Biossensores de glicose baseados na imobilização da glicose oxidase em filmes finos de óxido de grafeno reduzido
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Data
2017-04-24
Autores
Mascagni, Daniela Branco Tavares [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho, foram desenvolvidos biossensores eletroquímicos enzimáticos fabricados com óxido de grafeno reduzido (rGO) e funcionalizado depositados pelas técnicas LbL (Layer-by-Layer) e Langmuir-Blodgett (LB) para a detecção de glicose. Para isso, primeiramente foi sintetizado quimicamente o óxido de grafeno (GO) pela oxidação do grafite, em seguida, o GO foi reduzido para aumentar a sua condutividade elétrica e foi funcionalizado em meio estabilizante contendo cloridrato de poli(dialildimetilamônio), formando o GPDDA, ou poli(4-estireno sulfônico) PSS, formando GPSS. Com isso, foi possível formar dispersões aquosas estáveis das nanofolhas de grafeno, essencial para a fabricação de filmes LbL. Em um primeiro momento, foram fabricados biossensores com filmes LbL contendo GPDDA, GPSS e a enzima glucose oxidase (Gox). O desempenho desses biossensores na detecção de glicose foi avaliado em função do número de bicamadas contendo Gox. O melhor desempenho na detecção de glicose foi apresentado pelo biossensor com o filme LbL com a arquitetura (GPDDA/GPSS)/(GPDDA/GPSS)2. Este biossensor apresentou limite de detecção de 13,4 µmol.L-1, sensibilidade 2,47 μA.cm-2.mmol-1.L e faixa analítica entre 0,04 e 0,95 mmol.L-1. Este biossensor foi eficiente na detecção de glicose na presença de interferentes comumente encontrados em fluidos corporais, alimentos e fármacos. Quando avaliado na detecção de glicose em amostras reais, recuperou 100,8% para uma solução eletrolítica comercial e 88,8% para leite sem lactose. Em um segundo momento, foram fabricados biossensores a partir de filmes LB contendo os mesmos materiais utilizados para fabricar os biossensores com filmes LbL (GPDDA, GPSS e Gox), com a finalidade de comparar os dois métodos de fabricação de filmes no desempenho dos biossensores. O desempenho dos biossensores fabricados com filmes LB foi avaliado em relação à quantidade de monocamadas (GPDDA/GPSS/Gox) depositadas. O melhor desempenho na detecção de glicose entre os biossensores com filme LB foi apresentado pelo biossensor de arquitetura (GPDDA/GPSS/Gox)3. Este biossensor apresentou limite de detecção 0,54 µmol.L-1, sensibilidade de 8,69 μA.cm-2.mmol-1.L e faixa analítica entre 0,0018 e 1,5 mmol.L-1. Também se mostrou eficiente na detecção de glicose na presença de interferentes e na detecção de glicose em amostra real, com recuperação de 101,2 % para o leite sem lactose. A partir dos resultados de desempenho dos biossensores com filme LbL e LB foi possível concluir que a técnica LB promoveu uma maior sinergia entre os nanomateriais, atribuída ao maior ordenamento dos nanomateriais proporcionado pela técnica LB.
In this work, enzymatic electrochemical biosensors fabricated with reduced graphene oxide (rGO) and functionalized deposited by the LbL (Layer-by-Layer) and LangmuirBlodgett (LB) techniques were developed for the detection of glucose. Firstly, to get this, graphene oxide (GO) was chemically synthesized by the oxidation of graphite and after GO was reduced to increase its electrical conductivity and it was functionalized in stabilizing medium containing the poly (diallyl dimethyl ammonium chloride) PDDA, forming the GPDDA, or poly (4-styrene sulphonic) PSS, forming GPSS. Hence, stable aqueous dispersions of graphene nanosheets were formed, essential for the fabrication of LbL films. In a first moment, biosensors with LbL films containing GPDDA, GPSS and the enzyme glucose oxidase (Gox) were fabricated. The performance of these biosensors in the detection of glucose was evaluated as a function of the number of bilayers containing Gox. The best performance in the detection of glucose was presented by the biosensor with the LbL film with the architecture (GPDDA/GPSS)/(GPDDA/GPSS)2. It presented a detection limit of 13.4 μmol.L-1 , sensitivity 2.47 μA.cm-2 .mmol-1 .L and analytical range between 0.04 and 0.95 mmol.L-1 . This biosensor was efficient in detecting glucose in the presence of interferents commonly found in body fluids, foods and drugs. When evaluated in the detection of glucose in real samples, it recovered 100.8% for a commercial electrolytic solution and 88.8% for lactose-free milk. In a second moment, biosensors were fabricated from LB films containing the same materials used to fabricate the biosensors with LbL films (GPDDA, GPSS and Gox), in order to compare the two methods of films deposition in the performance of the biosensors. The performance of biosensors fabricated with LB films was evaluated in relation to the amount of deposited monolayers (GPDDA/GPSS/Gox). The best performance on the detection of glucose among LB film biosensors was presented by the architecture biosensor (GPDDA/GPSS/Gox)3. The detection limit was 0.54 μmol.L-1 , sensitivity of 8.69 μA.cm- 2 .mmol-1 .L and analytical range between 0.0018 and 1.5 mmol.L-1 . This biosensor was also efficient in the detection of glucose in the presence of interferents and in the detection of glucose in a real sample, with a recovery of 101.2% for lactose-free milk A conclusion derived from the performance results of the biosensors with LbL and LB films, may support that LB technique promoted a greater synergy among the nanomaterials, attributed to the best arrangement of nanomaterials provided by LB technique.
In this work, enzymatic electrochemical biosensors fabricated with reduced graphene oxide (rGO) and functionalized deposited by the LbL (Layer-by-Layer) and LangmuirBlodgett (LB) techniques were developed for the detection of glucose. Firstly, to get this, graphene oxide (GO) was chemically synthesized by the oxidation of graphite and after GO was reduced to increase its electrical conductivity and it was functionalized in stabilizing medium containing the poly (diallyl dimethyl ammonium chloride) PDDA, forming the GPDDA, or poly (4-styrene sulphonic) PSS, forming GPSS. Hence, stable aqueous dispersions of graphene nanosheets were formed, essential for the fabrication of LbL films. In a first moment, biosensors with LbL films containing GPDDA, GPSS and the enzyme glucose oxidase (Gox) were fabricated. The performance of these biosensors in the detection of glucose was evaluated as a function of the number of bilayers containing Gox. The best performance in the detection of glucose was presented by the biosensor with the LbL film with the architecture (GPDDA/GPSS)/(GPDDA/GPSS)2. It presented a detection limit of 13.4 μmol.L-1 , sensitivity 2.47 μA.cm-2 .mmol-1 .L and analytical range between 0.04 and 0.95 mmol.L-1 . This biosensor was efficient in detecting glucose in the presence of interferents commonly found in body fluids, foods and drugs. When evaluated in the detection of glucose in real samples, it recovered 100.8% for a commercial electrolytic solution and 88.8% for lactose-free milk. In a second moment, biosensors were fabricated from LB films containing the same materials used to fabricate the biosensors with LbL films (GPDDA, GPSS and Gox), in order to compare the two methods of films deposition in the performance of the biosensors. The performance of biosensors fabricated with LB films was evaluated in relation to the amount of deposited monolayers (GPDDA/GPSS/Gox). The best performance on the detection of glucose among LB film biosensors was presented by the architecture biosensor (GPDDA/GPSS/Gox)3. The detection limit was 0.54 μmol.L-1 , sensitivity of 8.69 μA.cm- 2 .mmol-1 .L and analytical range between 0.0018 and 1.5 mmol.L-1 . This biosensor was also efficient in the detection of glucose in the presence of interferents and in the detection of glucose in a real sample, with a recovery of 101.2% for lactose-free milk A conclusion derived from the performance results of the biosensors with LbL and LB films, may support that LB technique promoted a greater synergy among the nanomaterials, attributed to the best arrangement of nanomaterials provided by LB technique.
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Palavras-chave
Layer-by-Layer, Langmuir Blodgett, Biossensores eletroquímicos