Green Synthesis of Silver Nanoparticles Using the Cell-Free Supernatant of Haematococcus pluvialis Culture

Abstract

The green synthesis of silver nanoparticles (AgNPs) using the cell-free supernatant of a Haematococcus pluvialis culture (CFS) was implemented in the current study, under illumination conditions. The reduction of Ag+ to AgNPs by the CFS could be described by a pseudo-first-order kinetic equation at the temperature range tested. A high reaction rate during synthesis and stable AgNPs were obtained at 45 °C, while an alkaline pH (pH = 11.0) and a AgNO3 aqueous solution to CFS ratio of 90:10 (v/v) proved to be the most effective conditions in AgNPs synthesis. A metal precursor (AgNO3) at the concentration range tested (1–5 mM) was the limited reactant in the synthesis process. The synthesis of AgNPs was accomplished under static and agitated conditions. Continuous stirring enhanced the rate of reaction but induced aggregation at prolonged incubation times. Zeta potential and polydispersity index measurements indicated stable AgNPs and the majority of AgNPs formation occurred in the monodisperse phase. The X-ray diffraction (XRD) pattern revealed the face-centered cubic structure of the formed AgNPs, while TEM analysis revealed that the AgNPs were of a quasi-spherical shape with a size from 30 to 50 nm. The long-term stability of the AgNPs could be achieved in darkness and at 4 °C. In addition, the synthesized nanoparticles showed antibacterial activity against Escherichia coli.

Use of Residual Malt from an Artisanal Beer Brewing Process in the Biosynthesis of Silver Nanoparticles Mediated by Nucleating and Structure-Directing Agents

“…Physical and chemical techniques are the conventional methods used in the AgNPs synthesis; however, both methods are associated with major drawbacks such as the consumption of large amounts of energy (high costs) and the use of toxic substances as reducing agents (e.g., sodium borohydride and hydrazine), which are harmful to the environment. The above fact led to the development of biological methods as an eco-friendly option to synthesize AgNPs [1][2][3][4][5][6][7][8]. AgNPs produced by biological methods show numerous benefits: low cost, easy production at high scales, decrease in energy Molecules 2024, 29, 1660 2 of 16 consumption, and environmental compatibility.…”

Green Synthesized Chitosan Nanoparticles for Controlling Multidrug-Resistant mecA- and blaZ-Positive Staphylococcus aureus and aadA1-Positive Escherichia coli

“…The use of nanomaterials as alternatives to antibiotics has drawn significant attention due to their enhanced functionality, long-acting effects, surface-to-volume ratio, chemical complexation properties, high surface areas, enhanced ion-exchange capacity, low toxicity, high stability [21], and numerous potential applications in science and technology [21][22][23][24]. Metal, metal oxide, organic, and hybrid nanoparticles (NPs), such as AgNPs, ZnNPs, and TiO 2 NPs, have been utilized in versatile biomedical [25][26][27] and industrial applications [28,29]. However, they are not feasible for therapeutic applications due to their lack of biocompatibility [30].…”

“…Thus, efforts have been made to develop eco-friendly methods for synthesizing biocompatible nanoparticles. The recently promoted biological approaches like plant extracts as well as microbe-based synthesis of nanomaterials have filled the void of bio-incompatibility, exhibiting superiority over the chemical approaches [25,31,32]. It has been reported that biological/green synthesized nanomaterials have been effectively controlling many endemic diseases with less adverse effects [33].…”

“…It has been reported that biological/green synthesized nanomaterials have been effectively controlling many endemic diseases with less adverse effects [33]. Thus, the trend of using natural products as material sources has increased, and the active plant extracts and microbial agents are frequently employed for new drug discovery [25,29,[34][35][36]. Chitosan oligosaccharide, which can be extracted from chitinous organisms, has gained attention for its abundance in nature, safety, biodegradability, self-renewability, and antimicrobial activity [37].…”