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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.
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@#To establish a high performance liquid chromatography(HPLC)method to determine the content of bacteriostats in the ocular extractives eye drops, Diamonsil C18(4. 6 mm×250 mm, 5 μm)column was used, with gradient elusion by 1% triethylamine solution(pH 3. 0)(mobile phase A)and methanol(mobile phase B). The detection wavelength was 256 nm; the column temperature was 40 °C; and the flow rate was 1. 0 mL/min. Under these conditions, the three bacteriostats of methylparaben, ethylparoben and chlorhexidine acetate showed good resolution. The bacteriostats exhibited good linear relationship between the peak area and the concentration in the concentration range of 0. 1- 80 μg/mL(r> 0. 999 1). The recoveries were from 97. 2% to 104. 1%, and the RSD was 0. 8% to 1. 2%. The content of bacteriostats in all the five batches of ocular extractives eye drops was less than 10% of the prescription amount. It was found that the activated carbon used in the production process had strong adsorption effect on the bacteriostat, and that the lower the temperature and the higher the concentration of activated carbon, the stronger the adsorption of bacteriostatic agent. The adsorption capacity of activated carbon for different bacteriostats is: chlorhexidine acetate > ethylparoben > methylparaben. The results showed that the established HPLC method was easy to operate with high sensitivity and good repeatability. It can be used to determine the content of bacteriostat in ocular extractives eye drops quickly and accurately. In addition, this study reveals for the first time the effect of impurity removal process on bacteriostat in the production of ocular extractives eye drops. It is not suitable to use activated carbon to remove impurities before adding parabens and chlorhexidine acetate bacteriostats. The current work provides a new guiding basis for the monitoring and improvement of the quality of ocular extractives eye drops.
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Objective To investigate the chlorhexidine acetate-resistance in Klebsiella pneumoniae ( K. pneumoniae) clinical isolates and to analyze the possible mechanisms and molecular epidemiology of re-sistant isolates. Methods A total of 332 K. pneumoniae clinical isolates were collected in the First Affilia-ted Hospital of Wenzhou Medical University in 2015. Standard agar dilution was used to screen chlorhexidine acetate-resistant isolates. The minimum inhibition concentrations ( MIC) of chlorhexidine acetate to resistant isolates with and without the presence of carbonyl cyanide m-chlorophenyl hydrazone ( CCCP) , which was an efflux pump inhibitor, were analyzed. Efflux pump genes of cepA, qacE and qacΔE1 that carried by and ex-pressed in those isolates were detected by polymerase chain reaction ( PCR) and quantitative real-time PCR ( RT-qPCR) , respectively. The biofilm formation ability was measured by crystal violet staining. The homol-ogy among the chlorhexidine acetate-resistant isolates was investigated with multilocus sequence typing ( MLST) and pulsed-field gel electrophoresis ( PFGE) . Results Twenty-five K. pneumoniae strains were re-sistant to chlorhexidine acetate. The MIC values of chlorhexidine acetate for them were reduced by at least four-fold in the presence of CCCP. Strains carrying the genes of cepA, qacE and qacΔE1 accounted for 100％, 40％ and 40％, respectively. The expression of the efflux pump genes in the chlorhexidine acetate-resistant isolates was higher than that in the susceptible isolates. The biofilm formation ability of the chlo-rhexidine acetate-resistant isolates was better than that of the susceptible isolates. Furthermore, negative, weak-positive and positive biofilm formation ability was observed in four ( 16％) , 20 ( 80％) and one (4％) strains, respectively. The results of MLST and PFGE showed that the 25 chlorhexidine acetate-resist-ant isolates belonged to 19 different sequence types ( ST) with diverse PFGE patterns. Conclusions This study suggested that active efflux was the main mechanism of chlorhexidine acetate resistance in K. pneumoni-ae. The 25 chlorhexidine acetate-resistant K. pneumoniae strains possessed different biofilm formation ability and shared low homology.
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Objective:To establish the microbial limit test methods for three preparations containing chlorhexidine acetate. Meth-ods:The validation of microbiological limit test for three preparations including chlorhexidine acetate solution, chlorhexidine acetate ointment and chlorhexidine acetate cream was carried out respectively using the conventional method,dilution method,membrane filtra-tion method and neutralization method. Results:The recovery rates of five strains in the verification of counting method by membirane filtration and nearailzation method were more than 50%. Every positive test micrcorganism could be detected while negative control bacteria could not grow in the examination of control bacteria.Conclusion:The membrane filtration method can be used for the deter-mination of control bacteria for chlorhexidine acetate solution and chlorhexidine acetate ointment,and the neutralization method can be applied in the determination of control bacteria for chlorhexidine acetate cream.
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Objective To improve the standard of the quality control of compound chlorhexidine acetate ointment . Methods TLC was used to control the quality of menthol crystal and camphor .A method to determine chlorhexidine acetate and cocaine hydrochloride simultaneously by HPLC was established .Results The spots of menthol crystal and camphor in TLC were clear .Chlorhexidine acetate and cocaine hydrochloride showed excellent linearity ,which were at the range of 10.01-160.14 μg/ml and 10 .01-160 .14 μg/ml ,respectively .The average recoveries were 101 .5% (RSD=1 .8% ) and 100 .5% (RSD=2 .8% ) .Conclusion The methods were simple ,sensitive and with good reproducibility and could be used to control the quality of compound chlorhexidine acetate ointment .
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OBJECTIVE:To prepare the compound chlorhexidine acetate ear drops for treating anaerobic and aerobic infections of antrum auris METHODS:The compound chlorhexidine acetate ear drops was prepared with mixed solvent of glycerin,alcohol and distilled water The contents of two main ingredients were determined by dual-wavelength isobestic point spectrophotometry and the stability of preparation was examined RESULTS:The average recovery of metronidazole was 99 34%(RSD=0 57%,n=6) and that of chlorhexidine acetate was 101 17%(RSD=0 88%,n=6) CONCLUSION:The new preparation is rational in formula,simple in quality control and good in stability and has good prospects in development
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OBJECTIVE:To establish a RP-HPLC method for the determination of the content of chlorhexidine acetate in daobian suppository.METHODS:The determination was performed on Diamonsil C_(18)column,The mobile phase consisted of acetonitrile-water-triethylamine(30:70:0.5,with pH adjusted to 3.0 by phosphoric acid)at a flow rate of 1.0 mL?min~(-1),The detective wavelength was 260 nm,the sample size was 20?L and the column temperature was maintained at 30℃. RESULTS:The linear range of Chlorhexidine Acetate was 1.092～13.10?g?mL~(-1)(r=0.999 9)and its average recovery was 98.29%(RSD=2.16%,n=9).CONCLUSIONS:The method is simple and accurate,and it can be used for the determination of the content of chlorhexidine acetate in daobian suppository.
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OBJECTIVE:To prepare and establish the method for measuring the content of ornidazole gargle.METHODS:Maximal wavelength and dual-wavelength point spectrophotometries were used to determine the contents of ornidazole and chlorhexidine acetate respectively.RESULTS:The calibration curve of ornidazole and chlorhexidine acetate were linear in the range of5.5～16.6?g/ml and5.6～16.8?g/ml respectively.The average recovery rates of ornidazole and chlorhexidine acetate were100.23%and99.77%respectively,and their RSD were0.47%and0.31%respectively.CONCLUSION:The method of preparation and quality control is simple,quick and accurate.
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OBJECTIVE:To develop a HPLC method for determination of tinidazole and chlorhexidine acetate in co-tinidazole gargle.METHODS:Tinidazole and chlorhexidine acetate in co-tinidazole gargle were determined by RP-HPLC with metronidazole as the internal standard.ODS was adopted as stationary phase and acetonitrile-water(35∶65)as mobile phase.The detector was operated at UV254nm.RESULTS:The calibration curve of tinidazole was linear within the concen?tration range of(0.01～0.10)mg/ml(r=0.9999);The calibration curve of chlorhexidine acetate was linear within the con?centration range of(0.01～0.10)mg/ml(r=0.9997).The average recoveries of tinidazole and chlorhexidine were(97.06～102.02)%and(97.21～103.40)%,respectively.The within-day coefficients of variance were(0.20～1.26)%and(0.71～1.11)%,respectively.The between-days coefficients of variance were(0.50～2.06)%and(0.80～2.17)%,respective?ly.CONCLUSION:The method is suitable for determination of preparations containing tinidazole and chlorhexidine acetate.