Eco-friendly and effective antimicrobial Melaleuca alternifolia essential oil Pickering emulsions stabilized with cellulose nanofibrils against bacteria and SARS-CoV-2.

Melaleuca alternifolia essential oil (MaEO) is a green antimicrobial agent suitable for confection eco-friendly disinfectants to substitute conventional chemical disinfectants commonly formulated with toxic substances that cause dangerous environmental impacts. In this contribution, MaEO-in-water Pickering emulsions were successfully stabilized with cellulose nanofibrils (CNFs) by a simple mixing procedure. MaEO and the emulsions presented antimicrobial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Moreover, MaEO deactivated the SARS-CoV-2 virions immediately. FT-Raman and FTIR spectroscopies indicate that the CNF stabilizes the MaEO droplets in water by the dipole-induced-dipole interactions and hydrogen bonds. The factorial design of experiments (DoE) indicates that CNF content and mixing time have significant effects on preventing the MaEO droplets' coalescence during 30-day shelf life. The bacteria inhibition zone assays show that the most stable emulsions showed antimicrobial activity comparable to commercial disinfectant agents such as hypochlorite. The MaEO/water stabilized-CNF emulsion is a promissory natural disinfectant with antibacterial activity against these bacteria strains, including the capability to damage the spike proteins at the SARS-CoV-2 particle surface after 15 min of direct contact when the MaEO concentration is 30 % v/v.

Improvement and characterization of oral absorption behavior of clofazimine by SNEDDS: Quantitative evaluation of extensive lymphatic transport.

Clofazimine, an anti-leprosy drug, has been anticipated for a candidate to treat tuberculosis, cryptosporidiosis, and coronavirus infection, but its low oral bioavailability is considered a reason for its limited activity. In the current study, we have tried to improve the oral bioavailability of clofazimine by several SNEDDS formulations and characterized the absorption behavior from various aspects. Among four SNEDDS formulations prepared, SNEDDS A, prepared with castor oil as an oil component, provided the highest bioavailability (around 61%) and SNEDDS D, prepared with Capryol 90, gave the second highest bioavailability. SNEDDS A formed the finest nanoparticles, which were maintained under gastric and intestinal luminal conditions. The comparison in oral bioavailability between the SNEDDS formulation and its corresponding preformed nanoemulsion suggested that SNEDDS A would efficiently form nanoemulsion in the gastrointestinal tract after oral administration. AUC of mesenteric lymph node concentration was the highest for SNEDDS A, which would be one of the reasons for SNEDDS A to reveal the highest oral bioavailability. A cycloheximide-treated oral absorption study and single-pass perfusion study by utilizing a vascular-luminal perfused small intestine-liver preparation clearly indicated that over 90% of clofazimine absorbed to systemic circulation should be derived from lymphatic transport for both SNEDDS A and D. Furthermore, the fraction of dose absorbed was around 65% for SNEDDS D, but SNEDDS A achieved around 94%, indicating the excellent performance of SNEDDS A.

One-Step Synthesis of Self-Stratification Core-Shell Latex for Antimicrobial Coating.

Herein, we describe a one-step method for synthesizing cationic acrylate-based core-shell latex (CACS latex), which is used to prepare architectural coatings with excellent antimicrobial properties. Firstly, a polymerizable water-soluble quaternary ammonium salt (QAS-BN) was synthesized using 2-(Dimethylamine) ethyl methacrylate (DMAEMA) and benzyl bromide by the Hoffman alkylation reaction. Then QAS-BN, butyl acrylate (BA), methyl methacrylate (MMA), and vinyltriethoxysilane (VTES) as reactants and 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) as a water-soluble initiator were used to synthesize the CACS latex. The effect of the QAS-BN dosage on the properties of the emulsion and latex film was systematically investigated. The TGA results showed that using QAS-BN reduced the latex film's initial degradation temperature but improved its thermal stability. In the transmission electron microscopy (TEM) photographs, the self-stratification of latex particles with a high dosage of QAS-BN was observed, forming a core-shell structure of latex particles. The DSC, TGA, XPS, SEM, and performance tests confirmed the core-shell structure of the latex particles. The relationship between the formation of the core-shell structure and the content of QAS-BN was proved. The formation of the core-shell structure was due to the preferential reaction of water-soluble monomers in the aqueous phase, which led to the aggregation of hydrophilic groups, resulting in the formation of soft-core and hard-shell latex particles. However, the water resistance of the films formed by CACS latex was greatly reduced. We introduced a p-chloromethyl styrene and n-hexane diamine (p-CMS/EDA) crosslinking system, effectively improving the water resistance in this study. Finally, the antimicrobial coating was prepared with a CACS emulsion of 7 wt.% QAS-BN and 2 wt.% p-CMS/EDA. The antibacterial activity rates of this antimicrobial coating against E. coli and S. aureus were 99.99%. The antiviral activity rates against H3N2, HCoV-229E, and EV71 were 99.4%, 99.2%, and 97.9%, respectively. This study provides a novel idea for the morphological design of latex particles. A new architectural coating with broad-spectrum antimicrobial properties was obtained, which has important public health and safety applications.

Emulsion-based isothermal nucleic acid amplification for rapid SARS-CoV-2 detection via angle-dependent light scatter analysis.

The SARS-CoV-2 pandemic, an ongoing global health crisis, has revealed the need for new technologies that integrate the sensitivity and specificity of RT-PCR tests with a faster time-to-detection. Here, an emulsion loop-mediated isothermal amplification (eLAMP) platform was developed to allow for the compartmentalization of LAMP reactions, leading to faster changes in emulsion characteristics, and thus lowering time-to-detection. Within these droplets, ongoing LAMP reactions lead to adsorption of amplicons to the water-oil interface, causing a decrease in interfacial tension, resulting in smaller emulsion diameters. Changes in emulsion diameter allow for the monitoring of the reaction by use of angle-dependent light scatter (based off Mie scatter theory). Mie scatter simulations confirmed that light scatter intensity is diameter-dependent and smaller colloids have lower intensity values compared to larger colloids. Via spectrophotometers and fiber optic cables placed at 30° and 60°, light scatter intensity was monitored. Scatter intensities collected at 5 min, 30° could statistically differentiate 10, 103, and 105 copies/µL initial concentrations compared to NTC. Similarly, 5 min scatter intensities collected at 60° could statistically differentiate 105 copies/µL initial concentrations in comparison to NTC. The use of both angles during the eLAMP assay allows for distinction between high and low initial target concentrations. The efficacy of a smartphone-based platform was also tested and had a similar limit of detection and assay time of less than 10 min. Furthermore, fluorescence-labeled primers were used to validate target nucleic acid amplification. Compared to existing LAMP assays for SARS-CoV-2 detection, these times-to-detections are very rapid.