| Summary: | 碩士 === 中原大學 === 奈米科技碩士學位學程 === 98 === Acne vulgaris is known as infection of pathogenic bacteria, Propionibacterium
acnes (P. acnes). Lauric acid (LA) was found to kill P. acnes effectively. However,
LA is a sparingly soluble fatty acid in water in which dimethly sulfoxide (DMSO) is
used to increase solubility. In this study, amphiphilic micelles encapsulating LA was
developed to reduce DMSO-induced toxicity and improve bactericidal effect of LA.
Poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL)
triblock copolymer was sythysized by ring-opening polymerization. Different
molecular weights of PCL-PEG-PCL were synthesized and chararerized by 1H
nuclear magnegtic resonance, Fourier transform infared spectroscopy, differential
scanning calorimeter and gel permeation chromatography, respectively. The critical
micelle concentration(CMC) of the micelle solution was determined by using
fluorescent probe, 1,6-diphenyl-1,3,5-hexatriene(DPH). The results of particle size
analyzer and transmission electron microscopy show that the averge particles size of
placebo micelles and LA-encapsulated micelles were 49.8-198.1 nm and 24.7-89.3
nm, respectively. Upon encapsulation of LA, zeta potential decreased from -3.0 ~
-9.7mV to -4.2 ~ -18.4 mV, because of depronated carboxyl group in LA. A
High-performance liquid chromatography was used to quantitate LA encapsulated in
the micelles, after encapsulated LA was derived with naphthacyl ester. As the results,
the payload of PC50E40C50 for LA was 323.75 μg/mL which was the highest among
various PCL-PEG-PCL. In addition, as the length of PCL increased, the drug loading
contents decreased. The effect of LA-encapsulated micelles(micelle formulation)
were compared with LA dissolved in 5% DMSO(free LA formulation). For free LA
formulation, as free lauric acid dissolved in 5% DMSO, the minimum inhibitory
concentration(MIC) and minimum bactericidal concentration(MBC) were 20 μg/mL
and 80μg/mL, respectively. In contrasty, MIC and MBC of micelle formulation were
only 10-20 μg/mL and 40-80 μg/mL, respectively. Therefore, the micelle formulation
requires slightly lower LA to reach the same antibactirials effecacy of free LA
formulation. The cytotoxicities of free LA formulation and micelle formulation in
fibroblast and keratinocyte were conducted. It is found that micelle formulation
I I I
posses better biocompatibility over free LA. In summary, this study demonstrated that
PCL-PEG-PCL was a potential drug carrier to encapsulate LA. It worthshile to
further examine the efficacy to against the infection of P.acnes in animal study.
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