This study evaluates the impact of
two separate incubation periods
(4 and 6 weeks) on the morphology of sol–gel-fabricated ZnO
nanospikes (ZNs), that is, ZN1 and ZN2, respectively. We further analyzed
the inhibitory effects of ZN1 and ZN2 on quorum sensing (QS) and biofilm
formation in
Pseudomonas aeruginosa
(PAO1) and
Chromobacterium violaceum
(strains 12472 and CVO26). The size of the synthesized ZNs was in
the range of 40–130 nm, and finer nanoparticles were synthesized
after an incubation period of 6 weeks. Treatment with ZNs decreased
the production of violacein in the pathogen without affecting the
bacterial growth, which indicated that ZNs inhibited the QS signaling
regulated by
N
-acyl homoserine lactone. ZN2 had a
higher inhibitory action on the virulence factor productivity than
ZN1. Furthermore, ZN2-treated cells displayed a substantial decrease
in azocasein-degrading protease activity (80%), elastase activity
(83%), and pyocyanin production (85%) relative to untreated
P. aeruginosa
PAO1 cells. Treatment with ZN2 decreased
swarming motility and exopolysaccharide production by 89 and 85%,
respectively. ZN2 was effective against both the
las
&
pqs
systems of
P. aeruginosa
and exhibited broad-spectrum activity. Additionally, ZN2 was more
efficient in inhibiting the biofilm formation at the attachment stage
than ZN1. These findings revealed that in
P. aeruginosa
, ZN2 demonstrated inhibitory effects on QS as well as on the development
of biofilms. Thus, ZN2 can be potentially used to treat drug-resistant
P. aeruginosa
infections.