Porous Polymerized High Internal Phase Emulsions Prepared Using Proteins and Essential Oils for Antimicrobial Applications.

High internal phase emulsions (HIPEs) provide a versatile platform for encapsulating large volumes of therapeutics that are immiscible in water. A stable scaffold is obtained by polymerizing the external phase, resulting in polyHIPEs. However, fabrication of polyHIPEs usually requires using a considerable quantity of surfactants along with nonbiocompatible components, which hinders their biological applications, e.g., drug-eluting devices. We describe here a straightforward method for generating porous biomaterials by using proteins as both the emulsifier and the building blocks for the fabrication of polyHIPEs. We demonstrate the versatility of this method by using different essential oils as the internal phase. After the gelation of protein building blocks is triggered by the addition of reducing agents, a stable protein hydrogel containing essential oils can be formed. These oils can be either extracted to obtain protein-based porous scaffolds or slowly released for antimicrobial applications.

Mechanistic Insight into the Antibacterial Activity of Chitosan Exfoliated MoS2 Nanosheets: Membrane Damage, Metabolic Inactivation, and Oxidative Stress.

Two-dimensional molybdenum disulfide (MoS2) based nanosheets functionalized or loaded with an antimicrobial agent have recently attracted attention as highly efficient antibacterial agent. MoS2 sheets act as the photothermal transducers in inducing bacterial cell death on impingement of NIR radiation or enabled cell inactivation by wrapping around the cells. However, the intrinsic ability of MoS2 to act as an effective antibacterial agent without the use of any external stimuli or antimicrobial agent is still not well explored. This study provides a detailed mechanism of antibacterial action of chitosan exfoliated MoS2 nanosheets (CS-MoS2) by deciphering the key events happening both at the membrane surface and inside the bacteria as a result of interaction of bacterial cells with the nanosheets. A simple, green, one-step process was employed for synthesizing stable and positively charged MoS2 nanosheets. The prepared nanosheets showed excellent bactericidal activity against both Gram-positive (MIC = 90 µg/mL, MBC = 120 µg/mL) and Gram-negative bacteria (MIC = 30 µg/mL, MBC = 60 µg/mL). Investigations into deciphering the mechanism of action revealed that the CS-MoS2 nanosheets interacted strongly with the bacterial cells through electrostatic interactions and caused rapid depolarization of the membranes through dent formations. On account of strong van der Waals and electrostatic forces occurring between the CS-MoS2 nanosheets and membrane phospholipid molecules, deepening of dents occurred, which resulted in complete membrane disruption and leakage of cytoplasmic contents. This led to inactivation of the bacterial respiratory pathway through inhibition of dehydrogenase enzymes and induced metabolic arrest in the cells. Simultaneously, disruption of the antioxidant defense system of the cells by increased levels of intracellular ROS subjected the cells to oxidative damage and added to the overall bactericidal action. The nanosheets also displayed antibiofilm properties and were found to be compatible with mammalian cells even at high concentrations.

Recent advances in nanoparticle-based lateral flow immunoassay as a point-of-care diagnostic tool for infectious agents and diseases.

Lateral flow immunoassay (LFIA) technology is a paper-based, point-of-care strip biosensor designed to detect a specific analyte in a given sample. This type of assay is now of great interest to researchers for its cost-effectiveness, simplicity, portability and rapidness of detection of analytes, including but not limited to areas such as agriculture, food, biomedicine and pathogen detection. Various nanoparticles (such as metal nanoparticles, carbon-based nanoparticles, quantum dots, lanthanides and up-converting phosphor) functionalized by an antibody to detect an analyte protein or molecular marker present in the surface of an infectious pathogen are used for in LFIAs. Herein, we review the principle of the assay and recent advancements made in terms of the different approaches and designs of the assay towards the detection of infectious agents and diseases.