RESUMO
Xanthine (3,7-dihydro-purine-2,6-dione) is generated from guanine by guanine deaminase and hypoxanthine by xanthine oxidase (XOD). The determination of xanthine in meat indicates its freshness, while its level in serum/urine provides valuable information about diagnosis and medical management of certain metabolic disorders such as xanthinuria, hyperurecemia, gout and renal failure. Although chromatographic methods such a HPLC, capillary electrophoresis and mass spectrometry are available for quantification of xanthine in biological materials, these suffer from certain limitations such as complexity, time consuming sample preparation and requirement of expensive apparatus and trained persons to operate. Immobilized XOD based biosensors have emerged as simple, rapid, sensitive and economic tools for determination of xanthine in food industries and clinical diagnosis. This review article describes the various immobilization methods of XOD and different matrices used for construction of xanthine biosensors, their classification, analytical performance and applications along with their merits and demerits. The future perspectives for improvement of present xanthine biosensors are also discussed.
Assuntos
Técnicas Biossensoriais/métodos , Xantina/análise , Técnicas Biossensoriais/tendências , Testes de Química Clínica/métodos , Enzimas Imobilizadas , Análise de Alimentos/métodos , Humanos , Doenças Metabólicas/diagnóstico , Doenças Metabólicas/metabolismo , Xantina OxidaseRESUMO
A xanthine oxidase (XOD) from buttermilk was immobilized covalently onto boronic acid functionalized gold coated iron nanoparticles (Au@FeNPs) electrodeposited on pencil graphite (PG) electrode, via the boroester linkages, between free hydroxyl groups of boronic acid, α-COOH and -NH2 groups of enzyme. The surface functionalization of Fe/Au nanoparticles with boronic acid (Au@FeNPs) on pencil graphite (PG) electrode was characterized by Fourier transform infrared (FTIR), cyclic voltammetry (CV), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Electrochemical impedance spectroscopy (EIS) before and after immobilization of XOD. The biosensor exhibited optimum response within 3s at pH 7.2 and 30 °C and linearity in the range, 0.05 µM to 150 µM for hypoxanthine with a detection limit of 0.05 µM (S/N=3). Apparent Michaelis Menten constant (Km(app)) for hypoxanthine was 40 µM and Imax 0.125 mA. The biosensor was employed to determine hypoxanthine in fish, chicken, pork, beef meat and lost 50% of its initial activity after its 200 uses over 100 days, when stored at 4 °C.
Assuntos
Técnicas Biossensoriais , Ouro/química , Hipoxantina/química , Ferro/química , Carne/análise , Nanopartículas Metálicas/química , Animais , Bovinos , Galinhas , Espectroscopia Dielétrica , Concentração de Íons de Hidrogênio , Nanopartículas Metálicas/ultraestrutura , Microscopia de Força Atômica , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , SuínosRESUMO
Commercial enzymes, creatininase (CA) from Pseudomonas sp, creatinase (CI) from Pseudomonas sp, sarcosine oxidase (SO) from Bacillus sp were co-immobilized onto iron oxide nanoparticles/chitosan-graft-polyaniline (Fe(3)O(4)-NPs/CHIT-g-PANI) composite film electrodeposited on surface of Pt electrode through glutaraldehyde coupling. Transmission electron microscopy (TEM) was used for characterization of Fe(3)O(4)-NPs. A creatinine biosensor was fabricated using Enzymes/Fe(3)O(4)-NPs/CHIT-g-PANI/Pt electrode as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode. The enzyme electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopic and electrochemical impedance spectroscopy (EIS). The biosensor exhibited an optimum response within 2s at pH 7.5 and 30 °C, when polarized at 0.4V vs Ag/AgCl. The electrocatalytic response showed a linear dependence on creatinine concentration ranging from 1 to 800 µM. The sensitivity of the biosensor was 3.9 µA µM(-1) cm(-2), with a detection limit of 1 µM (S/N=3). Apparent Michaelis-Menton (K(m)) value for creatinine was 0.17 mM. The biosensor showed only 10% loss in its initial response after 120 uses over 200 days, when stored at 4 °C. The biosensor measured creatinine in the serum of apparently healthy persons which correlated well with a standard colorimetric method (r=0.99).
Assuntos
Compostos de Anilina/química , Técnicas Biossensoriais/métodos , Quitosana/química , Creatinina/sangue , Enzimas Imobilizadas/química , Nanopartículas Metálicas/química , Amidoidrolases/química , Amidoidrolases/metabolismo , Técnicas Biossensoriais/instrumentação , Biotecnologia/métodos , Eletrodos , Enzimas Imobilizadas/metabolismo , Compostos Férricos , Humanos , Microscopia Eletrônica de Varredura , Platina , Sarcosina Oxidase/química , Sarcosina Oxidase/metabolismo , Ureo-Hidrolases/química , Ureo-Hidrolases/metabolismoRESUMO
Xanthine oxidase (XOD) was immobilized on a composite film of zinc oxide nanoparticle/chitosan/carboxylated multiwalled carbon nanotube/polyaniline (ZnO-NP/CHIT/c-MWCNT/PANI) electrodeposited over the surface of a platinum (Pt) electrode. A xanthine biosensor was fabricated using XOD/ZnO-NP/CHIT/c-MWCNT/PANI/Pt as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode connected through a potentiostat. The ZnO-NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the enzyme electrode was characterized by cyclic voltammetry, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The biosensor showed optimum response within 4 s at 0.5 V potential, pH 7.0, 35 °C and linear range 0.1-100 µM with a detection limit of 0.1 µM. The enzyme electrode was employed for determination of xanthine in fish meat during storage. The electrode lost 30% of its initial activity after 80 uses over one month, when stored at 4 °C.
Assuntos
Eletroquímica/métodos , Produtos Pesqueiros/análise , Nanopartículas Metálicas , Nanotubos de Carbono , Xantina Oxidase/metabolismo , Xantina/análise , Óxido de Zinco/química , Compostos de Anilina/química , Técnicas Biossensoriais , Quitosana/química , Espectroscopia Dielétrica , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
A new zinc oxide nanoparticles/chitosan/carboxylated multiwall carbonnanotube/polyaniline (ZnO-NPs/CHIT/c-MWCNT/PANI) composite film has been synthesized on platinum (Pt) electrode using electrochemical techniques. Three enzymes, creatinine amidohydrolase (CA), creatine amidinohydrolase (CI) and sarcosine oxidase (SO) were immobilized on ZnO-NPs/CHIT/c-MWCNT/PANI/Pt electrode to construct the creatinine biosensor. The enzyme electrode was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The enzyme electrode detects creatinine level as low as 0.5 µM at a signal to noise ratio of 3 within 10s at pH 7.5 and 30°C. The fabricated creatinine biosensor showed linear working range of 10-650 µM creatinine with a sensitivity of 0.030 µA µM(-1)cm(-2). The biosensor shows only 15% loss of its initial response over a period of 120 days when stored at 4°C. The fabricated biosensor was successfully employed for determination of creatinine in human blood serum.
Assuntos
Compostos de Anilina/química , Técnicas Biossensoriais/métodos , Quitosana/química , Creatinina/análise , Técnicas Eletroquímicas/métodos , Nanotubos de Carbono/química , Óxido de Zinco/química , Espectroscopia Dielétrica , Nanopartículas , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Zinc oxide nanoparticles (ZnO-NPs) were synthesized from zinc nitrate by simple and efficient method in aqueous media at 55°C without any requirement of calcinations step. A mixture of ZnO-NPs and pyrrole was eletropolymerized on Pt electrode to form a ZnO-NPs-polypyrrole (PPy) composite film. Xanthine oxidase (XOD) was immobilized onto this nanocomposite film through physiosorption. The ZnO-NPs/polypyrrole/Pt electrode was characterized by Fourier transform infrared (FTIR), cyclic voltammetry (CV), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) before and after immobilization of XOD. The XOD/ZnO-NPs-PPy/Pt electrode as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode were connected through a potentiostat to construct a xanthine biosensor. The biosensor exhibited optimum response within 5s at pH 7.0, 35°C and linearity from 0.8 µM to 40 µM for xanthine with a detection limit 0.8 µM (S/E=3). Michaelis Menten constant (K(m)) for xanthine oxidase was 13.51 µM and I(max) 0.071 µA. The biosensor measured xanthine in fish meat and lost 40% of its initial activity after its 200 uses over 100 days, when stored at 4°C.
Assuntos
Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Nanopartículas/química , Polímeros/química , Pirróis/química , Xantina/análise , Óxido de Zinco/química , Animais , Eletrodos , Peixes , Carne/análise , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
A highly sensitive, specific and rapid electrochemical oxalate biosensor was constructed by covalently immobilizing sorghum leaf oxalate oxidase on carboxylated multiwalled carbon nanotubes and conducting polymer, polyaniline nanocomposite film electrodeposited over the surface of platinum (Pt) wire using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) chemistry. The modified electrode was characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectrophotometry. The optimized oxalate biosensor showed linear response range of 8.4-272 µM with correlation coefficient of 0.93 and rapid response within 5s at a potential of 0.4V vs Ag/AgCl. The sensitivity was approximately 0.0113 µA/µM with a detection limit of 3.0 µM. Proposed oxalate biosensor was successfully applied to human urine sample.