22 research outputs found
Evaluation of new cholinium-amino acids based room temperature ionic liquids (RTILs) as immobilization matrix for electrochemical biosensor development: proof-of-concept with trametes versicolor laccase
In this work, we present new cholinium-amino acids room temperature ionic liquids (ChAARTILs) that can be used as an efficient immobilization matrix for electrochemical biosensor development. The ideal immobilization strategy should be able to ensure the highest enzyme loading and a tight enzymatic immobilization, preserving its native structure and biological activity. In this regard, ChAARTILs present different side chains on the amino acids giving rise to van der Waals, π-π stacking and hydrogen bonding interactions. All these interactions can affect the nanomaterial organization onto the electrode surface. To this aim, we have evaluated the main electrochemical parameters, namely electroactive area (AEA) and the heterogeneous electron transfer rate constant (k0), showing how both cations and anions of room temperature ionic liquids (RTILs) can independently affect multi-walled carbon nanotubes (MWCNTs) organization. In particular, [Ch][Phe] showed the best performance in terms of AEA (3.432 cm2) and k0 (4.71·10−3 cm s−1) with a homogeneous distribution of MWCNTs bundles onto the electrodes and a faster electron transfer rate
ZnO/polyaniline composite based photoluminescence sensor for the determination of acetic acid vapor
Decision making based on hybrid modeling approach applied to cellulose acetate based historical films conservation
no. 760801\NEMOSINE
UID/QUI/50006/2020Preserving culture heritage cellulose acetate-based historical films is a challenge due to the long-term instability of these complex materials and a lack of prediction models that can guide conservation strategies for each particular film. In this work, a cellulose acetate degradation model is proposed as the basis for the selection of appropriate strategies for storage and conservation for each specimen, considering its specific information. Due to the formulation complexity and diversity of cellulose acetate-based films produced over the decades, we hereby propose a hybrid modeling approach to describe the films degradation process. The problem is addressed by a hybrid model that uses as a backbone a first-principles based model to describe the degradation kinetics of the pure cellulose diacetate polymer. The mechanistic model was successfully adapted to fit experimental data from accelerated aging of plasticized films. The hybrid model considers then the specificity of each historical film via the development of two chemometric models. These models resource on gas release data, namely acetic acid, and descriptors of the films (manufacturing date, AD-strip value and film type) to assess the current polymer degradation state and estimate the increase in the degradation rate. These estimations are then conjugated with storage conditions (e.g., temperature and relative humidity, presence of adsorbent in the film’s box) and used to feed the mechanistic model to provide the required time degradation simulations. The developed chemometric models provided predictions with accuracy more than 87%. We have found that the storage archive as well as the manufacturing company are not determining factors for conservation but rather the manufacturing date, off gas data as well as the film type. In summary, this hybrid modeling was able to develop a practical tool for conservators to assess films conservation state and to design storage and conservation policies that are best suited for each cultural heritage film.publishersversionpublishe
Preparation and characterization of screening methods for classification and quality control of olive oils
In questo lavoro di ricerca di Dottorato sono state sviluppate piattaforme sensoristiche, basate su elettrodi SPE modificati con nanomateriali, per permetterere una rapida, facile ed economica individuazione delle frodi legate alla produzione e al commercio dell'olio extravergine di oliva. Il risultato della ricerca è stata la creaziobne di due piattaforme in grado rispettivamente di catalogare oli extravergine di oliva a seconda della cultivar della pianta di origine e di quantificare il contenuto di antiossidanti polari in campioni incogniti di olii vegetali, permettendo di discriminare oli di oliva da oli di altri semi.In this PhD research work, sensor platforms have been developed, based on SPE electrodes modified with nanomaterials, to allow rapid, easy and economic identification of frauds linked to the production and trade of extra virgin olive oil. The result of the research was the creation of two platforms able respectively to catalog extra virgin olive oils according to the cultivar of the plant of origin and to quantify the content of polar antioxidants in unknown samples of vegetable oils, allowing to discriminate olive oils from oils of other seeds
Generation IV ionic liquids and nanomaterials to develop innovative electrochemical biosensing platforms
Different types of modified electrodes have been prepared and tested to assembly and construct portable sensing devices, useful to analyze, in a simple, fast and economic way, many analytes.
Bare glassy carbon electrodes (GCE) of the screen-printed type (SPE), with silver electrode as reference, have been modified, via drop casting on the working electrode surface, with a mixture of generation IV room temperature ionic liquids (RTILs) and nanomaterials. The ionic liquids choline-amino acids, were synthetized in our laboratory following the methodology known in literature1. These RTILs differ from the previous generation ones because they are nontoxic and completely biodegradable2,3. Like those of the previous generations, the RTILs used in this work have interesting properties regarding low volatility, low flammability, high ionic conductivity, high chemical and electrochemical stability4. Furthermore, these compounds allow to significantly increase the work potential range (V), electroactive area (Aea) and electron transfer constant (k0), so that anode or cathode peaks can be detected even for extremely low concentration of analytes. The nanomaterials used in this work were Multi-Walled Carbon Nanotubes (MWCNT) and Titanium Dioxide nanoparticles (anatase form). These two nanomaterials have been used both alone and together in different proportions with the chosen RTIL [Ch] [Phe]. All the so developed electrodes have been studied by means of cyclic voltammetry measurements to calculate the electroactive area (Aea) of the working electrode, in order to find the best combination of nanomaterials/ionic liquid/water for the drop casting mixture. All the proposed combinations have also been studied for stability: cyclic voltammetry measurements have been carried out at various time intervals after the preparation to investigate variations of the Aea of the modified electrodes. The electrochemical platform so developed has been used, after functionalization with the proper enzyme, as a biosensor. In particular, it has been tested for measuring glucose in food matrices and antioxidants in olive oils using Glucose Oxidase5 and Lipase6 respectively.
References
1. S. De Santis, G. Masci, F. Casciotta, et al.; Phys. Chem., 2015, 17,20687.
2. J. Arning, S. Stolte, A. Böschen, F. Stock, W.R. Pitner et al.; Green Chem.,
2008, 10, 47-58.
3. A. Romero, A. Santos, J. Tojo, A. Rodriguez; J. Hazard Matter, 2008,151,268-273.
4. J.S. Xu, G.C. Zhao;Int. J. Electrochem. Sci., 2008, 4, 519-527.
5. M.L. Antonelli, F. Arduini et al.;Biosensors and Bioelectronics, 2009,24,1382-88.
6. Álvarez G.A., J.A. Rodríguez, J.C. Escamilla, C.A. Galán;J. Mex. Chem. Soc., 2015, 59, 19-23
A new electrochemical sensor for extra-virgin olive oils classification
A screen-printed electrode was modified using multi-walled carbon nanotubes (MWCNT) and titanium oxide nanoparticles (TiO2), with a bio-based ionic liquid (RTIL) as a drop-casting medium. The RTILs here used have been proved to be useful for immobilizing nanomaterials on the working electrode surface. The proposed platform has been used to analyze extra-virgin olive oils (EVOOs), produced with olives of known cultivar and geographic origin. The EVOOs were produced with the olives that have been collected in the Italian region of Lazio during 2016, 2017 and 2018 harvesting seasons. The analyses of the oils were done by means of cyclic voltammetry measures. The results here obtained encourage the establishment of criteria for the classification of oils in terms of the corresponding cultivar. Both the electrode modification and the olive oil analysis do not involve any organic solvents. Therefore, the proposed approach represents an environmentally friendly method for field analyses of EVOOs. © 2019 Elsevier Lt
Photoautotrophs–Bacteria Co-Cultures: Advances, Challenges and Applications
Photosynthetic microorganisms are among the fundamental living organisms exploited for millennia in many industrial applications, including the food chain, thanks to their adaptable behavior and intrinsic proprieties. The great multipotency of these photoautotroph microorganisms has been described through their attitude to become biofarm for the production of value-added compounds to develop functional foods and personalized drugs. Furthermore, such biological systems demonstrated their potential for green energy production (e.g., biofuel and green nanomaterials). In particular, the exploitation of photoautotrophs represents a concrete biorefinery system toward sustainability, currently a highly sought-after concept at the industrial level and for the environmental protection. However, technical and economic issues have been highlighted in the literature, and in particular, challenges and limitations have been identified. In this context, a new perspective has been recently considered to offer solutions and advances for the biomanufacturing of photosynthetic materials: the co-culture of photoautotrophs and bacteria. The rational of this review is to describe the recently released information regarding this microbial consortium, analyzing the critical issues, the strengths and the next challenges to be faced for the intentions attainment
DES as a green extracting media for antioxidants electrochemical quantification in extra-virgin olive oils
A new electroanalytical method has been developed for the determination of phenolic compounds in extra virgin olive oils. This method is based on the extraction of phenolic compounds from EVOO with DES and their determination by GC/MWCNT/TiO2 electrode, whose sensitivity is based on the use of MWCNT and TiO2 nanoparticles as modifiers and Nafion as binders on the GCE. This built platform has shown very good sensitivity in detecting phenolic compounds in EVOO at a fairly wide range of concentrations. The measurements were performed by using square wave voltammetry. By using this method, we were able to divide antioxidants in two groups: the group of compounds oxidizing at about 220 mV (1st Group) was the mixture of CA and gallic acid (GA), while for the group oxidizing at about 570 mV (2nd Group) the mixture contained VA, p-Coumaric Acid (p-CA) and tyrosol (TS). The extraction could be performed without using organic solvents and the detection limits for CA and VA were found to be 1.82 and 5.32 µmol/L with GCE, whilst 0.6 and 1.03 µM with GC/MWCNT/TiO2. Based on the results compared with the spectrophotometric method we can say that this method can be used in the determination of phenolic compounds in EVOO
Deep eutectic solvents (DES) as green extraction media for antioxidants electrochemical quantification in extra-virgin olive oils
A new electroanalytical method has been developed for the determination of polar antioxidant compounds in
extra virgin olive oils. This method is based on the extraction of polar antioxidant compounds from extra-virgin
olive oils by means of a deep eutectic solvent and their determination by a modified screen-printed electrode
platform. The platform sensitivity was increased by modifying the working electrode with MWCNT and TiO2
nanoparticles as modifiers and Nafion as a binder. The platform showed very good sensitivity in detecting polar
antioxidant compounds in extra-virgin olive oils in a fairly wide range of concentrations. The measurements
were performed by using square wave voltammetry. The extraction was performed without using organic solvents,
making the method environmentally friendly. The proposed method has been compared with a common
spectrophotometric one, the results appeared in good agreement. The method is sufficiently easy and quick to be
used for screening analyses of polar antioxidant compounds in extra-virgin olive oils on the field