Natural Nanoclay-Based Silver–Phosphomolybdic Acid Composite with a Dual Antimicrobial Effect

Abstract

The problem of microbial growth on various surfaces has increased concern in society in the context of antibiotic misuse and the spreading of hospital infections. Thus, the development of new, antibiotic-free antibacterial strategies is required to combat bacteria resistant to usual antibiotic treatments. This work reports a new method for producing an antibiotic-free antibacterial halloysite-based nanocomposite with silver nanoparticles and phosphomolybdic acid as biocides, which can be used as components of smart antimicrobial coatings. The composite was characterized by using energy-dispersive X-ray fluorescence spectroscopy and transmission electron microscopy. The release of phosphomolybdic acid from the nanocomposite was studied by using UV–vis spectroscopy. It was shown that the antibiotic-free nanocomposite consisting of halloysite nanotubes decorated with silver nanoparticles loaded with phosphomolybdic acid and treated with calcium chloride possesses broad antibacterial properties, including the complete growth inhibition of Staphylococcus aureus and Pseudomonas aeruginosa bacteria at a 0.5 g × L –1 concentration and Acinetobacter baumannii at a 0.25 g × L –1 concentration.

Prokaryotic and eukaryotic toxicity of halloysite decorated with photoactive nanoparticles

“…Halloysite has been used as a carrier for various antimicrobial agents such as nanoparticles, metal ions, antibiotics, essential oils, biopolymers, phenolic compounds, surfactants and food preservatives. [51][52][53][54] The outer halloysite surface is composed of nonreactive siloxane (Si-O-Si) groups and chemically active Si-OH groups which exist only at the defect areas and edges of the tubes (Fig. 3).…”

Recent Advances of Halloysite Nanotubes in Biomedical Applications

“…Novikov [93] Ag; PMo Direct antibacterial effect HNT−PMo−Ag Load PMo and then immobilize AgNPs using seed-growth method.…”

“…A compendium of studies underscores that distinctly tailored HNT composites wield the capacity for targeted bacterial eradication, [88][89][90][91][92][93][94][95][96][97][98][99][100] with discernible modifiers classifiable into two principal categories: bioactive materials and minerals.…”

“…In a separate dimension, Novikov's group charted a unique trajectory, coupling phosphomolybdic acid loading with AgNP immobilization onto HNTs via a seed‐growth methodology. [ 93 ] The outcome bore testimony to the synergistic interplay between silver and phosphomolybdic acid, culminating in a composite with pervasive antibacterial potential, inclusive of the complete growth inhibition of S. aureus , P. aeruginosa bacteria, and Acinetobacter baumannii .…”

Antimicrobial Nanomaterials Based on Halloysite Clay Mineral: Research Advances and Outlook

“…Phosphomolybdic acid (PMo) was loaded into HNTs to synthesize nanomaterials with bactericidal properties, without the use of antibiotics [ 62 ]. The actual confinement of the PMo inside the tubes was verified by TEM analysis coupled with an EDX probe, and release experiments showed that the total amount of acid loaded in the tubes was released after 135 min.…”