Table 2.

Studies reporting the efficacy of single- and multi-walled CNTs conjugated with compounds displaying antimicrobial activity

CNT-antimicrobial compounds	Type	Medical application	Species	Major conclusions	Reference
Antimicrobial agents
Cefalexin	MWCNT	Nonspecified	B. subtilis E. coli P. aeruginosa S. aureus	MWCNT/cefalexin films reduced bacteria viability by 50%–80%	(Qi et al., 2012)
AZ	SWCNT	Drug delivery	M. luteus	SWCNT/AZ composites had a significant in vitro activity against M. luteus (p < 0.05)	(Darabi et al., 2014)
Rifampicin	MWCNT	Implant materials	S. epidermidis	MWCNT/rifampicin-coated surfaces caused a significant inhibition of biofilm formation for up to 5 days (50%)	(Hirschfeld et al., 2017)
Photosensitizers
APT	SWCNT	Nonspecified	S. aureus	A high reduction of bacterial growth (≈90%) was observed when bacteria were exposed to porphyrin-SWCNT composite	(Sah et al., 2018)
DTTC fluorophores	MWCNT	Nonspecified	P. aeruginosa S. aureus	P. aeruginosa exposed to MWNT/DTTC hybrid films and irradiated with NIR laser light were inactivated by 77%	(Oruc and Unal, 2019)
Antimicrobial peptides
EP	MWCNT	Medical devices	E. coli P. aeruginosa S. aureus	MWCNT/EP composites killed 97.6%, 91.5%, and 88.5% of E. coli, P. aeruginosa, and S. aureus, respectively	(Zhou and Qi, 2011)
PLL and PGA	SWCNT	Medical devices	E. coli S. epidermidis	SWCNT/AMP films inactivated E. coli and S. epidermidis up to 90%	(Aslan et al., 2012)
Nisin	MWCNT	Antimicrobial surfaces	B. subtilis E. coli P. aeruginosa S. aureus	MWCNT/nisin composites showed up to 7-fold higher antimicrobial activity than p-MWCNTs. Additionally, deposited films exhibited a 100-fold higher anti-biofilm activity than the p-MWCNT deposited film	(Qi et al., 2011)
Enzymes
LSZ	SWCNT	Medical devices	M. lysodeikticus S. aureus	Coatings terminating in SWNT/LSZ layer exhibited an antimicrobial activity of 84%	(Nepal et al., 2008)
Lysostaphin	MWCNT	Antimicrobial surfaces	B. cereus E. coli MRSA S. epidermidis	Enzyme-based composites were highly efficient in killing MRSA (> 99%)	(Pangule et al., 2010)
Laccase	MWCNT	Antimicrobial surfaces	B. anthracis B. cereus E. coli S. aureus	The laccase-CNT films showed > 99% bactericidal activity against E. coli and S. aureus, and > 98% sporicidal activity against B. anthracis and B. cereus	(Grover et al., 2012)

APT, antimicrobial photodynamic therapy; AMP, antimicrobial peptide; APT, amine-functionalized porphyrin; AZ, azithromycin; DTTC, 3,3′-diethylthiatricarbocyanine; EP, epsilon-polylysine; LSZ, lysozyme; MWCNT, multi-walled carbon nanotubes; PGA, poly(L-glutamic acid); PLL, polyelectrolytes poly(L-lysine); MRSA, MRSA, methicillin-resistant Staphylococcus aureus; NIR, near-infrared; SWCNT, single-walled carbon nanotubes.