Preparation And Characterization Of Antimicrobial Peptide-coated Superparamagnetic Iron Oxide Nanoparticles

Objective:In recent years,Superparamagnetic iron oxide nanoparticles(SPIONs)have attracted more and more attention in the field of biomedicine due to their characteristics of non-toxicity,magnetic targeting,and easily modified active surfaces.And antimicrobial peptides(AMPs)have also been widely favored in oral infection control.This study proposed a new type of antibacterial magnetic nanocomposite,antimicrobial peptides IDR-1018 functionalized SPIONs,as a potential approach to control root canal infection.Method:First,Superparamagnetic iron oxide nanoparticles(SPIONs)were synthesized by chemical co-precipitation method,and then modified with amino(-NH2)functional group using 3-aminopropyltriethoxysilane(APTES)(SPIONs@NH₂),followed by antimicrobial peptide IDR-1018 coating through amidation reaction to form SPIONs@IDR-1018 composite.X-ray diffractometer(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscope(SEM)with an energy disperse spectroscopy(EDS),and thermogravimetric technique(TG)were used to analyze and characterize the chemical composition and morphology of synthesized particles.The magnetic properties of the particles were identified using a vibrating sample magnetometer(VSM).The secondary structures of IDR-1018 in phosphate buffer solution(PBS)was analyzed by circular dichroism before and after being coated on SPIONs surface.Furthermore,the minimal inhibitory concentration(MIC)of IDR-1018 and synthesized particles against Enterococcus faecalis(ATCC29212,with a final bacterial suspension concentration of 5×10⁴CFU/ml per well tested)was measured using broth microdilution method.Results:Synthesized SPIONs were identified as magnetite.And IDR-1018 was confirmed successfully being coated on SPIONs surface.SPIONs@IDR-1018 particles were about 12.9±1.92 nm in diameter with a saturation magnetization of 54.177 emu/g.What's more,it showed good magnetic response and superparamagnetism as bare SPIONs.The CD spectrum indicated that IDR-1018 displayed a similar degree of?-helical content after being coated on SPIONs surface,but the?-sheet content decreased from 57.9%to 24.2%,while?-turn conformation increased from 14.9%to 39.0%.MIC of SPIONs@IDR-1018and free IDR-1018 against Enterococcus faecalis were both 4?g/m LConclusions:Synthesized Nanocomposites SPIONs@IDR-1018 with IDR-1018covalently attached to SPIONs surface exhibit superparamagnetism and antibacterial properties,which might be considered as a potential method of root canal infection control.