Publicação
Non-enzymatic electrochemical biosensor based on laser-induced graphene for glucose monitoring
| Resumo: | Diabetes Mellitus (DM) is a disease that affects millions of people worldwide and is characterized by an increase in blood glucose levels (hyperglycemia). There are various glucose monitoring devices on the market, such as the finger prick method (blood) and continuous monitoring (interstitial fluid), but these are used to monitor the state of the disease. Colorimetric strips (urine) are used for early detection, however, they are very susceptible to environmental conditions, not very sensitive, have a high detection limit and do not allow glucose quantification. Biosensors have been a major focus of the scientific community for glucose detection, namely non-enzymatic electrochemical ones. These use nanoparticles (NPs) that enable the selective electrooxidation of glucose. In addition, nanomaterials have played a key role in improving the performance of electrochemical biosensors. In particular, laser-induced graphene (LIG) is a graphene derivative that has been widely studied due to its rapid synthesis process and very promising electrochemical properties. In this work, a non-enzymatic sensor made of LIG and gold NPs (AuNPs, 5 nm) was developed for the detection of glucose. The LIG/AuNPs was first characterized morphologically and structurally using scanning electron microscopy and Raman spectroscopy. Then, in a first approach, and using a traditional electrochemical cell setup, the optimum amount of AuNPs deposited on the LIG (8 drops) and the most suitable pH for glucose detection (pH > 11) were concluded. In addition, the oxidation and reduction reactions involved in this process were identified and understood. In a second approach, the miniaturized LIG/AuNPs electrochemical cell showed a sensitivity of 2608.05 μA/mM cm² and a limit of detection of 0.07 mM for the detection of glucose in a range of 0.5 to 8.2 mM, in 0.2 M NaOH. Tests were carried out on synthetic urine, both at pH 6 and pH 12, which revealed the presence of interferents, namely uric acid (UA), creatinine and urea, which partially (UA) or totally (the other two) blocked the oxidation reaction between glucose and AuOH. Finally, a preliminary test was carried out on a real sample, but as expected, it was not possible to detect glucose. Therefore, in the future it will be necessary to develop strategies to minimize the interference of these compounds that are part of the composition of urine, exploring the use of other metal NPs, such as platinum NPs, or even searching enzymatic strategies taking advantage of the advantages of LIG. |
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| Autores principais: | Fidalgo, Maria Sousa |
| Assunto: | Diabetes mellitus Non enzymatic biosensors Laser induced graphene Gold nanoparticles Urine |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | Diabetes Mellitus (DM) is a disease that affects millions of people worldwide and is characterized by an increase in blood glucose levels (hyperglycemia). There are various glucose monitoring devices on the market, such as the finger prick method (blood) and continuous monitoring (interstitial fluid), but these are used to monitor the state of the disease. Colorimetric strips (urine) are used for early detection, however, they are very susceptible to environmental conditions, not very sensitive, have a high detection limit and do not allow glucose quantification. Biosensors have been a major focus of the scientific community for glucose detection, namely non-enzymatic electrochemical ones. These use nanoparticles (NPs) that enable the selective electrooxidation of glucose. In addition, nanomaterials have played a key role in improving the performance of electrochemical biosensors. In particular, laser-induced graphene (LIG) is a graphene derivative that has been widely studied due to its rapid synthesis process and very promising electrochemical properties. In this work, a non-enzymatic sensor made of LIG and gold NPs (AuNPs, 5 nm) was developed for the detection of glucose. The LIG/AuNPs was first characterized morphologically and structurally using scanning electron microscopy and Raman spectroscopy. Then, in a first approach, and using a traditional electrochemical cell setup, the optimum amount of AuNPs deposited on the LIG (8 drops) and the most suitable pH for glucose detection (pH > 11) were concluded. In addition, the oxidation and reduction reactions involved in this process were identified and understood. In a second approach, the miniaturized LIG/AuNPs electrochemical cell showed a sensitivity of 2608.05 μA/mM cm² and a limit of detection of 0.07 mM for the detection of glucose in a range of 0.5 to 8.2 mM, in 0.2 M NaOH. Tests were carried out on synthetic urine, both at pH 6 and pH 12, which revealed the presence of interferents, namely uric acid (UA), creatinine and urea, which partially (UA) or totally (the other two) blocked the oxidation reaction between glucose and AuOH. Finally, a preliminary test was carried out on a real sample, but as expected, it was not possible to detect glucose. Therefore, in the future it will be necessary to develop strategies to minimize the interference of these compounds that are part of the composition of urine, exploring the use of other metal NPs, such as platinum NPs, or even searching enzymatic strategies taking advantage of the advantages of LIG. |
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