The effect of ferulic acid encapsulated chitosan on methicillin-resistant Staphylococcus aureus

BACKGROUND AND OBJECTIVESIncreasing antibiotic resistance and diminishing pharmaceutical industry investments have increased the need for molecules that can treat infections caused by dangerous pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). Ferulic acid shows tremendoustherapeutic properties with potent antibacterial properties. Among the nanomaterials used for efficient delivery of drugs, chitosan has received emerging interest due to its physical and chemical properties. Besides, its combination with tripolyphosphate (TPP) not only enhances the entrapment efficiency of the drug but also results in controlled and targeted delivery. In this study, ferulic acid encapsulated chitosan-tripolyphosphate nanoparticles (FANPs) was investigated against methicillin-resistant Staphylococcus aureus (MRSA) and compared with native ferulic acid.MATERIALS AND METHODSSynthesis of ferulic acid encapsulated chitosan-TPPnanoparticles (FANPs)FANPs were synthesised by the ionic gelation method. Briefly, ferulic acid was added gradually into chitosan solution (۰.۲۵% w/v) under magnetic stirring at ambient temperature for ۳۰–۴۵ min followed by dropwise addition of ۰.۲۵ mg/ml of TPP solution in a ratio of ۱:۵ with respect to chitosan under continuous stirring at ۱۰۰۰ rpm for ۳۰ min to yield FANPs. The suspension of nanoparticles was then centrifuged at ۱۲,۰۰۰ rpm for ۶۰ min and washed with deionised water (three times) to remove the unloaded compounds.Physicochemical characterisation of synthesised FANPsDynamic light scattering (DLS) was used to measure the mean particle size of synthesised FANPs using particle size analyser (Malvern-Nano Series) at ۲۵°C with scattering angle of ۹۰°.Fourier transform infrared (FTIR) analysisFTIR spectra of chitosan, ferulic acid and FANPs were recorded to analyse the bonds and functional groups present.Determination of minimum inhibitory concentration (MIC)The MIC for the native ferulic acid and FANPs were determined as per the guidelines of Clinical and Laboratory Standards Institute.RESULTS AND DISCUSSIONSynthesis of FANPsFerulic acid was encapsulated into chitosan biopolymer where TPP was used as a crosslinker, in order to synthesise FANPs.Physico-chemical characterisation of synthesised FANPsThe DLS analysis confirmed the formation and size distribution of FANPs. The size of FANPs, analysed by DLS showed a Z-average value of ۲۱۵.۵۵ nm.FTIR spectrophotometer analysisIn order to confirm the successful formation of FANPs, FTIR studies were carried out. The presence of similar kind of functional group in FANPs in comparison to native ferulic acid and chitosan signifies that ferulic acid was successfully encapsulated into chitosan carrier where TPP act as crosslinker.Determination of MIC and sub-MICThe MIC of ferulic acid and FANPs against methicillin-resistant Staphylococcus aureus (MRSA) was found to be ۱۰۰۰ μg/ml where the growth and cell density were significantly inhibited as evident from the absence of turbidity. Hence, sub-MIC concentrations of ۲۵۰ and ۵۰۰ μg/ml (i.e. ۱/۲ and ۱/۴ MIC, respectively) were used for further activities.CONCLUSIONThis study showed as compared to native ferulic acid, the attenuation efficacy of FANPs was found to be significantly higher suggesting the role of a biocompatible nanocarrier system for effective targeting of the virulence with slow and controlled release of encapsulated drugs.

کلیدواژه ها:

MRSA ، FANPs ، DLS ، MIC