Toxic Ag+ detection based on Au@Ag core shell nanostructure formation using Tannic acid assisted synthesis of Pullulan stabilized gold nanoparticles

Abstract

Herein, a sensitive colorimetric detection strategy is proposed for Ag+ detection based on the use of environmentally friendly synthesis of gold nanoparticles (AuNPs), at room temperature, using (tannic acid, TA), as the reductant and pullulan (PUL) as stabilizing agent. The colloidal solution (TA/PUL-AuNPs), at the optimal synthesis conditions, showed maximum absorbance at 529 nm with a berry red color. TEM and FESEM validated that the particles are spherical and monodispersed, while other characterization results elucidated the role of pullulan in the nano-synthesis. Ag+ addition to the probe (TA/PUL-AuNPs), pH 11, resulted in naked-eye color changes, owing to Au@Ag core shell nanostructure formation. Further, the added Ag+ is reduced to AgNPs, on the surface of the TA/PUL-AuNPs probe. A hypsochromic shift in the absorption maximum, from 529 to 409 nm was observed, while (AAg+-Abl)@409 nm exhibited linearity with Ag+ concentrations, from 0.100 to 150 µM. The estimated limit of detection was 30.8 nM, which is far lower than the acceptable limit of 0.930 µM from the regulatory agency. The TA/PUL-AuNPs probe was further tested for Ag+ detection in lake water samples, and it displayed satisfactory detection performances for real sample applications.

Electrochemical Sensors based on Gold–Silver Core–Shell Nanoparticles Combined with a Graphene/PEDOT:PSS Composite Modified Glassy Carbon Electrode for Paraoxon-ethyl Detection

“…PEDOT:PSS could employed to avoid the restacking problem between the graphene layers. , In addition, gold–silver core–shell (Au–Ag) as a bimetallic particle has shown a synergistic effect in terms of its optical properties and electrocatalytic activity when employed as an electrode modifier . The employment of Au–Ag core–shell modified electrodes has been investigated for the quantitative detection of antimicrobial drugs, redox protein, , heavy metals, , fungicides, and antidepressants . However, to the best of our knowledge, no previous work has reported the employment of a combination between Au–Ag core–shell nanoparticles with the composite of graphene and PEDOT:PSS as a platform for electrochemical sensors.…”

Influence of Carboxymethyl Cellulose on the Green Synthesis of Gold Nanoparticles Using Gliricidia sepium and Petiveria alliacea Extracts: Surface-Enhanced Raman Scattering Effect Evaluation

“…Electrostatic stabilization is a mechanism susceptible to modifying the charge distribution around the nanoparticle. According to the stabilization of MNPs, fluorides, carboxylates, polymers, and acids have been reported; − however, these can modify the chemistry of the surface and the electrical, catalytic, and optical properties. Natural derivatives such as chitosan, hydroxypropylmethylcellulose, and other cellulose derivatives such as ethylcellulose , and carboxymethylcellulose , have also been used.…”

Zein-Induced Polyelectrolyte Complexes for Encapsulating Triterpenoid Phytochemicals

“…Polysaccharides, such as pullulan and pectin, are used as hydrophilic materials to coat the surfaces of protein vectors . Pullulan produced by Aureobasidium pullulans is a film-forming shell polysaccharide with maltotriose units (α-1,4-; α-1,6-glucan′) adsorption properties. − Pectin forms a cellulose–hemicellulose network hydrogel held together by hydrogen bonding and acts as a physical support fixture in a tree-grid-like structure. ,, Pectin is negatively charged in acidic environments, and low-methoxyl pectin has more carboxyl groups than high-methoxyl pectin . Therefore, it allows electrostatic repulsion and coassembly interactions with positively charged zein in the nanocomposites .…”

“… 13 Pullulan produced by Aureobasidium pullulans is a film-forming shell polysaccharide with maltotriose units (α-1,4-; α-1,6-glucan′) adsorption properties. 14 − 16 Pectin forms a cellulose–hemicellulose network hydrogel held together by hydrogen bonding and acts as a physical support fixture in a tree-grid-like structure. 13 , 17 , 18 Pectin is negatively charged in acidic environments, 18 and low-methoxyl pectin has more carboxyl groups than high-methoxyl pectin.…”

“…Previous studies have shown that proline-rich proteins can form hydrogen bonds and hydrophobic interactions with polyphenols and triterpenoids owing to the aromatic residues present in proline. 21 Furthermore, pullulan has ideal gel-forming properties in water 14 and is combined with aligned hydroxyl groups; therefore, it may have an appropriate immobilization ability between zein and negatively charged hydrophilic pectin. We hypothesized that formulating a polyelectrolyte complex by combining pullulan, pectin, and zein can increase the water solubility of phytochemicals and improve the storage stability of the complex.…”