Scheme 1
The interest of this research consists in using inorganic natural
alumino-silicates such as clay minerals, known to be harmless for human
health and biodiversity. Among these, smectite-type sodium
montmorillonite (NaMt) could be an interesting host matrice for metals
due to its natural abundance, cost effectiveness, non-toxicity, chemical
inertness, sorptive capabilities, large specific surface area (Komadel,
2016) and even beneficial medicinal effects (Carretero, 2002;
Nadziakiewicza, Kehoe, & Micek, 2019). .
To overcome this problem, inorganic carriers such as clay minerals for
metal nanoparticles have been investigated (Kim et al., 2007).
Successful attempts against bacteria were already achieved using other
clay minerals such as allophane and imogolite doped with metals like Ag,
Cu, Co, Zn (Stavitskaya et al., 2019; Williams et al., 2011). Attempts
were also achieved using functionalized clay minerals and vegetal fibers
for the dispersion of silver and copper ions (Joshi, Purwar, Udakhe, &
Sreedevi, 2015).
High adsorptive capabilities for metal nanoparticles in NaMt are largely
responsible for the antimicrobial properties of the metal-clays. The
adsorptive properties in NaMt are governed by a large specific surface
area with increased net negative charges on the sheets that can be
obtained by intercalation of NaMt with dendritic polyols like
BoltornTM H20 (Vdović, Jurina, Škapin, & Sondi,
2010). Reportedly, eco-friendly and cost-effective cotton fabric–based
composite materials doped with copper oxide showed antibacterial action
against Staphylococcus epidermis and Escherichia coli(Nabil, Christine, Julien, & Abdelkrim, 2018). The aim of this work was
to prepare organoclays and/or natural polymers for hosting metal
nanoparticles with long-term antibacterial effects.
Deeper insights in metal-matrice interaction will allow tailoring
optimal interactions with MNPs by modifying the type and number of
chemical functions of the organic moiety. This is expected to influence
the metal to be released, the release velocity and desired antibacterial
activity. This concept allows envisaging diverse applications for
controlled release of a wide variety and drugs and other medicinal
molecules.