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The present study demonstrates the thermal stability and photocatalytic activity of TiO2-based nanotubes with respect to post-hydrothermal treatment. Titanate nanotubes were synthesized by adapting an alkali hydrothermal method from TiO2 sol using NaOH as a catalyst. The effect of post-hydrothermal heating on the properties—such as structure, morphology, textural properties, and activity—of as-synthesized one-dimensional titania nanostructure is investigated in detail. The characterizations are carried out using SEM, EDX, TEM, XRD, and a BET surface area analyzer. When heated in the presence of water in an autoclave, the protonated titanate phase of the nanotubes converts to anatase phase. Meanwhile, the tubular morphology is gradually lost as the post-hydrothermal heating duration increases. The photocatalytic activity was assessed utilizing the photo-oxidation of an amaranth dye. It is discerned that the as-prepared nanotubes are photocatalytically inactive but become active after post-hydrothermal processing. The activity trend follows the formation of the active phase—the titanate phase crystallizes into a photocatalytically-active anatase phase during post-hydrothermal heating. The effect of experimental parameters, such as reaction pH, dye concentration, and amount of catalyst, on the dye removal is studied. The findings also highlight that the role of holes/OH• is more prominent as compared to conduction band electron/O2−• for the removal of the dye. In addition, the photocatalyst exhibited excellent stability and reusability. [ABSTRACT FROM AUTHOR]

This work demonstrates the facile and efficient preparation protocol of β-Cyclodextrin-reduced graphene oxide modified glassy carbon electrode (β-CD/RGO/GCE) sensor for an impressive chiral selectivity analysis for phenylalanine enantiomers. In this work, the immobilization of β-CD over graphene sheets allows the excellent enantiomer recognition due to the large surface area and high conductivity of graphene sheets and extraordinary supramolecular (host-guest interaction) property of β-CD. The proposed sensor was well characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS) techniques. The analytical studies demonstrated that the β-CD/RGO/GCE exhibit superior chiral recognition toward L -phenylalanine as compared to D -phenylalanine. Under optimum conditions, the developed sensor displayed a good linear range from 0.4 to 40 µM with the limit of detection (LOD) values of 0.10 µM and 0.15 µM for l - and D -phenylalanine, respectively. Furthermore, the proposed sensor exhibits good stability and regeneration capacity. Thus, the as-synthesized material can be exploited for electrochemical enantiomer recognition successfully. [ABSTRACT FROM AUTHOR]

Abstract: A simple and highly sensitive method for simultaneous detection of anticancer drugs is developed by integrating the preconcentration and separation steps in a microfluidic device with an amperometric biosensor. An amperometric detection with dsDNA and cardiolipin modified screen printed electrodes are used for the detection of anticancer drugs at the end of separation channel. The preconcentration capacity is enhanced thoroughly using field amplified sample stacking and field amplified sample injection techniques. The experimental parameters affecting the analytical performances, such as pH, temperature, buffer concentration, water plug length, and detection potential are optimized. A reproducible response is observed during multiple injections of samples with a RSD <5%. The calibration plots are linear with the correlation coefficient between 0.9913 and 0.9982 over the range of 2–60 pM. The detection limits of four drugs are determined to be between 1.2 (±0.05) and 5.5 (±0.3) fM. The applicability of the device to the direct analysis of anticancer drugs is successfully demonstrated in a real spiked urine sample. Device was also examined for interference effect of common chemicals present in real samples. [Copyright &y& Elsevier]

Herein, we propose a facile chemical reduction method to synthesize the molybdenum carbide (Mo 2 C) nanoparticles and its application for the electrochemical detection of folic acid (FA) through imprinting technique. Raman scattering, photoelectron spectroscopy and electron microscopy techniques were employed to study the properties of Mo 2 C nanoparticles. FA imprinting was carried out in the presence of pyrrole monomer over Mo 2 C modified glassy carbon electrode (GCE). The proposed sensor showed the detection behavior for wide range of FA concentrations from 0.01 μM to 120 μM with an excellent LOD value of 4 nM and good selectivity toward FA as compared to other co-existing species in real samples. The fabricated MIP-Mo 2 C/GCE sensors were able to be replicated with ∼1.9% RSD, and their reproduced sensor offered good repeatability (RSD; 1.6%) and stability. • A facile chemical reduction method employed to synthesis the Mo 2 C. • MIP-Mo 2 C/GCE sensor electrode successfully fabricated by electropolymerization. • MIP-Mo 2 C/GCE sensor showed the superior sensitivity performance than NIP–Mo 2 C/GCE. • High reproducibility and stability revealed with an excellent LOD value of 4 nM. [ABSTRACT FROM AUTHOR]

Despite their high analytical performance, conventional analytical biosensor devices are usually difficult to handle, time-consuming, bulky and expensive. As a result, their applications remain restricted to resource-limited environments. In particular, the transportation of conventional analytical equipment is challenging for the proper in-situ point of need (PON)/point of care (POC) detection of biomolecules. In this context, smartphones, the most widely utilized cutting-edge mobile gadgets, continue to be a favored option because of their ease of portability and revolutionary sensing capabilities. On the other hand, aptamers are molecular recognition units consisting of nucleic acids with highly sensitive and selective recognition capabilities towards their respective targets. The coupling of smartphones with aptamers have led the development of advanced, user-friendly, portable, and cost-effective in-situ PON/POC biosensors for the detection of biomolecules. Such sensors are well-suited for a variety of applications, including food safety, environmental monitoring, and disease diagnostics. Herein, for the first time, achievements made between 2017 and 2022 in the concept and design of the smartphone-enabled aptasensors for biosensing applications are reviewed. The review covers different fabrication strategies and the discussion of several operating systems, underlying programs, and related software. At the end, the important merits, challenges, and future prospects of smart phone-driven aptasensors are presented. This report intends to assist scientists and engineers in comprehending the fabrication of smartphone-based aptasensors and their underlying sensing principles, as well as stimulating the future developments in the direction of affordable, portable, simple, and readily available sensing devices. • The smartphone-based aptasensors facilitate advanced, user-friendly, portable, and cost-effective PON and POC biosensing. • Smartphone-enabled aptasensors are well-suited for applications in food safety, environmental monitoring, and disease diagnostics. • Fabrication strategies, working mechanisms, underlying operating systems, and related hardware/software have been reviewed. • Advantages, challenges and future outlook of smartphone-based aptasensors have been discussed. [ABSTRACT FROM AUTHOR]