Antimicrobial metal-based nanoparticles: a review on their synthesis, types and antimicrobial action

Abstract

The investigation of novel nanoparticles with antimicrobial activity has grown in recent years due to the increased incidence of nosocomial infections occurring during hospitalization and food poisoning derived from foodborne pathogens. Antimicrobial agents are necessary in various fields in which biological contamination occurs. For example, in food packaging they are used to control food contamination by microbes, in the medical field the microbial agents are important for reducing the risk of contamination in invasive and routine interventions, and in the textile industry, they can limit the growth of microorganisms due to sweat. The combination of nanotechnology with materials that have an intrinsic antimicrobial activity can result in the development of novel antimicrobial substances. Specifically, metal-based nanoparticles have attracted much interest due to their broad effectiveness against pathogenic microorganisms due to their high surface area and high reactivity. The aim of this review was to explore the state-of-the-art in metal-based nanoparticles, focusing on their synthesis methods, types, and their antimicrobial action. Different techniques used to synthesize metal-based nanoparticles were discussed, including chemical and physical methods and “green synthesis” methods that are free of chemical agents. Although the most studied nanoparticles with antimicrobial properties are metallic or metal-oxide nanoparticles, other types of nanoparticles, such as superparamagnetic iron-oxide nanoparticles and silica-releasing systems also exhibit antimicrobial properties. Finally, since the quantification and understanding of the antimicrobial action of metal-based nanoparticles are key topics, several methods for evaluating in vitro antimicrobial activity and the most common antimicrobial mechanisms (e.g., cell damage and changes in the expression of metabolic genes) were discussed in this review.

Recent progress in actuation technologies of micro/nanorobots

“…Third, the study of fabrication and new materials of micro/nanorobots. With the continuous development of nanotechnology, more and more new materials and new technologies have emerged [51,52]. In order to make good use of micro/nanorobots in biomedicine and other fields, new fabrication methods of micro/ nanorobots should be explored, and more biocompatible nanomaterials should be selected to reduce costs and expand applications.…”

Improving the Antimicrobial and Mechanical Properties of Epoxy Resins via Nanomodification: An Overview

“…Thus, the membrane damage by antimicrobial agents must occur through different mechanisms. It was observed that metal NPs (usually with positive charges) are more active against Gram-positive bacteria, having higher permeability and negative charges on the surface, that attract NPs, in comparison with Gram-negative bacteria, where the double membrane, with a lower negative charge, acts as a physical barrier against hydrophobic compounds [ 14 ].…”

“…(a) Nanocomposites. Since ancient times, materials containing silver or copper have been used as antimicrobial agents; nowadays metallic (i.e., Ag and Cu) and metal-oxide (i.e., ZnO, CuO, NiO, TiO 2 ) nanoparticles provide strong antimicrobial activity in small dosages against a wide variety of microorganisms due to their dimensions, shapes, charges, high ratio of surface areas to mass, and high reactivities [ 14 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Due to electronic, optical, and magnetic properties, multi-metallic nanoparticles were recently proposed as innovative antimicrobial agents, which could help to overcome antimicrobial resistance [ 32 ].…”

“…The properties of nanoparticles, in terms of morphology and size, strongly depend on the synthesis methods used [ 14 ], which could be physical (i.e., evaporation/condensation for Ag, magnetron sputtering, or mechanochemical processes for ZnO, microwave-thermal methods, and photoreduction processes for Ag or CuO, pulsed laser ablation for ZnO), chemical (i.e., atomic layer deposition for TiO 2 , chemical reduction for Ag, sol–gel for TiO 2 , reverse micellar route, or solvothermal or hydrothermal method for ZnO), or biological (through the usage of plant extracts, algae, bacteria, or fungi, which behave as biological nanofactories that can release proteic substances able to chemically reduce metal ions [ 34 , 35 , 36 ]).…”

Low‐Temperature Sn0 Nanoparticles Synthesis by Means of Tin(II) N,N‐Complexes Reduction

“…As an example of a top‐down approach from bulk metal, one can name high‐intensity ultrasound treatment, [8] the spark erosion method [9] or the surfactant‐assisted solution plasma technique [10] . The ablation method, the next top‐down method for the preparation of metallic nanoparticles, [11] was used for the Ge−Sn alloy or SnO x nanoparticles [12] . The tin nanoparticles resulting from the procedures mentioned above are nearly spherical but with a large size distribution (e. g. 50–3500 nm [8] ).…”