Novel Additive Manufactured Multielectrode Electrochemical Cell with Honeycomb Inspired Design for the Detection of Methyl Parathion in Honey Samples.

The development and increase in the number of crops recently have led to the requirement for greater efficiency in world food production and greater consumption of pesticides. In this context, the widespread use of pesticides has affected the decrease in the population of pollinating insects and has caused food contamination. Therefore, simple, low-cost, and quick analytical methods can be interesting alternatives for checking the quality of foods such as honey. In this work, we propose a new additively manufactured (3D-printed) device inspired by a honeycomb cell, with 6 working electrodes for the direct electrochemical analysis of methyl parathion by reduction process monitoring in food and environmental samples. Under optimized parameters, the proposed sensor presented a linear range between 0.85 and 19.6 µmol L-1, with a limit of detection of 0.20 µmol L-1. The sensors were successfully applied in honey and tap water samples by using the standard addition method. The proposed honeycomb cell made of polylactic acid and commercial conductive filament is easy to construct, and there is no need for chemical treatments to be used. These devices based on 6 working electrodes array are versatile platforms for rapid, highly repeatable analysis in food and environment, capable of performing detection in low concentrations.

Low-cost, facile droplet modification of screen-printed arrays for internally validated electrochemical detection of serum procalcitonin.

This manuscript presents the design and facile production of screen-printed arrays (SPAs) for the internally validated determination of raised levels of serum procalcitonin (PCT). The screen-printing methodology produced SPAs with six individual working electrodes that exhibit an inter-array reproducibility of 3.64% and 5.51% for the electrochemically active surface area and heterogenous electrochemical rate constant respectively. The SPAs were modified with antibodies specific for the detection of PCT through a facile methodology, where each stage simply uses droplets incubated on the surface, allowing for their mass-production. This platform was used for the detection of PCT, achieving a linear dynamic range between 1 and 10 ng mL-1 with a sensor sensitivity of 1.35 × 10-10 NIC%/ng mL-1. The SPA produced an intra- and inter-day %RSD of 4.00 and 5.05%, with a material cost of £1.14. Internally validated human serum results (3 sample measurements, 3 control) for raised levels of PCT (>2 ng mL-1) were obtained, with no interference effects seen from CRP and IL-6. This SPA platform has the potential to offer clinicians vital information to rapidly begin treatment for "query sepsis" patients while awaiting results from more lengthy remote laboratory testing methods. Analytical ranges tested make this an ideal approach for rapid testing in specific patient populations (such as neonates or critically ill patients) in which PCT ranges are inherently wider. Due to the facile modification methods, we predict this could be used for various analytes on a single array, or the array increased further to maintain the internal validation of the system.

Sensing of L-methionine in biological samples through fully 3D-printed electrodes.

The variation in biomarkers levels, such as L-methionine, can be an indicator of health problems or diseases, such as metabolism, neuropsychiatric disorders, or some virus infections. Thus, the development of accurate sensors, with low-cost and rapid response has been gaining increasing importance and attractiveness for the early diagnosis of diseases. In this regard, we have proposed a method for L-methionine electrochemical detection using a low-cost and simple arrangement of 3D-printed electrodes (working, reference, and auxiliary electrodes) based on polylactic acid/graphene filament (PLA-G), in which all electrodes were printed. The working electrode was chemically and electrochemically treated, showing a high electroactive area, with graphene edge plans exposure and better electron transfer when compared to the untreated electrode. An excellent analytical performance was obtained with a sensitivity of 0.176 µAL µmol-1, a linear dynamic range of 5.0 µmol L-1- 3000 µmol L-1 and limit of detection of 1.39 µmol L-1. The proposed device was successfully applied for L-methionine detection in spiked serum samples, showing satisfactory recovery values. This indicates the potentiality of the proposed arrangement of electrodes for the L-methionine detection in biological samples at different concentration levels.