Furaneol is a widely used flavoring agent, which can be naturally found in different products, such as strawberries or thermally processed foods. This is why it is extremely important to detect furaneol in the food industry using ultra-sensitive, stable, and selective sensors. In this context, electrochemical biosensors are particularly attractive as they provide a cheap and reliable alternative measurement device. Carbon nanotubes (CNTs) and silver nanoparticles (AgNPs) have been extensively investigated as suitable materials to effectively increase the sensitivity of the biosensors. However, a comparison of the performance of biosensors employing CNTs and AgNPs is still missing. Herein, the effect of CNTs and AgNPs on the biosensor performance has been thoughtfully analyzed. Therefore, disposable flexible and screen printed electrochemical aptasensor modified with CNTs (CNT-ME), or AgNPs (AgNP-ME) have been developed. Under optimized conditions, CNT-MEs showed better performance compared to AgNP-ME, yielding a linear range of detection over a dynamic concentration range of 1 fM–35 μM and 2 pM–200 nM, respectively, as well as high selectivity towards furaneol. Finally, our aptasensor was tested in a real sample (strawberry) and validated with high-performance liquid chromatography (HPLC), showing that it could find an application in the food industry.
Electrochemical biosensors are widely investigated as they represent attractive analytical tools for detection of a broad range of bio-molecules, thanks to their simplicity, high sensitivity and short response time. Especially, biosensors employing an electrolyte-gated field-effect transistors (EG-FETs) as electrochemical transduction element have gained increasing interest, due to the signal amplification and the intrinsic low voltage range of operation. In this work we report the fabrication of flexible EG-FETs using spray-deposited semiconducting carbon nanotubes (CNTs), with a specific focus on the optimization of the CNT channel to optimize the performance of the resulting CNT-based EG-FET (EG-CNTFET). The transfer and the output characteristic of different devices with varying spraying parameters were tested, finding out that only devices with source-drain resistance of about ≤ 10 kΩ showed proper EG-CNTFET operation: for these devices we recorded a typical p-type behavior with an on-off ratio of 214 A/A up to 469 A/A (depending on number of the spray-deposited CNT layers). The fabricated EG-CNTFETs were functionalized with anti-spermidine antibodies to detect polyamine spermidine -a well-known chemical indicator of food quality. To ensure controlled immobilization and at the same time to preserve the electrical properties of the nanotubes, the spray-deposited films were modified with a bifunctional molecule, which attaches to the CNT via non-covalent π − π interactions and leaves a free NHS-ester group for amide coupling of the antibodies. The fabricated EG-CNTFET-based immunosensors showed a linear detection range for spermidine from 10 −3 to 10 2 nM, with the sensitivities ranging from -1.03 to -2.45 µA/decade.
The growing usage and consumption of electronics-integrated items into the daily routine has raised concerns on the disposal and proper recycling of these components. Here, a fully sustainable and green technology for the fabrication of different electronics on fruit-waste derived paper substrate, is reported. The process relies on the carbonization of the topmost surface of different cellulose-based substrates, derived from apple-, kiwi-, and grape-based processes, by a CO 2 laser. By optimizing the lasing parameters, electronic devices, such as capacitors, biosensors, and electrodes for food monitoring as well as heart and respiration activity analysis, are realized. Biocompatibility tests on fruit-based cellulose reveal no shortcoming for onskin applications. The employment of such natural and plastic-free substrate allows twofold strategies for electronics recycling. As a first approach, device dissolution is achieved at room temperature within 40 days, revealing transient behavior in natural solution and leaving no harmful residuals. Alternatively, the cellulose-based electronics is reintroduced in nature, as possible support for plant seeding and growth or even soil amendment. These results demonstrate the realization of green, low-cost and circular electronics, with possible applications in smart agriculture and the Internet-of-Thing, with no waste creation and zero or even positive impact on the ecosystem.
This study described the comparison of different physicochemical parameters between fresh and frozen lamb meat. The pH measurement for fresh and frozen lamb meat did not show a significant difference. CIE L*a*b* (Commission Internationale de l'éclairage) color measurement technique was used and ∆E (distance between 2 colors) was found 5.32. On shrinkage measurement, there were significant differences (p<0.05) between the fresh and frozen meat. Frozen lamb sample showed 26.99% shrinkage compared to the fresh lamb which showed 18.09% shrinkage. The thawing loss did not show any significant difference. For texture analysis force and work were evaluated together for both fresh and frozen samples through Warner Bratzler texture analysis. The values did not show any significant difference. The absolute values of force and work were significantly different (p<0.05). Water binding capacity of the frozen and fresh sample were 56.57% and 59.27%, respectively. The moisture contents of fresh and frozen sample were 73.64% and 72.85%, respectively. Fat contents of fresh and frozen sample were 5.08% and 6.09% respectively. The study concludes that while comparing fresh and frozen lamb, only shrinkage and texture analysis showed significant difference whereas other physicochemical properties showed minor differences.
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