Formulation of Garlic Essential Oil-assisted Silver Nanoparticles and Mechanistic Evaluation of their Antimicrobial Activity against a Spectrum of Pathogenic Microorganisms.

BACKGROUND: The synthesis of nanoparticles using the principle of green chemistry has achieved huge potential in nanomedicine. Here, we report the synthesis of silver nanoparticles (Ag- NPs) employing garlic essential oil (GEO) due to wide applications of GEO in the biomedical and pharmaceutical industry. OBJECTIVE: This study aimed to synthesise garlic essential oil-assisted silver nanoparticles and present their antimicrobial and antibiofilm activities with mechanistic assessment. METHOD: Initially, the formulation of AgNPs was confirmed using different optical techniques, such as XRD, FT-IR, DLS, zeta potential, SEM, and EDX analysis, which confirmed the formulation of well-dispersed, stable, and spherical AgNPs. The antimicrobial and antibiofilm activity of GEO-assisted AgNPs was evaluated against a spectrum of pathogenic microorganisms, such as Gram-positive (S. aureus and B. subtilis) and Gram-negative (E. coli and P. aeruginosa) bacteria. RESULTS: The AgNPs exhibited remarkable antimicrobial and anti-biofilm activity against all tested strains. The mechanism behind the antimicrobial activity of AgNPs was explored by estimating the amount of reactive oxygen species (ROS) generated due to the interaction of AgNP with bacterial cells and observing the morphological changes of bacteria upon AgNP interaction. CONCLUSION: The findings of this study concluded that ROS generation due to the interaction of AgNPs with bacterial cells put stress on bacterial membranes, altering the morphology of bacteria, exhibiting remarkable antimicrobial activity, and preventing biofilm formation.

Nanoparticle-mediated diagnosis, treatment, and prevention of breast cancer.

By virtue of their advanced physicochemical properties, nanoparticles have attracted significant attention from researchers for application in diverse fields of medical science. Breast cancer, presenting a high risk of morbidity and mortality, frequently occurs in women and is considered a malignant tumor. Globally, breast cancer is considered the second leading cause of death. Accordingly, its poor prognosis, invasive metastasis, and relapse have motivated oncologists and nano-medical researchers to develop highly potent nanotherapies to cure this deadly disease. In this case, nanoparticles have emerged as responsive platforms for breast cancer management, providing new approaches to improve the diagnostic accuracy, deliver targeted therapies, and limit the progression of this disease. Recently, smart nano-carriers encapsulating drugs, ligands, and tracking probes have been developed for the specific therapy of breast cancers. Further, efforts have been devoted to developing various nano-systems with minimal toxicity. The aim of this review is to present a background on novel nanotheranostic methods that can be employed to diagnose and treat breast cancers and encourage readers to focus on the development of novel nanomedicine for breast cancers and other deadly diseases. In this context, we discuss different methods for the diagnosis, treatment, and prevention of breast cancers using different metal and metal oxide nanoparticles.

Isolation, characterization, and multimodal evaluation of novel glycolipid biosurfactant derived from Bacillus species: A promising Staphylococcus aureus tyrosyl-tRNA synthetase inhibitor through molecular docking and MD simulations.

Glycolipid-based biosurfactants (BSs), known for their intriguing and diverse properties, represent a largely uncharted territory in the realm of potential biomedical applications. This field holds great promise yet remains largely unexplored. This investigation provides new insights into the isolation, characterization, and comprehensive biomedical assessment of a novel glycolipid biosurfactant derived from Bacillus species, meeting the growing demand for understanding its multifaceted impact on various biomedical issues. Within this framework, two glycolipids, BG2A and BG2B, emerged as the most proficient strains in biosurfactant (BS) production. The biosurfactants (BSs) ascertained as glycolipids via thin layer chromatography (TLC) exhibited antimicrobial activity against S. aureus and E. coli. Both isolates exhibited anticancer effects against cervical carcinoma cells and demonstrated significant anti-biofilm activity against V. cholerae. Moreover, molecular docking and molecular dynamics (MD) simulations were employed to explore their antimicrobial resistance properties against Tyrosyl-tRNA synthetase (TyrRS) of Staphylococcus aureus, a well-annotated molecular target. Characterization and interpretation using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H and 13C NMR) confirmed that the BSs produced by each strain were glycolipids. These findings suggest that the isolated BSs can serve as effective agents with antibiofilm, antimicrobial, antioxidant, and anticancer properties, in addition to their considerable antibacterial resistance attributes.

Adsorption of antimicrobial peptide onto chitosan-coated iron oxide nanoparticles fosters oxidative stress triggering bacterial cell death.

In the prevailing environmental status quo, bacterial resistance has made antibiotics and antimicrobial peptides (AMPs) ineffective, imparting a serious threat and putting a much greater financial burden on the biomedical and food industries. For this reason, the present study investigates the potential of iron oxide nanoparticles (IONPs) coated with chitosan (CS-IONP) as a platform for augmenting the antimicrobial activity of antimicrobial peptides like nisin. Hence, the nisin is allowed to be adsorbed onto chitosan-coated IONPs to formulate nisin-loaded CS-IONP nanoconjugates. The nanoconjugates were characterized by various optical techniques, such as XRD, FTIR, SEM, zeta and DLS. Remarkably, lower concentrations of N-CS-IONP nanoconjugate exhibited significant and broad-spectrum antibacterial potency compared to bare IONPs and nisin against both Gram-positive and Gram-negative bacteria. Biofilm production was also found to be drastically reduced in the presence of nanoconjugates. Further investigation established a relationship between an increase in antibacterial activity and the enhanced generation of reactive oxygen species (ROS). Oxidative stress exhibited due to enhanced ROS generation is a conclusive reason for the rupturing of bacterial membranes and leakage of cytoplasmic contents, eventually leading to the death of the bacteria. Thus, the current study emphasizes the formulation of a novel antimicrobial agent which exploits magnetic nanoparticles modulated with chitosan for enhanced remediation of resistant bacteria due to oxidative stress imparted by the nanoconjugates upon interaction with the bacteria, leading to cell death.

Photocatalytic activity of biosynthesized silver nanoparticle fosters oxidative stress at nanoparticle interface resulting in antimicrobial and cytotoxic activities.

Inside the biological milieu, nanoparticles with photocatalytic activity have potential to trigger cell death non-specifically due to production of reactive oxygen species (ROS) upon reacting with biological entities. Silver nanoparticle (AgNP) possessing narrow band gap energy can exhibit high light absorption property and significant photocatalytic activity. This study intends to explore the effects of ROS generated due to photocatalytic activity of AgNP on antimicrobial and cytotoxic propensities. To this end, AgNP was synthesized using the principle of green chemistry from the peel extract of Punica granatum L., and was characterized using UV-Vis spectroscope, transmission electron microscope and x-ray diffraction, and so forth. The antimicrobial activity of AgNP against studied bacteria indicated that, ROS generated at AgNP interface develop stress on bacterial membrane leading to bacterial cell death, whereas Alamar Blue dye reduction assay indicated that increased cytotoxic activity with increasing concentrations of AgNP. The γH2AX activity assay revealed that increasing the concentrations of AgNP increased DNA damaging activity. The results altogether demonstrated that both antimicrobial and cytotoxic propensities are triggered primarily due interfacial ROS generation by photocatalytic AgNP, which caused membrane deformation in bacteria and DNA damage in HT1080 cells resulting in cell death.

Silver nanoparticles fabricated using medicinal plant extracts show enhanced antimicrobial and selective cytotoxic propensities.

Nanoparticles fabricated using medicinal plant extract have great potential in the area of nanomedicine. High surface-to-volume ratio of nanoparticle enhances the local active biomolecules concentration, leading to many fold increase in the medicinal potentials. The silver nanoparticles (AgNPs) fabricated using indigenous medicinal plants of India, Azadirachta indica and Syzygium cumini, have shown a significant effect on the viability of prokaryotic and eukaryotic cells. Biofabrication of AgNP was confirmed using different spectroscopic and microscopic techniques. Extraction and purification of AgNP from non-conjugated plant moieties are done using centrifugation and size exclusion chromatography. The cytotoxic propensity of AgNP formulations was screened against Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) bacteria, cancerous (HT1080) and non-cancerous (HEK293) cell lines. The nanoparticle formulations showed a relatively higher cytotoxic propensity against Gram-positive bacteria and cancerous cell lines. In addition, the surface roughness and reactive oxygen species (ROS) measurements indicated that AgNP formulations mediate the cell activity predominantly by ROS-mediated disruptive change in membrane morphology upon direct interaction with the membrane. Hence, the nanoparticle formulations show an enhanced selective cytotoxic propensity towards Gram-positive bacteria and cancerous cell lines.

Oxidative stress generated at nickel oxide nanoparticle interface results in bacterial membrane damage leading to cell death.

Metal oxide nanoparticles (NPs) have shown enhanced antibacterial effects against many bacteria. Thus, understanding the potential antibacterial effects of nickel oxide nanoparticles (NiO NPs) against Gram-positive and Gram-negative pathogenic bacteria is an urgent need to enable the exploration of NiO NP use in biomedical sciences. To this end, NiO NPs were synthesized by microwave assisted hydrothermal synthesis method. The synthesized NPs were characterized by X-ray diffraction (XRD) and Fourier Transfer Infrared (FT-IR) and UV-visible spectroscopy. The morphological features of the synthesized NiO NPs were analysed using Transmission Electron Microscopy (TEM) and FE-SEM analysis. The antibacterial activity of NiO NP was explored using different antimicrobial and biophysical studies. The obtained data reveals that the NiO NP has stronger antibacterial activity against Gram-positive bacteria compared to Gram-negative bacteria. The mechanism behind the antibacterial activity of the NiO NP was explored by evaluating the amount of ROS generation at the NiO NP interface. The effect of ROS generation on the bacterial membrane was evaluated by BacLight assay and morphological analysis of the bacterial membrane using FE-SEM. The data altogether suggested that the oxidative stress generated at the NiO NP interface resulted in membrane damage leading to bacterial cell death.

Preferential binding to zinc oxide nanoparticle interface inhibits lysozyme fibrillation and cytotoxicity.

The aim of present investigation is to explore the effect of zinc oxide nanoparticles (ZnONP, 30 nm) interface on conformational dynamics and stability of lysozyme, at pH 7.4 and pH 9.0. Lysozyme adopts partially disordered conformation at pH 9.0, which adopts fibril morphology in presence of sodium dodecyl sulfate (SDS), compared to the conformation adopted at pH 7.4. However, the presence of ZnONP interface renders partially disordered lysozyme relatively regular and non-amyloidogenic conformation, and enhances the functional efficacy of lysozyme at pH 9.0. Additionally, the thermograms reveal a non-cooperative unfolding of the pH 9.0 lysozyme conformation, which accompanied with intermediate conformations that increased with increase in the interface concentration. The binding thermodynamics indicate that at pH 9.0, lysozyme conformation preferentially binds to ZnONP interface than SDS interface. The preferential binding is attributed for the resulting anti-fibrillation propensity of ZnONP interface. The data, altogether, suggest that the presence of ZnONP interface resulted in conformational rearrangements in the partially disordered lysozyme at pH 9.0 causing accumulation of non-amyloidogenic and functionally active intermediates, thus shielding the lysozyme from SDS induced fibrillation and cytotoxicity.

Zinc oxide nanoparticle energy band gap reduction triggers the oxidative stress resulting into autophagy-mediated apoptotic cell death.

The physico-chemical properties of nanoparticle (NP), such as particle size, surface defects, crystallinity and accessible surface, affect NP photocatalytic activity that in turn defines the NP cytotoxic propensity. Since zinc oxide nanoparticle (ZnONP) energy band gap falls in a range of a semiconductor, the particle possesses photocatalytic activity. Hence, the study correlates energy band gap with cytotoxic propensity of ZnONP. To this end, ZnONPs with varying energy band gap are fabricated by varying calcination temperature. Cytotoxic propensity of the fabricated ZnONPs against HT1080 cell indicates that the particle with least energy band gap shows highest cytotoxicity. The data also indicate that the cytotoxicity is triggered primarily through reactive oxygen species (ROS)-mediated pathway. Additionally, the comet assay and γH2AX activity assay reveal that decreasing energy band gap of the particle increases DNA damaging propensity. Furthermore, cell cycle analysis indicates that the cell treatment with decreasing energy band gap ZnONP results in significant increase in cell population fraction in subG1 phase. Whereas, acridine orange binding assay and increased expression level of LC3II indicate that the cell tries to recover the stress by scavenging damaged cellular biomolecules and ROS using autophagosomes. Nevertheless, cell with the non-recoverable damages led into apoptotic cell death, as confirmed by Annexin V apoptosis assay, DNA fragmentation assay and 4,6-Diamidino-2-phenylindole dihydrochloride (DAPI) staining.

Antimicrobial activity of iron oxide nanoparticle upon modulation of nanoparticle-bacteria interface.

Investigating the interaction patterns at nano-bio interface is a key challenge for safe use of nanoparticles (NPs) to any biological system. The study intends to explore the role of interaction pattern at the iron oxide nanoparticle (IONP)-bacteria interface affecting antimicrobial propensity of IONP. To this end, IONP with magnetite like atomic arrangement and negative surface potential (n-IONP) was synthesized by co-precipitation method. Positively charged chitosan molecule coating was used to reverse the surface potential of n-IONP, i.e. positive surface potential IONP (p-IONP). The comparative data from fourier transform infrared spectroscope, XRD, and zeta potential analyzer indicated the successful coating of IONP surface with chitosan molecule. Additionally, the nanocrystals obtained were found to have spherical size with 10-20 nm diameter. The BacLight fluorescence assay, bacterial growth kinetic and colony forming unit studies indicated that n-IONP (<50 µM) has insignificant antimicrobial activity against Bacillus subtilis and Escherichia coli. However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP. Additionally, the assay to study reactive oxygen species (ROS) indicated relatively higher ROS production upon p-IONP treatment of the bacteria. The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity.