Novel I–V Disposable Urea Biosensor Based on a Dip‐coated Hierarchical Magnetic Nanocomposite (Fe₃O₄@SiO₂@NH₂) on SnO₂:F Layer

Abstract

Silicon oxide was initially loaded on a Fe3O4 magnetic nanoparticle substrate (Fe3O4@SiO2) and then functionalized with ─NH2 group (Fe3O4@SiO2@NH2) to construct a novel hierarchical magnetic nanocomposite. A sensitive urea biosensor medium involving a dip‐coated hierarchical magnetic nanocomposite on F‐doped SnO2 conducting glass was designed (Fe3O4@SiO2@NH2/SnO2:F) to achieve an excellent platform for urease (Urs) enzyme immobilization via covalent linking to the exposed NH2 groups through glutaraldehyde (Urs/Fe3O4@SiO2@NH2/SnO2:F). The hierarchical magnetic nanocomposite selection criteria were based on enhancement of urea biosensing by Urs immobilization via covalent linking to the exposed NH2 groups, while the SnO2:F selection as substrate was based on its ability to afford high electronic density to the biosensor surface as an electrostatic repulsion layer for the anionic interferents in the biological environment. FE‐SEM, TEM, FTIR, CV, EIS, and I–V techniques established the morphology of the modified electrode's surface and electrochemical behavior of urea on the fabricated Urs/Fe3O4@SiO2@NH2/SnO2:F biosensor. The sensing mechanism can be clarified on the basis of the two reactions, namely (1) catalytic reaction and (2) oxidation or reduction of metal oxides, same as in the case of solid‐state gas sensors. The I–V results display high sensitivity for urea detection of within 5–210 mg/dL and a limit of detection of 3 mg/dL.

Improved Sensing Performance of Amperometric Urea Biosensor by Using Platinum Nanoparticles

“…Among the tested substances, NaCl exhibited the biggest interfering signal; however, this change was relatively small in comparison to urea response. It has been observed that especially the interference effect of glucose and ascorbic acid is lower than other urea biosensors [55, 57, 60, 61]. The results showed that the prepared biosensor is suitable for the selective detection of urea in real samples such as municipal wastewater and blood serum, containing glucose and ascorbic acid.…”

“…Among the tested substances, NaCl exhibited the biggest interfering signal; however, this change was relatively small in comparison to urea response. It has been observed that especially the interference effect of glucose and ascorbic acid is lower than other urea biosensors [55,57,60,61].…”

Studying physicochemical characteristics of Flutamide adsorption on the Zn doped SWCNT (5,5), using DFT and MO calculations

“…Proved amazing and unique properties of these structure led to a widespread use of them in various categories of science, including medicine, industry and technology. Due to their inherent features, SWCNTs are able to not only Review Article deliver the bioactive molecules across cell membranes, but also into the cell nuclei because of their very high surface areas [5][6][7][8]. Certain theoretical studies on the behaviors of 1, 3-dipolar cycloadditions on the (n,n) SWCNTs have been performed and the results of this investigation have been reported by the authors [9].…”

Highly sensitive electrochemical azaperone sensor based on magnetic silica –NH2-CS2 in the ostrich meat and rat plasma and its comparison with HPLC–MS/MS

“…The outer silica shell stabilizes Fe 3 O 4 nanoparticles in solution as well as provides reactive sites on its surface for functionalization [21,22]. Amine groups are one of the active functional groups that can lead to the functionalization of the aforementioned SiO 2 surface or silicate shell through the reaction of aminoalkyl triethoxysilane with the silica surface [23,24]. In the following, other additives (like S-contents compounds) and compression reactions can be performed on this amino nucleophile group to reach the desired level [25].…”