According to the recent statistics, Salmonella is still an important public health issue in the whole world. Legislated reference methods, based on counting plate methods, are sensitive enough but are inadequate as an effective emergency response tool, and are far from a rapid device, simple to use out of lab. An overview of the commercially available rapid methods for Salmonella detection is provided along with a critical discussion of their limitations, benefits and potential use in a real context. The distinguished potentialities of electrochemical biosensors for the development of rapid devices are highlighted. The state-of-art and the newest technologic approaches in electrochemical biosensors for Salmonella detection are presented and a critical analysis of the literature is made in an attempt to identify the current challenges towards a complete solution for Salmonella detection in microbial food control based on electrochemical biosensors.

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This work reports a new paper-based sensing platform and its application in a label-free potentiometric immunosensor for Salmonella typhimurium detection based on the blocking surface principle. A paper-based strip electrode was integrated with a filter paper pad which acted as a reservoir of the internal solution. The design offers a convenient platform for antibody immobilization and sampling, proving also that is a simple and affordable methodology to control an ionic flux through a polymer membrane. Two different immunosensing interfaces were assembled on the developed paper-strip electrode. The simplest interface relied on direct conjugation of the antibody to the polymer membrane and the second one resorted to an intermediate layer of a polyamidoamine dendrimer, with an ethylenediamine core from the fourth generation. Electrochemical impedance spectroscopy was used to assess the successive interface modification steps and the resulting analytical performance of both immunosensors was compared. For such, the potential shift derived from the blocking effect of the ionic flux caused by antigen-antibody conjugation was correlated with the logarithm of the Salmonella typhimurium concentration in the sample. In optimized conditions, a limit of detection of 5 cells mL −1 was achieved. As a proof-of-concept, the proposed method was applied to apple juice samples, demonstrating to be a suitable prototype to be used in real scenarios in useful time (< 1 h assay).

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Automated synthesis of [ 18 F]ciprofloxacin in a TRACERlab TM FX FDG (GE Healthcare) synthesis module was developed. Dependence of radiochemical yield on reactor type was observed. 3-mL V-shaped borosilicate glass reactor gave higher radiochemical yield as compared with standard 15-mL glassy carbon reactor. V-shaped borosilicate glass reactor might also give higher radiochemical yield for other [ 18 F]radiotracers than [ 18 F]ciprofloxacin. a b s t r a c tWe transferred the previously published manual synthesis of [ 18 F]ciprofloxacin (decay-corrected RCY: 5.5 71.0%) to an automated synthesis module (TRACERlab TM FX FDG , GE Healthcare) and observed a strong decrease in RCY (0.4 70.4%). When replacing the standard 15-mL glassy carbon reactor of the synthesis module with a 3-mL V-shaped borosilicate glass reactor a considerable improvement in RCY was observed. [ 18 F]Ciprofloxacin was obtained in a RCY of 2.7 71.4% (n ¼23) with a specific activity at EOS of 1.47 0.5 GBq/mmol in a synthesis time of 160 min.

Polymeric ion selective electrodes are highly sensitive to changes in zero current ion flow and this offers a route to signal amplification in label-free potentiometric immunosensors. In this work, a label-free potentiometric immunosensor toward Salmonella typhimurium (ST) assembled in a home-made pipette-tip electrode is described. The signal-output amplification was implemented on a gold nanoparticle polymer inclusion membrane (AuNPs-PIM) which was used as sensing platform and for antibody immobilization. Additionally, a marker ion was used to detect the antibody-antigen binding event at the electrode surface. The immunosensor construction was performed in several steps: i) gold salt ions extraction in PVC membrane; ii) AuNPs formation using Na 2 EDTA as reduction agent; iii) antibody anti-Salmonella conjugation on AuNPs-PIM in pipette-tip electrodes. The potential shift observed in potentiometric measurements was derived simply from the blocking effect in the ionic flux caused by antigen-antibody conjugation, without no extra steps, mimetizing the ion-channel sensors. A detection limit of 6 cells mL −1 was attained. As proof-of-concept, recovery studies were performed in spiked commercial apple juice samples with success. Due to the simplicity of use, the appealing cost of equipment and sensor production and being able to provide a quick analytical response (less than 1 h for a complete assay, including sample preparation for analysis), this scheme represents a good prototype device for the detection of foodborne pathogens like ST or other immune-responsive bacteria.

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