Relationship between Targeting Efficacy of Liposomes and the Dosage of Targeting Antibody Using Surface Plasmon Resonance

SPRi analysis of molecular interactions of mApoE-functionalized liposomes as drug delivery systems for brain diseases

The application of liposomes (LPs) to central nervous system disorders could represents a turning point in the therapy and quality of life of patients. Indeed, LPs have demonstrated their ability to cross the blood-brain barrier (BBB) and, as a consequence, to enhance the therapeutics delivery into the brain. Some approaches for BBB crossing involve the modification of LP surfaces with biologically active ligands. Among them, the Apolipoprotein E-modified peptide (mApoE) has been used for several LP-based nanovectors under investigation. In this study, we propose Surface Plasmon Resonance imaging (SPRi) for the characterization of multifunctionalized LPs for Glioblastoma treatment. LPs were functionalized with mApoE and with a metallo-protease sensitive lipopeptide to deliver and guarantee the localized release of an encapsulated drug in diseased areas. The SPRi analysis was optimized in order to evaluate the binding affinity between LPs and mApoE receptors, finding that mApoE-LPs generated SPRi signals referred to interactions between mApoE and receptors mainly present in the brain. Moreover, a significant binding between LPs and VCAM-1 (endothelial receptor) was observed, whereas LPs did not interact significantly with peripheral receptors expressed on monocytes and lymphocytes. SPRi results confirmed not only the presence of mApoE on LP surfaces, but also its binding affinity, thanks to the specific interaction with selected receptors. In conclusion, the high sensitivity and the multiplexing capability associated with the low volumes of sample required and the minimal sample preparation, make SPRi an excellent technique for the characterization of multifunctionalized nanoparticles-based formulations.

Surface Plasmon Resonance Monitoring of Mono-Rhamnolipid Interaction with Phospholipid-Based Liposomes

The interactions of mono-rhamnolipids (mono-RLs) with model membranes were investigated through a biomimetic approach using phospholipid-based liposomes immobilized on a gold substrate and also by the multiparametric surface plasmon resonance (MP-SPR) technique. Biotinylated liposomes were bound onto an SPR gold chip surface coated with a streptavidin layer. The resulting MP-SPR signal proved the efficient binding of the liposomes. The thickness of the liposome layer calculated by modeling the MP-SPR signal was about 80 nm, which matched the average diameter of the liposomes. The mono-RL binding to the film of the phospholipid liposomes was monitored by SPR and the morphological changes of the liposome layer were assessed by modeling the SPR signal. We demonstrated the capacity of the MP-SPR technique to characterize the different steps of the liposome architecture evolution, i.e., from a monolayer of phospholipid liposomes to a single phospholipid bilayer induced by the interaction with mono-RLs. Further washing treatment with Triton X-100 detergent left a monolayer of phospholipid on the surface. As a possible practical application, our method based on a biomimetic membrane coupled to an SPR measurement proved to be a robust and sensitive analytical tool for the detection of mono-RLs with a limit of detection of 2 μg mL^-1.

Surface Plasmon Resonance as a Characterization Tool for Lipid Nanoparticles Used in Drug Delivery

The development of drug carriers based in lipid nanoparticles (LNPs) aims toward the synthesis of non-toxic multifunctional nanovehicles that can bypass the immune system and allow specific site targeting, controlled release and complete degradation of the carrier components. Among label free techniques, Surface Plasmon Resonance (SPR) biosensing is a versatile tool to study LNPs in the field of nanotherapeutics research. SPR, widely used for the analysis of molecular interactions, is based on the immobilization of one of the interacting partners to the sensor surface, which can be easily achieved in the case of LNPs by hydrophobic attachment onto commercial lipid- capture sensor chips. In the last years SPR technology has emerged as an interesting strategy for studying molecular aspects of drug delivery that determines the efficacy of the nanotherapeutical such as LNPs' interactions with biological targets, with serum proteins and with tumor extracelullar matrix. Moreover, SPR has contributed to the obtention and characterization of LNPs, gathering information about the interplay between components of the formulations, their response to organic molecules and, more recently, the quantification and molecular characterization of exosomes. By the combination of available sensor platforms, assay quickness and straight forward platform adaptation for new carrier systems, SPR is becoming a high throughput technique for LNPs' characterization and analysis.

Fast, Efficient, and Targeted Liposome Delivery Mediated by DNA Hybridization

Safety and efficacy, two significant parameters in drug administration, can be improved by site-specific delivery approaches. Here a fast, efficient, and targeted liposome delivery system steered by a DNA hybridization recognition mechanism is presented. For this purpose, lipid-terminated DNA is inserted in both liposome and cell membranes by simple mixing of the components. Cellular accumulation of cargo encapsulated in the liposomal core is substantially enhanced when the DNA sequence on the cell is complementary to that on the liposome. Additionally, in mixed cell populations, liposomes discriminate targets by their complementary DNA sequences. Exposure of cells to low temperature and endocytosis inhibitors suggests a caveolae-dependent endocytosis uptake pathway. Mechanistically, hybridization between DNA strands spatially traps liposomes and cell membranes in close proximity, consequently increases the local liposome concentration, and thereby enhances cellular uptake of liposomes and their payload. This programmable delivery system might contribute to new applications in molecular biology and drug delivery.

Coadministration of Oligomeric Hyaluronic Acid-Modified Liposomes with Tumor-Penetrating Peptide-iRGD Enhances the Antitumor Efficacy of Doxorubicin against Melanoma

A safe and efficient tumor-targeting strategy based on oligomeric hyaluronic acid (HA) modification and coadministration of tumor-penetrating peptide-iRGD was successfully developed. In this study, common liposomes (cLip) were modified by oligomeric HA to obtain HA-Lip. After injection into rats, HA-Lip showed good stealth in the bloodstream and lower liver distribution compared with cLip. Moreover, our HA-Lip could be internalized into B16F10 cells (CD44-overexpressing tumor cells) through HA-CD44 interaction. After systemic administration to B16F10 melanoma-bearing mice, HA-Lip showed an increased distribution in tumor due to the prolonged blood circulation time and the enhanced penetration and retention effect. When coadministered with iRGD, the tumor penetration of HA-Lip was significantly enhanced, which could promote HA-Lip internalization by tumors cells located in deep tumor regions through receptor-mediated endocytosis. Furthermore, doxorubicin (DOX)-loaded HA-Lip coadministering with iRGD showed much better antitumor effect compared to DOX-loaded cLip and DOX-loaded cLip in combination with iRGD. In systemic toxicity test, DOX-loaded HA-Lip could significantly decrease the cardiotoxicity and myelosuppression of DOX. Taken together, our results demonstrated that coadministration of oligomeric HA-modified liposomes with iRGD could be a promising treatment strategy for targeted therapy of melanoma.