Atmospheric Plasma Treatment of Biomaterials with Eugenol and Carvacrol Thin Films for Inhibiting Bacterial Adhesion and Proliferation
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Data
2020-10-16
Autores
Getnet, Tsegaye Gashaw
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Universidade Estadual Paulista (Unesp)
Resumo
Um dispositivo médico implantado (IMD) é qualquer material inserido ou enxertado nocorpo para fins protéticos, diagnósticos, terapêuticos ou experimentais. O uso dos IMD´s temcrescido significativamente em todas as áreas da medicina devido à sua capacidade de repararou substituir tecidos e órgãos danificados. No entanto, deve-se atentar para a escolha dosmateriais a serem utilizados nos IMD´s para garantir o melhor desempenho do dispositivoquando em ambiente biológico. Além de boa biocompatibilidade e estabilidade química, emdiversas situações o material também deve ser capaz de inibir a colonização bacteriana doimplante. Embora infecções bacterianas possam ser tratadas com antibióticos, o uso excessivode tais drogas levou ao desenvolvimento de microrganismos resistentes aos antibióticos. Alémdisso, quando aderidas a uma superfície, as bactérias podem formar biofilmes, ou seja, umaaglomeração de células que as protege de agentes externos. Nesse contexto, a modificação desuperfícies de biomateriais com compostos antimicrobianos naturais apresenta grandepotencial para resolver muitos dos inconvenientes relacionados ao uso de implantes. Nessecenário, neste trabalho foi investigada a deposição e caracterização de filmes finos produzidosa partir de monômeros naturais de carvacrol e eugenol empregaudo plasmas de Descargas deBarreiras Dielétricas (DBD). As características elétricas das descargas foram avaliadasmedindo-se a queda de tensão em um resistor e capacitor, respectivamente, e a tensão aplicadafoi medida com um divisor de tensão. A tensão máxima aplicada foi de 14,4 kV pico a pico e apotência em torno de 1,2 W. O estudo também compreendeu a avaliação das propriedadesfísicas e químicas dos filmes por espectroscopia de reflexão-absorção no infravermelho,microscopias eletrônica de varredura e de força atômica, perfilometria e medidas de ângulo decontato. Avaliou-se ainda o efeito dos revestimentos sobre a formação de biofilmes deStaphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli e Candida albicans sobresubstratos de aço inoxidável. Filmes uniformes, densos e quimicamente semelhantes aosrespectivos monômeros foram obtidos. Os resultados de espectroscopia de impedânciaeletroquímica revelaram que os revestimentos aumentaram em mais de 10 vezes a resistência àcorrosão dos substratos quando imersos em soluções de NaCl. Embora tenha sido observada aformação de biofilmes de todos os micróbios sobre as amostras não tratadas, os filmesderivados do carvacrol inibiram completamente a adesão de E. coli e reduziram em 90% aproliferação de S. aureus. O revestimento também inibiu a adesão de P. aeruginosa e C.albicans em mais de 40%. Da mesma forma, filmes produzidos em plasmas contendo eugenolinibiram em mais de 65% a adesão de E. coli e S. aureus e em mais de 30% a adesão de P.aeruginosa e C. Albicans.
Owing to their ability to repair and substitute damaged tissue or organs, the use ofimplantable medical devices (IMD) is rising in modern medicine and healthcare. However,attention must be paid when choosing the materials to be used in IMD´s to assure the bestperformance of the device when in a biological environment. In addition to goodbiocompatibility and chemical stability, in several situations, the ideal material must also beable to inhibit implant bacterial colonization. Although bacterial infections may be treated withantibiotics, the overuse of such drugs has led to the development of antibiotic-resistantmicroorganisms. Furthermore, when adhered to a surface, bacteria can form biofilms, i.e. anagglomeration of cells that shields them from external agents. In this context, the modificationof biomaterial surfaces with natural antimicrobial compounds has the potential to address thesecommon implant-related inconveniences. In this scenario, we have examined the deposition andcharacterization of polymeric thin films produced from natural carvacrol and eugenolmonomers in a Dielectric Barrier Discharge (DBD) plasma reactor. The electrical dischargecharacteristics were diagnosed by measuring the drop of voltage on a resistor and capacitor,and its applied voltage was measured by a voltage divider. The maximum applied voltage was14.4 kV peak-to-peak and the power around 1.2 W. The study also included the analysis of thefilm structure using infrared reflectance spectroscopy, scanning electron and atomic forcemicroscopies, profilometry, and contact angle measurements. Uniform, smooth, and dense filmshaving chemical similarity to the corresponding monomer have been obtained. Inhibition ofbiofilms of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candidaalbicans on stainless steel was evaluated. While it has been observed the formation of biofilm ofall the microbes on the untreated samples, the coatings derived from carvacrol completelyinhibited the adhesion of E. coli and reduced by 90% the proliferation of S. aureus. The coatinghas also inhibited the adhesion of P. aeruginosa and C. albicans in up to 44% and 60%,respectively. Similarly, films produced in plasmas containing eugenol inhibited by more than75% and 65% the adhesion of E. coli and S. aureus, respectively, and the adhesion of P.aeruginosa and C. albicans by more than 30% and 40%, respectively. Electrochemicalimpedance spectroscopy and the potentiodynamic results revealed that both carvacrol- andeugenol-derived films have increased by at least 10 times the corrosion resistance of stainlesssteel in NaCl solution.
Owing to their ability to repair and substitute damaged tissue or organs, the use ofimplantable medical devices (IMD) is rising in modern medicine and healthcare. However,attention must be paid when choosing the materials to be used in IMD´s to assure the bestperformance of the device when in a biological environment. In addition to goodbiocompatibility and chemical stability, in several situations, the ideal material must also beable to inhibit implant bacterial colonization. Although bacterial infections may be treated withantibiotics, the overuse of such drugs has led to the development of antibiotic-resistantmicroorganisms. Furthermore, when adhered to a surface, bacteria can form biofilms, i.e. anagglomeration of cells that shields them from external agents. In this context, the modificationof biomaterial surfaces with natural antimicrobial compounds has the potential to address thesecommon implant-related inconveniences. In this scenario, we have examined the deposition andcharacterization of polymeric thin films produced from natural carvacrol and eugenolmonomers in a Dielectric Barrier Discharge (DBD) plasma reactor. The electrical dischargecharacteristics were diagnosed by measuring the drop of voltage on a resistor and capacitor,and its applied voltage was measured by a voltage divider. The maximum applied voltage was14.4 kV peak-to-peak and the power around 1.2 W. The study also included the analysis of thefilm structure using infrared reflectance spectroscopy, scanning electron and atomic forcemicroscopies, profilometry, and contact angle measurements. Uniform, smooth, and dense filmshaving chemical similarity to the corresponding monomer have been obtained. Inhibition ofbiofilms of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candidaalbicans on stainless steel was evaluated. While it has been observed the formation of biofilm ofall the microbes on the untreated samples, the coatings derived from carvacrol completelyinhibited the adhesion of E. coli and reduced by 90% the proliferation of S. aureus. The coatinghas also inhibited the adhesion of P. aeruginosa and C. albicans in up to 44% and 60%,respectively. Similarly, films produced in plasmas containing eugenol inhibited by more than75% and 65% the adhesion of E. coli and S. aureus, respectively, and the adhesion of P.aeruginosa and C. albicans by more than 30% and 40%, respectively. Electrochemicalimpedance spectroscopy and the potentiodynamic results revealed that both carvacrol- andeugenol-derived films have increased by at least 10 times the corrosion resistance of stainlesssteel in NaCl solution.
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Palavras-chave
Dielectric barrier discharge, Plasma diagnostics, Plasma polymer, Descarga de barreira dielétrica, Diagnóstico de plasma, Polimerização em plasma