A gold electrode modified with hemoglobin and the chitosan@Fe3O4 nanocomposite particles for direct electrochemistry of hydrogen peroxide

Electroconductive bioplatform based on dextrin for the immobilization of hemoglobin: Application for electrochemical monitoring of H2O2

A novel biodegradable dextrin-based nanocomposite, involving polypyrrole (PPy) and hydrophilic dextrin (Dex) (PPy@Dex) was prepared using in-situ radical chemical polymerization technique. The obtained PPy@Dex bionanocomposite was fully characterized by FT-IR, XRD, FESEM, and DSC methods. The exceptional properties such as biocompatibility, high surface area, the proper functional group on the surface, and outstanding electrical conductivity of synthesized bionanocomposite made it a superior candidate over biomolecules immobilization. Electrochemical observations revealed that the PPy@Dex-coated glassy carbon electrode (GCE) demonstrated improved performance, making it a suitable substrate for immobilizing hemoglobin (Hb) and constructing an efficient biosensor. The resulting biosensor, named Hb-PPy@Dex/GCE, exhibited high activity in the reduction of hydrogen peroxide (H2O2). Amperometric examinations demonstrated an extensive linear range from 2 to 350 μM for Hb-PPy@Dex/GCE. The detection limit of the proposed approach was calculated to be 0.54 μM, following the S/N = 3 protocol.

Efficiency improvement in non-enzymatic H2O2 detection induced by the simultaneous synthesis of Au and Ag nanoparticles in an RGO/Au/Fe3O4/Ag nanocomposite

Developing a quick and precise technique for hydrogen peroxide (H₂O₂) detection would open up a new class of technologies for biological, medical and chemical applications.

Patchy gold coated Fe3O4 nanospheres with enhanced catalytic activity applied for paper-based bipolar electrode-electrochemiluminescence aptasensors

In this work, novel multifunctional patchy gold coated Fe₃O₄ hybrid nanoparticles (PG-Fe₃O₄ NPs) have been successfully synthesized in aqueous medium via a facile adsorption-reduction method. A rational formation mechanism has been proposed by monitoring the morphological evolution. The PG-Fe₃O₄ NPs retained the good magnetic property and exhibited excellent catalytical effeciency towards the electrochemical reduction of hydrogen peroxide. Chronoamperometric and amperometric experiments indicated a relatively high catalytic rate constant of 3.13 × 10⁵ M^-1 s^-1, a high sensitivity of 578.87 µA mM^-1 cm^-2 and a low Michaelis-Menten constant of 462 µM. Meanwhile, the introduction of patchy gold could help biofunctionalization via Au-S bond for different biodetection and biosensing purposes. Here, as an example, thiol-terminated aptamers were immobilized onto the patchy gold part as a signal probe to detect carcinoembryonic antigen (CEA). A related paper-based bipolar electrode-electrochemiluminescence (pBPE-ECL) aptasensor was fabricated as the low-cost, disposable and miniature platform. To improve the sensitivity, Au nanodendrites were electrodeposited at the BPE cathode as the matrix for Apt1 immobilization. This aptasensor showed a wide linear range of 0.1 pg mL^-1-15 ng mL^-1 with a low detection limit of 0.03 pg mL^-1, remaining competitive against other ones, and also demonstrating the PG-Fe₃O₄ NPs have promising potential for catalysis and bioassays.

MoS2 nanosheet–Au nanorod hybrids for highly sensitive amperometric detection of H2O2 in living cells

MoS₂–Au hybrids were utilized to construct a sensitive H₂O₂ electrochemical biosensor for the determination of H₂O₂ released from living cells.

Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications

Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.