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A LOx-based electrochemical biosensor for high-level lactate determination was developed. For the construction of the biosensor, chitosan and Nafion layers were integrated by using a spin coating procedure, leading to less porous surfaces in comparison with those recorded after a drop casting procedure. The analytical performance of the resulting biosensor for lactate determination was evaluated in batch and flow regime, displaying satisfactory results in both modes ranging from 0.5 to 20 mM concentration range for assessing the lactic acidosis. Finally, the lactate levels in raw serum samples were estimated using the biosensor developed and verified with a blood gas analyzer. Based on these results, the biosensor developed is promising for its use in healthcare environment, after its proper miniaturization. A pH probe based on common polyaniline-based electrochemical sensor was also developed to assist the biosensor for the lactic acidosis monitoring, leading to excellent results in stock solutions ranging from 6.0 to 8.0 mM and raw plasma samples. The results were confirmed by using two different approaches, blood gas analyzer and pH-meter. Consequently, the lactic acidosis monitoring could be achieved in continuous flow regime using both (bio)sensors. [ABSTRACT FROM AUTHOR]

A new electrochemical sensor device has been developed through the modification of a polyaniline-silicon oxide network with carbon black (CB). Enhanced electrical conductivity and antifouling properties have been achieved due to the integration of this cheap nanomaterial into the bulk of the sensor. The structure of the developed material was characterized using Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy techniques. Cyclic voltammetry was used to characterize electrochemically the Sonogel-Carbon/Carbon Black-PANI (SNG-C/CB-PANI) sensor device. In addition, differential pulse voltammetry was employed to evaluate the analytical response of the sensor towards sundry chlorophenols, common environmental hazards in aqueous ecosystems. The modified sensor material showed excellent antifouling properties, which led to a better electroanalytical performance than the one displayed with the bare sensor. Notably, a sensitivity of 5.48 × 103 μA mM−1 cm−2 and a limit of detection of 0.83 μM were obtained in the determination of 4-chloro-3-methylphenol (PCMC) at a working potential of 0.78 V (vs. 3 M Ag/AgCl/KCl), along with proficient values of reproducibility and repeatability (relative standard deviation < 3%). Finally, the analysis of PCMC was carried out in multiple validated water samples using the synthesized SNG-C/CB-PANI sensor device, obtaining excellent results of recovery values (97–104%). The synergetic effect of polyaniline and carbon black leads to novel antifouling and electrocatalytic effects that improve the applicability of this sensor in sample analysis versus complex conventional devices. [ABSTRACT FROM AUTHOR]

Here, we describe a novel, fast, simple and green method for synthesis of gold sononanoparticles (AuSNPs) employing three different parts of Geranium (Pelargonium graveolens) extracts such as stems (AuSNPs-G.S), leaves (AuSNPs-G.L) and the mixture of both (AuSNPs-G.M), in which plant biomaterials were used as reducing and capping agents using a high energy ultrasound. The resulting AuSNPs were characterized using a wide range of instrumental techniques including UV–Vis spectrophotometry, FTIR, STEM, TEM, SEM, and EDS. The formation of AuSNPs was confirmed by UV–Vis, showing an absorption peak in the range of 532–540 nm. The FTIR analysis identifies the interactions between gold and the bioactive molecules implicated in nanoparticle synthesis. The STEM, TEM and SEM results determine the morphology of the AuSNPs responsible for the three different extracts in the synthesis process. Biosynthesized AuSNPs have an average size of 16–33 nm with varied morphology. Then, for the first time we have demonstrated an eco-friendly sensor based on Sonogel-Carbon electrode (SNGCE) modified with biosynthesized AuSNPs-G.M for phenol determination. This sensor was showing a lower limit of detection of 67 nM (n = 3), excellent sensitivity, reproducibility, repeatability and high selectivity; thanks to the AuSNPs as cost-effective nanomaterials. Finally, the analytical sensor was applied successfully for the determination of phenol in real sample olive oil with a satsisfactory recoveries. [ABSTRACT FROM AUTHOR]