Desenvolvimento de nanocarreadores lipídicos veiculando o óleo de citronela para a obtenção de um repelente
Data
2019-04-26
Autores
Sales, Caroline Cianga 
Orientadores
Andréo Filho, Newton
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Os surtos de doenças transmitidas por mosquitos tem sido um problema de saúde pública,
uma vez que são responsáveis por morbidade e mortalidade significativa em todo o mundo.
Compostos de origem natural, como o óleo de citronela (OC), apresentam atividade repelente,
como alternativa à repelentes de origem sintética. Apesar de sua eficiência, o tempo de ação é
curto em razão de sua elevada volatilidade. Nesse sentido, a encapsulação em sistemas
lipídicos pode ser considerada alternativa para a veiculação de tais óleos, buscando a
estabilidade e o prolongamento da ação. Esse trabalho teve como objetivo desenvolver
sistemas lipídicos nanoestruturados veiculando OC para efeito repelente de longa duração.
Inicialmente foram desenvolvidas nanopartículas lipídicas sólidas (NLS) variando-se o tipo de
tensoativo (aniônico, catiônico e não iônico), e a forma de processamento em
homogeneizador de alta pressão (HPH) (sistema aberto – número de ciclos ou sistema
fechado – tempo de circulação). Os sistemas lipídicos formados foram caracterizados quanto
ao tamanho médio, distribuição de tamanho de partícula, pH e condutividade. NLS e
carreadores lipídicos nanoestruturados (CLN) contendo OC foram produzidos pela
emulsificação prévia do óleo com monoestearato de glicerila e/ou triglicerídeos de ácido
cáprico/caprílico como fase oleosa nas proporções entre lipídeos sólidos e líquidos de 10:0,
7,5:2,5 e 5:5, utilizando também os mesmos três tipos de tensoativos citados anteriormente.
Os sistemas emulsionados foram submetidos à HPH para obtenção dos sistemas
nanoestruturados, sendo caracterizados quanto ao tamanho médio, distribuição de tamanho,
potencial zeta, pH e condutividade. A liberação do OC dos sistemas nanoestruturados foi
avaliada por meio do decaimento das concentrações dos marcadores do OC (citronelal,
citronelol e geraniol) analisados por cromatografia líquida de alta eficiência. Os
procedimentos adotados para obtenção das nanopartículas lipídicas possibilitaram a obtenção
de partículas da ordem de 110 nm e pH 8,0, sendo os melhores valores obtidos para
homogeneização em sistema fechado, com circulação de 10 minutos. Os tensoativos, apesar
de interferirem ativamente na carga superficial das nanopartículas não demonstraram
diferença significativa quanto o tamanho, dispersão e estabilidade até 75 dias. As formulações
contendo óleo de citronela, ao contrário, apresentaram comportamento distinto quanto à
estabilidade na a ausência de lipídeos líquido, revelando ser essencial ser essencial esse tipo
de material para a formação e manutenção da estabilidade por até 60 dias. Todos os
tensoativos utilizados permitiram a obtenção de sistemas nanoestruturados, sendo que o
catiônico possibilitou a formação de partículas de até 100 nm e índice de polidispersão (PI)
0,25, enquanto os demais levaram à obtenção de partículas maiores (até 400 nm) e menos
homogêneas (PI = 0,8). Os ensaios de liberação permitiram verificar a extensão da liberação
dos componentes do óleo de citronela por até 8h (liberação média de ordem de 40% do
conteúdo de óleo). Conclui-se que a presença de lipídeos líquido é essencial para a formação
de nanoestruturas estáveis veiculando OC capazes de reter o óleo de citronela por um período
de até 8h, favorecendo o prolongamento do efeito repelente pretendido.
Outbreaks of mosquito-borne diseases have been a public health problem since they are responsible for significant morbidity and mortality worldwide. Compounds of natural origin, such as citronella oil (OC), present repellent activity, as an alternative to synthetic repellents. Despite its efficiency, the action time is short because of its high volatility. In this sense, the encapsulation in lipid systems can be considered as an alternative for the transport of these oils, seeking stability and prolongation of the action. The aim of this work was to develop nanostructured lipid systems with OC for a long - lasting repellent effect. Initially, solid lipid nanoparticles (SLN) were developed by varying the type of surfactant (anionic, cationic and non-ionic) and the high pressure homogenizer (HPH) (open system - number of cycles or closed system - time circulation). The lipid systems formed were characterized as medium size, particle size distribution, pH and conductivity. SLN and OC-containing nanostructured lipid carriers (NLC) were produced by the prior emulsification of the oil with glyceryl monostearate and caprylic/capric triglyceride as the oil phase in the ratio of solid to liquid lipids of 10: 0, 7.5: 2 , 5 and 5: 5, also using the same three types of surfactants mentioned above. The emulsified systems were submitted to HPH to obtain the nanostructured systems, being characterized by the average size, distribution, zeta potential, pH and conductivity. The release of the OC from the nanostructured systems was evaluated by means of the decay of the concentrations of the OC markers (citronellal, citronellol and geraniol) analyzed by high performance liquid chromatography. The procedures adopted to obtain the lipid nanoparticles allowed to obtain particles of the order of 110 nm and pH 8.0, being the best values obtained for homogenization in a closed system, with circulation of 10 minutes. The surfactants, although actively interfering with the surface charge of the nanoparticles, showed no significant difference in size, dispersion and stability up to 75 days. The formulations containing citronella oil, on the other hand, presented different behavior regarding the stability in the absence of liquid lipid, showing that it is essential that this type of material is essential for the formation and maintenance of stability for up to 60 days. All the surfactants used allowed nanostructured systems to be obtained. The cationic material allowed the formation of particles up to 100 nm and a polydispersity index (PI) of 0.25, while the others led to the formation of larger particles (up to 400 nm) and less homogeneous (PI = 0.8). The release tests allowed to verify the extent of the release of the components of the citronella oil for up to 8 h (average release on the order of 40% of the oil content). It is concluded that the presence of liquid lipid is essential for the formation of stable nanostructures conveying OC capable of retaining the citronella oil for up to 8 hours, favoring the prolongation of the desired repellent effect.
Outbreaks of mosquito-borne diseases have been a public health problem since they are responsible for significant morbidity and mortality worldwide. Compounds of natural origin, such as citronella oil (OC), present repellent activity, as an alternative to synthetic repellents. Despite its efficiency, the action time is short because of its high volatility. In this sense, the encapsulation in lipid systems can be considered as an alternative for the transport of these oils, seeking stability and prolongation of the action. The aim of this work was to develop nanostructured lipid systems with OC for a long - lasting repellent effect. Initially, solid lipid nanoparticles (SLN) were developed by varying the type of surfactant (anionic, cationic and non-ionic) and the high pressure homogenizer (HPH) (open system - number of cycles or closed system - time circulation). The lipid systems formed were characterized as medium size, particle size distribution, pH and conductivity. SLN and OC-containing nanostructured lipid carriers (NLC) were produced by the prior emulsification of the oil with glyceryl monostearate and caprylic/capric triglyceride as the oil phase in the ratio of solid to liquid lipids of 10: 0, 7.5: 2 , 5 and 5: 5, also using the same three types of surfactants mentioned above. The emulsified systems were submitted to HPH to obtain the nanostructured systems, being characterized by the average size, distribution, zeta potential, pH and conductivity. The release of the OC from the nanostructured systems was evaluated by means of the decay of the concentrations of the OC markers (citronellal, citronellol and geraniol) analyzed by high performance liquid chromatography. The procedures adopted to obtain the lipid nanoparticles allowed to obtain particles of the order of 110 nm and pH 8.0, being the best values obtained for homogenization in a closed system, with circulation of 10 minutes. The surfactants, although actively interfering with the surface charge of the nanoparticles, showed no significant difference in size, dispersion and stability up to 75 days. The formulations containing citronella oil, on the other hand, presented different behavior regarding the stability in the absence of liquid lipid, showing that it is essential that this type of material is essential for the formation and maintenance of stability for up to 60 days. All the surfactants used allowed nanostructured systems to be obtained. The cationic material allowed the formation of particles up to 100 nm and a polydispersity index (PI) of 0.25, while the others led to the formation of larger particles (up to 400 nm) and less homogeneous (PI = 0.8). The release tests allowed to verify the extent of the release of the components of the citronella oil for up to 8 h (average release on the order of 40% of the oil content). It is concluded that the presence of liquid lipid is essential for the formation of stable nanostructures conveying OC capable of retaining the citronella oil for up to 8 hours, favoring the prolongation of the desired repellent effect.