Understanding the Thermodynamic Mechanisms Leading to the Binding of Albumin to Lipid Nanocapsules

Heavy-Atom-Free Photosensitizer-Loaded Lipid Nanocapsules for Photodynamic Therapy

Photodynamic therapy (PDT) is a clinically approved noninvasive treatment for cancer that employs a photosensitizer (PS) to generate cytotoxic reactive singlet oxygen (ROS) species that precisely destroy cancer cells at the targeted tumor sites. There is growing interest in the development of innovative photosensitizing agents and advanced delivery methods, offering superior phototherapeutic performance. The delivery of PS is a challenging task in PDT in regard to the high hydrophobicity of the PS molecule. To address this challenge, the incorporation of heavy-atom-free PS (HAF-PS) in effective drug delivery carriers is promising for PDT improvement. Herein, we propose a strategy to encapsulate the HAF-PS from the perylenediimide (PDI) family in the oily core of lipid nanocapsules (LNCs). The resulting HAF-PS-loaded LNCs formulations have the advantage to efficiently generate singlet oxygen (1O2) in a biorelevant environment. The LNCs formulations loaded with O-PDI (O-PDI@LNC) and 1S-PDI (1S-PDI@LNC) were obtained by a solvent-free phase-inversion temperature (PIT) method. Our study demonstrates that optimized LNCs formulation loaded with 1S-PDI acting as PS is a highly efficient approach to deliver phototherapeutic agents for PDT. Overall, it has been shown that illumination of 1S-PDI leads to dramatic 1O2 production with an impressive quantum yield (φSOQY = 0.94) which was tested with 1,3-diphenylisobenzofuran (DPBF) as a specific trap. Moreover, the 1O2 generation was calculated in a phosphate buffer solution (φSOQY = 0.52) for loaded nanocarrier 1S-PDI@LNC. In vitro cytotoxicity studies demonstrated a low dark toxicity of 1S-PDI@LNC while illumination significantly enhanced its photocytotoxicity in cells. Furthermore, the cellular internalization of LNCs was demonstrated in U-87 MG cells using O-PDI@LNC as a model, exploiting the excellent fluorescence properties of O-PDI. This study has significant potential for advancing the development of HAF-PS-loaded LNCs for minimally invasive PDT.

Incorporating Span 80 surfactant into lipid nanocapsules improves their biocompatibility and cellular uptake in B16F10 melanoma cells

Surfactant-shell lipid nanocapsules (LNCs) are promising skin delivery systems. They are composed of an oily core with a stabilising shell of surfactant and phosphatidylcholine. LNCs' hydrodynamic diameter can be easily tuned by varying the surfactant content in the formulation. Hydrophilic surfactants incorporated into LNCs have shown toxicity in mammalian cells. To date, the toxicity of all published surfactant-shelled LNCs produced by the the phase inverson temperature (PIT) method has been investigated using hydrophilic surfactants, with no studies examining the impact of incorporating hydrophobic surfactants on LNCs' in vitro behaviour. Span 80 is a hydrophobic surfactant and has been extensively used in manufacturing various ranges of nanoparticles. The present study formulated Span 80-containing LNCs to evaluate their in vitro behaviour in the B16F10 melanoma cell line. LNC-100-S8 of Kolliphor HS15/Span 80 (65/35 w/w%) and original LNC100-0 LNCs of Kolliphor HS15 with a hydrodynamic diameter of 100 nm were prepared using the PIT method. A salt aggregation test confirmed increased surface hydrophobicity of LNC100-S8 compared to LNC100-0. Cytotoxicity assays demonstrated that LNC100-S8 had a three-fold lower cytotoxicity than LNC100-0 (IC80 = 11757 μg/mL vs 3184 μg/mL). Flow cytometry analysis indicated significantly higher cellular uptake of LNC100-S8 compared to LNC100-0, with 1.52-fold, 1.46-fold, and 1.67-fold increase at 1 h, 3 h, and 24 h, respectively . Mechanistic investigations revealed that LNC100-S8 uptake predominantly occured via phosphoinositide 3-kinase (PI3K)-regulated macropinocytosis and actin-dependent endocytosis, whereas LNC100-0 also utilised Na+/H+ exchanger-mediated macropinocytosis. Furthermore, protein corona analysis demonstrated increased interactions between LNC100-S8 and B16F10-conditioned media proteins, leading to bimodal size distribution and elevated polydispersity index (>0.3), which influenced their endocytic pathways. Overall, Our findings revealed the high promise of our Span 80-containing LNCs as a drug delivery system with enhanced cellular uptake and biocompatibility in B16F10 melanoma cells compared to conventional LNCs composed of Kolliphor HS15 surfactant, highlighting their potential uses in topical delivery to melanoma and other skin diseases.

The Impact of Multiple Functional Layers in the Structure of Magnetic Nanoparticles and Their Influence on Albumin Interaction

In nanomedicine, hybrid nanomaterials stand out for providing new insights in both the diagnosis and treatment of several diseases. Once administered, engineered nanoparticles (NPs) interact with biological molecules, and the nature of this interaction might directly interfere with the biological fate and action of the NPs. In this work, we synthesized a hybrid magnetic nanostructure, with antibacterial and antitumoral potential applications, composed of a magnetite core covered by silver NPs, and coated with a modified chitosan polymer. As magnetite NPs readily oxidize to maghemite, we investigated the structural properties of the NPs after addition of the two successive layers using Mössbauer spectroscopy. Then, the structural characteristics of the NPs were correlated to their interaction with albumin, the major blood protein, to evidence the consequences of its binding on NP properties and protein retention. Thermodynamic parameters of the NPs–albumin interaction were determined. We observed that the more stable NPs (coated with modified chitosan) present a lower affinity for albumin in comparison to pure magnetite and magnetite/silver hybrid NPs. Surface properties were key players at the NP–biological interface. To the best of our knowledge, this is the first study that demonstrates a correlation between the structural properties of complex hybrid NPs and their interaction with albumin.