Design and fabrication of novel flexible sensor based on 2D Ni-MOF nanosheets as a preliminary step toward wearable sensor for onsite Ni (II) ions detection in biological and environmental samples.

Herein, for the first time, an innovative and sensitive flexible sensor for efficient potentiometric monitoring of Ni (II) ions has been designed and developed. The developed flexible sensor is constructed from highly porous activated flexible carbon cloth decorated with nitrogen and spherical porous carbon nanoparticles derived from low-cost cotton doped with polypyrrole nanoparticles via simple carbonization-activation process followed by dip-coating in membrane cocktail containing 2D Ni-MOF nanosheets as an electroactive material. The developed flexible sensor affords rapid, accurate and stable response for the Ni (II) ions monitoring at its trace level in the biological fluids including human saliva and sweat samples in addition to tap water as an environmental sample without any preconditioning steps over pH range of 2-8 with detection limit of 2.7 × 10-6. Additionally, the flexible sensor shows good antibacterial properties against both of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria presenting safe handling for human skin as a flexible sensor for wearable system applications. This study presents a forward step for the fabrication of a wearable sensor for rapid onsite monitoring of Ni (II) ions in biological and environmental samples.

Exploitation of 2D Cu-MOF nanosheets as a unique electroactive material for ultrasensitive Cu(II) ion estimation in various real samples.

Herein, hybrid carbon sensor has been developed with graphite sheets as a matrix, tricresyl phosphate (TCP) as a plasticizer and nanosheets of 2D Cu-MOF (metal-organic framework) as an electroactive material for the ultrasensitive Cu(II) ion detection in various real samples. Where, the present study proves the efficiency of 2D Cu-MOF as a promising sensing material for the development of Cu(II) ion selective carbon sensor. The developed 2D Cu-MOF nanosheets based sensor containing 2D Cu-MOF: TCP: graphite in the ratio of 2.67: 30.54: 66.79 (% wt/wt) displayed unique Nernstian behavior over two linearity ranges of 1.0 × 10-11-1.0 × 10-9 and 1.0 × 10-5-1.0 × 10-1 mol L-1 with slopes of 29.5 ± 0.25 and 29.6 ± 0.13 mV decade-1, respectively. The fabricated carbon sensor achieved a widely pH independency, fast response time and superior thermal stability with highly selective and ultrasensitive performance. Moreover, It has been efficiently applied for the Cu(II) ion potentiometric estimation in human hair, sesames seeds, two different tea infusions and tap water real samples.

Exploitation of o-benzoyl benzoic acid as an efficient electroactive material for selective determination of Cr (III) ions in pharmaceutical samples and industrial waste water using carbon sensor.

Herein, for the first time, o-benzoyl benzoic acid has been explored as a promising electroactive material for the fabrication of sensitive, precise and accurate carbon paste electrode (CPE) for selective detection of Cr (III) ion. o-benzoyl benzoic acid (o-BBA) as a sensing material and tricresylphosphate (TCP) as a solvent mediator improved the developed sensor performance to get the Nernstian cationic slope of 20.03 ± 0.11 mV decade-1 within the concentration range of 5.0 × 10-7-1.0 × 10-1 mol L-1. The sensor displayed a fast response time of 12 s reflecting a pH independency over the pH range of 3.1-4.7. Moreover, the reaction between the sensing material and Cr (III) ion on the developed sensor surface was elucidated using the microscopic technique such as scanning electron microscope (SEM) in addition to the energy dispersive X-ray analyzer (EDX). The proposed sensor showed an adequate shelf lifetime (∼33 days). The values of potentiometric selectivity coefficient were obtained by fixed interference and separate solution methods affirming a high distinguishing power of the fabricated sensor toward Cr (III) ions over the other interfering ions. The established sensor could be utilized with a promising success for the Cr (III) ion estimation in the industrial waste water and in the pharmaceutical forms. Additionally, it has been employed as a promising indicator sensor with a superior performance for potentiometric titration of Cr (III) ion against EDTA.