE bond system (p = 0.005).

Effect of two different calcium hydroxide paste removal techniques on apical leakage: an electrochemical study / 대한치과보존학회지

This study evaluated the effect of two different calcium hydroxide (Ca(OH)2) paste removal techniques on the apical leakage of canals obturated with gutta percha cones and sealer after removing a Ca(OH)2 dressing using an electrochemical method. Seventy extracted single-rooted teeth were instrumented on with Profile rotary files under NaOCl irrigation. Fifty-eight canals were filled with calcium hydroxide paste, which was then removed using one of the following two techniques. In group A, calcium hydroxide was removed using only NaOCl irrigation, and in group B, the canals were re-prepared with a Profile rotary files-one size larger than the previous instrument and were irrigated with NaOCl. In both groups, the root surfaces were coated twice with nail varnish from CEJ to an area 4 mm away from the apex after canal obturation. Apical leakage was measured using an electrochemical method for 24 days. All the specimens showed leakage that increased markedly in the first three days. There was no significant difference between the two groups (p > 0.05). The effect of two calcium hydroxide paste removal techniques on the apical leakage was not different during a short period.

The effect of MTAD on the apical leakage of obturated root canals: an electrochemical study / 대한치과보존학회지

The purpose of this study was to evaluate the effect of newly developed endodontic root canal cleanser (MTAD) on the apical leakage of obturated root canal using an electrochemical method. Canals of 60 extracted single-rooted human teeth were prepared by using a crown-down technique with rotary nickel-titanium files. In Group 1 (positive control group) and 2 (negative control group), 5.25% NaOCl was used as a canal irrigant and no canal wall treatment was done. In group 3, only 5.25% NaOCl were used as canal irrigant, canal wall treatment and final rinse. In group 4, specimens were irrigated with 5.25% NaOCl, treated with 5 ml of 17% EDTA for 5 minutes and final rinsed with 5.25% NaOCl. Specimens of group 5 were irrigated with 1.3% NaOCl and treated with 5 ml of MTAD for 5 minutes. All root canals are dried with paper points and obtuated with gutta-percha and AH plus as a sealer using a continuous wave of condensation technique except in the group 1. The electrical resistance between the standard and experimental electrodes in canals was measured over a period of 10 days. Rising of apical leakage with time was observed for all the groups. Group 4 and 5 showed lower apical leakage than group 3 but differences between the group 3, 4 and 5 were no statistical significance at any measurement time.

The effect of additional enamel etching on microleakage of the adhesion of self-etching primer system / 대한치과보존학회지

The purpose of this study is to evaluate the effect of additional enamel etching with phosphoric acid on the microleakage of the adhesion of self-etching primer system. Class V cavity(4 mmx3 mmx1.5 mm) preparations with all margins in enamel were prepared on buccal surface of 42 extracted human upper central incisor teeth. Prepared teeth were randomly divided into 3 groups. Group 1 : no additional pretreatment with 37% phosphoric acid (NE). Group 2 : additional pretreatment with 37% phosphoric acid for 10 seconds (E10s). Group 3 : additional pretreatment with 37% phosphoric acid for 20 seconds (E20s). The adhesives(Clearfil SE Bond(R), Kuraray, Osaka, Japan) and composite resins(Clearfil AP-X(R), Osaka, Kuraray, Japan) were applied following the manufacturer's instructions. All the specimens were finished with the polishing disc(3M dental product, St Paul, MN, USA), thermocycled for 500 cycles between 5degrees C and 55degrees C and resected apical 3-mm root. 0.028 stainless steel wire was inserted apically into the pulp chamber of each tooth and sealed into position with sticky wax. Surrounding tooth surface was covered with a nail varnish 2 times except areas 1 mm far from all the margins. After drying for one day, soaked the samples in the distilled water. Microleakage was assessed by electrochemical method(System 6514, Electrometer(R), Keithley, USA) in the distilled water. In this study, the microleakage was the lowest in group 1(NE) and the highest in group 3(E20s)(NE

The effects of Streptococcus sobrinus on corrosion behavior of metal-ceramic alloys / 实用口腔医学杂志

Objective:To study the corrosion resistance of four metal-ceramic alloys in the presence of Streptococcus sobrinus, and to compare the effects of bacteria action in liquid and solid environment.Methods:Four metal-ceramic alloys were exposured to BHIA or BHI media with or without Streptococcus sobrinus and served as different groups. After inoculating 10 weeks, their I_ corr ,E_ corr ,E_ tp through cyclic polarization curves were obtained through Corrview 2 corrosion analyses software;and their surface changes after electrochemical corrosion were observed by field emission scanning electron microscopy (FESEM).Results:The E_ corr of four alloys were decreased in presence of oral microorganism, and the declines were more remarkable in BHI with bacteria. SEM observation showed the pittings in their surface.The corrosion resistance in BHI without bacteria were significant increased than that in the blank control. Conclusion:Streptococcus sobrinus can promote the corrosion behavior of metal-ceramic alloys and the corrosion resistance is more worse in BHI than BHIA with bacteria.