Single-Step Green Synthesis of Highly Concentrated and Stable Colloidal Dispersion of Core-Shell Silver Nanoparticles and Their Antimicrobial and Ultra-High Catalytic Properties

Abstract

The versatile one-pot green synthesis of a highly concentrated and stable colloidal dispersion of silver nanoparticles (Ag NPs) was carried out using the self-assembled tannic acid without using any other hazardous chemicals. Tannic acid (Plant-based polyphenol) was used as a reducing and stabilizing agent for silver nitrate in a mild alkaline condition. The synthesized Ag NPs were characterized for their concentration, capping, size distribution, and shape. The experimental results confirmed the successful synthesis of nearly spherical and highly concentrated (2281 ppm) Ag NPs, capped with poly-tannic acid (Ag NPs-PTA). The average particle size of Ag NPs-PTA was found to be 9.90 ± 1.60 nm. The colloidal dispersion of synthesized nanoparticles was observed to be stable for more than 15 months in the ambient environment (25 °C, 65% relative humidity). The synthesized AgNPs-PTA showed an effective antimicrobial activity against Staphylococcus Aureus (ZOI 3.0 mM) and Escherichia coli (ZOI 3.5 mM). Ag NPs-PTA also exhibited enhanced catalytic properties. It reduces 4-nitrophenol into 4-aminophenol in the presence of NaBH4 with a normalized rate constant (Knor = K/m) of 615.04 mL·s−1·mg−1. For comparison, bare Ag NPs show catalytic activity with a normalized rate constant of 139.78 mL·s−1·mg−1. Furthermore, AgNPs-PTA were stable for more than 15 months under ambient conditions. The ultra-high catalytic and good antimicrobial properties can be attributed to the fine size and good aqueous stability of Ag NPs-PTA. The unique core-shell structure and ease of synthesis render the synthesized nanoparticles superior to others, with potential for large-scale applications, especially in the field of catalysis and medical.

Recent progress in tannic acid-driven antibacterial/antifouling surface coating strategies

“…The TA-functionalized MNPs and metal ions were coated by various methods such as drop-coating, 115 UV-assisted deposition, 85 self-assembly deposition 113 electrochemical coating, 116 and spray-coating. 117 Because of its outstanding and well-known antibacterial/antibiofilm characteristics, Ag has attracted much attention among the various MNPs.…”

One‐Pot Preparation of Polysaccharide‐Based Antibacterial Hydrogel for Skin Wound Repair

“…[29,30] Tannic acid (TA) [31,32] is a natural plant polyphenol with good reducibility, and Ag + can be reduced by TA without having to subsequently remove it from the hydrogel, as it is a nontoxic reducing agent. [33,34] In addition, Ag + initiates the oxidation of TA to begin Schiff base reaction. [35,36] The addition of Ag + can exert antibacterial and cross-linking effects.…”

Development of Novel Antimicrobial and Antiviral Green Synthesized Silver Nanocomposites for the Visual Detection of Fe3+ Ions

“…Polymer-coated metallic nanocomposites have gained considerable attention due to their unique applications, especially in the field of catalysis [ 17 , 18 ], medical [ 19 , 20 ], energy storage devices [ 21 ], flexible electronics [ 22 , 23 , 24 , 25 ], and sensing [ 26 ]. However, current methods are multi-step, and they require high energy input for the fabrication of metallic nanocomposites [ 27 ].…”

“…The color change can be observed by the naked eye. It was reported that encapsulated silver nanocomposites with higher aqueous stability have a strong effect against pathogens (viruses, bacteria, and fungus) [ 17 , 35 ]. Thus, we analyzed the antibacterial, antiviral, and antifungal behavior of the synthesized silver nanocomposites by incubating them with bacteria ( Escherichia coli and Staphylococcus aureus), viruses ( Influenza virus and Feline calicivirus) and yeast (Candida albicans).…”