The Construction Of Farnesol/mPEG-PDLLA Micelles And Their Inhibitory Effect On The Decalcification Of Dental Enamel And Streptococcus Mutans

Objective:Using nanotechnology,the copolymer containing hydrophilic terminal methoxy polyethylene glycol-polylactic acid(m PEG-PDLLA)was used as a carrier,loaded with the natural drug Farnesol to construct water-soluble Farnesol/mPEG-PDLLA nanomicelles.The Farnesol/mPEG-PDLLA nanomicelles were used to study the inhibitory effect on the acid production of Streptococcus mutans and decalcification of enamel,and provide experimental basis for the development of natural anti-carious materials with no toxic and side effects.Methods:1.Farnesol was coated with mPEG-PDLLA to construct the Farnesol/m PEG-PDLLA nanomicelles.High performance liquid chromatography(HPLC)was used to determine the specificity of Farnesol,drug loading and encapsulation efficiency of nanomicelles with certain chromatographic conditions.The morphological characteristic of Farnesol/mPEG-PDLLA nanomicelles was observed using transmission electron microscope.The particle size,polymer dispersion coefficient(PDI)and Zeta potential were detected using Marvin laser particle size analyzer to further explore the stability,water solubility and in vitro release behavior of Farnesol/mPEG-PDLLA nanomicelles.2.The colony counting method was used to compare the bacteriostatic effect of Farnesol/mPEG-PDLLA nanomicelles with free Farnesol at the same concentration.3.The bacteriostatic effects of Farnesol/mPEG-PDLLA nano-micelles at different concentrations were compared.The Farnesol/mPEG-PDLLA nanomicelles were divided into 4 groups,group A: 100 ?mol/L,group B: 200 ?mol/L,Group C: 400 ?mol/L,group D(blank control group): 0 ?mol/L.Through colony counting to detect the bacteriostatic effect of different concentrations of nano micelles on Streptococcus mutans in free state;The effect of Farnesol/ mPEG-PDLLA nano-micelle on the morphology of streptococcus mutans plaque biofilm was evaluated using scanning electron microscope.The premolars extracted by orthodontic reduction were used to make enamel sections,and the inhibitory effect of Farnesol/mPEG-PDLLA nanomicelles on enamel decalcitfication was observed.pH value of bacterial suspension after drug treatment was detected using PH meter to observe the inhibitory effect of nanomicelle on the acid production of Streptococcus mutans.Results:1.HPLC analysis determined that Farnesol has good specificity.The drug loading of Farnesol/mPEG-PDLLA micelle was(8.3 ± 0.5)%,the encapsulation rate was(46.89 ± 1.1)%,and the particle size was(19.78 ± 0.21)nm,the Zeta potential was(-12.2 ± 0.4)mV,and the PDI was(0.089 ± 0.04).The indices are normally distributed.2.Farnesol/ mPEG-PDLLA micelles were observed under transmission electron microscopy,with uniform particle size,round appearance and good dispersion.3.The Farnesol/mPEG-PDLLA nanomicelles were released about 70% at 12 h and remained in a delayed release state within 48 h.The aqueous solution showed no agglomeration in particle size at 10 h.the freeze-dried powder of Farnesol/mPEG-PDLLA nanomicelles was placed at 4 ? for 2 months,with no obvious change in those indexes mentioned above.Results proved the Farnesol/mPEG-PDLLA nanomicelles had good stability.4.At the same concentration,the antibacterial effect of Farnesol/mPEG-PDLLA nanomicelles was more obvious than that of free Farnesol,and the difference between the two groups was statistically significant(P <0.05).5.100,200,and 400 ?mol/L nanomicelles can inhibit the growth of Streptococcus mutans of the free state,and the difference between the groups is statistically significant(P <0.05).In the range of 100-400 ?mol/L,the growth of Streptococcus mutans decreases with increasing drug concentration.6.With the increase of drug concentration,the biofilm of Streptococcus mutans plaque was seriously damaged,and the number of bacteria was significantly reduced.The biofilm of the 400 ?mol/L experimental group could hardly be formed.7.The calciumion concentration in supernatant of the experimental group at 24 h,48 h and 72 h was significantly lower than that of the control group(P < 0.05).The higher the drug concentration,the lower the calciumion concentration,and the inhibition effect of Farnesol/mPEG-PDLLA nanomicelles on enamel demineralization of Streptococcus mutans is concentration-dependent.8.The pH values of the bacterial suspension in different groups after 72 h treated with nano-micellar were 6.38,6.68,6.89 and 5.57.There were significant differences between the experimental groups and the control group(P < 0.05),while there was no significant difference between the experimental groups(P > 0.05).However,the pH value increases gradually with increasing concentration.The Farnesol/mPEG-PDLLA nanomicelles can reduce the acid production capacity of Streptococcus mutans.Conclusion:1.The copolymer containing hydrophilic terminal methoxy polyethylene glycol-polylactic acid(mPEG-PDLLA)was used as a carrier to load with the natural drug Farnesol(Farnesol).The Farnesol/mPEG-PDLLA nanomicelles were successfully prepared by the nano-technology to solve the water solubility of Farnesol and overcome the limitation of free drugs in clinical application.The Farnesol/mPEG-PDLLA nanomicelle has good stability and slow release.2.The Farnesol/mPEG-PDLLA nanomicelles can inhibit the formation of Streptococcus mutans plaque biofilm,inhibit the production of bacterial acid and demineralization of tooth enamel.And at the same concentration,the inhibition of Farnesol/mPEG-PDLLA nanomicelles on Streptococcus mutans is more obvious than that of free Farnesol.This study has important clinical guiding value for the prevention and treatment of caries.