Berberine-loaded nanoemulsions as a natural food preservative; the impact of femtosecond laser irradiation on the antibacterial activity.

There is a growing concern among food safety regulators, the food industry, and consumers about foodborne illnesses. To improve food safety and increase shelf life, it is necessary to use natural preservatives. Natural antimicrobials are safer than artificial preservatives because they can prevent microbial resistance while also meeting consumers' demands for healthier food. This study used Berberine to enhance the antibacterial activity of Satureja Khuzistanica essential oil nanoemulsions (SKEO NE) against Staphylococcus aureus (S. aureus) bacteria, making them a promising option as preservatives. Response Surface Methodology (RSM) was employed to determine the optimized Berberine loaded SKEO NE (Berberine/SKEO NE), resulting in a mean droplet size of 88.60 nm at 6.91, 3.21, and 0.08% w/w of surfactant, essential oil, and Berberine, respectively. Berberine utilization in SKEO NE has led to an increase in antibacterial activity. The nanoemulsion samples significantly ruptured the S. aureus bacterial cell membrane, rapidly discharging cell contents. The use of a microfluidic system in tandem based on the conventional approach significantly accelerated this process. Enhancing the interaction between nanodroplets and the bacterial membrane can be achieved through the nanoemulsification process of EOs, which involves modifying their surface characteristics. This enhancement is particularly pronounced when employing microfluidic systems due to their substantial contact surface area. We investigated the potential of using femtosecond laser irradiation at a wavelength of 1040 nm to augment the antibacterial action of nanoemulsions. The combined treatment of laser and nanoemulsions significantly increased the antibacterial effect of nanoemulsions by approximately 15% for each bacterium, suggesting the potential utility of this treatment to bolster the antibacterial activity of nanoemulsions. Bacteria were trapped using optical tweezers for up to 20 min, with bacterial destruction observed starting at 3 min and exhaustive destruction evident after 20 min.

Nanoencapsulated Thymus daenensis and Mentha piperita essential oil for bacterial and biofilm eradication using microfluidic technology.

The use of essential oil (EO) nanoemulsions is expanding to meet customer demand for all-natural antibacterial agents. Thymus daenensis (T) and Mentha piperita (M) EOs were employed to make nanoemulsions (TEO and MEO NE), using Tween 80/Span 80 as surfactant/cosurfactant and a high-speed homogenizer. The TEO and MEO NEs were then characterized in terms of particle size (121, 113 nm), surface charge (-11.2 and -12.6 mV), morphology, and stability over time. Then, the antibacterial activity of EOs and their nanoformulations against Escherichia coli (E. coli) were evaluated based on various residence times, and concentrations on a microfluidic chip. The release of cytoplasmic constituents was used to compare the antibacterial activity of bulk EOs and nanoformulations. After completing MIC, MBC, and time-killing assays, the inhibitory effect of nanoformulations on E. coli biofilm formation was examined. Remarkable intensification was observed by employing a microfluidic chip owing to high-contact surface area provision between nanoemulsions and bacteria. Once compared to the conventional method for 3 h operation, the bacterial activity was nearly completely inhibited in a 24-min residence time using nanoemulsions. After 6 min of treatment, the cell membrane began to rupture, indicating that nanoemulsions could improve the antibacterial activity of bulk essential oils.

Interaction of a natural compound nanoemulsion with Gram negative and Gram positive bacterial membrane; a mechanism based study using a microfluidic chip and DESI technique.

The antibacterial activity of a nanoemulsion prepared from Satureja Khusitanica essential oil against a Gram-negative (Escherichia coli) and a Gram-positive (Bacillus atrophaeus) bacteria evaluated using microfluidic and conventional techniques. The effect of different residence time and concentrations on the antibacterial activity of nanoemulsion was studied by measuring the release of protein, nucleic acids, potassium, and also recording the MIC, MBC and time killing assays. Remarkable intensification was observed by employing microfluidic chip regarding a high-contact surface area between nanodroplets and bacterial membrane. The MIC and MBC values for E. coli and B. atrophaeus in conventional method were 400 and 1600 µg mL-1, respectively, whereas these values reduced to 11 to 50 µg mL-1 using microfluidic system. B. atrophaeus seemed to be more resistant than E. coli to the nanoemulsion treatment, perhaps due to different cell wall structures. Bacterial cell wall changes were examined using a desorption electrospray ionization (DESI) technique. It was found that the structural changes were more imminent in Gram negative E. coli by detecting a number of released lipids including phosphatidyl glycerol and phosphatidyl ethanolamines. The DESI spectra of B. atrophaeus revealed no M/Z related lipid release. These findings may help providing novel nano based natural antibacterials.

Rapid and green synthesis of cadmium telluride quantum dots with low toxicity based on a plant-mediated approach after microwave and ultrasonic assisted extraction: Synthesis, characterization, biological potentials and comparison study.

In this work, a quick, facile and efficient approach was presented for green synthesis of cadmium telluride quantum dots (CdTe QDs) based on an aqueous extract of the Ficus johannis plant. Two extraction methods involving microwave assisted extraction (MWAE; 90 and 270 w; 15 min) and ultrasonic assisted extraction (USAE; 15 min; 45 °C) were performed as eco-friendly, effective, green and fast techniques for the extract preparation of the fruit's plant. The as-prepared plant extracts were used as natural stabilizing precursors in the synthesis of CdTe QDs. The synthesized QDs were characterized using various techniques. The average particle size of the QDs from the X-ray diffraction patterns was calculated to be 1.2 nm. UV-Vis absorption and fluorescence spectroscopic studies show a wide absorption band from 400 to 425 nm and a maximum emission peak around 470 nm, which confirmed the successful synthesis of CdTe QDs via the applied synthetic method. After synthesis and characterization of the samples, the antimicrobial properties, genotoxicity, toxicity and antifungal activities of the as-prepared CdTe QDs were investigated. In addition, antioxidant properties of the samples (QDs and extracts), were evaluated by different antioxidant assays. The results indicate the significant antimicrobial activity of the extract and CdTe QDs samples, with negligible toxicity and genotoxicity impacts.