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The viscosity that ensures the controlled diffusion of biomolecules in cells is a crucial biophysical parameter. Consequently, fluorescent probes capable of reporting viscosity variations are valuable tools in bioimaging. In this field, red-shifted probes are essential, as the widely used and gold standard probe remains green-emitting molecular rotors based on BODIPY. Here, we demonstrate that pyrrolyl squaraines, red-emissive fluorophores, exhibit high sensitivity over a wide viscosity range from 30 to 4890 mPa·s. Upon alkylation of the pyrrole moieties, the probes improve their sensitivity to viscosity through an enhanced twisted intramolecular charge transfer phenomenon. We utilized this scaffold to develop a plasma membrane probe, pSQ-PM, that efficiently stains the plasma membrane in a fluorogenic manner. Using fluorescence lifetime imaging, pSQ-PM enabled efficient sensing of viscosity variations in the plasma membrane under various conditions and in different cell lines (HeLa, U2OS, and NIH/3T3). Moreover, upon incubation, pSQ-PM stained the membrane of intracellular vesicles and suggested that the lysosomal membranes displayed enhanced fluidity.
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Membrana Celular , Ciclobutanos , Colorantes Fluorescentes , Imagen Óptica , Fenoles , Pirroles , Membrana Celular/química , Membrana Celular/metabolismo , Viscosidad , Colorantes Fluorescentes/química , Ratones , Animales , Humanos , Ciclobutanos/química , Pirroles/química , Fenoles/química , Células 3T3 NIH , Células HeLa , Estructura MolecularRESUMEN
Many strategies for regenerating the damaged tissues or degenerating cells are employed in regenerative medicine. Stem cell technology is a modern strategy of the recent approaches, particularly the use of mesenchymal stem cells (MCSs). The ability of MSCs to differentiate as well as their characteristic behaviour as paracrine effector has established them as key elements in tissue repair. Recently, extracellular vesicles (EVs) shed by MSCs have emerged as a promising cell free therapy. This comprehensive review encompasses MSCs-derived exosomes and their therapeutic potential as nanotherapeutics. We also discuss their potency as drug delivery nano-carriers in comparison with liposomes. A better knowledge of EVs behaviour in vivo and of their mechanism of action are key to determine parameters of an optimal formulation in pilot studies and to establish industrial processes.
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Exosomas , Células Madre Mesenquimatosas , Exosomas/metabolismo , Exosomas/química , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/metabolismo , Humanos , Animales , Sistemas de Liberación de Medicamentos/métodos , Portadores de Fármacos/química , Medicina Regenerativa/métodos , Nanopartículas/químicaRESUMEN
In this study, we present a new type of polymer-free hydrogel made only from nonionic surfactants, oil, and water. Such a system is produced by taking advantage of the physicochemical behavior and interactions between nonionic surfactants and oil and water phases, according to a process close to spontaneous emulsification used in the production of nano-emulsions. Contrary to the classical process of emulsion-based gel formulation, we propose a simple one-step approach. Beyond the originality of the concept, these nanoemulgels appear as very promising systems able to encapsulate and deliver various molecules with different solubilities. In the first section, we propose a comprehensive investigation of the gel formation process and its limits through oscillatory rheological characterization, characterization of the sol/gel transitions, and gel strength. The second section is focused on the follow-up of the release of an encapsulated model hydrophilic molecule and on the impact of the rheological gel properties on the release profiles.
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Computed tomography (CT) is a powerful and widely used imaging technique in modern medicine. However, it often requires the use of contrast agents to visualize structures with similar radiographic density. Unfortunately, current clinical contrast agents (CAs) for CT have remained largely unchanged for decades and come with several significant drawbacks, including serious nephrotoxicity and short circulation half-lives. The next generation of CT radiocontrast agents should strive to be long-circulating, non-toxic, and non-immunogenic. Nanoparticle contrast agents have shown promise in recent years and are likely to comprise the majority of next-generation CT contrast agents. This review highlights the fundamental mechanism and background of X-ray and contrast agents. It also focuses on the challenges associated with current clinical contrast agents and provides a brief overview of potential future agents that are based on various materials such as lipids, polymers, dendrimers, metallic, and non-metallic inorganic nanoparticles (NPs). STATEMENT OF SIGNIFICANCE: We realized a need for clarification on a number of concerns related to the use of iodinated contrast material as debates regarding the safety of these agents with patients with kidney disease, shellfish allergies, and thyroid dysfunction remain ongoing in medical practice. This review was partially inspired by debates witnessed in medical practice regarding outdated misconceptions of contrast material that warrant clarification in translational and clinical arenas. Given that conversation around currently available agents is at somewhat of a high water mark, and nanoparticle research has now reached an unprecedented number of readers, we find that this review is timely and unique in the context of recent discussions in the field.
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Medios de Contraste , Nanopartículas , Humanos , Medios de Contraste/química , Rayos X , Tomografía Computarizada por Rayos X/métodos , Nanopartículas/uso terapéutico , Nanopartículas/química , AguaRESUMEN
The fundamental purpose of this study was to develop a stable lyophilised finasteride nanosystem (FNS-NS) for topical delivery. The FNS-NS was fabricated using an ultrasonication technique. The impact of two different cryoprotectants on the physicochemical characteristics of FNS-NS before and after lyophilisation was thoroughly investigated. The lyophilised FNS-NS had spherical shape with particle size lied between 188.6 nm ± 4.4 and 298.7 nm ± 4.7, low PDI values (0.26 ± 0.02 to 0.32 ± 0.02) and zeta potential ranging from -38.3 to +53.3 mV. The confocal laser microscopy depicted a comparatively higher cellular internalisation achieved for undecorated FNS-NS with respect to its chitosan-decorated counterpart. The lyophilised FNS-NS was stable for 90 days at proper storage conditions. The FNS-NS with 15% trehalose had appropriate physicochemical attributes that could be a promising carrier for topical delivery to treat androgenic alopecia.
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Finasterida , Nanopartículas , Humanos , Finasterida/farmacología , Alopecia , Liofilización , Tamaño de la PartículaRESUMEN
Current biomedical applications of nanocarriers are focused on drug delivery, where encapsulated cargo is released in the target tissues under the control of external stimuli. Here, we propose a very different approach, where the active toxic molecules are removed from biological tissues by the nanocarrier. It is based on the drug-sponge concept, where specific molecules are captured by the lipid nanoemulsion (NE) droplets due to dynamic covalent chemistry inside their oil core. To this end, we designed a highly lipophilic amine (LipoAmine) capable of reacting with a free cargo-aldehyde (fluorescent dye and 4-hydroxynonenal toxin) directly inside lipid NEs, yielding a lipophilic imine conjugate well encapsulated in the oil core. The formation of imine bonds was first validated using a push-pull pyrene aldehyde dye, which changes its emission color during the reaction. The conjugate formation was independently confirmed by mass spectrometry. As a result, LipoAmine-loaded NEs spontaneously loaded cargo-aldehydes, yielding formulations stable against leakage at pH 7.4, which can further release the cargo in a low pH range (4-6) in solutions and living cells. Using fluorescence microscopy, we showed that LipoAmine NEs can extract pyrene aldehyde dye from cells as well as from an epithelial tissue (chicken skin). Moreover, successful extraction from cells was also achieved for a highly toxic aliphatic aldehyde 4-hydroxynonenal, which allowed obtaining the proof of concept for detoxification of living cells. Taken together, these results show that the dynamic imine chemistry inside NEs can be used to develop detoxification platforms.
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Portadores de Fármacos , Iminas , Portadores de Fármacos/química , Preparaciones de Acción Retardada , Aldehídos , LípidosRESUMEN
INTRODUCTION: In most of the studies, nano-emulsion characterization is limited to their size distribution and zeta potential. In this review, we present an updated insight of the characterization methods of nano-emulsions, including new or unconventional experimental approaches to explore in depth the nano-emulsion properties. AREA COVERED: We propose an overview of all the main techniques used to characterize nano-emulsions, including the most classical ones, up to in vitro, ex vivo and in vivo evaluation. Innovative approaches are then presented in the second part of the review that presents innovative, experimental techniques less known in the field of nano-emulsion such as the nanoparticle tracking analysis, small-angle X-ray scattering, Raman spectroscopy, and nuclear magnetic resonance. Finally, in the last part we discuss the use of lipophilic fluorescent probes and imaging techniques as an emerging tool to understand the nano-emulsion droplet stability, surface decoration, release mechanisms, and in vivo fate. EXPERT OPINION: This review is mostly intended for a broad readership and provides key tools regarding the choice of the approach to characterize nano-emulsions. Innovative and uncommon methods will be precious to disclose the information potentially reachable behind a formulation of nano-emulsions, not always known in first intention and with conventional methods.
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Nanopartículas , Emulsiones/química , Nanopartículas/química , Tamaño de la PartículaRESUMEN
In this study, we explored how chemical reactions of amphiphile compounds can be characterized and followed-up on model interfaces. A custom-made surfactant containing three alkyne sites was first adsorbed and characterized at a water/oil interface. These amphiphiles then underwent interfacial crosslinking by click chemistry upon the addition of a second reactive agent. The monolayer properties and dilatational elasticity, were compared before and after the polymerization. Using bulk phase exchange, the composition of the aqueous bulk phase was finely controlled and washed to specifically measure the interfacial effects of the entities adsorbed and trapped at the interface. In this study, we aim to emphasize an original experimental approach to follow complex phenomena occurring on model interfaces, and also show the potential of this method to characterize multifactorial processes.
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Surfactantes Pulmonares , Tensoactivos , Tensoactivos/química , Agua/química , Química Clic , AdsorciónRESUMEN
In this study, oil-in-water Pickering emulsions (PEs) were prepared by modified silica nanoparticles (MSNs) with cetyltrimethylammonium bromide (CTAB) using the Taguchi approach. The surface modification of SiO2 nanoparticles (NPs) was performed in different conditions, temperatures, pH levels, and amounts of CTAB as a coating agent, followed by an evaluation of their physicochemical properties. After treatment of the SiO2 NPs, the relationship of the MSNs' surface properties and their efficiency in stabilizing Pickering emulsions was investigated by considering the zeta potential (ZP) and emulsion physical stability as main responses, respectively. Results disclosed were then supported by additional characterization, such as thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, contact angle (CA), and scanning electron microscopy. Results demonstrated that temperature has the most important role in the treatment of SiO2 nanoparticles, and allows for the identification of the best experimental conditions, i.e., range of zeta potential of MSNs to produce more efficient NPs, as well as the best stabilization of PEs.
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Nano-emulsions consist of stable suspensions of nano-scaled droplets that have huge loading capacities and are formulated with safe compounds. For these reasons, a large number of studies have described the potential uses of nano-emulsions, focusing on various aspects such as formulation processes, loading capabilities, and surface modifications. These studies typically concern direct nano-emulsions (i.e., oil-in-water), whereas studies on reverse nano-emulsions (i.e., water-in-oil) remain anecdotal. However, reverse nano-emulsion technology is very promising (e.g., as an alternative to liposome technology) for the development of drug delivery systems that encapsulate hydrophilic compounds within double droplets. The spontaneous emulsification process has the added advantages of optimization of the energetic yield, potential for industrial scale-up, improved loading capabilities, and preservation of fragile compounds targeted for encapsulation. In this study, we propose a detailed investigation of the processes and formulation parameters involved in the spontaneous nano-emulsification that produces water-in-oil nano-emulsions. The following details were addressed: (i) the order of mixing of the different compounds (method A and method B), (ii) mixing rates, (iii) amount of surfactants, (iv) type and mixture of surfactants, (v) amount of dispersed phase, and (vi) influence of the nature of the oil. The results emphasized the effects of the formulation parameters (e.g., the volume fraction of the dispersed phase, nature or concentration of surfactant, or nature of the oil) on the nature and properties of the nano-emulsions formed.
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Nanoemulsions (NEs) are water-dispersed oil droplets that constitute stealth biocompatible nanomaterials. NEs can reach an impressive degree of fluorescent brightness owing to their oily core that can encapsulate a large number of fluorophores on the condition the latter are sufficiently hydrophobic and oil-soluble. BODIPYs are among the brightest green emitting fluorophores and as neutral molecules possess high lipophilicity. Herein, we synthesized three different natural lipid-BODIPY conjugates by esterification of an acidic BODIPY by natural lipids, namely: α-tocopherol (vitamin E), cholesterol, and stearyl alcohol. The new BODIPY conjugates were characterized in solvents and oils before being encapsulated in NEs at various concentrations. The physical (size, stability over time, leakage) and photophysical properties (absorption and emission wavelength, brightness, photostability) are reported and showed that the nature of the lipid anchor and the nature of the oil used for emulsification greatly influence the properties of the bright NEs.
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Endothelial senescence has been identified as an early event in the development of endothelial dysfunction, a hallmark of cardiovascular disease. This study developed theranostic nanocarriers (NC) decorated with VCAM-1 antibodies (NC-VCAM-1) in order to target cell surface VCAM-1, which is overexpressed in senescent endothelial cells (ECs) for diagnostic and therapeutic purposes. Incubation of Ang II-induced premature senescent ECs or replicative senescent ECs with NC-VCAM-1 loaded with lipophilic fluorescent dyes showed higher fluorescence signals than healthy EC, which was dependent on the NC size and VCAM-1 antibodies concentration, and not observed following masking of VCAM-1. NC loaded with omega 3 polyunsaturated fatty acid (NC-EPA:DHA6:1) were more effective than native EPA:DHA 6:1 to prevent Ang II-induced VCAM-1 and p53 upregulation, and SA-ß-galactosidase activity in coronary artery segments. These theranostic NC might be of interest to evaluate the extent and localization of endothelial senescence and to prevent pro-senescent endothelial responses.
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Senescencia Celular , Portadores de Fármacos , Endotelio Vascular/citología , Colorantes Fluorescentes/química , Molécula 1 de Adhesión Celular Vascular/metabolismo , Animales , Autoanticuerpos/inmunología , Proliferación Celular , Endotelio Vascular/metabolismo , Medicina de Precisión , Porcinos , Molécula 1 de Adhesión Celular Vascular/inmunologíaRESUMEN
In this work, we used an original experimental setup to examine the behavior of insoluble monolayers made with pH-sensitive lipids. Two kinds of unsaturated lipids were chosen: a cationic one (lipid 1) bearing an ammonium headgroup and an anionic one (lipid 2) terminated with an acidic phenol group. The lipids were deposited onto an air bubble interface maintained in an aqueous phase and, after stabilization, were subjected to a series of compressions performed at different pH values. These experiments disclosed a gradual increase in the specific area per molecule when lipids were neutralized. Imposing a pH variation at constant bubble volume also provided surface pressure profiles that confirmed this molecular behavior. As complementary characterization, dilatational rheology disclosed a phase transition from a purely elastic monophasic system to a viscoelastic two-phase system. We hypothesized that this unexpected increase in the specific area with lipid neutralization is related to the presence of unsaturations in each of the two branches of the hydrophobic tails that induce disorder, thereby increasing the molecular area at the interface. Application of the two-dimensional Volmer equation of state allowed the generation of quantitative values for the specific areas that showed variations with pH. It also allowed the determination of apparent pKa values, which are affected by both the electrostatic potential within the monolayer and the affinity of the lipid polar head for the aqueous phase.
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Nano-emulsions are defined as stable oil droplets sizing below 300 nm. Their singular particularity lies in the loading capabilities of their oily core, much higher than other kinds of carrier. On the other hand, functionalizing the dynamic oil/water interface, to date, has remained a challenge. To ensure the best anchoring of the reactive functions onto the surface of the droplets, we have designed specific amphiphilic polymers (APs) based on poly(maleic anhydride-alt-1-octadecene), stabilizing the nano-emulsions instead of surfactants. Aliphatic C18 chains of the APs are anchored in the droplet core, while the hydrophilic parts of the APs are poly(ethylene glycol) (PEG) chains. In addition, PEG chains are terminated with reactive (i) azide functions in order to prove the concept of the droplet decoration with clickable rhodamine (Rh-DBCO, specifically synthesized for this study), or (ii) biotin functions to verify the potential droplet functionalization with fluorescent streptavidin (streptavidin-AF-488). This study describes AP synthesis, physico-chemical characterization of the functional droplets (electron microscopy), and finally fluorescence labeling and droplet decoration. To conclude, these APs constitute an interesting solution for the stable functionalization of nano-emulsion droplets, paving a new way for the applications of nano-emulsions in targeting drug delivery.
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Polímeros , Tensoactivos , Emulsiones , Interacciones Hidrofóbicas e Hidrofílicas , PolietilenglicolesRESUMEN
Conjugation of the bioactive apelin-17 peptide with a fluorocarbon chain results in self-organization of the peptide into micelles. Fluorine NMR spectroscopy studies show that the fluoropeptide's micelles are monodisperse, while proton NMR indicates that the peptide moiety remains largely disordered despite micellization. A very fast exchange rate is measured between the free and micellar states of the peptide which enables the number of molecules present in the micelle to be estimated as 200, in agreement with values found by dynamic light scattering measurements.
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Flúor/química , Halogenación , Péptidos y Proteínas de Señalización Intercelular/química , Resonancia Magnética Nuclear Biomolecular/métodos , Humanos , MicelasRESUMEN
Lipid nanoemulsions (NEs), owing to their controllable size (20 to 500 nm), stability and biocompatibility, are now frequently used in various fields, such as food, cosmetics, pharmaceuticals, drug delivery, and even as nanoreactors for chemical synthesis. Moreover, being composed of components generally recognized as safe (GRAS), they can be considered as "green" nanoparticles that mimic closely lipoproteins and intracellular lipid droplets. Therefore, they attracted attention as carriers of drugs and fluorescent dyes for both bioimaging and studying the fate of nanoemulsions in cells and small animals. In this review, the composition of dye-loaded NEs, methods for their preparation, and emerging biological applications are described. The design of bright fluorescent NEs with high dye loading and minimal aggregation-caused quenching (ACQ) is focused on. Common issues including dye leakage and NEs stability are discussed, highlighting advanced techniques for their characterization, such as Förster resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS). Attempts to functionalize NEs surface are also discussed. Thereafter, biological applications for bioimaging and single-particle tracking in cells and small animals as well as biomedical applications for photodynamic therapy are described. Finally, challenges and future perspectives of fluorescent NEs are discussed.
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Portadores de Fármacos , Nanopartículas , Animales , Biomimética , Colorantes Fluorescentes , Lípidos , NanomedicinaRESUMEN
The prevalence of nosocomial infections due to multidrug resistant (MDR) bacterial strains is associated with high morbidity and mortality. Folk medicine and ethnopharmacological data can provide a broad range of plants with promising antimicrobial activity. Triphala, an Ayurvedic formula composed of three different plants: Terminalia chebula Retz., Terminalia bellirica (Gaertn.) Roxb. (Combretaceae), and Phyllanthus emblica L. (Phyllanthaceae), is used widely for various microbial infections. Various extraction techniques were applied in the extraction of the biologically active constituents of Triphala in order to compare their efficiency. Microwave-assisted extraction (MAE) was shown to be the most efficient method based on yield, extraction time, and selectivity. The Triphala hydroalcoholic extract (TAE) has been chemically characterized with spectroscopic and chromatographic techniques. Triphala hydroalcoholic extract was evaluated alone or with carvacrol. Different drug formulations including cream and nanoemulsion hydrogel were prepared to assess the antimicrobial activity against selected microorganism strains including Gram-positive and Gram-negative bacteria and fungi. We used a lipophilic oil of carvacrol (5 mg/mL) and a hydrophilic TAE (5 mg/mL) ingredient in a dosage form. Two solutions were created: hydrogel containing nanoemulsion as a lipophilic vector dispersed in the gel as a hydrophilic vehicle and a cream formulation, an oil-in-water emulsion. In both cases, the concentration was 250 mg of active ingredient in 50 mL of final formulation. The formulas developed were stable from a physical and chemical perspective. In the nanoemulsion hydrogel, the oil droplet size ranged from 124 to 129 nm, with low polydispersity index (PdI) 0.132 ± 0.013 and negative zeta potential -46.4 ± 4.3 mV. For the cream, the consistency factor (cetyl alcohol and white wax) induced immobilization of the matrix structure and the stability. Triphala hydroalcoholic extract in drug nanoformulation illustrated might be an adjuvant antimicrobial agent for treating various microbial infections.
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Nanoemulsions (NEs) are biocompatible and stealth nanodroplets that can efficiently encapsulate hydrophobic cytoactive drugs in their oily core. NEs were shown to accumulate in tumors by enhanced permeability and retention (EPR) effect and thus display appealing features as nanocarriers to selectively deliver drugs to the tumors. However, to ensure efficient encapsulation with minimal early release, drugs must possess a high degree of lipophilicity. To circumvent this limitation, the latter could be transformed into prodrugs with enhanced hydrophobicity. In return, once delivered in the cell, the prodrug must be efficiently transformed into its active drug form. Herein we chemically and reversibly modified a near infrared Huda dye (HD) into pro-fluorophore (Pro-HD), a non-fluorescent and lipophilic prodrug model that was efficiently loaded in NEs. Thanks to the fluorogenecity of the system (fluorescence enhancement of 35-fold at 723 nm), we demonstrated that Pro-HD did not leak out of NEs, was efficiently delivered into cancer cells and was transformed in cellulo into HD. This proof of concept demonstrates the high potential of lipophilic "pro-fluorophore" approach for visualizing delivery of cargos using NEs as nanocarriers.
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Emulsiones/química , Colorantes Fluorescentes/química , Nanocápsulas/química , Profármacos/química , Permeabilidad de la Membrana Celular , Composición de Medicamentos , Liberación de Fármacos , Emulsiones/metabolismo , Colorantes Fluorescentes/metabolismo , Células HeLa , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Rayos InfrarrojosRESUMEN
Statins have been proposed as potential adjuvant to periodontal treatment due to their pleiotropic properties. A new thermosensitive chitosan hydrogel loaded with statins (atorvastatin and lovastatin) nanoemulsions was synthesized to allow a spatially controlled local administration of active compounds at lesion site. Spontaneous nano-emulsification method was used to synthesize statins loaded nanoemulsions. In vitro, atorvastatin and lovastatin loaded nanoemulsions were cytocompatible and were able to be uptake by oral epithelial cells. Treatment of Porphyromonas gingivalis infected oral epithelial cells and gingival fibroblasts with atorvastatin and lovastatin loaded nanoemulsions decreased significantly pro-inflammatory markers expression (TNF-α and IL-1ß) and pro-osteoclastic RANKL. Nevertheless, such treatment induced the expression of Bone sialoprotein 2 (BSP2) in osteoblast emphasizing the pro-healing properties of atorvastatin and lovastatin nanoemulsions. In vivo, in a calvarial bone defect model (2â¯mm), treatment with the hydrogel loaded with atorvastatin and lovastatin nanoemulsions induced a significant increase of the neobone formation in comparison with systemic administration of statins. This study demonstrates the potential of this statins loaded hydrogel to improve bone regeneration and to decrease soft tissue inflammation. Its use in the specific context of periodontitis management could be considered in the future with a reduced risk of side effects.
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Atorvastatina/farmacología , Regeneración Ósea/efectos de los fármacos , Quitosano/química , Lovastatina/farmacología , Animales , Atorvastatina/administración & dosificación , Células Cultivadas , Células Epiteliales/efectos de los fármacos , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Encía/citología , Encía/efectos de los fármacos , Humanos , Hidrogeles , Inhibidores de Hidroximetilglutaril-CoA Reductasas/administración & dosificación , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Lovastatina/administración & dosificación , Masculino , Ratones , Ratones Endogámicos C57BL , Porphyromonas gingivalis/efectos de los fármacosRESUMEN
Nano-emulsion consists of a dispersion of oil droplets sizing below 200 nm, in aqueous continuous phase, and generally stabilized by low-molecular-weight surfactants. These stable nano-carriers are able to encapsulate and transport lipophilic molecules poorly soluble in water. However, the question on the leakage and release mechanisms of an active pharmaceutical ingredient, from oil nano-droplets to an acceptor medium has not been clearly addressed. Herein, we developed a simple fluorescence approach based on self-quenching of lipophilic fluorophore-based on Nile Red (NR668) to monitor cargo transfer from lipid nano-droplets to the acceptor medium. In this method, the fluorophore release can be monitored by the increase in its fluorescence quantum yield and the blue shift in its emission spectrum. The studies of the release process allow emphasizing an important role of the bulk aqueous medium in controlling the droplet to droplet fluorophore transfer and the attained equilibrium. The developed methodology could be applied to monitor release of other lipophilic dyes and it could help to better understand the cargo release from nanocarriers.