pH Peroxide Research Articles

Label-free differential chemiluminescent immunosensor based on magnetic nanoparticles CuFe2O4@ABEI-GNPs with dual catalytic sites

BackgroundCancer has become one of the main causes of death globally. The level of tumor markers in serum is correlated with the occurrence of cancer. Carcinoembryonic antigen (CEA) is the most commonly utilized tumor marker for cancer detection. Recently, various analytical technologies have been reported to detect biomarkers. However, developing a simple, sensitive, and noninvasive approach for CEA detection remains challenging in cancer diagnosis. Consequently, there is an urgent need for researchers to carry out innovative approaches for CEA detection. ResultIn this work, copper ferrite nanoparticles (CuFe2O4 NPs) with excellent dispersity and fascinating magnetism have been successfully synthesized. To get CuFe2O4@ABEI-GNPs, ABEI-gold NPs (ABEI-GNPs) were generated on the surface of CuFe2O4 NPs by using N-(4-Aminobutyl)-N-ethylisoluminol (ABEI) as a mild reduction reagent to reduce chloroauric acid tetrahydrate (HAuCl4·4H2O). The CuFe2O4@ABEI-GNPs exhibited a superior chemiluminescence (CL) performance compared with CuFe2O4@ABEI NPs, which was attributed to the synergistic catalysis effects of CuFe2O4 NPs and GNPs. Interestingly, two unique CL emission peaks were observed in the kinetic curve of CuFe2O4@ABEI-GNPs. Furthermore, it was found that the kinetic curve could be regulated by the pH of hydrogen peroxide (H2O2) and a possible CL mechanism was proposed. Owing to the favorable CL properties of CuFe2O4@ABEI-GNPs, a label-free differential immunosensor was fabricated for CEA monitoring using the intensity difference between CL-1 and CL-2. The developed immunosensor exhibited a wide linear range from 0.1 to 5000 pg/mL, and a low detection limit of 0.05 pg/mL. Significance and noveltyThe immunosensor was capable of determining CEA in real samples with simple operation, high accuracy, and good sensitivity. This study introduces a novel approach for developing CL functionalized materials, which have broad application potential in bioassays. The proposed differential method could serve as a novel tool for determining CEA in the diagnosis of clinical cancer.

Bleaching efficacy, decomposition rate and pH of experimental bleaching gels incorporating bioactive materials

Aim: To evaluate the bleaching efficacy, decomposition rate, and pH of experimental gels containing 35% hydrogen peroxide (HP) and different concentrations of 45S5-bioglass (BG) or Biosilicate® (BS). Methods: Bovine enamel/dentin blocks (n=10) were allocated into the groups HP_BG or HP_BS (2.5, 5, 7.5 and 10 wt%) and HP (35% HP – positive control). The blocks were submitted to three sessions of 40 min and 7-day intervals. During the interval, the blocks were kept in artificial saliva at 37ºC. Color change (ΔE00) and whiteness index change (ΔWID) were determined after staining with black tea (T1) and 24 h after the 3rd bleaching session (T2). HP decomposition rate (%) and pH were evaluated for 40 min. Two-way ANOVA and Tukey analyzed ΔE00 and ΔWID data, while the Kruskal-Wallis test determined the decomposition rate and pH of the gels. Results: There were no differences in ΔE00 and ΔWID among the experimental bleaching gels containing BG or BS and 35% HP (p > 0.05), but BG and BS gels displayed lower HP concentration than 35% HP, regardless of the bioactive material concentration (p < 0.05). The experimental BG and BS gels exhibited alkaline pH (ranging from 9.28 to 9.82), which was higher than that of 35% HP (p < 0.05). But regardless of the gel, all kept the pH values stable for 40 min. Conclusion: The experimental gels containing BG and BS did not hamper the 35% HP bleaching efficacy. Moreover, BG or BS gels decreased the hydrogen peroxide concentration and exhibited alkaline pH values.

The decomposition rate and bleaching efficacy of in-office bleaching gels with different pHs: a randomized controlled trial.

To evaluate the decomposition rate of active hydrogen peroxide (HP) and bleaching efficacy during in-office bleaching using high-concentration HP gels with different pHs. A randomized, parallel, double-blind controlled trial was conducted with 40 volunteers randomized into four groups (pH 5.4; pH 7.0; pH 7.7, and pH 8.0). During the first session in-office bleaching, approximately 0.01g of the gel was collected and titrated with potassium permanganate to obtain the concentration of active HP and pH values were measured using an electrode. Bleaching efficacy was assessed using a spectrophotometer [∆Eab, ∆E00, and WID], Vita Classical and Vita Bleachedguide scales [∆SGU]. The decomposition rate of HP concentration and pH values change were calculated using ANOVA one-way. The bleaching efficacy was assessed using two-way repeated measures ANOVA. Tukey's test was applied as a post-hoc test (p < 0.05). All gels experienced decreasing HP concentration over time. pH 5.4 gel showed greatest reduction after 50min (p < 0.001). pH 8.0 and 7.7 gels remained stable; pH 5.4 remained acidic, while pH 7.0 turned acidic (p < 0.001). No significant difference in bleaching degree was observed among gels. They all showed a similar and clinically important color change after two clinical sessions, remained stable 1-month post-treatment (p > 0.05). All bleaching gels kept at least 70% of their HP content after 50min, suggesting that there is a surplus of HP. They provided similar whitening efficacy 1-month after bleaching. It is possible that lower HP concentrations may be equally effective in achieving desired results while reducing the potential for side effects. RBR-35q7s3v.

Effect of whitening toothpastes with different hydrogen peroxide concentrations: Penetration into the pulp chamber and color change

ObjectivesThis study evaluated the efficacy of simulated brushing with toothpastes containing different concentrations of hydrogen peroxide (HP) in pulp chamber penetration and color change. Also, physical-chemical properties (concentration, pH and viscosity) were evaluated. MethodsForty-nine premolars were divided into seven groups (n = 7): untreated (control); whitening gel (White Class 6 %, 6 %BG) with one 90 min application (6 %BG 90 min) and 14 applications of 90 min (6 %BG 14×90 min); toothpastes (Colgate Luminous White Glow 3 %, 3 %TP; Crest 3D White Brilliance 4 %, 4 %TP; Colgate Optic White Pro-Series 5 %, 5 %TP) and 6 %BG toothbrushing for 14 applications of 90 s. HP penetration into the pulp chamber was measured through UV–Vis spectrophotometry and color change with a spectrophotometer (ΔEab, ΔE00, and ΔWID). Initial concentration, pH, and viscosity were measured through Titration, Digital pH-meter, and Rheometer, respectively. Statistical analysis used one-way ANOVA and Tukey's test (α = 0.05). Results6 %BG (14×90 min) and 4 %TP groups showed acidic pH and higher concentrations of HP in the pulp chamber compared to the other groups (p < 0.05). On the other side, 3 %TP and 5 %TP groups showed alkaline pH, higher viscosity between the toothpastes and lower HP penetration (p < 0.05). The 6 %BG AH (14×90 min) group exhibited the most significant color change (ΔEab, ΔE00, and ΔWID) (p < 0.05). ConclusionsBrushing with whitening toothpaste with an acidic pH leads to greater HP penetration into pulp chamber; but, even when a high concentrated HP whitening toothpaste was used, a lower whitening effect was observed when compared to a two-week at-home bleaching. Clinical SignificanceWhitening toothpastes containing up to 5 % HP produced lower whitening effect than two-week at-home bleaching. Additionally, HP was detected within the pulp chamber which can potentially impact in tooth sensitivity.

Influence of whitening gel application protocol on dental color change.

Objectives. To evaluate the influence of different whitening protocols on the efficacy of 35% hydrogen peroxide (HP) tooth whitening and gel pH and concentration. Material and Methods. Eighty-four enamel/dentin discs from bovine incisors were used. The baseline color was measured with a spectrophotometer. Two sessions of in-office whitening with 35% HP were performed under different protocols: G1: 3 applications of HP (10 min each) per session; G2: 1 application of 30 min per session; G3: 1 application of 40 min per session, with no gel replenishment within session for groups 2 and 3. HP titration and pH evaluation at baseline, after 10, 30, and 40 min were also performed. The final color was measured 24 h after the 1st and 2nd whitening sessions. Data were submitted to Repeated Measures ANOVA and Tukey's test. Results. For color evaluation, no differences were observed among groups after two sessions. HP titration showed no drop on concentration after 10, 30, or 40 min. The pH was 5.54 at baseline and 5.41 after 40 min. Conclusion. Replenishment or extended application time of in-office whitening gel does not affect gel pH and concentration, a fact that supports the similar effectiveness of whitening observed among the tested protocols.

Reactions of soybean peroxidase and hydrogen peroxide pH 2.4–12.0, and veratryl alcohol at pH 2.4

Peroxidase from soybean seed coat (SBP) has properties that makes it particularly suited for practical applications. Therefore, it is essential to know its fundamental enzymatic properties. Stopped-flow techniques were used to investigate the pH dependence of the reaction of SBP and hydrogen peroxide. The reaction is linearly dependent on hydrogen peroxide concentration at acidic and neutral pH with the second order rate constant k1=2.0×107 M−1 s−1, pH 4–8. From pH 9.3 to 10.2 the reaction is biphasic, a novel observation for a peroxidase at alkaline pH. A fast reaction has the characteristics of the reaction at neutral pH, and a slow reaction shows hyperbolic dependence on hydrogen peroxide concentration. At pH >10.5 only the slow reaction is seen. The shift in mechanism is coincident with the change in haem iron co-ordination to a six-coordinate low spin hydroxy ligated alkaline form. The pKa value for the alkaline transition was observed at 9.7±0.1, 9.6±0.1 and 9.9±0.2 by spectrophotometric titration, the fast phase amplitude, and decrease in the apparent second order rate constant, respectively. An acidic pKa at 3.2±0.3 was also determined from the apparent second order rate constant. The reactions of soybean peroxidase compounds I and II with veratryl alcohol at pH 2.44 give very similar second order rate constants, k2=(2.5±0.1)×104 M−1 s−1 and k3=(2.2±0.1)×104 M−1 s−1, respectively, which is unusual. The electronic absorption spectra of compounds I, II and III at pH 7.07 show characteristic bands at 400 and 651 nm (compound I), 416, 527 and 555 nm (compound II), and 414, 541 and 576 nm (compound III). No additional intermediates were observed.

Sporicidal Action of Hydrogen Peroxide on Conidia From Toxigenic Strains of Aspergillus flavus and Aspergillus parasiticus

Effects of pH, sucrose, glucose, and sodium chloride on resistance of 14-day-old conidiospores of Aspergillus parasiticus NRRL 2999 and 3315, and Aspergillus flavus NRRL 3353 to a solution of 6% hydrogen peroxide at 20 C were determined. An increase in time necessary to attain 99.9% destruction of spores resulted when the pH of hydrogen peroxide was adjusted from an initial value of 3.79 to 6.40 and 8.30. However, the amount of the increase was strain-dependent and was directly related to resistance of spores to peroxide. Addition of 10 to 40% sucrose or 3 to 10% sodium chloride to the menstruum caused either an increase or decrease in the time needed to destroy 99.9% of the spore population, depending on the amount of additive that was used. Spores were more difficult to inactivate by peroxide in the presence rather than absence of sucrose or salt, but protection afforded by the additives diminished when their concentration was great. Addition of 10 to 30% glucose elicited a similar response only from spores produced by the most resistant of the three strains tested, whereas resistance of spores from the other strains was not markedly affected.