159
biofilm- forming Gram-negative pathogenic strain of Pseudomonas aeruginosa
(Casciaro et al. 2017). Similarly, antimicrobial peptide–graphene oxide nanoparticle–DNA aptamer conjugates were developed as highly effective antibacterial therapeutics against Vibrio vulnificus (Lee et al. 2017). Other than graphene oxide
nanoparticles, the conjugation of antimicrobial peptide, Clavanin A, with Fe 3 O 4 –
silane nanoshells for antimicrobial activity against Staphylococcus aureus,
Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae has also
been reported (Ribeiro et al. 2018). Conjugation of silver nanoparticles with
Ubiquicidin (29–41), an antimicrobial peptide, demonstrated significant antibacterial effects against E. coli and P. aeruginosa (Morales-Avila et al. 2017).
(vi) Nanoparticle–Antibiotic Conjugates
Nanoparticles have been conjugated with known antibiotics via covalent or noncovalent interactions. Such nanoparticle–antibiotic conjugates have reportedly
enhanced antimicrobial activity against multidrug-resistant bacteria. It is understood that this antimicrobial strategy using antibiotic functionalized onto metal
nanoparticles can have promising applications in the design of antimicrobial, antiviral, or anticancer therapies. Moreover, the approach is also considered useful for
reviving old unresponsive drugs, the efficacy of which can be restored upon conjugation with nanoparticles (Shaikh et al. 2017). Table 6.5 shows some of the metal/
metal oxide nanoparticles that have been conjugated with antibiotics such as ampicillin, vancomycin, ciprofloxacin, imipenem, etc. and their efficacy against resistant/multidrug-resistant bacteria. Since multidrug-resistant bacteria are known to
have evolved methods for countering all classes of beta-lactam antibiotics, Brown
et al. (2012) explored the efficacy of ampicillin molecules conjugated onto silver
and graphene oxide nanoparticles against beta-lactam-resistant bacteria. Both graphene oxide nanoparticle–ampicillin and silver nanoparticle–ampicillin conjugates
were found to exhibit potent bactericidal activity against multidrug-resistant bacteria. Similarly, ampicillin was conjugated onto lysozyme-capped graphene oxide
nanoclusters (AUNC-L-Amp) to form a “broad-spectrum antibacterial hybrid”
(Kalita et al. 2018). The system showed reversion of resistance by methicillinresistant S. aureus and increased inhibitory effect. This was attributed to multiple
reasons such as increased ampicillin concentration at antibiotic–bacteria interaction
site, multivalent presentation of ampicillin, enhanced permeation of the antibiotic
through lysozyme-mediated cell wall lysis, or graphene oxide ion-induced cell
destabilization. Capeletti et al. (2014) demonstrated the encapsulation of tetracycline into silica nanoparticles and their high bactericidal effects against multiple
resistant E. coli. A study conducted on titanium/titanium oxide nanoparticles also
showed the enhancement in their bactericidal effect against S. aureus when they
were functionalized with ampicillin (Pissinis et al. 2018).
(vii)
Effect of Quantum Dots
Quantum dots are a unique class of semiconductors, with size ranging
from 2–10 nm. Very recently, quantum dots are have also been investigated for their
effectiveness in combating superbugs. Courtney et al. (2016) showed that
6 Exploring Microbial Nanotoxicity Against Drug Resistance in Bacteria
biofilm- forming Gram-negative pathogenic strain of Pseudomonas aeruginosa
(Casciaro et al. 2017). Similarly, antimicrobial peptide–graphene oxide nanoparticle–DNA aptamer conjugates were developed as highly effective antibacterial therapeutics against Vibrio vulnificus (Lee et al. 2017). Other than graphene oxide
nanoparticles, the conjugation of antimicrobial peptide, Clavanin A, with Fe 3 O 4 –
silane nanoshells for antimicrobial activity against Staphylococcus aureus,
Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae has also
been reported (Ribeiro et al. 2018). Conjugation of silver nanoparticles with
Ubiquicidin (29–41), an antimicrobial peptide, demonstrated significant antibacterial effects against E. coli and P. aeruginosa (Morales-Avila et al. 2017).
(vi) Nanoparticle–Antibiotic Conjugates
Nanoparticles have been conjugated with known antibiotics via covalent or noncovalent interactions. Such nanoparticle–antibiotic conjugates have reportedly
enhanced antimicrobial activity against multidrug-resistant bacteria. It is understood that this antimicrobial strategy using antibiotic functionalized onto metal
nanoparticles can have promising applications in the design of antimicrobial, antiviral, or anticancer therapies. Moreover, the approach is also considered useful for
reviving old unresponsive drugs, the efficacy of which can be restored upon conjugation with nanoparticles (Shaikh et al. 2017). Table 6.5 shows some of the metal/
metal oxide nanoparticles that have been conjugated with antibiotics such as ampicillin, vancomycin, ciprofloxacin, imipenem, etc. and their efficacy against resistant/multidrug-resistant bacteria. Since multidrug-resistant bacteria are known to
have evolved methods for countering all classes of beta-lactam antibiotics, Brown
et al. (2012) explored the efficacy of ampicillin molecules conjugated onto silver
and graphene oxide nanoparticles against beta-lactam-resistant bacteria. Both graphene oxide nanoparticle–ampicillin and silver nanoparticle–ampicillin conjugates
were found to exhibit potent bactericidal activity against multidrug-resistant bacteria. Similarly, ampicillin was conjugated onto lysozyme-capped graphene oxide
nanoclusters (AUNC-L-Amp) to form a “broad-spectrum antibacterial hybrid”
(Kalita et al. 2018). The system showed reversion of resistance by methicillinresistant S. aureus and increased inhibitory effect. This was attributed to multiple
reasons such as increased ampicillin concentration at antibiotic–bacteria interaction
site, multivalent presentation of ampicillin, enhanced permeation of the antibiotic
through lysozyme-mediated cell wall lysis, or graphene oxide ion-induced cell
destabilization. Capeletti et al. (2014) demonstrated the encapsulation of tetracycline into silica nanoparticles and their high bactericidal effects against multiple
resistant E. coli. A study conducted on titanium/titanium oxide nanoparticles also
showed the enhancement in their bactericidal effect against S. aureus when they
were functionalized with ampicillin (Pissinis et al. 2018).
(vii)
Effect of Quantum Dots
Quantum dots are a unique class of semiconductors, with size ranging
from 2–10 nm. Very recently, quantum dots are have also been investigated for their
effectiveness in combating superbugs. Courtney et al. (2016) showed that
6 Exploring Microbial Nanotoxicity Against Drug Resistance in Bacteria