Cell penetrating peptide amphiphile integrated liposomal systems for enhanced delivery of anticancer drugs to tumor cells

High throughput microfluidics-based synthesis of PEGylated liposomes for precise size control and efficient drug encapsulation

The low scalability and reproducibility of existing synthesis methods have hindered the translation of liposome nanoparticles as carriers for targeted drug delivery from conventional laboratory techniques to mass production. To this end, in this study, we present a high-throughput microfluidics-based approach for the synthesis of PEGylated liposomes with a primary focus on achieving precise size control and efficient encapsulation of hydrophobic drug molecules. In this platform, liposomes were self-assembled through a controllable mixing of lipids (EYPC, cholesterol, and DSPE-PEG 2000) dissolved in ethanol and an aqueous solution. The key parameters, including the chip design, total flow rate, flow rate ratio, lipid concentrations, as well as variations in buffer (HEPES and NaCl) and solvent composition (commercial and reagent-grade ethanol) were explored in detail. Through comprehensive parametric studies, we gained valuable insights into the influence of these variables on the size distribution of liposomes and succeeded in producing highly reproducible liposomes ranging from approximately 60 nm (corresponding to small unilamellar vesicles) to 150 nm (representing large unilamellar vesicles), all while maintaining a polydispersity index (PDI) of less than 0.2. To assess the encapsulation efficiency of hydrophobic drug molecules, Nile red (NR) was employed as a surrogate. We meticulously examined the impact of NR concentration on the drug encapsulation process, resulting in up to 74% drug encapsulation efficiency within the PEGylated liposomes. This research offers crucial advances in liposome synthesis and drug delivery, providing a high-throughput, controllable method for PEGylated liposomes with potential in pharmaceutical and biomedical fields.

Recent applications of cell-penetrating peptide guidance of nanosystems in breast and prostate cancer (Review)

Cell-penetrating peptides (CPPs) are small peptides from natural sources or designed from other protein sequences that can penetrate cell membranes. This property has been used in biomedicine to add them to biomolecules to improve their capacity for cell internalization and as a guidance tool for specific cell types. CPPs have been shown to enhance cellular uptake in vitro and in vivo, improving the efficacy of anticancer drugs such as doxorubicin and paclitaxel, while also limiting their cytotoxic effects on healthy cells and tissues. The current study reviews the internalization and major therapeutic results achieved from the functionalization of nanosystems with CPPs for guidance into breast and prostate cancer cells in vitro and in vivo. In addition, the practical results obtained are specifically discussed for use as a starting point for scientists looking to begin research in this field.

Self-assembled peptide and protein nanostructures for anti-cancer therapy: Targeted delivery, stimuli-responsive devices and immunotherapy

Self-assembled peptides and proteins possess tremendous potential as targeted drug delivery systems and key applications of these well-defined nanostructures reside in anti-cancer therapy. Peptides and proteins can self-assemble into nanostructures of diverse sizes and shapes in response to changing environmental conditions such as pH, temperature, ionic strength, as well as host and guest molecular interactions; their countless benefits include good biocompatibility and high loading capacity for hydrophobic and hydrophilic drugs. These self-assembled nanomaterials can be adorned with functional moieties to specifically target tumor cells. Stimuli-responsive features can also be incorporated with respect to the tumor microenvironment. This review sheds light on the growing interest in self-assembled peptides and proteins and their burgeoning applications in cancer treatment and immunotherapy.

Liposome mimicking polymersomes; A comparative study of the merits of polymersomes in terms of formulation and stability

The past few decades have seen a significant rise in research into alternative polymer based nanosized unilamellar drug delivery systems, termed polymersomes. The reported benefits of polymersomes over the more traditional liposomes include increased stability, higher encapsulation efficacies, better adaptability and reduced water permeation due to an increased bilayer thickness. Together, these advantages render them suitable for a plethora of therapies. The work presented in this manuscript creates and compares four such drug delivery systems, two based on the traditional liposome and two prepared from amphiphilic polymers. From there we assess these systems in terms of size, stability, encapsulation efficiency, drug release, cellular toxicity and cellular uptake. We can confirm from this comprehensive investigation that the multi-functional synthetic polymersomes are undoubtedly a future contender in this expanding field of nanomedicines. Their ability to encapsulate a cocktail of different compounds, high stability as well as their ease of adaptability will ensure that they feature prominently in the future of advanced drug delivery systems.

Adjuvant potency of Astragaloside VII embedded cholesterol nanoparticles for H3N2 influenza vaccine

Adjuvants are substances that increase the immune response to a given antigen. In the development of novel vaccine adjuvants/systems, saponins are one of the most attractive molecules due to their altered immunomodulatory activities. In this study, we tried to develop PEG (polyethylene glycol)/cholesterol-based lipid nanoparticles (LNPs) to deliver the Astragaloside VII (AST-VII) and potentiate adjuvant properties of AST-VII for the influenza vaccine. In the formation of PEG/cholesterol/AST-VII-based LNPs (PEG300: Chol-AST-VII LNPs), 3 different primary solvents (acetone, ethanol, and chloroform) were evaluated, employing their effects on hydrodynamic particle size, distribution, surface chemistry, and colloidal stability. Prepared nanoparticles were simply admixtured with inactivated influenza antigen (H3N2) and applied to PMA (phorbol 12-myristate 13-acetate)-ionomycin treated human whole blood to evaluate their cytokine release profile. PEG300: Chol-AST-VII LNPs (80.2 ± 7.7 nm) were obtained using chloroform as a desolvation agent. Co-treatment of PMA-ionomycin with AST-VII and PEG300: Chol-AST-VII LNPs significantly increased the levels of IL-2 and IFN-g, compared to PMA-ionomycin alone. In the presence of H3N2, AST-VII was able to augment IL-17A, while PEG300: Chol-AST-VII LNPs stimulated the production of IFN-g. Hemolysis was only observed in PEG300: Chol-AST-VII LNPs (250 μg/mL) treatment. AST-VII and AST-VII-integrated LNPs could be used as efficacious adjuvants for an inactivated H3N2 vaccine in vitro, and cytokine response through Th1/Th17 route was reported.

Endocytosis in cellular uptake of drug delivery vectors: Molecular aspects in drug development

Drug delivery vectors are widely applied to increase drug efficacy while reducing the side effects and potential toxicity of a drug. They allow for patient-tailored therapy, dose titration, and therapeutic drug monitoring. A major part of drug delivery systems makes use of large nanocarriers: liposomes or virus-like particles (VLPs). These systems allow for a relatively large amount of cargo with good stability of vectors, and they offer multiple options for targeting vectors in vivo. Here we discuss endocytic pathways that are available for drug delivery by large nanocarriers. We focus on molecular aspects of the process, including an overview of potential molecular targets for studies of drug delivery vectors and for future solutions allowing targeted drug delivery.

Enhanced combination cancer therapy using lipid-calcium carbonate/phosphate nanoparticles as a targeted delivery platform

Aim: Melanoma, the most life-threatening skin cancer, requires more effective therapies. Methodology: A new folic acid (FA) receptor-targeted lipid-coated calcium carbonate/phosphate (LCCP) nanoparticle was synthesized, incorporating two often-used therapeutics, cell death siRNA and α-tocopheryl succinate. Results: The nanoparticles were spherical, with an average size of 40 nm. The nanoparticles exhibited a high gene/drug loading efficiency (60%), with folic acid-enhanced cellular uptake. The nanoparticles with both therapeutics enhanced inhibition of B16F0 melanoma cell growth, showing a moderate synergistic effect. The mechanism of the inhibition is associated with induction of cell apoptosis and cell cycle arrest at G1 phase. Conclusion: Our data indicate that lipid-coated calcium carbonate/phosphate nanoparticles are a potential platform for targeted therapy for melanoma.

Codelivery of a cytotoxin and photosensitiser via a liposomal nanocarrier: a novel strategy for light-triggered cytosolic release

Endosomal entrapment is a key issue for the intracellular delivery of many nano-sized biotherapeutics to their cytosolic or nuclear targets. Photochemical internalisation (PCI) is a novel light-based solution that can be used to trigger the endosomal escape of a range of bioactive agents into the cytosol leading to improved efficacy in pre-clinical and clinical studies. PCI typically depends upon the endolysosomal colocalisation of the bioactive agent with a suitable photosensitiser that is administered separately. In this study we demonstrate that both these components may be combined for codelivery via a novel multifunctional liposomal nanocarrier, with a corresponding increase in the biological efficacy of the encapsulated agent. As proof of concept, we show here that the cytotoxicity of the 30 kDa protein toxin, saporin, in MC28 fibrosarcoma cells is significantly enhanced when delivered via a cell penetrating peptide (CPP)-modified liposome, with the CPP additionally functionalised with a photosensitiser that is targeted to endolysosomal membranes. This innovation opens the way for the efficient delivery of a range of biotherapeutics by the PCI approach, incorporating a clinically proven liposome delivery platform and using bioorthogonal ligation chemistries to append photosensitisers and peptides of choice.

Reconstitution and functional studies of hamster P-glycoprotein in giant liposomes

This paper describes the preparation of giant unilamellar vesicles with reconstituted hamster P-glycoprotein (Pgp, ABCB1) for studying the transport activity of this efflux pump in individual liposomes using optical microscopy. Pgp, a member of ABC (ATP-binding cassette) transporter family, is known to contribute to the cellular multidrug resistance (MDR) against variety of drugs. The efficacy of many therapeutics is, thus, hampered by this efflux pump, leading to a high demand for simple and effective strategies to monitor the interactions of candidate drugs with this protein. Here, we applied small Pgp proteoliposomes to prepare giant Pgp-bearing liposomes via modified electroformation techniques. The presence of Pgp in the membrane of giant proteoliposomes was confirmed using immunohistochemistry. Assessment of Pgp ATPase activity suggested that this transporter retained its activity upon reconstitution into giant liposomes, with an ATPase specific activity of 439 ± 103 nmol/mg protein/min. For further confirmation, we assessed the transport activity of Pgp in these proteoliposomes by monitoring the translocation of rhodamine 123 (Rho123) across the membrane using confocal microscopy at various ATP concentrations (0-2 mM) and in the presence of Pgp inhibitors. Rate of change in Rho123 concentration inside the liposomal lumen was used to estimate the Rho123 transport rates (1/s) for various ATP concentrations, which were then applied to retrieve the Michaelis-Menten constant (Km) of ATP in Rho123 transport (0.42 ± 0.75 mM). Similarly, inhibitory effects of verapamil, colchicine, and cyclosporin A on Pgp were studied in this system and the IC50 values for these Pgp inhibitors were found 26.6 ± 6.1 μM, 94.6 ± 47.6 μM, and 0.21 ± 0.07 μM, respectively. We further analyzed the transport data using a kinetic model that enabled dissecting the passive diffusion of Rho123 from its Pgp-mediated transport across the membrane. Based on this model, the permeability coefficient of Rho123 across the liposomal membrane was approximately 1.25×10-7 cm/s. Comparing the membrane permeability in liposomes with and without Pgp revealed that the presence of this protein did not have a significant impact on membrane integrity and permeability. Furthermore, we used this model to obtain transport rate constants for the Pgp-mediated transport of Rho123 (m3/mol/s) at various ATP and inhibitor concentrations, which were then applied to estimate values of 0.53 ± 0.66 mM for Km of ATP and 25.2 ± 5.0 μM for verapamil IC50, 61.8 ± 34.8 μM for colchicine IC50, and 0.23 ± 0.09 μM for cyclosporin A IC50. The kinetic parameters obtained from the two analyses were comparable, suggesting a minimal contribution from the passive Rho123 diffusion across the membrane. This approach may, therefore, be applied for screening the transport activity of Pgp against potential drug candidates.

Lipogels for Encapsulation of Hydrophilic Proteins and Hydrophobic Small Molecules

Lipid-polymer hybrid materials have the potential to exhibit enhanced stability and loading capabilities in comparison to parent liposome or polymer materials. However, complexities lie in formulating and characterizing such complex nanomaterials. Here we describe a lipid-coated polymer gel (lipogel) formulated using a single-pot methodology, where self-assembling liposomes template a UV-curable polymer gel core. Using fluorescently labeled lipids, protein, and hydrophobic molecules, we characterized their formation, purification, stability, and encapsulation efficiency via common instrumentation methods such as dynamic light scattering (DLS), matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS), UV-vis spectroscopy, fluorescence spectroscopy, and single-particle total internal reflection fluorescence (TIRF) microscopy. In addition, we confirmed that these dual-guest-loaded lipogels are stable in solution for several months. The simplicity of this complete aqueous formation and noncovalent dual-guest encapsulation holds potential as a tunable nanomaterial scaffold.

Incorporating gold nanoclusters and target-directed liposomes as a synergistic amplified colorimetric sensor for HER2-positive breast cancer cell detection

Breast cancer is the second leading cause of cancer-related mortality in women. Successful development of sensitive nanoprobes for breast cancer cell detection is of great importance for breast cancer diagnosis and symptomatic treatment. Herein, inspired by the intrinsic peroxidase property of gold nanoclusters, high loading, and targeting ability of ErbB2/Her2 antibody functionalized liposomes, we report that gold nanoclusters-loaded, target-directed, functionalized liposomes can serve as a robust sensing platform for amplified colorimetric detection of HER2-positive breast cancer cells. This approach allows HER2-positive breast cancer cell identification at high sensitivity with high selectivity. In addition, the colorimetric “readout” offers extra advantages in terms of low-cost, portability, and easy-to-use applications. The practicality of this platform was further proved by successful detection of HER2-positive breast cancer cells in human serum samples and in breast cancer tissue, which indicated our proposed method has potential for application in cancer theranostics.

The design of peptide-amphiphiles as functional ligands for liposomal anticancer drug and gene delivery

Liposomal nanomedicine has led to clinically useful cancer therapeutics like Doxil and DaunoXome. In addition, peptide-functionalized liposomes represent an effective drug and gene delivery vehicle with increased cancer cell specificity, enhanced tumor-penetrating ability and high tumor growth inhibition. The goal of this article is to review the recently published literature of the peptide-amphiphiles that were used to functionalize liposomes, to highlight successful designs that improved drug and gene delivery to cancer cells in vitro, and cancer tumors in vivo, and to discuss the current challenges of designing these peptide-decorated liposomes for effective cancer treatment.

Self-assembled peptide-based nanostructures: Smart nanomaterials toward targeted drug delivery

Self-assembly of peptides can yield an array of well-defined nanostructures that are highly attractive nanomaterials for many biomedical applications such as drug delivery. Some of the advantages of self-assembled peptide nanostructures over other delivery platforms include their chemical diversity, biocompatibility, high loading capacity for both hydrophobic and hydrophilic drugs, and their ability to target molecular recognition sites. Furthermore, these self-assembled nanostructures could be designed with novel peptide motifs, making them stimuli-responsive and achieving triggered drug delivery at disease sites. The goal of this work is to present a comprehensive review of the most recent studies on self-assembled peptides with a focus on their "smart" activity for formation of targeted and responsive drug-delivery carriers.

First Evidence of the Liposome-Mediated Deintercalation of Anticancer Drug Doxorubicin from the Drug-DNA Complex: A Spectroscopic Approach

Biocompatible liposomes were used for the first time to study the deintercalation process of a prominent anticancer drug, doxorubicin (DOX), from doxorubicin-intercalated DNA (DOX-DNA complex) under controlled experimental conditions. The study revealed that anionic liposomes (DMPG liposomes) appeared to be the most effective to bring in the highest percentage of drug release while cationic liposomes (DOTAP liposomes) scored the lowest percentage of release. The drug release was primarily attributed to the electrostatic interaction between liposomes and drug molecules. Apart from this interaction, changes in the hydrophobicity of the medium upon addition of liposomes to the DNA-drug solution accompanied by lipoplex formation between DNA and liposomes were also attributed to the observed deintercalation. The CD and the time-resolved rotational relaxation studies confirmed that lipoplex formation took place between liposomes and DNA owing to electrostatic interaction. The confocal study revealed that in the postrelease period, DOX binds with liposomes. The reason behind the binding is electrostatic interaction as well as the unique bilayer structure of liposomes which helps it to act as a "hydrophobic sink" for DOX. The study overall highlighted a novel strategy for deintercalation of drug using biocompatible liposomes, as the release of the drug can be controlled over a period of time by varying the concentration and composition of the liposomes.

Development and in vitro evaluation of core-shell type lipid-polymer hybrid nanoparticles for the delivery of erlotinib in non-small cell lung cancer

Core-shell type lipid-polymer hybrid nanoparticles (CSLPHNPs) have emerged as a multifunctional drug delivery platform. The delivery system combines mechanical advantages of polymeric core and biomimetic advantages of the phospholipid shell into a single platform. We report the development of CSLPHNPs composed of the lipid monolayer shell and the biodegradable polymeric core for the delivery of erlotinib, an anticancer drug, clinically used to treat non-small cell lung cancer (NSCLC). Erlotinib loaded CSLPHNPs were prepared by previously reported single-step sonication method using polycaprolactone (PCL) as the biodegradable polymeric core and phospholipid-shell composed of hydrogenated soy phosphatidylcholine (HSPC) and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000 (DSPE-PEG2000). Erlotinib loaded CSLPHNPs were characterized for physicochemical properties including mean particle size, polydispersity index (PDI), zeta potential, morphology, thermal and infrared spectral analysis, drug loading, in vitro drug release, in vitro serum stability, and storage stability. The effect of critical formulation and process variables on two critical quality attributes (mean particle size and drug entrapment efficiency) of erlotinib loaded CSLPHNPs was studied and optimized. In addition, in vitro cellular uptake, luminescent cell viability assay and colony formation assay were performed to evaluate efficacy of erlotinib loaded CSLPHNPs in A549 cells, a human lung adenocarcinoma cell line. Optimized erlotinib loaded CSLPHNPs were prepared with mean particle size of about 170nm, PDI<0.2, drug entrapment efficiency of about 66% with good serum and storage stability. The evaluation of in vitro cellular efficacy results indicated enhanced uptake and efficacy of erlotinib loaded CSLPHNPs compared to erlotinib solution in A549 cells. Therefore, CSLPHNPs could be a potential delivery system for erlotinib in the therapy of NSCLC.

Aggregation behavior of a gemini surfactant with a tripeptide spacer

A peptide gemini surfactant, 12-G(NH2)LG(NH2)-12, has been constructed with two dodecyl chains separately attached to the two terminals of a glutamic acid-lysine-glutamic acid peptide and the aggregation behavior of the surfactant was studied in aqueous solution. The 12-G(NH2)LG(NH2)-12 molecules form fiber-like precipitates around pH 7.0, and the precipitation range is widened on increasing the concentration. At pHs 3.0 and 11.0, 12-G(NH2)LG(NH2)-12 forms soluble aggregates because each molecule carries two positively charged amino groups at the two ends of the peptide spacer at pH 3.0, while each molecule carries one negatively charged carboxyl group in the middle of the peptide spacer at pH 11.0. 12-G(NH2)LG(NH2)-12 displays a similar concentration-dependent process at these two pHs: forming small micelles above the critical micelle concentration and transferring to fibers at pH 3.0 or twisted ribbons at pH 11.0 above the second critical concentration. The fibers formed at pH 3.0 tend to aggregate into bundles with twisted structure. Both the twisted fibers at pH 3.0 and the twisted ribbons at pH 11.0 contain β-sheet structure formed by the peptide spacer.

A new class of pegylated plasmonic liposomes: synthesis and characterization

The multifunctional nanoobjects that can be controlled, manipulated and triggered using external stimuli represent very promising candidates for nanoscale therapeutic and diagnostic applications. In this study we report the successful synthesis and characterization of a new class of very stable multifunctional nanoobjects, containing cationic liposomes decorated with PEGylated gold nanoparticles (PEGAuNPs). The multifunctional hybrid nanoobjects (mHyNp) were prepared by taking advantage of the electrostatic interactions between small unilamelar cationic liposomes and negatively charged gold nanoparticles. The mHyNps have been investigated by UV-VIS absorption spectroscopy, Dynamic Light Scattering (DLS), Zeta Potential Measurements and Transmission Electron Microscopy (TEM). The TEM images clearly revealed the attachment of individual gold nanoparticles onto the spherical outer surface of the cationic liposomes which was also confirmed by DLS and UV-VIS data. Furthermore, the plasmonic properties of the hybrid complexes have been evaluated by using the Surface Enhanced Raman Spectroscopy (SERS) technique. It is shown that PEG mediated interaction between the liposomes and the gold nanoparticles enabled the recording of the SER spectra of the liposomes in aqueous environment, thus demonstrating the plasmonic properties of the hybrids.