ABSTRACT
A sensitive and disposable amperometric immunosensor for Saccharomyces cerevisiae was constructed by using carbon screen-printed electrodes modified with propionic acid-functionalized graphene oxide as transduction element. The affinity-based biosensing interface was assembled by covalent immobilization of a specific polyclonal antibody on the carboxylate-enriched electrode surface via a water-soluble carbodiimide/N-hydroxysuccinimide coupling approach. A concanavalin A-peroxidase conjugate was further used as signaling element. The immunosensor allowed the amperometric detection of the yeast in buffer solution and white wine samples in the range of 10-107 CFU/mL. This electroanalytical device also exhibited low detection limit and high selectivity, reproducibility, and storage stability. The immunosensor was successfully validated in spiked white wine samples.
Subject(s)
Graphite/chemistry , Saccharomyces cerevisiae/chemistry , Biosensing Techniques , Carbon Dioxide , Electrochemical Techniques , Electrodes , Hydrogen Peroxide/chemistry , Immunoassay , Limit of Detection , Oxides/chemistry , Propionates/chemistry , Reproducibility of Results , Wine/analysisABSTRACT
The assembly of a novel disposable amperometric immunosensor for the detection of the red wine spoilage yeast Brettanomyces bruxellensis is reported. The nanostructured sensing interface was prepared by first coating carbon screen printed electrodes with a gold nanoparticles-reduced graphene oxide hybrid nanomaterial, which was then modified with 3-mercaptopropionic acid to further immobilize specific antibodies for B. bruxellensis via a carbodiimide-coupling reaction. The functionalized electrode allowed the amperometric detection of B. bruxellensis in buffered solutions and red wine samples in the range of 10-106 CFU/mL and 102-106 CFU/mL, with low detection limits of 8 CFU/mL and 56 CFU/mL, respectively. The electrochemical immunosensor also exhibited high reproducibility, selectivity, and storage stability. Graphical abstract A novel disposable electrochemical immunosensor for the detection of the red wine spoilage yeast B. bruxellensis.
Subject(s)
Antibodies, Immobilized/chemistry , Brettanomyces/isolation & purification , Gold/chemistry , Graphite/chemistry , Immunoassay/methods , Nanostructures/chemistry , Electrochemical Techniques/methods , Limit of Detection , Metal Nanoparticles/chemistry , Oxidation-Reduction , Oxides/chemistry , Reproducibility of Results , Wine/microbiologyABSTRACT
Au nanoparticles modified with 4-mercaptopyridine and 6-mercapto-1-hexanol were used as coordination agents to prepare a novel hybrid nanomaterial with Ag:4,4'-bipyridine nanobelts. This nanohybrid was employed to modify glassy carbon electrodes and to construct a horseradish peroxidase-based mediatorless amperometric biosensor for H2O2. The electrode, poised at -100mV, exhibited a rapid response within 4s and a linear calibration range from 90pM to 6.5nM H2O2. The biosensor showed a high sensitivity of 283A/Mcm(2) and a very low detection limit of 45pM at a signal-to-noise ratio of 3. The enzyme biosensor showed high stability when stored at 4°C under dry conditions, retaining over 96% and 78% of its initial activity after 15 and 30days of storage at 4°C, respectively.
Subject(s)
Biosensing Techniques/methods , Electrochemical Techniques , Gold/chemistry , Hydrogen Peroxide/analysis , Metal Nanoparticles/chemistry , Pyridines/chemistry , Calibration , Carbon/chemistry , Electrodes , Enzymes, Immobilized/chemistry , Hexanols/chemistry , Horseradish Peroxidase/chemistry , Limit of Detection , Metal Nanoparticles/ultrastructure , Reproducibility of Results , Signal-To-Noise Ratio , Sulfhydryl Compounds/chemistryABSTRACT
A novel water-soluble graphene derivative was prepared from graphene oxide via a two-step modification approach. Graphene oxide was first functionalised with reactive epoxy groups by covalent modification with (3-glycidyloxypropyl)trimethoxysilane and further cross-linked with glycol chitosan. This graphene derivative was characterized using different microscopy and physicochemical methods and employed as a coating material for a glassy carbon electrode. The nanostructured surface was used as a support for the covalent immobilization of the enzyme laccase through cross-linking with glutaraldehyde. The enzyme electrode was tested for the amperometric detection of different phenolic compounds, which displayed excellent analytical behaviour toward catechol with a linear range of response from 200 nM to 15 µM, sensitivity of 93 mA M(-1) cm(-2), and low detection limit of 76 nM. The enzyme biosensor showed high stability when stored at 4 °C under dry conditions and was successfully employed to quantify the total phenolic compounds in commercial herbal tea samples.
Subject(s)
Biosensing Techniques , Chitosan , Enzymes, Immobilized/chemistry , Glycols , Graphite , Nanoparticles/chemistry , Phenols/analysis , Electrodes , OxidesABSTRACT
A novel strategy was employed to prepare a water-soluble graphene derivative by using dextran-based polymer brushes as solubilizing agents. Graphene oxide was grafted with (3-mercaptopropyl) trimethoxysilane and further decorated with Au nanoparticles. This hybrid nanomaterial was then reduced and anchored with polysaccharide-based polymer brushes by chemisorption of an end-group thiolated dextran derivative on the Au nanoparticles. The resulting hybrid nonmaterial allowed highly stable aqueous dispersions to be obtained, which were used to coat glassy carbon electrodes for the preparation of a model tyrosinase electrochemical biosensor for catechol. The enzyme electrode showed excellent electroanalytical performance with fast response in about 5 s, a linear range of 100 pM-120 nM, a very high sensitivity of 45.9 A M-1 and a very low detection limit of 40 pM for catechol.
