Preparation of α-Linolenic-Acid-Loaded Water-in-Oil-in-Water Microemulsion and Its Potential as a Fluorescent Delivery Carrier with a Free Label

Abstract

Our previous work has demonstrated that α-linolenic acid (ALA)-loaded oil-in-water (O/W) microemulsion could enhance ALA antioxidant capacity. Meanwhile, we also observed that synthesized microemulsion itself had fluorescence. In this work, we have prepared a multiple water-in-oil-in-water (W/O/W) microemulsion to further enhance ALA antioxidant capacity and activate this delivery carrier application potential with a free label. The compositions of primary water-in-oil (W/ O) microemulsion were obtained using pseudo-ternary phase diagrams, and then W/O/W microemulsion was prepared adopting the "two-step heterotherm method". The conductivity of W/O/W microemulsion was measured to lie between 250.0 and 350.0 μs/cm. The spherical droplets with a mean particle diameter of 10.0−20.0 nm were confirmed by transmission electron microscopy and dynamic light scattering. Nuclear magnetic resonance confirmed that ALA diffused to the multiple water−oily interface simultaneously. In addition, the in vitro release and antioxidant capacity measurements of ALA-loaded W/ O/W microemulsion concluded the sustained-release effect and excellent antioxidant capacity. The fluorescent intensity of W/ O/W microemulsion was markedly increased in comparison to O/W microemulsion. The synthesized microemulsion could lead to important applications and have advantages of a label-free fluorescent carrier for optical imaging purposes.

Antiproliferative Ability and Fluorescence Tracking of α-Linolenic Acid-Loaded Microemulsion as Label-Free Delivery Carriers in MDA-MB-231 Cells

“…It was worth noticing that the particle sizes of undiluted O/W and W/O/W microemulsions in our previous research were 18.493 ± 0.030 and 15.402 ± 0.037 nm, respectively. 18 Therefore, the dilution process had a significant effect on the particle size and PDI compared to the undiluted microemulsion.…”

“…Our previous studies showed that the concentration of the surfactant was positively correlated with the fluorescence intensity of the microemulsion. 18 Furthermore, there was no significant difference in the fluorescence intensity of the O/W and W/O/W At the diluted concentrations of 0.25 and 0.625%, the cell viability of the O/W and W/O/W microemulsions with different ALA loading amounts was determined in order to analyze whether ALA had an effect of inhibiting the growth of cancer cells. When the cells were exposed to microemulsions with different ALA loading amounts, there was an obvious dose-dependent decrease in cell viability, both for O/W and W/O/W microemulsions.…”

“…In detail, the mass fraction of CrEL/water phase/ ethanol/isoamyl acetate was 7:2:1:12 in the light of previous research. 18 Based on these, when the W/O microemulsion was cooled to room temperature, the CrEL, ethanol, and W/O microemulsion were mixed again and dispersed in double-distilled water at room temperature. Similarly, the formula (CrEL/W/O microemulsion/ethanol/double-distilled water = 7:2:1:28) was selected to form a transparent W/O/W microemulsion.…”

“…In detail, the excitation and emission wavelengths of the microemulsion were 360 and 440 nm according to our previous study. 18 Fluorescence Mechanism of the Microemulsion. The fluorescence mechanism of the microemulsion was explored by measuring the fluorescence intensity of a mixture of different proportions of the surfactant and aqueous phase or oil phase.…”

In Vitro Evaluation of a Fluorescent Microemulsion as an Oral Delivery Carrier and its Potential Application in Tracking Bioactive Compounds Label-Free

“…Afterward, the dialysis tubes were placed in homologous electrolyte solutions (1000 mL) and incubated in a shaking bath at 37 °C at a stirring speed of 200 rpm. At predetermined time intervals, aliquots of the incubated samples (2.0 mL) were withdrawn to quantify the concentration of ALA using a UV-3300 spectrophotometer (320 nm); , thereafter, the incubated samples were added to the dialysis tubes again, and the release was calculated as follows: where m 1 is the concentration of the incubated samples at each time point, and m i is the initial concentration of the samples.…”