At present, antibiotic resistance is one of the most pressing issues in healthcare globally. The development of new medicine for clinical applications is significantly less than the emergence of multiple drug-resistant bacteria, thus modification of existing medicines is a useful avenue. Among several approaches, nanomedicine is considered of potential therapeutic value. Herein, we have synthesized Zinc oxide nanoparticles (ZnO-NPs) conjugated with clinically-approved drugs (Quercetin, Ceftriaxone, Ampicillin, Naringin and Amphotericin B) with the aim to evaluate their antibacterial activity against several Gram-positive (Methicillin resistant Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus pyogenes) and Gram-negative (Escherichia coli K1, Serratia marcescens and Pseudomonas aeruginosa) bacteria. The nanoparticles and their drug conjugates were characterized using UV-visible spectrophotometry, dynamic light scattering, Fourier transform infrared spectroscopy and atomic force microscopy. Antibacterial activity was performed by dilution colony forming unit method and finally 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were performed to determine their cytotoxic effects against human cell lines. ZnO-NPs revealed maxima surface plasmon resonance band at 374 and after conjugation with beta-cyclodextrin at 379 nm, polydispersity with size in range of 25–45 nm with pointed shaped morphology. When conjugated with ZnO-NPs, drug efficacy against MDR bacteria was enhanced significantly. In particular, Ceftriaxone- and Ampicillin-conjugated ZnO-NPs exhibited potent antibacterial effects. Conversely, ZnO-NPs and drugs conjugated NPs showed negligible cytotoxicity against human cell lines except Amphotericin B (57% host cell death) and Amphotericin B-conjugated with ZnO-NPs (37% host cell death). In conclusion, the results revealed that drugs loaded on ZnO-NPs offer a promising approach to combat increasingly resistant bacterial infections.
Naegleria fowleri (N. fowleri) causes primary
amoebic meningoencephalitis (PAM) which almost always
results in death. N. fowleri is also known as “brain-eating
amoeba” due to its literal infestation of the brain leading
to an inflammatory response in the brain tissues. Currently, there
is no single drug that is available to treat PAM, and most treatments
are combinations of antifungal, anticancer, and anti-inflammatory
drugs. Recently nanotechnology has gained attention in chemotherapeutic
research converging on drug delivery, while oleic acid (OA) has shown
positive effects on the human immune system and inflammatory processes.
In continuation of our recent research in which we reported the effects
of oleic acid conjugated with silver nanoparticles (OA-AgNPs) against
free-living amoeba Acanthamoeba castellanii, in this
report, we show their antiamoebic effects against N. fowleri. OA alone and its nanoconjugates were tested against the amoeba
by using amoebicidal and host cell cytopathogenicity assays. Trypan
blue exclusion assay was used to determine cell viability. The results
revealed that OA-AgNPs exhibited significantly enhanced antiamoebic
effects (P < 0.05) against N. fowleri as compared to OA alone. Evidently, lactate dehydrogenase release
shows reduced N. fowleri-mediated host cell cytotoxicity.
Based on our study, we anticipate that further studies on OA-AgNPs
could potentially provide an alternative treatment of PAM.
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