Objective: The antibacterial properties and bonding strength of 3M orthodontic adhesive resin modified by chlorhexidine acetate (CHA) composite mesoporous silica were investigated. Methods: CHA with different mass fractions was encapsulated in mesoporous silica nanoparticles (MSNs) (denoted CHA@MSNs). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the samples. The 3M Z350XT flow resin was divided into 4 groups: group A: 3M+CHA@MSNs (0%); group B: 3M+CHA@MSNs (3%); group C: 3M+CHA@MSNs (5%); and group D: 3M+CHA@MSNs (6.4%), with mass scores of 0%, 3%, 5%, and 6.4%, respectively. The shear strength of the modified adhesive was tested by a universal electronic material testing machine, the adhesive residue was observed by a 10 × magnifying glass, and the adhesive Remnant index (ARI) was calculated. The four groups of modified adhesives were cultured with Streptococcus mutans. The OD540 value of the bacterial solution was measured by a spectrophotometer, and the amount of plaque attachment was observed by scanning electron microscopy to evaluate the antibacterial performance of the adhesives. Results: Infrared spectroscopic analysis of CHA@MSNs showed that CHA was successfully loaded onto MSNs. Under scanning electron microscopy, it could be seen that, after Cha was combined with MSNs, the structure of MSNs changed, as the boundary was fuzzy and aggregated into a layered structure. A comparison of shear strength revealed a statistically significant difference between the groups containing CHA@MSNs and the groups without CHA@MSNs (P<0.05). The value of the shear strength in group D decreased the most, while there was no statistically significant difference between group B and group C (P > 0.05). There was no statistical significance across all groups (P > 0.05), suggesting that the addition of CHA@MSNs had little effect on the bracket shedding. The OD540 value of bacterial fluid indicated that the difference among groups A, B and C was statistically significant (P < 0.05), and the antibacterial effect of group C was the best; there was no statistically significant difference between group C and group D (P > 0.05). Conclusions Therefore, adding 5% CHA@MSN antibacterial agent significantly improved the antibacterial effect and did not affect the bond strength.

Objective : To explore the effect of ( - ) Ⅳmeptazinol⁃serotonin hybrid , [( - ) ⅣMep⁃S] on scopolamineinduced learning and memory impairment in mice. Methods: The binding of ( - ) ⅣMep⁃S and hAChE was analyzed by molecular docking. The effect of ( - ) ⅣMep⁃S on AChE activity was observed in vivo and in vitro. The effect of ( - ) ⅣMep⁃S on learning and memory impairment induced by scopolamine was examined in Morris water maze test in mice. The effect of ( - ) ⅣMep⁃S on the motor behaviors of mice was detected by open field test. results: Molecular docking analysis revealed that ( - ) ⅣMep⁃S binded to human AChE. In parallel , ( - ) ⅣMep⁃S overtly inhibited the activity of AChE derived from mouse forebrain and SH⁃SY5Y neuronal cells , and IC50 values were lower than those of the positive control drug rivastigmine. In the Morris water maze test , mice treated with ( - ) ⅣMep⁃S (2. 5 mg/kg) showed significantly reduced latency on day 4 (P < 0. 05) . Moreover, they exhibited significantly greater percentage of distance travelled and percentage of time spent in the target quadrant in the probe trial on day 5 (P < 0. 05) . ( - ) ⅣMep⁃S at 0. 5 mg/kg did not show any significant effects. In addition , ( - ) Ⅳ Mep⁃S inhibited the enhancement of forebrain AChE activity induced by scopolamine (P < 0. 05) . The open field test showed that the effect of ( - ) ⅣMep⁃S on scopolamine⁃induced learning and memory impairment was not due to the difference on the motor behaviors of mice. Conclusion ( - ) ⅣMep⁃S can effectively inhibit AChE activity and ameliorate scopolamineinduced learning and memory impairment in mice.