New Low-Energy Method for Nanoemulsion Formation: pH Regulation Based on Fatty Acid/Amine Complexes

Green antiseptic for hand hygiene with high activity against SARS-CoV-2: Iota-carrageenan, quercetin, and Melaleuca alternifolia essential oil based nanoemulsion

The World Health Organization (WHO) has determined a series of guidelines to contain the advance and spread of COVID-19 and other influenza viruses. Among them, frequent hand hygiene has been widely recommended, resulting in an increased consumption of alcohol-based antiseptic products or synthetic molecules. However, when used in excess, these products might cause adverse consequences for human health, such as dermatitis, and for the environment, i.e., the selection of resistant bacterial genotypes. One of the alternatives to overcome this problem is the replacement of common antiseptics by formulations based on natural bioactive compounds with antimicrobial/antiviral activity. In addition, by nanostructuring formulations, it is possible to increase the bioavailability, stability, solubility, and absorption of bioactives in biological systems. In this sense, this study aimed to develop an antiseptic nanoemulsion based on natural bioactive compounds with virucidal activity against SARS-CoV-2. For that, oil-in-water (O/W) nanoemulsions were prepared, being the oil phase composed by Melaleuca alternifolia essential oil, quercetin, PEG400, and surfactants, while the aqueous phase presented carrageenan and purified water. Physicochemical characterization and stability studies were developed to evaluate the viability of the formulations over time. In addition, bactericidal activities against Staphylococcus aureus and antiviral activity against SARS-CoV-2 were determined by in vitro assays. As a result, the average size of the nanoparticles was recorded at 150 nm, with a Polydispersity Index (PdI) of 0.2 and a zeta potential around -10.0 mV. The stability of nanoformulations indicated the occurrence of quercetin-dependent creaming and sedimentation. In addition, the products presented a minimum shelf-life of 3 months. Regarding the bactericidal activity, a minimum inhibition concentration of 1.25 % for S. aureus was found. The cytotoxicity and antiviral assays revealed that the nano-based products showed 100 % of viral replication inhibition and proved to be safe for epithelial cells. In conclusion, two antiseptic nanoformulations with high anti-SARS-CoV-2 activity and great industrial and pharmacological potential were developed.

The cellulose nanocrystal jammed interfaces induced by CO2-assisted self-assembly for enhancing oil recovery

Stability of displacement front is of great importance in the immiscible fluid displacement for enhancing oil recovery. Here, a CO2-strenghened assembly approach is demonstrated for the fabrication of highly jammed CNSs (cellulose nanocrystal surfactants) with EPD (N'-ethylpropane-1,3-diamine) and TOCNC (TEMPO oxidized cellulose nanocrystal), which produce a structured film at the oil-water interface to counteract the capillary force, and thus governing the local displacing pattern. In this approach, EPD molecules can be deeply protonated in the presence of CO2, favoring their binding forces with TOCNC at the interface to produce more CNSs. Meanwhile, the strong intermolecular attractions among CO2-bearing CNSs promote to form a striped interfacial film with both the close-packed rod-like arrays in horizontal and the multi-layer in lateral. Further, the CNSs-based film confers with a high strength and elasticity can reduce the capillary force by 87 % in micro-channels, yielding a smooth water-to-oil displacement front, which markedly enhances the oil recovery by 20.6 % compared to the surfactant-only flooding. This self-assembly strategy has a great implication in eco-friendly and cost-effective applications, such as enhanced oil recovery, CO2 geo-sequestration, and water infiltration.

pH-Switchable W/O Polymer Emulsion: A Promising Strategy for Rapid Dissolution of Drag Reducers

Additional hydrophilic surfactants are generally introduced into W/O emulsion drag reducer systems to enhance the dissolution capacity of polymers. The hydrophilic surfactants may decrease the stability of W/O emulsion, which leads to deterioration of polymer emulsions in the storage and transport process instead. Herein, a pH-switchable surfactant, N-(2-morpholinoethyl) oleamide (NMEO) was designed for stabilizing a W/O emulsion drag reducer. The surface activity and solubility changes occurring at pH < 6 of NMEO guaranteed the phase inversion from W/O to O/W of emulsions upon pH stimulation. Based on optimal conditions (oil-water ratio of 0.429, NMEO concentration of 3 wt%, and pH of 6.5), the inverse emulsion polymerization of poly(acrylamide-co-acrylic acid-co-2-acrylamide-2-methylpropane sulfonic acid) was proceeded to obtain a W/O polymer emulsion with the pH-switchable behavior. It was demonstrated that the polymer emulsions were provided with prolonged storage stability by NMEO and could be stored for at least 30 days due to the absence of hydrophilic surfactants. The polymers were released and completely dissolved within 2.5 min by pH stimulation, compared with traditional emulsion polymers and powder polymers that require 4 and 17 min, respectively. In addition, the emulsion drag reducer prepared by NMEO provided drag-reduction performance of 64.67% at 0.021 wt% concentration. The pH-switchable behavior of NMEO promotes the validity of W/O polymer emulsions along with the capacity of rapid release and solubilization, which eliminates the imbalance between the long-term storage stability and rapid solubility of traditional drag reducers. Thus, NMEO-stabilized emulsion drag reducers are expected to be a promising alternative for traditional products.

Study on the solubilization effect of 7-ethyl-10-hydroxycamptothecin based on molecular docking and molecular dynamics simulation

CONTEXT

With the continuous improvement of anticancer drugs, the condition of patients has been controlled to a certain extent, but the problem that still needs to be urgently solved is that most anticancer drug candidates' solubility is low. On the one hand, the low solubility of anticancer drugs may lead to a decrease in the absorption rate of anticancer drugs, poor treatment effect, and even death in severe cases. On the other hand, it will also lead to a waste of medical resources. At the same time, the rapid and scientific screening of ideal anticancer drugs has become a difficult problem that researchers have to face in the research process. In this study, we found two kinds of SN38-ligand complexes that solubilize 7-ethyl-10-hydroxycamptothecin (SN38) through molecular docking and molecular dynamics simulation methods. This process not only provided valuable information on improving the solubility of SN38, but also helped to discover effective potential complexes that solubilize SN38 quickly and scientifically.

METHODS

The interaction of the SN38 with folic acid and isoproterenol hydrochloride was rapidly determined by molecular docking and molecular dynamics simulation methods. We used Discovery Studio software to perform molecular docking. And then, we used Gromacs 2019.3 software to perform molecular dynamics, analyzing and comparing the hydrogen bonds, solvent-accessible surface areas, energies, and so on between SN38 and SN38-ligand complexes. And the force field adopted the Gromos 54a7.

Isoliquiritigenin Nanoemulsion Preparation by Combined Sonication and Phase-Inversion Composition Method: In Vitro Anticancer Activities

Isoliquiritigenin (ILQ) has a number of biological activities such as antitumor and anti-inflammatory effects. However, biomedical applications of ILQ are impeded by its poor aqueous solubility. Therefore, in this research, we prepared a novel ILQ-loaded nanoemulsion, i.e., ILQ-NE, which consisted of Labrafil® M 1944 CS (oil), Cremophor® EL (surfactant), ILQ, and phosphate-buffered saline, by employing a combined sonication (high-energy) and phase-inversion composition (low-energy) method (denoted as the SPIC method). The ILQ-NE increased the ILQ solubility ~1000 times more than its intrinsic solubility. It contained spherical droplets with a mean diameter of 44.10 ± 0.28 nm and a narrow size distribution. The ILQ loading capacity was 4%. The droplet size of ILQ-NE remained unchanged during storage at 4 °C for 56 days. Nanoemulsion encapsulation effectively prevented ILQ from degradation under ultraviolet light irradiation, and enhanced the ILQ in vitro release rate. In addition, ILQ-NE showed higher cellular uptake and superior cytotoxicity to 4T1 cancer cells compared with free ILQ formulations. In conclusion, ILQ-NE may facilitate the biomedical application of ILQ, and the SPIC method presents an attractive avenue for bridging the merits and eliminating the shortcomings of traditional high-energy methods and low-energy methods.

pH-Responsive Regulation of a Surfactant-Free Microemulsion Based on Hydrophobic Deep Eutectic Solvents

Microemulsions containing a responsive hydrophobic deep eutectic solvent (HDES) as the oil phase that can replace conventional organic solvents are considered to be a green strategy. It is anticipated that a pH-responsive HDES is synthesized to prepare rapid responsive surfactant-free microemulsions (SFMEs), which enable the transition from SFMEs to nanoemulsions. Menthol and n-octanoic acid (OA) were assembled into HDES by hydrogen bonding at a molar ratio of 1:2. The pH-responsive HDES as the oil phase and isopropyl alcohol (IPA) as the double solvent could form HDES/IPA/water SFMEs, which have unique responsiveness. Specifically, from the nuclear magnetic resonance hydrogen spectrum, pH, thermogravimetry, and Fourier transform infrared spectroscopy investigations, the excellent switchability and stability of menthol-OA were demonstrated. On the basis of these complexes, microemulsions were successfully prepared. Electrical conductivity and pH measurements were used to determine the structures of microemulsions and the phase inversion process. The effects of the contents of water and HDES, NaCl concentration, and pH of the system were investigated. Nanoemulsions were successfully prepared on the basis of the pH response of the microemulsions. In addition, the prepared nanoemulsion has a unique pH-responsive behavior that can be controllably regulated among nanoemulsions, microemulsions, and phase separation systems.

Development of Phosphatidylcholine/Tween 80 based biocompatible clove oil-in-water nanoemulsion as a green nanocarrier for controlled herbicide delivery

Recently, the development of ecofriendly and biocompatible agrochemical delivery systems has garnered widespread attention because of their great potential in sustainable agri-food applications. Atrazine (ATZ) is a globally used herbicide used to control weeds, but it suffers from poor aqueous solubility, poor efficacy, and environmental loss. Herein, we report a novel, eco-friendly and biocompatible clove oil-based nanoemulsion as a green nanocarrier to enhance the solubility, bioavailability, and control release of ATZ. Food grade surfactants, Tween 80 and Phosphatidylcholine (PC) were used to formulate clove oil nanoemulsion with size <200 nm using ultrasonic emulsification technique, without any use of organic solvent. The ATZ encapsulation efficiency in NEm was greater than 95%. DLS confirms the nanosize (106 nm) and monodispersity of NEm. HRTEM reveals the spherical morphology of the nanodroplets. FTIR and DSC confirm the successful incorporation of ATZ inside the NEm oil droplet core. ATZ loaded NEm showed excellent thermal and storage stability, low Ostwald ripening rate, slow and sustained herbicide release behavior, which is of vital importance for an herbicide formulation. The release rate was better than commercial ATZ and free ATZ formulations. Results from herbicidal activity assays demonstrate that ATZ NEm exhibited excellent herbicidal activity even at low concentrations as compared to commercial ATZ analogs. In consideration of biocompatible excipients, free of organic solvent, and a simple fabrication process, ATZ loaded clove oil NEm can hold great potential in weed control and sustainable agri-food applications.

A pH-sensitive W/O emulsion for the preparation and rapid dissolution of polyacrylamide-based friction reducer

The pH-sensitive modified-polyacrylamide emulsion shows a fast dissolution rate with a dissolution time of about 1 min and long storage stability.

Lipid-based nanoparticles for psoriasis treatment: a review on conventional treatments, recent works, and future prospects

Psoriasis is a lingering inflammatory skin disease that attacks the immune system. The abnormal interactions between T cells, immune cells, and inflammatory cytokines causing the epidermal thickening. International guidelines have recommended topical treatments for mild to moderate psoriasis whilst systemic and phototherapy treatments for moderate to severe psoriasis. However, current therapeutic approaches have a wider extent to treat moderate to severe type of psoriasis especially since the emergence of diverse biologic agents. In the meantime, topical delivery of conventional treatments has prompted many unsatisfactory effects to penetrate through the skin (stratum corneum). By understanding the physiology of stratum corneum barrier functions, scientists have developed different types of lipid-based nanoparticles like solid lipid nanoparticles, nanostructured lipid carriers, nanovesicles, and nanoemulsions. These novel drug delivery systems help the poorly solubilised active pharmaceutical ingredient reaches the targeted site seamlessly because of the bioavailability feature of the nanosized molecules. Lipid-based nanoparticles for psoriasis treatments create a paradigm for topical drug delivery due to their lipids' amphiphilic feature to efficiently encapsulate both lipophilic and hydrophilic drugs. This review highlights different types of lipid-based nanoparticles and their recent works of nano formulated psoriasis treatments. The encapsulation of psoriasis drugs through lipid nanocarriers unfold numerous research opportunities in pharmaceutical applications but also draw challenges for the future development of nano drugs.