ABSTRACT
Silica nanoparticles (SiNPs) have emerged as a multipurpose solution with wide-ranging applications in various industries such as medicine, agriculture, construction, cosmetics, and food production. In 1961, Stöber introduced a ground-breaking sol-gel method for synthesizing SiNPs, which carried a new era of exploration both in academia and industry, uncovering numerous possibilities for these simple yet multifaceted particles. Inspite of numerous reported literature with wide applicability, the synthesis of these nanoparticles with the desired size and functionalities poses considerable challenges. Over time, researchers have strived to optimize the synthetic route, particularly by developing greener approaches that minimize environmental impact. By reducing hazardous chemicals, energy consumption, and waste generation, these greener synthesis methods have become an important focus in the field. This review aims to provide a comprehensive analysis of the various synthetic approaches available for different types of SiNPs. Starting from the Stöber' method, we analyze other methods as well to synthesis different types of SiNPs including mesoporous, core-shell and functionalized nanoparticles. With increasing concerns with the chemical methods associated for environmental issues, we aim to assist readers in identifying suitable greener synthesis methods tailored to their specific requirements. By highlighting the advancements in reaction time optimization, waste reduction, and environmentally friendly precursors, we offer insights into the latest techniques that contribute to greener and more sustainable SiNPs synthesis. Additionally, we briefly discuss the diverse applications of SiNPs, demonstrating their relevance and potential impact in fields such as medicine, agriculture, and cosmetics. By emphasizing the greener synthesis methods and economical aspects, this review aims to inspire researchers and industry professionals to adopt environmentally conscious practices while harnessing the immense capabilities of SiNPs.
ABSTRACT
Nowadays, silica nanoparticles are gaining tremendous importance because of their wide applications across different domains such as drug delivery, chromatography, biosensors, and chemosensors. The synthesis of silica nanoparticles generally requires a high percentage composition of organic solvent in an alkali medium. The eco-friendly synthesis of silica nanoparticles in bulk amounts can help save the environment and is cost-effective. Herein, efforts have been made to minimize the concentration of organic solvents used during synthesis via the addition of a low concentration of electrolytes, e.g., NaCl. The effects of electrolytes and solvent concentrations on nucleation kinetics, particle growth, and particle size were investigated. Ethanol was used as a solvent in various concentrations, ranging from 60% to 30%, and to optimize and validate the reaction conditions, isopropanol and methanol were also utilized as solvents. The concentration of aqua-soluble silica was determined using the molybdate assay to establish reaction kinetics, and this approach was also utilized to quantify the relative concentration changes in particles throughout the synthesis. The prime feature of the synthesis is the reduction in organic solvent usage by up to 50% using 68 mM NaCl. The surface zeta potential was reduced after the addition of an electrolyte, which made the condensation process faster and helped reaching the critical aggregation concentration in a shorter time. The effect of temperature was also monitored, and we obtained homogeneous and uniform nanoparticles by increasing the temperature. We found that it is possible to tune the size of the nanoparticles by changing the concentration of electrolytes and the temperature of the reaction using an eco-friendly approach. The overall cost of the synthesis can also be reduced by â¼35% by adding electrolytes.
ABSTRACT
Since the identification of the first human coronavirus in the 1960s, a total of six coronaviruses that are known to affect humans have been identified: 229E, OC43, severe acute respiratory syndrome coronavirus (SARS-CoV), NL63, HKU1, and Middle East respiratory syndrome coronavirus (MERS-CoV). Presently, the human world is affected by a novel version of the coronavirus family known as SARS-CoV-2, which has an extremely high contagion rate. Although the infection fatality rate (IFR) of this rapidly spreading virus is not high (ranging from 0.00% to 1.54% across 51 different locations), the increasing number of infections and deaths has created a worldwide pandemic situation. To provide therapy to severely infected patients, instant therapeutic support is urgently needed and the repurposing of already approved drugs is presently in progress. In this regard, the development of nanoparticles as effective transporters for therapeutic drugs or as alternative medicines is highly encouraged and currently needed. The size range of the viruses is within 60-140 nm, which is slightly larger than the diameters of nanoparticles, making nanomaterials efficacious tools with antiviral properties. Silver-based nanomaterials (AgNMs) demonstrate antimicrobial and disinfectant effects mostly by generating reactive oxygen species (ROS) and are presently considered as a versatile tool for the treatment of COVID-19 patients. Other metal-based nanoparticles have been primarily reported as delivery agents or surface modifying agents, vaccine adjuvant against coronavirus. The present review summarizes and discusses the possible effectiveness of various surface-modified AgNMs against animal coronaviruses and presents a concept for AgNM-based therapeutic treatment of SARS-CoV-2 in the near future.
