Nanoplataformas de prata e ouro e sílica mesoporosa aplicáveis em inativação fotodinâmica
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Data
2021-06-25
Autores
Pereira, Daniela Vassalo
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Universidade Estadual Paulista (Unesp)
Resumo
Atualmente, os microrganismos multirresistentes aos antibióticos convencionais representam um sério problema de saúde pública global. Com isso, houve a necessidade de desenvolver novas estratégias antimicrobianas, como a Inativação Fotodinâmica (PDI). Baseado no fato de que muitos fotossensibilizadores (FS) utilizados em PDI apresentam baixa disponibilidade em meio aquoso e necessidade de aumentar sua eficiência quântica, foram propostas nanoplataformas baseadas em sílica mesoporosa (SiO2M) e nanopartículas metálicas, prata e ouro, que podem ser utilizadas para aprimorar a aplicação dos FS, superando os problemas apresentados. Nesse sentido, esse trabalho descreve as sínteses e caracterizações da nanoplataforma de nanoesferas de SiO2M com nanopartículas de prata sintetizadas com citrato de sódio como agente estabilizante (NPsAg-1) e da nanoplataforma núcleo/casca de SiO2M com nanopartículas de prata sintetizadas com polivinilpirrolidona como agente estabilizante (NPsAg-2), SiO2M@NPsAg-1 e SiO2M@NPsAg-2, respectivamente. Ambas plataformas poderiam ter curcumina incorporada nos mesoporos da sílica, uma vez que a faixa de absorção da curcumina e das nanopartículas de prata são na mesma região. Além disso, foram feitas as sínteses e caracterizações de nanoesferas de ouro (NPsAu) e nanobastões de ouro (NBsAu) como proposta para serem associadas com estruturas de SiO2M. As caracterizações dos nanomateriais foram feitas por meio de espectroscopia de absorção na região do ultravioleta e visível (UV-Vis), potencial zeta e medidas de espalhamento dinâmico de luz (DLS), espectroscopia de infravermelho com transformada de Fourier (FTIR), microscopia eletrônica de transmissão (MET) e microscopia eletrônica de varredura (MEV). As NPsAg-1 apresentaram formato esférico, tamanho de 10 nm, raio hidrodinâmico de 22 nm, banda de absorção máxima em 398 nm e potencial zeta de -36,8 mV com excelente estabilidade coloidal. As NPsAg-2 mostraram tamanho de 10 a 90 nm e forma quase esférica, raio hidrodinâmico de 155 nm, potencial zeta de -23,9 mV, boa estabilidade coloidal, com banda de absorção máxima em 414 nm e depois de serem recobertas com casca de SiO2M com espessura de 10 nm, SiO2M@NPsAg-2, a máxima absorção passou a ser em 428 nm. As nanoesferas de SiO2M9 mostraram diâmetro médio de 50 nm e indícios de mesoporos, raio hidrodinâmico médio de 268 nm, potencial zeta médio de -19,4 mV e o espectro FTIR revelou presença de grupos Si–O–Si e Si–OH. As NPsAu apresentaram formato esférico regular, diâmetro médio de 9,9 nm, boa monodispersividade, absorção máxima em 520 nm, raio hidrodinâmico de 23 nm, com potencial zeta igual a 41,2 mV, indicando boa estabilidade coloidal. Os NBsAu mostraram diâmetros entre 13,9 nm e 16,2 nm e comprimentos entre 151 nm e 250 nm, raio hidrodinâmico predominante em 43 nm e potencial zeta médio igual a 59,1 mV, evidenciando que a suspensão coloidal é estável. Assim, a exploração do uso LSPR das nanopartículas metálicas associadas a estruturas de SiO2M podem melhorar a atividade antimicrobiana de diversos fármacos devido ao efeito chamado Aumento da Geração de Oxigênio Singleto via Metal (MEO), que ocorre ao combinar nanopartículas metálicas com FS que possuem faixa de absorção coincidentes, aprimorando protocolos PDI.
Currently, microorganisms that are multiresistant to conventional antibiotics represent a serious global public health problem. Thus, there was a need to develop new antimicrobial strategies, such as Photodynamic Inactivation (PDI). Based on the fact that many photosensitizers (FS) used in PDI have low availability in aqueous media and the need to increase their quantum efficiency, nanoplatforms based on mesoporous silica (SiO2M) and metallic, silver and gold nanoparticles were proposed, which can be used for improve the application of FS, overcoming the problems presented. In this sense, this work describes the syntheses and characterizations of the nanoplatform of SiO2M nanospheres with silver nanoparticles synthesized with sodium citrate as stabilizing agent (NPsAg- 1) and of the SiO2M core/shell nanoplatform with silver nanoparticles synthesized with polyvinylpyrrolidone as agent stabilizer (NPsAg-2), SiO2M@NPsAg-1 and SiO2M@NPsAg-2, respectively. Both platforms could have curcumin incorporated in the silica mesopores, since the absorption range of curcumin and silver nanoparticles are in the same region. Furthermore, syntheses and characterizations of gold nanospheres (NPsAu) and gold nanorods (NBsAu) were carried out as proposed to be associated with SiO2M structures. The characterizations of the nanomaterials were performed by means of ultraviolet and visible absorption spectroscopy (UV-Vis), zeta potential and dynamic light scattering (DLS) measurements, Fourier transform infrared spectroscopy (FTIR), electron microscopy transmission (TEM) and scanning electron microscopy (SEM). The NPsAg-1 had a spherical shape, size of 10 nm, hydrodynamic radius of 22 nm, maximum absorption band at 398 nm and zeta potential of -36.8 mV with excellent colloidal stability. The NPsAg-2 showed a size of 10 to 90 nm and almost spherical shape, hydrodynamic radius of 155 nm, zeta potential of -23.9 mV, good colloidal stability, with maximum absorption band at 414 nm and after being covered with shell of SiO2M with a thickness of 10 nm, SiO2M@NPsAg-2, the maximum absorption was at 428 nm. The SiO2M nanospheres showed an average diameter of 50 nm and evidence of mesopores, an average hydrodynamic radius of 268 nm, an average zeta potential of -19.4 mV and the FTIR spectrum revealed the presence of Si–O–Si and Si–OH groups. The NPsAu showed regular spherical shape, mean diameter of 9.9 nm, good monodispersity,11 maximum absorption at 520 nm, hydrodynamic radius of 23 nm, with zeta potential equal to 41.2 mV, indicating good colloidal stability. The NBsAu showed diameters between 13.9 nm and 16.2 nm and lengths between 151 nm and 250 nm, predominant hydrodynamic radius at 43 nm and mean zeta potential equal to 59.1 mV, showing that the colloidal suspension is stable. Thus, the exploration of the LSPR use of metallic nanoparticles associated with SiO2M structures can improve the antimicrobial activity of several drugs due to the effect called Increased Singlet Oxygen Generation via Metal (MEO), which occurs when combining metallic nanoparticles with FS that have a range of coincident absorption, enhancing PDI protocols.
Currently, microorganisms that are multiresistant to conventional antibiotics represent a serious global public health problem. Thus, there was a need to develop new antimicrobial strategies, such as Photodynamic Inactivation (PDI). Based on the fact that many photosensitizers (FS) used in PDI have low availability in aqueous media and the need to increase their quantum efficiency, nanoplatforms based on mesoporous silica (SiO2M) and metallic, silver and gold nanoparticles were proposed, which can be used for improve the application of FS, overcoming the problems presented. In this sense, this work describes the syntheses and characterizations of the nanoplatform of SiO2M nanospheres with silver nanoparticles synthesized with sodium citrate as stabilizing agent (NPsAg- 1) and of the SiO2M core/shell nanoplatform with silver nanoparticles synthesized with polyvinylpyrrolidone as agent stabilizer (NPsAg-2), SiO2M@NPsAg-1 and SiO2M@NPsAg-2, respectively. Both platforms could have curcumin incorporated in the silica mesopores, since the absorption range of curcumin and silver nanoparticles are in the same region. Furthermore, syntheses and characterizations of gold nanospheres (NPsAu) and gold nanorods (NBsAu) were carried out as proposed to be associated with SiO2M structures. The characterizations of the nanomaterials were performed by means of ultraviolet and visible absorption spectroscopy (UV-Vis), zeta potential and dynamic light scattering (DLS) measurements, Fourier transform infrared spectroscopy (FTIR), electron microscopy transmission (TEM) and scanning electron microscopy (SEM). The NPsAg-1 had a spherical shape, size of 10 nm, hydrodynamic radius of 22 nm, maximum absorption band at 398 nm and zeta potential of -36.8 mV with excellent colloidal stability. The NPsAg-2 showed a size of 10 to 90 nm and almost spherical shape, hydrodynamic radius of 155 nm, zeta potential of -23.9 mV, good colloidal stability, with maximum absorption band at 414 nm and after being covered with shell of SiO2M with a thickness of 10 nm, SiO2M@NPsAg-2, the maximum absorption was at 428 nm. The SiO2M nanospheres showed an average diameter of 50 nm and evidence of mesopores, an average hydrodynamic radius of 268 nm, an average zeta potential of -19.4 mV and the FTIR spectrum revealed the presence of Si–O–Si and Si–OH groups. The NPsAu showed regular spherical shape, mean diameter of 9.9 nm, good monodispersity,11 maximum absorption at 520 nm, hydrodynamic radius of 23 nm, with zeta potential equal to 41.2 mV, indicating good colloidal stability. The NBsAu showed diameters between 13.9 nm and 16.2 nm and lengths between 151 nm and 250 nm, predominant hydrodynamic radius at 43 nm and mean zeta potential equal to 59.1 mV, showing that the colloidal suspension is stable. Thus, the exploration of the LSPR use of metallic nanoparticles associated with SiO2M structures can improve the antimicrobial activity of several drugs due to the effect called Increased Singlet Oxygen Generation via Metal (MEO), which occurs when combining metallic nanoparticles with FS that have a range of coincident absorption, enhancing PDI protocols.
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Palavras-chave
Nanopartículas metálicas, Nanopartículas de prata, Nanopartículas de ouro, Sílica mesoporosa, Fotossensibilizadores, Inativação fotodinâmica, Bactérias resistentes a medicamentos, Nanoplataformas, Entrega de medicamentos baseados em nanotecnologia, Metallic nanoparticles, Silver nanoparticles, Gold nanoparticles, Mesoporous silica, Photosensitizers, Photodynamic inactivation, Drug-resistant bacteria, Nanoplatforms, Nanotechnology-based drug delivery