Voltammetric determination of doxycycline in feedstock using modified carbon screen-printed electrode

In this work, we describe the development of an electrochemical sensing platform that employs electrochemically reduced graphene oxide (ErGO) and gold (Au) deposited on a screen-printed carbon electrode (SPCE) to synthesize Au/ErGO/SPCE for the determination of the antibiotic drug doxycycline (DC). A modified Hummer's approach was adopted to initially prepare graphene oxide, which was then characterized by using powder XRD, FTIR, and UV spectroscopy before being utilized for modification on SPCE. Cyclic voltammetry was performed to form ErGO on SPCE to give ErGO/SPCE followed by electrodeposition of gold to get a final modified electrode Au/ErGO/SPCE. The effect of experimental conditions, like scan rate and pH on the electrochemical behavior of DC for Au/ErGO/SPCE, was evaluated. Square wave voltammetry (SWV) and cyclic voltammetry (CV) measurements were used to assess the electro-oxidation of DC on Au/ErGO/SPCE, and the electrochemical reaction conditions were also optimized. Furthermore, Au/ErGO/SPCE-based electrochemical sensors showed good recovery and high accuracy for DC determination in the complex food matrix and blood serum. The limit of detection (LOD), the limit of quantification (LOQ), and the linear calibration range of DC on Au/ErGO/SPCE under optimum experimental conditions were 0.124 µm, 0.415 µm, and 1-100 µm respectively, with high sensitivity of 0.194 μA μM-1 cm-2. Finally, the proposed electrochemical sensing platform was effectively used to determine low DC concentrations in real samples such as chicken flesh and blood serum, indicating its wide range of applications in quality control.

Surface engineering of carbon selenide nanofilms on carbon cloth: An advanced and ultrasensitive self-supporting binder-free electrode for nitrite sensing

Large uptakes of nitrite have been proven to be detrimental to human health, therefore, the development of high-performance nitrite sensors is highly emergent. Herein, a carbon selenide nanofilms modified carbon fiber cloth (CSe₂ NF/CC) electrode was obtained via in-situ synthesis to detect nitrite. The electrode integrates the collective merits of macroporous CC and pleated carbon selenide nanofilms, possessing a low overpotential of 0.83 V, a high electrochemical active surface area (EASA) of 5.39 cm², great electrical conductivity, and fast charge transport as well as ion diffusion. The proposed electrode achieved a low limit of detection of 0.04 μmol L^-1 (S/N = 3), a high sensitivity of 2048.56 μA mmol L^-1 cm^-2, excellent selectivity, and long-term stability. Additionally, the CSe₂ NF/CC was successfully used for nitrite detection in different food samples such as pickled vegetables and sausage samples.

Functional Graphene Nanomaterials Based Architectures: Biointeractions, Fabrications, and Emerging Biological Applications

Functional graphene nanomaterials (FGNs) are fast emerging materials with extremely unique physical and chemical properties and physiological ability to interfere and/or interact with bioorganisms; as a result, FGNs present manifold possibilities for diverse biological applications. Beyond their use in drug/gene delivery, phototherapy, and bioimaging, recent studies have revealed that FGNs can significantly promote interfacial biointeractions, in particular, with proteins, mammalian cells/stem cells, and microbials. FGNs can adsorb and concentrate nutrition factors including proteins from physiological media. This accelerates the formation of extracellular matrix, which eventually promotes cell colonization by providing a more beneficial microenvironment for cell adhesion and growth. Furthermore, FGNs can also interact with cocultured cells by physical or chemical stimulation, which significantly mediate their cellular signaling and biological performance. In this review, we elucidate FGNs-bioorganism interactions and summarize recent advancements on designing FGN-based two-dimensional and three-dimensional architectures as multifunctional biological platforms. We have also discussed the representative biological applications regarding these FGN-based bioactive architectures. Furthermore, the future perspectives and emerging challenges will also be highlighted. Due to the lack of comprehensive reviews in this emerging field, this review may catch great interest and inspire many new opportunities across a broad range of disciplines.

Phase transformation-controlled synthesis of CuO nanostructures and their application as an improved material in a carbon-based modified electrode

Column-shaped CuO nanorods have been synthesized by a two-step “precursor formation-crystallization” process using a hydrothermal method with advantages of being template- and surfactant-free.