149
6.2.3 Effect of Functionalized Nanoparticles
on Drug-Resistant Bacteria
Functionalization of nanoparticles using different types of ligands enables multivalent interactions and stronger adherence to biological molecules. As a result, such
functionalized nanoparticles have also demonstrated nanotoxic effects against resistant bacteria (Table 6.3). Surface functionalization of nanoparticles has been carried
out by different approaches such as linking to side chains or capping with polymeric
agents. Capping of silver nanoparticles with carboxymethyl tamarind prevented
self-aggregation and enabled long-term nanoparticle stabilization (Sanyasi et al.
2016). These nanoparticles effectively inhibited the growth of multidrug-resistant
bacterial strains S. haemolyticus, S. epidermis, E. coli, K. pneumoniae, and E. cloacae, in comparison to commonly used antibiotics. Very recently, silver nanoparticles
have been developed having hydroxyapatite–zoledronate functional groups. These
were found to be active against multidrug-resistant Gram-positive and Gramnegative bacteria (Boanini et al. 2018). Alcohol- functionalized silver nanoparticles
were active against antibiotic-resistant E. coli, S. aureus, and S. typhimurium
(Dorjnamjin et al. 2008). Similarly, silver nanoparticles modified with polyvinyl
alcohol–melamine formaldehyde were able to inhibit infections caused by antibiotic-resistant strains (Kakkar et al. 2015).
Table 6.3 also shows that in addition to silver, zinc oxide nanoparticles have also
been functionalized quite frequently and used for their antibacterial effect against a
range of resistant bacteria. Zinc oxide alginate beads exerted 98% antibacterial
effect over resistant E. coli DH5-α (Baek et al. 2019a). In another interesting study,
gold nanoparticles modified with cationic functional groups were found to remarkably inhibit the bacterial resistance for as many as 20 generations (Li et al. 2014).
Gold nanoparticles have also been functionalized with enzymes or amino acids
(Tiwari et al. 2011, Chen et al. 2010). Functionalized metal oxide nanoparticles
such as alumina-coated iron oxide magnetic nanoparticles and Fe 3 O 4 –gold nanoeggs
have also been reported for their antimicrobial efficacy against multidrug-resistant
bacteria (Malka et al. 2013; Huang et al. 2009; Yu et al. 2011).
It is also interesting to note that metal-doped nanoparticles have also shown
promising antimicrobial features against resistant bacteria (Kunkalekar et al. 2013,
Malka et al. 2013, Hameed et al. 2016). Antimicrobial activity of the zinc-doped
copper oxide nanocomposite on methicillin-resistant S. aureus and multidrugresistant E. coli was 10,000 times more as compared to individual nanoparticles
(Malka et al. 2013). A comparative study on extended-spectrum beta-lactamaseproducing strains of E. coli and K. pneumoniae showed that neodymium doped zinc
oxide nanoparticles had greater antibacterial effect than pure zinc oxide nanoparticles (Hameed et al. 2016). Das et al. (2017b) have also reported the disinfection of
multidrug-resistant E. coli using iron-doped zinc oxide nanoparticles. When used as
a photocatalyst for disinfection, the nanoparticles induced lipid peroxidation and
potassium ion leakage indicating membrane disintegration.
6 Exploring Microbial Nanotoxicity Against Drug Resistance in Bacteria
6.2.3 Effect of Functionalized Nanoparticles
on Drug-Resistant Bacteria
Functionalization of nanoparticles using different types of ligands enables multivalent interactions and stronger adherence to biological molecules. As a result, such
functionalized nanoparticles have also demonstrated nanotoxic effects against resistant bacteria (Table 6.3). Surface functionalization of nanoparticles has been carried
out by different approaches such as linking to side chains or capping with polymeric
agents. Capping of silver nanoparticles with carboxymethyl tamarind prevented
self-aggregation and enabled long-term nanoparticle stabilization (Sanyasi et al.
2016). These nanoparticles effectively inhibited the growth of multidrug-resistant
bacterial strains S. haemolyticus, S. epidermis, E. coli, K. pneumoniae, and E. cloacae, in comparison to commonly used antibiotics. Very recently, silver nanoparticles
have been developed having hydroxyapatite–zoledronate functional groups. These
were found to be active against multidrug-resistant Gram-positive and Gramnegative bacteria (Boanini et al. 2018). Alcohol- functionalized silver nanoparticles
were active against antibiotic-resistant E. coli, S. aureus, and S. typhimurium
(Dorjnamjin et al. 2008). Similarly, silver nanoparticles modified with polyvinyl
alcohol–melamine formaldehyde were able to inhibit infections caused by antibiotic-resistant strains (Kakkar et al. 2015).
Table 6.3 also shows that in addition to silver, zinc oxide nanoparticles have also
been functionalized quite frequently and used for their antibacterial effect against a
range of resistant bacteria. Zinc oxide alginate beads exerted 98% antibacterial
effect over resistant E. coli DH5-α (Baek et al. 2019a). In another interesting study,
gold nanoparticles modified with cationic functional groups were found to remarkably inhibit the bacterial resistance for as many as 20 generations (Li et al. 2014).
Gold nanoparticles have also been functionalized with enzymes or amino acids
(Tiwari et al. 2011, Chen et al. 2010). Functionalized metal oxide nanoparticles
such as alumina-coated iron oxide magnetic nanoparticles and Fe 3 O 4 –gold nanoeggs
have also been reported for their antimicrobial efficacy against multidrug-resistant
bacteria (Malka et al. 2013; Huang et al. 2009; Yu et al. 2011).
It is also interesting to note that metal-doped nanoparticles have also shown
promising antimicrobial features against resistant bacteria (Kunkalekar et al. 2013,
Malka et al. 2013, Hameed et al. 2016). Antimicrobial activity of the zinc-doped
copper oxide nanocomposite on methicillin-resistant S. aureus and multidrugresistant E. coli was 10,000 times more as compared to individual nanoparticles
(Malka et al. 2013). A comparative study on extended-spectrum beta-lactamaseproducing strains of E. coli and K. pneumoniae showed that neodymium doped zinc
oxide nanoparticles had greater antibacterial effect than pure zinc oxide nanoparticles (Hameed et al. 2016). Das et al. (2017b) have also reported the disinfection of
multidrug-resistant E. coli using iron-doped zinc oxide nanoparticles. When used as
a photocatalyst for disinfection, the nanoparticles induced lipid peroxidation and
potassium ion leakage indicating membrane disintegration.
6 Exploring Microbial Nanotoxicity Against Drug Resistance in Bacteria