RESUMO
Graphene is a highly promising material for biosensors due to its excellent physical and chemical properties which facilitate electron transfer between the active locales of enzymes or other biomaterials and a transducer surface. Printing technology has recently emerged as a low-cost and practical method for fabrication of flexible and disposable electronics devices. The combination of these technologies is promising for the production and commercialization of low cost sensors. In this review, recent developments in organo-functionalized graphene and printed biosensor technologies are comprehensively covered. Firstly, various methods for printing graphene-based fluids on different substrates are discussed. Secondly, different graphene-based ink materials and preparation methods are described. Lastly, biosensing performances of printed or printable graphene-based electrochemical and field effect transistor sensors for some important analytes are elaborated. The reported printed graphene based sensors exhibit promising properties with good reliability suitable for commercial applications. Among most reports, only a few printed graphene-based biosensors including screen-printed oxidase-functionalized graphene biosensor have been demonstrated. The technology is still at early stage but rapidly growing and will earn great attention in the near future due to increasing demand of low-cost and disposable biosensors.
Assuntos
Bioimpressão/métodos , Técnicas Biossensoriais/métodos , Grafite/química , Animais , Materiais Biocompatíveis/química , Bioimpressão/economia , Bioimpressão/instrumentação , Técnicas Biossensoriais/economia , Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas/economia , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Desenho de Equipamento , Humanos , Tinta , Modelos Moleculares , Compostos Orgânicos/química , Transistores EletrônicosRESUMO
This work reports a new cholesterol detection scheme using functionalized carbon nanotube (CNT) electrode in a polydimethylsiloxane/glass based flow injection microfluidic chip. CNTs working, silver reference and platinum counter electrode layers were fabricated on the chip by sputtering and low temperature chemical vapor deposition methods. Cholesterol oxidase prepared in polyvinyl alcohol solution was immobilized on CNTs by in-channel flow technique. Cholesterol analysis based on flow injection chronoamperometric measurement was performed in 150-µm-wide and 150-µm-deep microchannels. Fast and sensitive real-time detection was achieved with high throughput of more than 60 samples per hour and small sample volume of 15 µl. The cholesterol sensor had a linear detection range between 50 and 400 mg/dl. In addition, low cross-sensitivities toward glucose, ascorbic acid, acetaminophen and uric acid were confirmed. The proposed system is promising for clinical diagnostics of cholesterol with high speed real-time detection capability, very low sample consumption, high sensitivity, low interference and good stability.
Assuntos
Técnicas Biossensoriais/instrumentação , Colesterol/análise , Técnicas Analíticas Microfluídicas/instrumentação , Nanotubos de Carbono , Técnicas Biossensoriais/estatística & dados numéricos , Análise Química do Sangue/instrumentação , Colesterol/sangue , Colesterol Oxidase , Técnicas Eletroquímicas , Enzimas Imobilizadas , Desenho de Equipamento , Humanos , Técnicas Analíticas Microfluídicas/estatística & dados numéricos , Microscopia Eletrônica de Varredura , Nanotubos de Carbono/ultraestrutura , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
This paper describes the use of a pervaporation (PV) technique in a flow injection (FI) system for selective improvement in iodide analysis. Iodide in the sample zone is oxidized to iodine, which permeates through a hydrophobic membrane. Detection of the diffused iodine is achieved using the chemiluminescent (CL) emission at 425nm that results from the reaction between iodine and luminol. The method was applied for the analysis of some pharmaceutical products, such as nuclear emergency tablets and multivitamin tablets. Ascorbic acid present in multivitamin samples interfered seriously with the analysis, and off-line sample treatment using anion exchange resin was employed to successfully remove ascorbic acid before the analysis. Ascorbic acid was flushed from the column using 0.4M sodium nitrate followed by elution of iodide with 2M sodium nitrate. The detection limit (3S.D.) of the system was 0.5mgl(-1), with reproducibility of 5.2% R.S.D. at 5mgl(-1). Sample throughput was determined as 30injectionsh(-1). There was good agreement between iodide concentrations from extracted samples determined using four different methods, i.e., PV-FI, gas diffusion-flow injection, potentiometry and ICP-MS. A comparison of the analytical features of the developed pervaporation system with these of the previously reported chemiluminescence gas diffusion-flow injection previously reported is also described.
