S.aureus skin infections represent a major threat to public health related to the widespread emergence of methicillin-resistant S.aureus (MRSA) strains. MRSA often develops superficially located in wound infections. These infections often weakly respond to topical drug applications, due to bacterial antimicrobial resistance and to drug inability to cross the external skin barrier reaching dermal regions were bacteria are nested. Hence, the increasing bacterial resistance to antibiotics has to be faced by non-conventional approaches, such as nanostructured multifunctional carriers combined to non-invasive activation by external stimuli. Nanobubbles (NBs) constituted by dextran shell and fluorocarbon inner core, are small gas-filled nanospheres with sizes lower than 1µ, easily transcutaneously deliverable via ultrasound-induced sonophoresis. Dextran shelled NBs can also be effectively loaded with drugs. Vancomycin (VN)-loaded nanobubbles (VNLNBs) were compared to VN alone for MRSA killing and for potential cytotoxicity on human keratinocytes (HaCaT cell line). Dextran-shelled/perfluoropentane-containing VNLNBs were prepared and characterized for physical-chemical properties by optical microscopy, laser light scattering, and drug release studies. Liquid formulations of VN (1 mg/ml)and VNLNBs (30% titrated)were tested on MRSA(104CFU/ml) after 2,3,4,6,24h incubation. At each incubation time, the samples were spread on agar medium to determine the CFU/ml. VN and VNLNBs were incubated with HaCaT cells in DMEM medium plus 10% FCS for 24h, and citotoxicity was evaluated by measuring lactate dehydrogenase activity, whereas cell viability was checked by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.VNLNBs showed sizes less than 500 nm, a negative surface charge and a spherical shape. In vitro studies displayed prolonged drug release kinetics. The antibacterial efficiency was assessed for different formulations and their responses during time monitored and compared. No toxic effects were displayed on human keratinocytes, and cell viability was not significantly affected. VNLNBs proved to be effective in MRSA killing without showing toxic effects on human keratinocytes. Thus, they appear to be good therapeutic tools for treatment of infected chronic wounds.
Vancomycin–loaded dextran-shelled/perfluoropentane-containing nanobubbles are effective in MRSA killing
BANCHE, Giuliana;ALLIZOND, VALERIA;TULLIO, Viviana Cristina;MANDRAS, Narcisa;CAVALLI, Roberta;GUIOT, Caterina;ARGENZIANO, MONICA;PRATO, Mauro;KHADJAVI, AMINA;ROANA, Janira;SCALAS, Daniela;GIRIBALDI, Giuliana;CUFFINI, Annamaria
2013-01-01
Abstract
S.aureus skin infections represent a major threat to public health related to the widespread emergence of methicillin-resistant S.aureus (MRSA) strains. MRSA often develops superficially located in wound infections. These infections often weakly respond to topical drug applications, due to bacterial antimicrobial resistance and to drug inability to cross the external skin barrier reaching dermal regions were bacteria are nested. Hence, the increasing bacterial resistance to antibiotics has to be faced by non-conventional approaches, such as nanostructured multifunctional carriers combined to non-invasive activation by external stimuli. Nanobubbles (NBs) constituted by dextran shell and fluorocarbon inner core, are small gas-filled nanospheres with sizes lower than 1µ, easily transcutaneously deliverable via ultrasound-induced sonophoresis. Dextran shelled NBs can also be effectively loaded with drugs. Vancomycin (VN)-loaded nanobubbles (VNLNBs) were compared to VN alone for MRSA killing and for potential cytotoxicity on human keratinocytes (HaCaT cell line). Dextran-shelled/perfluoropentane-containing VNLNBs were prepared and characterized for physical-chemical properties by optical microscopy, laser light scattering, and drug release studies. Liquid formulations of VN (1 mg/ml)and VNLNBs (30% titrated)were tested on MRSA(104CFU/ml) after 2,3,4,6,24h incubation. At each incubation time, the samples were spread on agar medium to determine the CFU/ml. VN and VNLNBs were incubated with HaCaT cells in DMEM medium plus 10% FCS for 24h, and citotoxicity was evaluated by measuring lactate dehydrogenase activity, whereas cell viability was checked by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.VNLNBs showed sizes less than 500 nm, a negative surface charge and a spherical shape. In vitro studies displayed prolonged drug release kinetics. The antibacterial efficiency was assessed for different formulations and their responses during time monitored and compared. No toxic effects were displayed on human keratinocytes, and cell viability was not significantly affected. VNLNBs proved to be effective in MRSA killing without showing toxic effects on human keratinocytes. Thus, they appear to be good therapeutic tools for treatment of infected chronic wounds.
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