RESUMO
Widespread resistance to antibiotics amongst pathogens has become a tremendous challenge of high morbidity and mortality rates which increases the needs to exploring novel methods of treatment. An efficient antimicrobial procedure to root out pathogenic bacteria is photothermal therapy. In this study, antimicrobial effects of a polypyrrole-carbon nanocomposite (PPy-C) upon laser irradiation in order to destroy the pathogenic gram-positive bacterium, methicillin-resistant Staphylococcus aureus (MRSA) were assessed. The bacterial cells were incubated with 500, 750 and 1000â µg ml-1 concentrations of PPy-C and irradiated with an 808-nm laser at a power density of 1.0â W cm-2. To indicate the biocompatibility and toxic effect of the nanocomposite without and with laser irradiation, the authors counted the number of CFUs and compared it to an untreated sample. Antibacterial mechanisms of PPy-C were assessed through temperature increment, reactive oxygen species production, and protein and DNA leakages. Photothermal heating assay showed that 26°C temperature increases in the presence of 1000â µg ml-1 PPy-C led to >98% killing of MRSA. Furthermore, 20â min radiation of near-infrared light to PPy-C in different concentrations indicated destruction and reduction in the MRSA biofilm formation. Therefore, PPy-C was introduced as a photothermal absorber with a bactericidal effect in MRSA.
Assuntos
Biofilmes , Carbono/química , Temperatura Alta/uso terapêutico , Staphylococcus aureus Resistente à Meticilina , Nanocompostos/uso terapêutico , Fototerapia/métodos , Polímeros/química , Pirróis/química , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Biofilmes/efeitos da radiação , Carbono/farmacologia , Carbono/uso terapêutico , Materiais Revestidos Biocompatíveis/síntese química , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/uso terapêutico , Humanos , Teste de Materiais , Resistência a Meticilina/efeitos dos fármacos , Resistência a Meticilina/efeitos da radiação , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/fisiologia , Staphylococcus aureus Resistente à Meticilina/efeitos da radiação , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos da radiação , Nanocompostos/química , Polímeros/farmacologia , Polímeros/uso terapêutico , Pirróis/farmacologia , Pirróis/uso terapêutico , Infecções Estafilocócicas/terapiaRESUMO
BACKGROUND: Due to current antibiotic resistance worldwide, there is an urgent need to find new alternative antibacterial approaches capable of dealing with multidrug-resistant pathogens. Most recent studies have demonstrated the antibacterial activity and non-cytotoxicity of carbon nanomaterials such as graphene oxide (GO) and carbon nanofibers (CNFs). On the other hand, light-emitting diodes (LEDs) have shown great potential in a wide range of biomedical applications. METHODS: We investigated a nanotechnological strategy consisting of GO or CNFs combined with light-emitting diod (LED) irradiation as novel nanoweapons against two clinically relevant Gram-positive multidrug-resistant pathogens: methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). The cytotoxicity of GO and CNFs was studied in the presence of human keratinocyte HaCaT cells. RESULTS: GO or CNFs exhibited no cytotoxicity and high antibacterial activity in direct contact with MRSE and MRSA cells. Furthermore, when GO or CNFs were illuminated with LED light, the MRSE and MRSA cells lost viability. The rate of decrease in colony forming units from 0 to 3 h, measured per mL, increased to 98.5 ± 1.6% and 95.8 ± 1.4% for GO and 99.5 ± 0.6% and 99.7 ± 0.2% for CNFs. CONCLUSIONS: This combined antimicrobial approach opens up many biomedical research opportunities and provides an enhanced strategy for the prevention and treatment of Gram-positive multidrug-resistant infections.
Assuntos
Antibacterianos/farmacologia , Grafite/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos da radiação , Nanoestruturas/química , Nanotubos de Carbono/química , Staphylococcus epidermidis/efeitos da radiação , Linhagem Celular , Sobrevivência Celular/efeitos da radiação , Técnicas de Cocultura , Relação Dose-Resposta à Radiação , Humanos , Queratinócitos/citologia , Queratinócitos/fisiologia , Queratinócitos/efeitos da radiação , Luz , Resistência a Meticilina/efeitos da radiação , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos da radiação , Nanoestruturas/ultraestrutura , Nanotubos de Carbono/ultraestrutura , Fototerapia/métodos , Staphylococcus epidermidis/crescimento & desenvolvimentoRESUMO
Systemic infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and other bacteria are responsible for millions of deaths worldwide, and much of this mortality is due to the rise of antibiotic-resistant organisms as a result of natural selection. Gold nanoparticles synthesized using the standard wet chemical procedure were photoexcited using an 808 nm 2 W laser diode and further administered to MRSA bacteria. Flow cytometry, transmission electron microscopy, contrast phase microscopy, and fluorescence microscopy combined with immunochemical staining were used to examine the interaction of the photoexcited gold nano-particles with MRSA bacteria. We show here that phonon-phonon interactions following laser photoexcitation of gold nanoparticles exhibit increased MRSA necrotic rates at low concentrations and short incubation times compared with MRSA treated with gold nanoparticles alone. These unique data may represent a step forward in the study of bactericidal effects of various nanomaterials, with applications in biology and medicine.