In this work, mesoporous
(pore size below 4 nm) composite nanoparticles
of ZnO–Ag2O/Ag, ZnO–CuO, and ZnO–SnO2 of size d ≤ 10 nm (dia.) have been
synthesized through the in situ solvochemical reduction
method using NaBH4. These composite nanoparticles exhibited
excellent killing efficacy against Gram-positive/negative bacterial
and fungal strains even at a very low dose of 0.010 μg/mL. Additionally,
by applying the in silico docking approach, the nanoparticles
and microorganism-specific targeted proteins and their interactions
have been identified to explain the best anti-bacterial/anti-fungal
activities of these composites. For this purpose, the virulence and
resistance causing target proteins such as PqsR, RstA, FosA, and Hsp90 of Pseudomonas aeruginosa, Acinetobacter
baumannii, Klebsiella pneumoniae, and Candida albicans have been identified
to find out the best inhibitory action mechanisms involved. From the in vitro study, it is revealed that all the composite nanoparticle
types used here can act as potent antimicrobial components. All the
composite nanoparticles have exhibited excellent inhibition against
the microorganisms compared to their constituent single metal or metal
oxide nanoparticles. Among the nanoparticle types, the ZnO–Ag2O/Ag composite nanoparticles exhibited the best inhibition
activity compared to the other reported nanoparticles. The microorganisms
which are associated with severe infections lead to the multidrug
resistance and have become a huge concern in the healthcare sector.
Conventional organic antibiotics are less stable at a higher temperature.
Therefore, based on the current demands, this work has been focused
on designing inorganic antibiotics which possess stability even under
harsh conditions. In this direction, our developed composite nanoparticles
were explored for potential uses in the healthcare technology, and
they may solve many problems in global emergency and epidemics caused
by the microorganisms.