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Herein, we describe a rapid and facile fabrication of electrochemical sensors utilizing two different toll-like receptor (TLR) proteins as biorecognition elements to detect bacterial pathogen associated molecular patterns (PAMPs). Using potential-assisted self-assembly, binary mixtures of 11-mercaptoundecanoic acid (MUA) and 6-mercapto-1-hexanol (MCH), or MUA and an in-house synthesized zwitterionic sulfobetaine thiol (DPS) were assembled on a gold working electrode within 5 minutes, which is >200 times shorter than other TLR sensors' preparation time. Electrochemical methods and X-ray photoelectron microscopy were used to characterize the SAM layers. SAMs composed of the betaine terminated thiol exhibited superior resistance to nonspecific interactions, and were used to develop the TLR sensors. Biosensors containing two individually immobilized TLRs (TLR4 and TLR9) were fabricated on separate MUA-DPS SAM modified Au electrodes (MUA-DPS/Au) and tested for their response towards their respective PAMPs. The changes to electron transfer resistance in EIS of the TLR4/MUA-DPS/Au sensor showed a detection limit of 4 ng mL -1 for E. coli 0157:H7 endotoxin (lipopolysaccharide, LPS) and a dynamic range of up to 1000 ng mL -1 . The TLR4-based sensor showed negligible response when tested with LPS spiked human plasma samples, showing no interference from the plasma matrix. The TLR9/MUA-DPS/Au sensor responded linearly up to 350 μg mL -1 bacterial DNA, with a detection limit of 7 μg mL -1 . The rapid assembly of the TLR sensors, excellent antifouling properties of the mixed SAM assembly, small size and ease of operation of EIS hold great promise for the development of a portable and automated broad-spectrum pathogen detection and classification tool.

The adoption of supplementary cementitious materials (SCMs) as a partial replacement of Ordinary Portland Cement (OPC) is increasing in anticipation of reducing the carbon footprint of cement and concrete industry. The resistance of concretes with SCMs against natural carbonation (a reactive-diffusion mechanism) is still a topic of research. Most literature adopt accelerated carbonation tests (under constant humidity and temperature conditions) to estimate the natural carbonation depth (d CO2 ) in concrete. This does not always represent the actual scenario in the field structures. Moreover, accelerated carbonation conditions could result in significantly different pore structure than that are formed in the case of natural carbonation; hence, not always reliable to model the service life. Hence, there is a need for data on long-term natural d CO2 to help design reinforced concrete for a target service life. The data presented in this paper contains long-term natural d CO2 data of 45 different concretes prepared using various SCMs like volcanic ash (from Greece), fly ash, slag, and limestone (from France). The concrete specimens were prepared in France, shipped to India by air (in moist burlap and plastic cover), and then kept in sheltered and unsheltered exposure conditions on the terrace of a building in Chennai, India, experiencing tropical climate (warm and humid conditions). The data includes mixture proportions (type of binder, water-to-binder ratio, binder content, % SCMs, fine and coarse aggregate (river sand and gravel) content, and air content). In addition, curing time and compressive strength of concrete mixes are provided in Set A. Sets B and C consist of the natural d CO2 of concrete measured at various time instances between 1 and 11 years of natural exposure. Arguably, this is the first of its kind natural d CO2 database from a tropical climate zone. The natural d CO2 values were measured using a phenolphthalein indicator prepared according to RILEM CPC 18. This data can be used by researchers and practitioners to calibrate the existing carbonation models or to develop new models to estimate natural d CO2 for concretes exposed to tropical climates. Such models can help design concretes to achieve the target corrosion-free service life for reinforced concrete systems., (© 2024 The Authors.)

In this work, we report the direct electrochemical oxidation of fentanyl using commercial screen-printed carbon electrodes (SPCEs) modified with carboxyl-functionalized carbon nanofibers (fCNFs). CNFs have surface chemistry and reactivity similar to carbon nanotubes (CNTs), yet they are easier to produce and are of a lower cost than CNTs. By monitoring the current produced during the electrochemical oxidation of fentanyl, variables such as fCNF loading, fentanyl accumulation time, electrolyte pH, and differential pulse voltammetry parameters were optimized. Under an optimized set of conditions, the fCNF/SPCEs responded linearly to fentanyl in the concentration range of 0.125-10 μM, with a limit of detection of 75 nM. The fCNF/SPCEs also demonstrated excellent selectivity against common cutting agents found in illicit drugs (e.g., glucose, sucrose, caffeine, acetaminophen, and theophylline) and interferents found in biological samples (e.g., ascorbic acid, NaCl, urea, creatinine, and uric acid). The performance of the sensor was also successfully tested using fentanyl spiked into an artificial urine sample. The straightforward electrode assembly process, low cost, ease of use, and rapid response make the fCNF/SPCEs prime candidates for the detection of fentanyl in both physiological samples and street drugs., Competing Interests: The authors declare no competing financial interest., (Crown © 2024. Published by American Chemical Society.)