Lab

Gino Bontempelli's Lab

Institution: University of Udine

Featured research (4)

A low-cost portable analytical device, suitable for performing reflectance measurements on paper supports is proposed. It consists of a simple module consisting of a matrix of six types of photodiodes (six channels) with maximum sensitivity at six different wavelengths in the visible region. The device was used in combination with paper-based analytical devices (PADs) suitably prepared by 3D printing using polycaprolactone, i.e. a biodegradable and biocompatible polymer. These PADs were used both as substrates for the imbibition of colored solutions and of reagents for colorimetric reactions. The constructive and electronic aspects are described and the instrumental noise, as well as the performance of this device were carefully evaluated in terms of repeatability and reproducibility by using three different food dye and a colorimetric assay for the determination of nitrites with the Griess reagent. The development of this device also included the management of the output signals that, once converted from raw signals into reflectance values, have been elaborated by the Kubelka-Munk theory. Finally, the application to real samples consisting of commercial aqueous solutions of Tartrazine yellow (E102), Ponceau red 4R (E124) and Patent blue V (E131), usually adopted for the coloration and/or decoration of homemade cakes and sugarcoated almonds, gave results in good agreement with values obtained by absorbance measurements performed by a benchtop spectrophotometer. This type of comparison pointed out that also the nitrite detection performed by reflectance measurements on synthetic samples allowed more than reliable results to be obtained.
Paper has been widely employed as cheap material for the development of a great number of sensors such as pregnancy tests, strips to measure blood sugar, and COVID-19 rapid tests. The need for new low-cost analytical devices is growing, and consequently the use of these platforms will be extended to different assays, both for the final consumer and within laboratories. This work describes a paper-based electrochemical sensing platform that uses a paper disc conveniently modified with recognition molecules and a screen-printed carbon electrode (SPCE) to achieve the detection of gluten in a deep eutectic solvent (DES). This is the first method coupling a paper biosensor based on aptamers and antibodies with the DES ethaline. Ethaline proved to be an excellent extraction medium allowing the determination of very low gluten concentrations. The biosensor is appropriate for the determination of gluten with a limit of detection (LOD) of 0.2 mg L ⁻¹ of sample; it can detect gluten extracted in DES with a dynamic range between 0.2 and 20 mg L ⁻¹ and an intra-assay coefficient of 10.69%. This approach can be of great interest for highly gluten-sensitive people, who suffer from ingestion of gluten quantities well below the legal limit, which is 20 parts per million in foods labeled gluten-free and for which highly sensitive devices are essential. Graphical abstract
This investigation was carried out with the aim of verifying whether transmittance detection modes on soaked paper, which is a simple and attractive determination approach for microfluidic paper-based analytical devices, can be improved by using deep eutectic solvents (DESs) as suitable media for minimizing reflection and refraction phenomena affecting these measurements. With this purpose, we tested two DESs such as ethaline and glyceline by checking that paper soaked with both two DESs displayed a quite higher transparency than that soaked with water (the absorbance decreased of about 25%). This result is particularly important in that DESs offer the appreciable advantage of being characterized by a negligible vapor pressure, unlike water or the majority of organic media, thus allowing long-term detections or analysis of very small samples to be conducted avoiding any problem caused by the solvent evaporation. As a proof of concept, we have then compared the detection of the patent blue V dye (E131) in ethaline solutions with that of the same dye dissolved in water. These determinations were performed on paper discs defined by a circular hydrophobic barrier which were installed into a plastic holder, which was constructed on purpose by the 3D technology to fit the cell housing of a Varian Cary 50 bio benchtop spectrophotometer adopted in our spectrophotometric measurements. The results found on paper discs soaked with ethaline were totally satisfactory in that they were characterized by a good repeatability and allowed a calibration plot to be constructed in a quite wide concentration range which allowed quite low concentrations to be detected (in the µM range) and was characterized by a good enough correlation coefficient. On the contrary, the results found on paper discs soaked with water were totally unsatisfactory since they were strongly affected by both the solvent evaporation and a more marked ripple present in the recorded spectra.
Deep Eutectic Solvents (DESs) are a new class of solvents characterized by a remarkable decrease in melting point compared to those of the starting components. The eutectic mixtures can be simply prepared by mixing a Hydrogen Bond Acceptor (HBA) with a Hydrogen Bond Donor (HBD) at a temperature of about 80 • C. They have found applications in different research fields; for instance, they have been employed in organic synthesis, electrochemistry, and bio-catalysis, showing improved biodegradability and lower toxicity compared to other solvents. Herein, we review the use of DESs in biosensor development. We consider the emerging interest in different fields of this green class of solvents and the possibility of their use for the improvement of biosensor performance. We point out some promising examples of approaches for the assembly of biosensors exploiting their compelling characteristics. Furthermore, the extensive ability of DESs to solubilize a wide range of molecules provides the possibility to set up new devices, even for analytes that are usually insoluble and difficult to quantify.

Lab head

Gino Bontempelli
Department
  • Department of Agrifood, Environmental and Animal Science

Members (8)

Rosanna Toniolo
  • University of Udine
Nicolò Dossi
  • University of Udine
Agnese Giacomino
  • Università degli Studi di Torino
Franco Tubaro
  • University of Udine
Rossella Svigelj
  • University of Udine
Georgina Faura
  • University of Udine
Cristian Grazioli
  • University of Udine
Renzo Bortolomeazzi
Renzo Bortolomeazzi
  • Not confirmed yet
Evandro Piccin
Evandro Piccin
  • Not confirmed yet
Stefano Petrazzi
Stefano Petrazzi
  • Not confirmed yet