Mechanisms of Solubilization of Mixed Liposomes: Preferential Dissolution of Liposome Components

Novel mechanisms of alkyldimethylbenzalkonium chloride in virucidal activity

The cationic surfactant, alkyldimethylbenzalkonium chloride (BAC), effectively inactivates enveloped viruses, but the underlying mechanism of action is poorly understood. Therefore, this study attempted to elucidate the inactivation mechanism of BAC using actual viruses and characterize the state of BAC in water under the same conditions. Here, we show that at concentrations below the critical micelle concentration (CMC), partial membrane disruption by BAC monomers contributes to the inactivation mechanism. At concentrations above the CMC, solubilization of the envelope component also contributes to virucidal activity. Concentration-related differences in the inactivation mechanism were further evaluated based on the kinetic equation of the reaction, which showed that physicochemical studies are directly related to biochemistry. As enveloped viruses can be viewed as vesicles based on their structure, the results of this study should enhance investigations of non-virus biological vesicles, such as exosomes and drug delivery systems.

Preparation of antiviral multispray with cationic antimicrobial dialkyldimethyl ammonium salt and sulfobetaine against new coronaviruses (SARS-CoV-2)

The novel sudden acute respiratory syndrome coronavirus 2 is an enveloped virus currently causing severe illness and death worldwide. Common antiseptics such as alcohol have some efficacy in disinfecting everyday surroundings, but development of more effective disinfectants is imperative. A series of studies focusing on cationic antimicrobials resulted in the development of a safe and effective novel coronavirus disinfectant, DEA-171, which provides ≥99.98 % inhibition of all novel coronavirus variants within 1 min.

Aloe derived nanovesicle as a functional carrier for indocyanine green encapsulation and phototherapy

Background

Cancer is one of the devastating diseases in the world. The development of nanocarrier provides a promising perspective for improving cancer therapeutic efficacy. However, the issues with potential toxicity, quantity production, and excessive costs limit their further applications in clinical practice.

Results

Herein, we proposed a nanocarrier obtained from aloe with stability and leak-proofness. We isolated nanovesicles from the gel and rind of aloe (gADNVs and rADNVs) with higher quality and yield by controlling the final centrifugation time within 20 min, and modulating the viscosity at 2.98 mPa S and 1.57 mPa S respectively. The gADNVs showed great structure and storage stability, antioxidant and antidetergent capacity. They could be efficiently taken up by melanoma cells, and with no toxicity in vitro or in vivo. Indocyanine green (ICG) loaded in gADNVs (ICG/gADNVs) showed great stability in both heating system and in serum, and its retention rate exceeded 90% after 30 days stored in gADNVs. ICG/gADNVs stored 30 days could still effectively damage melanoma cells and inhibit melanoma growth, outperforming free ICG and ICG liposomes. Interestingly, gADNVs showed prominent penetrability to mice skin which might be beneficial to noninvasive transdermal administration.

Conclusions

Our research was designed to simplify the preparation of drug carrier, and reduce production cost, which provided an alternative for the development of economic and safe drug delivery system.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01195-7.

Direct Synthesis of Rhenium and Technetium-99m Metallosurfactants by a Transmetallation Reaction of Lipophilic Groups: Potential Applications in the Radiolabeling of Liposomes

A new zinc dithiocarbamate functionalized with palmitoyl groups is described as a useful tool for the preparation of metallosurfactants through a transmetallation reaction with the transition metals rhenium and technetium. An amphiphilic rhenium complex is synthesized by a transmetallation reaction with the zinc complex in presence of the polar phosphine sodium triphenylphosphine trisulfonate, which leads to a rhenium complex with a lipophilic dithiocarbamate and a polar phosphine ligand. The study of this rhenium complex has shown that it self-aggregates, leading to the formation of aggregates that have been analyzed by dynamic light scattering and cryotransmission electron microscopy (cryo-TEM). In addition, this amphiphilic rhenium complex is incorporated into soy phosphatidylcholine liposomes, whether liposomes are prepared by mixing phospholipid and the rhenium complex or by the incorporation of the rhenium complex into preformed liposomes. The one-pot reaction of the radiocompound [^99mTc(H₂O)₃(CO)₃]⁺ with the above-mentioned zinc dithiocarbamate, the phosphine sodium triphenylphosphine trisulfonate and the phospholipid soy phosphatidylcholine, leads to liposomes labeled with a Tc-99m homologous complex of the rhenium complex, in accordance with the high-performance liquid chromatography (HPLC) data.

Encapsulation, protection, and release of hydrophilic active components: potential and limitations of colloidal delivery systems

There have been major advances in the development of edible colloidal delivery systems for hydrophobic bioactives in recent years. However, there are still many challenges associated with the development of effective delivery systems for hydrophilic bioactives. This review highlights the major challenges associated with developing colloidal delivery systems for hydrophilic bioactive components that can be utilized in foods, pharmaceuticals, and other products intended for oral ingestion. Special emphasis is given to the fundamental physicochemical phenomena associated with encapsulation, stabilization, and release of these bioactive components, such as solubility, partitioning, barriers, and mass transport processes. Delivery systems suitable for encapsulating hydrophilic bioactive components are then reviewed, including liposomes, multiple emulsions, solid fat particles, multiple emulsions, biopolymer particles, cubosomes, and biologically-derived systems. The advantages and limitations of each of these delivery systems are highlighted. This information should facilitate the rational selection of the most appropriate colloidal delivery systems for particular applications in the food and other industries.

In vitro analysis of the effect of alkyl-chain length of anionic surfactants on the skin by using a reconstructed human epidermal model

We investigated the effect of the alkyl-chain length of anionic surfactants on the skin using an in vitro model. The evaluated anionic surfactants were sodium alkyl sulfate (AS) and sodium fatty acid methyl ester sulfonate (MES), which had different alkyl-chain lengths (C8-C14). Skin tissue damage and permeability were examined using a reconstructed human epidermal model, LabCyte EPI-MODEL24. Skin tissue damage was examined by measuring cytotoxicity with an MTT assay. Liquid chromatography/tandem mass spectrometry (LC/MS-MS) and liquid chromatography/mass spectrometry (LC/MS) were used to detect surfactants that permeated into the assay medium through an epidermal model. To assess the permeation mechanism and cell damage caused by the surfactants through the epidermis, we evaluated the structural changes of Bovine Serum Albumin (BSA), used as a simple model protein, and the fluidity of 1,2-dipalmitoyl-sn-glycero-3-phosphpcholine (DPPC) liposome, which serves as one of the most abundant phospholipid models of living cell membranes in the epidermis. The effects of the surfactants on the proteins were measured using Circular Dichroism (CD) spectroscopy, while the effects on membrane fluidity were investigated by electron spin resonance (ESR) spectroscopy. ET50 (the 50% median effective time) increased as follows: C10 < C12 < C8 < C14 in AS and C8, C10 < C12 < C14 in MES. The order of permeation through the LabCyte EPI-MODEL24 was C10 > C12 > C14, for both AS and MES. For both AS and MES, the order parameter, which is the criteria for the microscopic viscosity of lipid bilayers, increased as follows: C10 < C12 < C14, which means the membrane fluidity is C10 > C12 > C14. It was determined that the difference in skin tissue damage in the LabCyte EPI-MODEL24 with C10 to C14 AS and MES was caused by the difference in permeation and cell membrane fluidity through the lipid bilayer path in the epidermis.

Use of simple kinetic and reaction-order measurements for the evaluation of the mechanism of surfactant-liposome interactions

Surfactant-liposome interactions have been previously studied through different methods and techniques. We present here a classical physical chemistry study on liposome solutions added to destabilizing agents at concentrations well above the solubilization concentration, which enable us to draw useful and interesting conclusions about the mechanism of surfactant-induced liposomal breakdown by simply exploiting the kinetics and the reaction order of the liposomal content release. In such excess of surfactant, the mechanism of surfactant-induced rupture of the liposomes has been demonstrated to be different from that proposed for low surfactant concentrations. Thus, depending on the surfactant concentration, two prevailing processes have been evidenced: (i) a cooperative mechanism that implies the assembly of a critical number of surfactant molecules to trigger the formation of a channel and therefore the release of the liposomal content and (ii) a mechanism driven by direct interaction of the surfactant molecules with the lipids that causes the complete solubilization of the liposomes. The former mechanism occurs at low surfactant concentrations, whereas the latter occurs at higher concentrations and above the CMC of the surfactants. The effect of different guests embedded into the liposomal bilayer on the mechanism of surfactant-induced liposomal breakdown has been compared by using the second-order rate constants measured for the liposome breakdown process.

Solubilization of lipid bilayers by myristyl sucrose ester: effect of cholesterol and phospholipid head group size

The solubilization of biological membranes by detergents has been used as a major method for the isolation and purification of membrane proteins and other constituents. Considerable interest in this field has resulted from the finding that different components can be solubilized selectively. Certain membrane constituents are incorporated into small micelles, whereas others remain in the so-called detergent-resistant membrane domains that are large enough to be separated by centrifugation. The detergent-resistant fractions contain an elevated percentage of cholesterol, and thus its interaction with specific lipids and proteins may be key for membrane organization and regulation of cellular signaling events. This report focuses on the solubilization process induced by the sucrose monoester of myristic acid, beta-D-fructofuranosyl-6-O-myristyl-alpha-D-glucopyranoside (MMS), a nonionic detergent. We studied the effect of the head group and the cholesterol content on the process. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and dioctadecyl-dimethyl-ammonium chloride (DODAC) vesicles were used, and the solubilization process was followed using Laurdan (6-dodecanoyl-2-dimethylaminonaphthalene) generalized polarization (GP) measurements, carried out in the cuvette and in the 2-photon microscope. Our results indicate that: (i) localization of the MMS moieties in the lipid bilayer depends on the characteristics of the lipid polar head group and influences the solubilization process. (ii) Insertion of cholesterol molecules into the lipid bilayer protects it from solubilizaton and (iii) the microscopic mechanism of solubilization by MMS implies the decrease in size of the individual liposomes.