A Self‐assembled L‐Cysteine and Electrodeposited Gold Nanoparticles‐reduced Graphene Oxide Modified Electrode for Adsorptive Stripping Determination of Copper

Abstract

Glassy carbon electrode (GCE) modified with L-cysteine and gold nanoparticles-reduced graphene oxide (AuNPs-RGO) composite was fabricated as a novel electrochemical sensor for the determination of Cu 2 + . The AuNPs-RGO composite was formed on GCE surface by electrodeposition. The L-cysteine was decorated on AuNPs by self-assembly. Physicochemical and electrochemical properties of L-cysteine/AuNPs-RGO/GCE were characterized by scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy, Raman spectroscopy, X-ray diffraction, cyclic voltammetry and adsorptive stripping voltammetry. The results validated that the prepared electrode had many attractive features, such as large electroactive area, good electrical conductivity and high sensitivity. Experimental conditions, including electrodeposition cycle, self-assembly time, electrolyte pH and preconcentration time were studied and optimized. Stripping signals obtained from L-cysteine/ AuNPs-RGO/GCE exhibited good linear relationship with Cu 2 + concentrations in the range from 2 to 60 mg L À1 , with a detection limit of 0.037 mg L À1 . Finally, the prepared electrode was applied for the determination of Cu 2 + in soil samples, and the results were in agreement with those obtained by inductively coupled plasma mass spectrometry.

Deposition of nanomaterials: A crucial step in biosensor fabrication

“…In another study, a hybrid composite of NiO NPs, PANI, and GO was deposited onto GCE using a two-step process [224]. Aniline and GO were mixed and coated on the surface of GCE followed by NiO NPs electrodeposition on aniline/GO/GCE in NiCl2 solution using a chronoamperometric process, which polymerized the aniline and deposited NiO NPs [249]; graphene embedded in a bowl-shaped PPy microcontainer was used for dopamine detection [250], Pt-incorporated fullerene-like ZnO nanospheres deposited onto GCE was used for cholesterol detection [251], Au NPs-rGO deposited onto GCE was used for determination of methylmercury (CH3Hg + ) in fish [252], and many more [253][254][255][256]. Notably, the direct electrodeposition of composite nanomaterials has been preferred for realizing the high conductivity and synergistic effect between the composite materials for biosensing applications.…”

“…To fabricate highly selective and sensitive glucose biosensors, GOx was immobilized on electrochemically deposited nanostructures, which presented excellent sensing performance during glucose detection[234][235][236][237][238][239][240]. However, the stability of such biosensors remains challenging due to the use of enzymes.In addition, electrochemically deposited nanomaterials onto electrode surfaces were used for a variety of biosensor applications[241][242][243][244][245][246][247][248][249][250][251][252][253][254][255][256]. For instance, electrochemical co-deposited cytochrome c and vertically aligned rGO onto GCE were used for H2O2 and Au nanostructures deposited onto an FTO substrate was used for Escherichia coli detection[245]; a two-dimensional (2D) MoS2 nanosheet onto Au-coated was used for nonesterified fatty acid biomarker monitoring[246]; iron terephthalate SPEs metal-organic framework onto GCE was used for H2O2 and nitrite detection[247]; cubic Cu2O nanocages loaded with Au NPs onto GCE was used for thrombin detection [248]; Nafion-coated mesoporous Pd film onto an Au substrate was used for detection of lactic acid…”

Graphene‐AuNP Enhanced Inkjet‐printed Silver Nanoparticle Paper Electrodes for the Detection of Nickel(II)‐Dimethylglyoxime [Ni(dmgH2)] Complexes by Adsorptive Cathodic Stripping Voltammetry (AdCSV)

“…Of these, metallic modifications remain crucial in the analysis of metal ions and have been well documented. Metal electrodes [40][41][42][43], metallic films [44][45][46][47] and metal nanoparticles [48][49][50] have been extensively studied to improve the detection efficiency of the AdSV technique. To date, all work dedicated to the electrochemical sensing of metals at paper-based sensing devices have been limited to ASV approaches.…”