β-Carotene is a natural lipid-soluble carotenoid with diverse biological activities, but its poor water solubility and sensitivity to light, heat, and oxygen limit its application. In this study, β-carotene nanoliposomes (βC-NL-1) were prepared using the thin-film hydration method and optimized by response surface methodology. The optimized formulation consisted of a soy lecithin-to-cholesterol mass ratio of 6:1, a β-carotene loading of 0.22 mg/10 mL ethanol, and 25 mL PBS, resulting in an encapsulation efficiency of 63.89 ± 1.09%. The optimized nanoliposomes had a particle size of 121.9 ± 1.24 nm, a polydispersity index (PDI) of 0.2654 ± 0.0136, and a zeta potential of −54.25 ± 1.26 mV. Transmission electron microscopy revealed relatively uniform spherical or ellipsoidal vesicles, while Fourier transform infrared spectroscopy showed characteristic spectral changes consistent with the incorporation of β-carotene into the lipid system. After 20 days of storage at 4 °C, the β-carotene retention rate was 81.43%. During simulated gastrointestinal digestion, β-carotene exhibited a relatively low release in the gastric phase, followed by increased release in the intestinal phase. Furthermore, βC-NL-1 exhibited higher hydroxyl and DPPH radical-scavenging activities than free β-carotene under the tested conditions. These findings demonstrate the potential of βC-NL-1 as a liposomal delivery system for β-carotene and provide a basis for further investigation of its application in functional foods.
Understanding drug–lipid interactions is essential for the rational design of lipid-based nanocarriers. Dapagliflozin (DAPA), a highly selective sodium–glucose cotransporter 2 (SGLT2) inhibitor with expanding therapeutic applications, represents an attractive candidate for lipid-based delivery systems; however, the physicochemical basis of its interactions with lipid membranes remains insufficiently understood. In this study, Langmuir monolayers and lipid vesicles were employed as complementary systems to investigate DAPA–lipid interactions and their modulation by the edge activator Tween 20. Langmuir monolayer experiments demonstrated that DAPA markedly affected lipid packing, compressional properties, and relaxation behavior. Importantly, these effects depended on the presence of Tween 20, revealing a composition-dependent interplay between the drug, lipids, and edge activator rather than independent effects of the individual components. The interfacial studies also showed that the role of Tween 20 cannot be described solely in terms of monolayer fluidization. DAPA-loaded liposomes and Tween 20-containing transferosomes exhibited high apparent encapsulation efficiencies. DAPA markedly altered the particle-size distributions of both formulations, producing a multimodal distribution in liposomes and shifting the predominant intensity-weighted population of transferosomes toward the micrometer range. AFM measurements further demonstrated pronounced changes in vesicle nanomechanics, with both DAPA and Tween 20 reducing stiffness and Young’s modulus relative to empty liposomes. Adhesion parameters increased when DAPA was encapsulated in the vesicles. Overall, the combined monolayer–vesicle approach reveals a composition-dependent interplay between DAPA, lipids, and Tween 20 that governs interfacial organization, particle-size distribution, and nanomechanical behavior. These findings highlight the importance of considering the drug as an active contributor to membrane properties rather than merely an encapsulated cargo and provide a physicochemical basis for further optimization of DAPA-containing transferosomal systems.
Background Oily skin is not synonymous with acne. However, the skin surface lipid differences between healthy and acne-associated states within an oily-skin population remain insufficiently characterised. Objectives To characterise compositional and structural differences in skin surface lipids (SSLs) between healthy and acne-associated unhealthy states among young women with oily skin. Methods Sixty-six women aged 18–24 years with oily skin were enrolled, including 33 with healthy oily skin and 33 with mild-to-moderate acne-associated unhealthy oily skin. SSLs were analysed by ultra-performance liquid chromatography–quadrupole time-of-flight mass spectrometry combined with multivariate analysis, with emphasis on lipid abundance, fatty acyl chain length and unsaturation. Results The two groups showed distinct SSL profiles. The acne-associated unhealthy oily skin group exhibited a lower relative abundance of saturated fatty acids, a higher relative abundance of unsaturated fatty acids and a reduced monounsaturated/polyunsaturated fatty acid ratio. Abundance-weighted mean chain lengths of fatty acids and triglycerides were reduced. Ceramides showed fatty acyl chain-length redistribution, with increased long-chain and decreased very-long-chain species. Phosphatidylserine and phosphatidylinositol were also increased. Conclusions Acne-associated unhealthy oily skin in young women is characterised by multilayered lipid remodelling involving sebum-associated, barrier-related and membrane-associated lipids. Phosphatidylserine-related alterations may represent a candidate lipid feature associated with deviation from healthy oily skin homeostasis.
Polymers such as Styrene Maleic Acid (SMA) have become valuable tools for studying membrane proteins within lipid bilayers due to their ability to solubilize membrane proteins in their native environments. However, limitations in the use of SMA copolymers have led to the development of SMA derivatives. In this study, we investigate the impact of the charge properties of several SMA derivatives on various lipid systems, which may also carry charges. We employed neutral, positively charged, and negatively charged SMA-derivative copolymers (SMA-Neut, SMA-Pos, SMA-AE, SMA Glu, and SMA-BZ30) to investigate their impact on bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), and a 9:1 molar ratio mixture of POPC and POPG. No single technique, however, is effective across the wide array of different MPs, and there are often significant discrepancies between structures determined by different methods if the protein's environment is far from a native lipid bilayer. In this study, we utilized biophysical techniques, including dynamic light scattering (DLS), electron paramagnetic resonance (EPR) spectroscopy, and solid-state nuclear magnetic resonance (ssNMR) spectroscopy, to analyze the interactions between polymers and lipid bilayers. Our EPR findings indicate that all the polymers preserved the POPC/POPG lipid bilayer. Meanwhile, our ssNMR result analysis suggests that neutral polymers may disrupt the bilayer less than charged polymers do. This implies that the electrostatic interactions between charged polymers and lipids can significantly alter the native environment of the bilayer, potentially impacting the stability and dynamics of encapsulated membrane proteins. Although this work primarily focuses on lipid systems, our results underscore the importance of considering polymer-lipid electrostatic interactions when selecting SMA derivatives and polymers for biophysical studies of membrane proteins, as the choice of polymer can profoundly affect the integrity and behavior of the lipid bilayer system.
Environmental factors such as temperature and ion concentration can induce the phase transition from the liquid-crystalline to gel phase. In our work, we investigate the effect of temperatures and NaCl concentrations on phase transitions for two model lipids, i.e., an ether linked lipid with methyl branches (phosphatidyl glycerophosphate methyl ester, PGP-Me) and a more common ester phospholipid (dimyristoylphosphatidylcholine, DMPC). At 5.0 M NaCl 30 °C, the temperature closest to DMPC's phase transition temperature (Tm) in pure water, DMPC experiences a phase transition, but PGP-Me does not. Since PGP-Me is a model lipid for those found in archaea, it suggests that salt resistance for archaea might be related to maintaining a fluid phase at high salt concentrations. This is supported as the lipid surface areas, membrane compressibility, chain order, and electron density profiles all show that at 30 °C between 0.1 M and 5.0 M NaCl, PGP-Me has smaller changes than DMPC, meaning that PGP-Me maintains membrane fluidity more effectively. The sn-1 phosphate/carbonyl electrostatic interactions are primarily responsible for the phase transition in DMPC, while these electrostatic interactions are no longer chain specific in the gel phase. PGP-Me resists the phase transition better than DMPC because its methyl branches prevent tight lipid packing and its ether linkages decrease the interaction with Na+ ions. These quantitative measurements of the electrostatic interaction types formed during the liquid-crystalline, phase transition, gel phase, and by chain specificity uncover the mechanism of the phase transition induced by Na+ ions and is confirmed through our machine learning process.
