A microfluidic immobilized-enzyme reactor for polymer degradation was developed. Lipase was immobilized in a microfluidic reactor through vinylazlactone chemistry.The reactor was used for on-line degradation of polymeric nanoparticles. Degradation products were analysed on-line by size-exclusion chromatography.A residence time of a few minutes proved sufficient for full degradation.
Despite the fact that a considerable amount of effort has been invested in the development of biosensors for the detection of pesticides, there is still a lack of a simple and low-cost platform that can reliably and sensitively detect their presence in real samples. Herein, an enzyme-based biosensor for the determination of both carbamate and organophosphorus pesticides is presented that is based on acetylcholinesterase (AChE) immobilized on commercially available screen-printed carbon electrodes (SPEs) modified with carbon black (CB), as a means to enhance their conductivity. Most interestingly, two different methodologies to deposit the enzyme onto the sensor surfaces were followed; strikingly different results were obtained depending on the family of pesticides under investigation. Furthermore, and towards the uniform application of the functionalization layer onto the SPEs’ surfaces, the laser induced forward transfer (LIFT) technique was employed in conjunction with CB functionalization, which allowed a considerable improvement of the sensor’s performance. Under the optimized conditions, the fabricated sensors can effectively detect carbofuran in a linear range from 1.1 × 10−9 to 2.3 × 10−8 mol/L, with a limit of detection equal to 0.6 × 10−9 mol/L and chlorpyrifos in a linear range from 0.7 × 10−9 up to 1.4 × 10−8 mol/L and a limit of detection 0.4 × 10−9 mol/L in buffer. The developed biosensor was also interrogated with olive oil samples, and was able to detect both pesticides at concentrations below 10 ppb, which is the maximum residue limit permitted by the European Food Safety Authority.
Electrochemical stripping analysis (ESA) is a trace electroanalytical technique for the determination of metal cations, inorganic ions, organic compounds and biomolecules. It is based on a pre-concentration step of the target analyte(s), or a compound of the target, on a suitable working electrode. This is followed by a stripping step of the accumulated analyte using an electroanalytical technique. Advantages of ESA include high sensitivity and low limits of detection, multi-analyte capability, low cost of instrumentation and consumables, low power requirements, potential for on-site analysis, speciation capability and scope for indirect biosensing. This Primer covers fundamental aspects of ESA and discusses methods of pre-concentration and stripping, instrumentation, types of working electrodes and sensors, guidelines for method optimization, typical applications, data interpretation and interferences, and method limitations and workarounds. Finally, the current trends and future prospects of ESA are highlighted.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.