1,721,004 research outputs found
Development of nanoparticle based technologies for food safety
No full textBackground
Nanoscience and nanotechnology are highly promising and rapidly emerging areas for research and industrial innovation. Due to the remarkable physicochemical properties of manufactured nanomaterials, several promising applications were recently developed in the areas of agriculture and food production. Recently, a new method to synthesize superparamagnetic nanoparticles has been developed. These nanoparticles consist of stoichiometric maghemite, γ-Fe2O3, with unique spectroscopic properties and well-defined crystalline structure, and have been called “surface-active maghemite nanoparticles” (SAMNs). They form stable colloidal suspensions in water without any organic or inorganic coating to prevent their aggregation. At the same time, they are able to specifically and reversibly bind organic molecules, leading to composite colloidal materials, which can be exploited for biotechnological applications. In recent years nanotechnology was combined with various sensing techniques to develop the so-called "nano-sensors". Several promising applications were recently developed in the areas of agriculture and food production, with the capacity to impact both food industry and consumers. These sensors can be an effective alternative to the traditional methods for the detection of toxins and pathogens in food. Electrochemical detection is a popular method involving nanomaterial-based sensors with applications in the food industry. SAMNs show remarkable electrocatalytic properties and were used for the development of electrodes and biosensors. In this thesis, a set of different hybrids that include SAMNs are presented and the electrochemical features of the hybrids are reported.
Results
Tannic acid (TA), Quaternized Carbon Dots (Q-CD) and hexavalent chromium (CrVI) were successfully immobilized on SAMN surface. SAMN@TA was characterized using electrical impedance spectroscopy, voltammetry and chronoamperometry. The nanostructured ferric tannate interface showed improved conductivity and selective electrocatalytic activity toward the oxidation of polyphenols. A carbon-paste electrode modified with SAMN@TA was used for the determination of polyphenols in blueberry extracts by square-wave voltammetry. Q-CD @SAMN revealed specific electrocatalytic behavior toward the oxidation of phenols and the system was applied to develop a sensor for the coulometric determination of polyphenols from plant extracts. which displayed peculiar electrocatalytic properties attributable to the influence of the strong electrostatic interactions exerted by Q-CDs on the SAMN surface. The sensor is composed of a simple carbon paste electrode in a small volume electrochemical flow cell (1 μL), and is used for the complete direct electro-oxidation of polyphenols from plant extracts. Finally, SAMNs were successfully applied to remove CrVI from water. The hybrid SAMN@CrVI was used to immobilize bovine serum amine oxidase (BSAO) and this complex was electrochemical showed good performances toward H2O2 detection. SAMN@CrVI-BSAO was applied for the development of a polyamine biosensor, which was successfully exploited for the discrimination of tumorous and healthy tissues obtained from liver extracts.
Conclusions
Sensing strategies based on SAMNs offer unique advantages over other techniques. They are produced by a low-cost procedure, they are physically and chemically stable, biocompatible and environmentally safe. In this thesis, SAMNs were utilized to prepare three different hybrids and
were successfully applied for the construction of three different electrochemical sensors, showing good performances, and successfully applied to real samples.La nanoscienza e la nanotecnologia sono aree altamente promettenti e rapidamente emergenti per la ricerca e l'innovazione industriale. A causa delle notevoli proprietà fisico-chimiche dei nanomateriali prodotti, sono state recentemente sviluppate diverse applicazioni promettenti nelle aree dell'agricoltura e della produzione alimentare. Recentemente, è stato sviluppato un nuovo metodo per sintetizzare nanoparticelle superparamagnetiche. Queste nanoparticelle consistono di maghemite stechiometrica, γ-Fe2O3, con proprietà spettroscopiche uniche e struttura cristallina ben definita, e sono state chiamate surface active maghemite nanoparticles (SAMN). Formano sospensioni colloidali stabili in acqua senza alcun rivestimento organico o inorganico per impedire la loro aggregazione. Allo stesso tempo, sono in grado di legare in modo specifico e reversibile molecole organiche, portando a materiali colloidali compositi, che possono essere sfruttati per applicazioni biotecnologiche. Negli ultimi anni la nanotecnologia è stata combinata con varie tecniche di rilevamento per sviluppare i cosiddetti "nano-sensori". Diverse applicazioni promettenti sono state recentemente sviluppate nei settori dell'agricoltura e della produzione alimentare, con la capacità di influenzare sia l'industria alimentare che i consumatori. Questi sensori possono essere un'alternativa efficace ai metodi tradizionali per la rilevazione di tossine e patogeni negli alimenti. Il rilevamento elettrochimico è un metodo popolare che coinvolge sensori basati su nanomateriali con applicazioni nell'industria alimentare. Le SAMN mostrano notevoli proprietà elettrocatalitiche e sono stati utilizzati per lo sviluppo di elettrodi e biosensori. In questa tesi vengono presentati un insieme di diversi ibridi che includono SAMN e vengono riportate le caratteristiche elettrochimiche degli ibridi.
Risultati
L'acido tannico (TA), quantum dots di carbonio (Q-CD) e il cromo esavalente (CrVI) sono stati immobilizzati con successo sulla superficie del SAMN. SAMN@TA è stato caratterizzato mediante spettroscopia di impedenza elettrica, voltammetria e cronoamperometria. L'interfaccia di tannato ferrico nanostrutturata mostrava conduttività migliorata e attività elettrocatalitica selettiva verso l'ossidazione dei polifenoli. Un elettrodo di pasta di carbone modificato con SAMN@TA è stato utilizzato per la determinazione dei polifenoli negli estratti di mirtillo mediante voltammetria. Q-CD@SAMN ha rivelato un comportamento elettrocatalitico specifico verso l'ossidazione dei fenoli e il sistema è stato applicato per sviluppare un sensore per la determinazione coulometrica dei polifenoli dagli estratti vegetali. che mostrava proprietà elettrocatalitiche peculiari attribuibili all'influenza delle forti interazioni elettrostatiche esercitate dai Q-CD sulla superficie del SAMN. Il sensore è composto da un semplice elettrodo di pasta di carbone in una cella a flusso elettrochimico di piccolo volume (1 μL), ed è utilizzato per l'elettro-ossidazione diretta completa di polifenoli da estratti vegetali. Infine, i SAMN sono stati applicati con successo per rimuovere CrVI dall'acqua. L'ibrido SAMN@CrVI è stato utilizzato per immobilizzare l'ammina ossidasi del siero bovino (BSAO) e questo complesso era elettrochimico ha mostrato buone prestazioni per il rilevamento di H2O2. SAMN@CrVI-BSAO è stato applicato per lo sviluppo di un biosensore in poliammide, che è stato sfruttato con successo per la discriminazione dei tessuti tumorali e sani ottenuti da estratti di fegato.
Conclusioni
Le strategie di sensing basate sui SAMN offrono vantaggi unici rispetto ad altre tecniche. Sono prodotti con una procedura a basso costo, sono fisicamente e chimicamente stabili, biocompatibili e sicuri per l'ambiente. In questa tesi, i SAMN sono stati utilizzati per preparare tre diversi ibridi e
sono stati applicati con successo per la costruzione di tre diversi sensori elettrochimici, mostrando buone prestazioni e applicati con successo a campioni reali
Enzyme-iron nanoparticle direct interactions: complex formation and application for a coulometric biosensor for aminoaldehydes
No full textRecombinant aminoaldehyde dehydrogenase from tomato (LeAMADH1) was used as a model protein for studying the intimate interaction at the interface between proteins and surface active maghemite nanoparticles (SAMNs). SAMNs represent a new class of maghemite nanoparticles, displaying great colloidal behavior and specific surface chemical properties, as well as, peculiar electrochemical characteristics and specificity toward protein binding [1-2]. A potential anchor zone was individuated in a carboxylic rich surface area of the protein structure by molecular modeling. LeAMADH1 was successfully bound to the surface of bare SAMNs and its enzymatic activity was preserved, leading to a magnetic drivable enzymatic hybrid (SAMN@LeAMADH1). The catalytic parameters of SAMN@LeAMADH1 were determined, and exploited for the construction of a coulometric biosensor for the determination of aminoaldehydes in alcoholic beverages. A suspension of SAMN@LeAMADH1, used inside a low volume (1 μL) electrochemical flow cell, fabricated in-house, led to the complete oxidation of aminoaldehydes, producing a correspondent amount of NADH. The hybrid nanomaterial was magnetically removed after the enzymatic reaction allowing its reutilization. At the same time, a SAMN modified carbon paste electrode, inserted in the microcell was used for the direct electro-oxidation of NADH, leading to the coulometric determination of NADH produced during the enzymatic process. The novel biosensor showed a series of peculiarities: a) SAMN modified carbon paste electrode was used for NADH electro-oxidation; b) the complete enzymatic oxidation of sample aminoaldehydes, producing NADH, was carried out in a colloidal suspension, inside a low volume electrochemical flow cell, optimizing reactant diffusion; c) NADH, produced during the complete enzymatic oxidation of aminoaldehydes, was coulometrically determined at the SAMN modified lectrode; d) the capture of the hybrid, by the application of an external magnet, makes it reusable. 1)Baratella et al., Biosensors and Bioelectronics, 2013, 45, 13–18. 2)Magro et al., Biosensors and Bioelectronics, 2014, 52, 159–165
Avidin functionalized maghemite nanoparticles and their application for recombinant human biotinyl-SERCA purification
No full textWe report on the surface characterization, functionalization and application of stable water suspensions of novel surface active maghemite nanoparticles (SAMNs), characterized by a diameter of 11 ± 2 nm and possessing peculiar colloidal properties and surface interactions. These features permitted the acquisition of titration curves and aqueous UV-Vis spectrum and suggested a role played by surface under-coordinated iron atoms. This new class of nanoparticles was obtained through an easy, inexpensive, one-step, green procedure and functionalized with ligands of high biotechnological interest, such as biotin and avidin, by simple incubation in aqueous solution. Bound avidin was determined by measuring the disappearance of free avidin absorbance at 280 nm, as a function of nanoparticle increasing concentration, showing the presence of 10 ± 3 avidin molecules per nanoparticle. The biological activity of SAMN@avidin complex was evaluated and the number of available biotin binding sites was determined, using biotinyl-fluorescein as a probe, showing that each bound avidin molecule is able to bind 2.8 ± 0.8 biotin molecules, confirming the maintenance of biological activity and excellent binding capacity of SAMN@avidin complex. Furthermore Langmuir isotherm model was used to describe the biomolecule specific monolayer adsorption onto the particle surface, and, in the case of avidin, the maximum adsorption capacity was 100 ± 27 μg avidin/mg SAMN, while the binding constant is 45.18 μL μg-1. The SAMN@avidin complex was characterized by UV-Vis spectroscopy, quartz crystal microbalance, FTIR spectroscopy and transmission electron microscopy. Finally, SAMN@avidin was applied for the large scale purification of recombinant biotinylated human sarco/endoplasmic reticulum Ca2+-ATPase (hSERCA-2a), expressed by Saccharomyces. cerevisiae. The protein was magnetically purified and about 500 μg of a 70% pure hSERCA-2a were recovered from 4 liters of yeast culture, with a purification yield of 64%
Oxidized whey proteins as potential biomarkers of oxidative stress: preliminary studies of milk exposure to the myeloperoxidase product HOCl
No full textDetermination of MAO activity on intact mitochondria by a reagentless hydrogen peroxide amperometric sensor based on maghemite (-Fe2O3) nanoparticles
No full textA glucose biosensor based on surface active maghemite nanoparticles
No full textA simple carbon paste (CP) electrode, modified with novel maghemite (-Fe2O3) nanoparticles, called SAMNs (suface active maghemite nanoparticles) and characterized by a mean diameter of about 10 nm, has been developed. The electrode catalyzes the electro-reduction of hydrogen peroxide at low applied potentials (-0.1 V vs. SCE). In order to improve the electrocatalytic properties of the modified electrode an ionic liquid, namely 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), was introduced. At -0.1 V, the sensitivity of the SAMN-BMIM-PF6-CP electrode was 206.51 nA μM-1cm-2, with a detection limit (S/N = 3) of 0.8 μM, in the 0 – 1.5 mM H2O2 concentration range. Furthermore, glucose oxidase was immobilized on the surface of maghemite nanoparticles as a monomolecular layer, by a bridge constituted of rhodamine B isothiocyanate, leading to a fluorescent, magnetic drivable nanocatalyst, containing 10 ± 2 enzyme molecules per nanoparticle. The resulting enzyme electrode presents a linear calibration curve toward glucose in solution in the concentration range of 0 – 1.5 mM glucose, characterized by a sensitivity of 45.85 nA μM-1cm-2 and a detection limit (S/N = 3) of 0.9 μM. The storage stability of the system was evaluated and a half-life of 2 months was calculated, if the electrode is stored at 4°C in buffer. The present work demonstrates the feasibility of these surface active maghemite nanoparticles as efficient hydrogen peroxide electro-catalyst, which can be easily coupled to hydrogen peroxide producing enzymes in order to develop oxidase based reagentless biosensor devices
Enzyme self-assembly on naked iron oxide nanoparticles for aminoaldehyde biosensing
No full textThe preservation of enzymatic activity is a fundamental requirement for exploiting hybrid nano-bio-conjugates, and the control over protein–nanoparticle interactions, leading to stable and catalytically active hybrids, represents the key for designing new biosensing platforms. In this scenario, surface active maghemite nanoparticles (SAMNs) represent a new class of naked magnetic nanoparticles, displaying peculiar electrocatalytic features and the ability to selectively bind proteins. Recombinant aminoaldehyde dehydrogenase from tomato (SlAMADH1) was used as a model protein, and successfully immobilized by self-assembly on the surface of naked SAMNs, where its enzymatic activity resulted preserved for more than 6 months. The hybrid nanomaterial (SAMN@SlAMADH1) was characterized by UV–Vis spectroscopy, mass spectrometry, and TEM microscopy, and applied for the development of a biosensor for the determination of aminoaldehydes in alcoholic beverages. Measurements were carried out in a low volume electrochemical flow cell comprising a SAMN modified carbon paste electrode for the coulometric determination of the NADH produced during the enzymatic catalysis. The present findings, besides representing the first example of an electrochemical biosensor for aminoaldehydes in an alcoholic matrix, open the door to the use of immobilized enzymes on naked metal oxides nanomaterials for biosensing
Nanocrystalline Iron Oxides, Composites and Related Materials as a Platform for Electrochemical, Magnetic, and Chemical Biosensors
No full textThis review represents a comprehensive attempt to summarize and discuss various sensing applications of iron oxide nanoparticles (NPs), which have attracted a great deal of attention over recent years because of their easy preparation, biocompatibility, nontoxicity, and broad range of biomedical applications. We review the application potential of nanomagnetite based amperometic sensors possessing an intrinsic enzyme mimetic activity similar to that found in natural peroxidases. In addition, we discuss the properties and applications of enzymatic sensors exploiting glucose oxidase, tyrosinase, and other enzymes for sensing a variety of important biomedical species. Among iron oxide-based nanocomposites, we highlight the use of Fe3O4@Au hybrids for designing new electrochemical aptasensors with unique versatility for binding diverse targets, including proteins and peptides. Similarly, sensing applications of composites of iron oxide NPs with graphene derivatives and carbon nanotubes are reviewed. A large part of the review focuses on the development of DNA sensors and iron oxide based immunosensors for the detection of biological and chemical pathogens, contaminants, and other important analytes. Attention is also given to nonelectrochemical sensing, including various types of magnetic, fluorescence, and surface plasmon resonance sensors
Coulometric biosensor for aminoaldehydes based on the direct electro-oxidation of NADH on iron oxide nanoparticle modified electrode
No full textRemoval of Cr(VI) in contaminated water of Stoppani S.p.a. site (Liguria, Italy) by surface active maghemite nanoparticles
No full textThe importance of the interface between geosphere and biosphere represents one of the most fascinating frontiers of mineral science.Heavy metal release, transport and dispersion into the biosphere have a direct impact on the environment and on human health.New technologies for water and soils remediation represent a main task, and magnetic nanoparticles emerge as one of the most promising mean in this field.Environmental applications and risk assessment of manufactured nanoparticles greatly depend on the understanding of their interactions with water and soils.Novel superparamagnetic nanoparticles (Surface Active Maghemite Nanoparticles, SAMNs) constituted of stoichiometric maghemite, characterized by specific surface chemical behavior without any coating or superficial modification, stable in water for months as colloidal suspensions, were used as adsorbent of chromium(VI) in water.SAMNs can be superficially modified by simple incubation in presence of K2Cr2O7, forming a hybrid nanomaterial, SAMN@Cr(VI), stable without any release of Cr(VI) in solution.The aim of this work is to test the efficiency of SAMNs for Cr(VI) removal from Stoppani Spa site, an extreme environmental polluted Cr(VI) site.Stoppani industry located in the Cogoleto and Arenzano Area (Genova, Italy), transformed Cr(III) from chromite mineral (FeCr2O4) (Piccardo et al., 1989) to Cr(VI).It ceased the activity at the beginning of 2003, and since 2001, the Stoppani S.p.A. has been included, with DM n.468, into the national program of environmental remediation and restoration.In the 1918-1982 period, it discharged up to 1 million tons of post-treatment mud on the neighbouring beaches, groundwater resulted heavily polluted by Cr(VI). The water samples object of this work are representative of 3 pumping wells distinguished on the basis on the Cr(VI)-content in: sample W1(527< Cr(VI) < 11700 g/lt); W6 (83800 < Cr(VI) < 146000 g/lt); W9 (10500 < Cr(VI) < 232000 g/lt).Water temperature, electrical conductivity, alkalinity by acidimetric titration, pH, and Eh were determined during sampling. In the laboratory, waters have been analyzed for: Mg, and Ca by AAS, Na and K by AES Cl, SO42-, and NO3- by ion-chromatography, Si, Fe, minor and trace elements by ICP-OES.The application of SAMNs (100 mg mL-1) of three water samples removed 75-80% of Cr(VI), while, if the same treatment was accomplished at pH 3.0, Cr(VI) removal was about 95% with respect the initial concentration.Temperature, in the 4-25 °C range, did not influence Cr(VI) removal by SAMNs.A second SAMN treatment on the same water samples increased Cr(VI) removal efficiency up to 98 %, leading to a final Cr(VI) concentration below the limits stated by Italian law.SAMNs represent efficient candidates for Cr(VI) removal from aqueous polluted environments
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