Liposomal Carrier System Research Articles

Nebulization and In Vitro Upper Airway Deposition of Liposomal Carrier Systems.

Liposomal carrier systems have emerged as a promising technology for pulmonary drug delivery. This study focuses on two selected liposomal systems, namely, dipalmitoylphosphatidylcholine stabilized by phosphatidic acid and cholesterol (DPPC-PA-Chol) and dipalmitoylphosphatidylcholine stabilized by polyethylene glycol and cholesterol (DPPC-PEG-Chol). First, the research investigates the stability of these liposomal systems during the atomization process using different kinds of nebulizers (air-jet, vibrating mesh, and ultrasonic). The study further explores the aerodynamic particle size distribution of the aerosol generated by the nebulizers. The nebulizer that demonstrated optimal stability and particle size was selected for more detailed investigation, including Andersen cascade impactor measurements, an assessment of the influence of flow rate and breathing profiles on aerosol particle size, and an in vitro deposition study on a realistic replica of the upper airways. The most suitable combination of a nebulizer and liposomal system was DPPC-PA-Chol nebulized by a Pari LC Sprint Star in terms of stability and particle size. The influence of the inspiration flow rate on the particle size was not very strong but was not negligible either (decrease of Dv50 by 1.34 μm with the flow rate increase from 8 to 60 L/min). A similar effect was observed for realistic transient inhalation. According to the in vitro deposition measurement, approximately 90% and 70% of the aerosol penetrated downstream of the trachea using the stationary flow rate and the realistic breathing profile, respectively. These data provide an image of the potential applicability of liposomal carrier systems for nebulizer therapy. Regional lung drug deposition is patient-specific; therefore, deposition results might vary for different airway geometries. However, deposition measurement with realistic boundary conditions (airway geometry, breathing profile) brings a more realistic image of the drug delivery by the selected technology. Our results show how much data from cascade impactor testing or estimates from the fine fraction concept differ from those of a more realistic case.

Development and Evaluation of Novel Encapsulated Isoeugenol-Liposomal Gel Carrier System for Methicillin-Resistant Staphylococcus aureus.

In recent years, methicillin-resistant Staphylococcus aureus (MRSA) bacteria have seriously threatened the health and safety of the world's population. This challenge demands the development of alternative therapies based on plant origin. This molecular docking study ascertained the orientation and intermolecular interactions of isoeugenol within penicillin-binding protein 2a. In this present work, isoeugenol as an anti-MRSA therapy was selected by encapsulating it into a liposomal carrier system. After encapsulation into the liposomal carrier, it was evaluated for encapsulation efficiency (%), particle size, zeta potential, and morphology. The percentage entrapment efficiency (% EE) was observed to be 57.8 ± 2.89% with a particle size of 143.31 ± 7.165 nm, a zeta potential of (-)25 mV, and morphology was found to be spherical and smooth. After this evaluation, it was incorporated into a 0.5% Carbopol gel for a smooth and uniform distribution on the skin. Notably, the isoeugenol-liposomal gel was smooth on the surface with a pH of 6.4, suitable viscosity, and spreadability. Interestingly, the developed isoeugenol-liposomal gel was safe for human use, with more than 80% cell viability. The in vitro drug release study shows promising results with 75.95 ± 3.79% of drug release after 24 h. The minimum inhibitory concentration (MIC) was 8.236 µg/mL. Based on this, it can be concluded that encapsulating isoeugenol into the liposomal gel is a potential carrier for MRSA treatment.

Liposomal bupivacaine-No breakthrough in postoperative pain management

One of the main limitations concerning the use of local anesthetics is due to their restricted duration of action. In recent years, liposomal formulations with prolonged release kinetics have been developed to extend the pharmacological duration of action of the 1‑stage peripheral regional anesthesia (single-shot procedure) and thus bring about alonger duration of action. The focus here is particularly on achieving postoperative freedom from pain for at least 24 h (or even better 48 h) and thus early mobilization of patients using on-demand medication causing (at most) minor local sensory blockade without causing motor impairments (at least that is the ideal). Therefore, methods of utilizing slow-release drugs as seen in liposomal carrier systems have experienced increasing scientific attention in the last few years. Acommon modern pharmacological example with atheoretically significantly longer duration of action is liposomal bupivacaine, an amide local anesthetic. Due to amultivesicular liposome structure, the retarded release of the active component bupivacaine HCl leads to atheoretical pharmacological effectiveness of up to 72 h. Previous studies consistently showed asafety profile comparable to conventional bupivacaine HCl. Liposomal bupivacaine has been approved by the U.S. Food and Drug Administration (FDA) under the trade name Exparel© (Pacira Pharmaceuticals, Parsippany, NJ, USA) since 2011; however, its use is currently limited to local wound infiltration, transverse abdominis plane (TAP) blocks, and interscalene nerve blocks of the brachial plexus. In 2020, the European Medicines Agency (EMA) also approved the use of liposomal bupivacaine for blockade of the brachial plexus or the femoral nerve and as afield block or for wound infiltration to treat postoperative pain. So far, studies on the clinical effectiveness of liposomal bupivacaine have been very heterogeneous and there have been no conclusive meta-analyses with sufficient rigor or significance. Recent systematic reviews and meta-analyses, combining the results of clinical studies regarding the analgesic efficiency of liposomal bupivacaine in different fields of application, consistently refuted any benefit of clinical relevance provided by the liposomal formulation. There is currently sufficient evidence to now end the ongoing debate around liposomal bupivacaine. The aim of this work is to give the reader acurrent, evidence-based overview of this substance.

Development of ACE2 loaded decoy liposomes and their effect on SARS-CoV-2 for Covid-19 treatment

SARS-CoV-2 is a novel coronavirus with a positively oriented single-stranded RNA that first appeared in December 2019. In this study, Angiotensin Converting Enzyme 2 (ACE2) loaded decoy liposomes were developed and characterized. ACE2 protein was loaded onto a liposomal carrier system and its toxicity and effectiveness were evaluated in cell culture and in vitro virus neutralization studies. Liposomes were prepared with the film hydration method and adjusted for size with the dialysis membrane method or the ultrasonic homogenization method. All formulations showed high entrapment efficiency between 99.98–79.6%. Liposomes with two different particle sizes above 2 µm and below 500 nm were obtained with the dialysis membrane method and homogenization method. Two optimum formulations, M6-S90 with a PDI value of 0.383 ± 0.053 and particle size of 397.7 ± 28.25 nm which was produced by ultrasonic homogenization and M6-4 with a PDI 0.769 ± 0.205 and particle size of 2606 ± 1396.00 were chosen as optimum formulations for further studies. M6-S90 was stable and showed low toxicity on Calu3 lung epithelial cells. Pre-incubation of M6-S90 with with 3.1 × 105 PFU/mL of SARS-CoV-2 followed by incubation with Vero E6 cells resulted in a 4 log fold change reduction in cell death compared to virus alone. This suggests that MS6-S90 had good neutralization activity on SARS-CoV-2 whilst maintaining viability of the host cell. The novel ACE-2 loaded decoy liposomes described in this study can be further evaluated for the treatment of COVID-19.

Her-2 directed systemic delivery of fatty acid synthase (FASN) siRNA with novel liposomal carrier systems in the breast cancer mouse model

Despite the current advancements in the gene silencing therapy in vitro, the systemic delivery of siRNA still remains a challenging task for its transition into clinics. We have previously developed the Her2-targeted fatty acid synthase (FASN) siRNA-encapsulating immunoliposomes (ILs) with a great stability in the presence of serum. We report here the therapeutic potential of the lipid-based novel formulations in the breast cancer mouse model. The growth inhibitory and gene silencing effects of various formulations were determined by measuring the size of the tumor, cell proliferation, apoptotic index and immunoassays against Her2-over expressed tumor xenografts in nude mice. The pegylated DSPC/Chol and DOPE/CHEMS immunoliposomes containing FASN-siRNA significantly decreased the tumor growth relative to non-targeted liposomes. They induced the 1.5-fold increase in cellular apoptosis and several fold decrease in proliferation as compared to non-targeted liposomal formulations of FASN-siRNA. Moreover, FASN-siRNA-ILs produced several fold increase in the ratios of p53/p21 and Bax/Bcl-2. The gene silencing effects of targeted FASN-liposomes were found significantly superior, resulting in 30%-40% downregulation in FASN as compared to non-targeted similar formulations. Both types of FASN immunoliposomes provided a highly efficient approach for targeted delivery in Her-2-expressed breast cancer and thus offered a promising anticancer strategy in the clinical therapy.

Development of a protein replacement therapy for peeling skin syndrome

British Journal of DermatologyVolume 184, Issue 6 p. e197-e197 Plain Language SummaryFree Access Development of a protein replacement therapy for peeling skin syndrome First published: 06 June 2021 https://doi.org/10.1111/bjd.20101AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat Abstract Linked article: Valentin et al. Br J Dermatol 2021; 184:1123–1131. Peeling skin syndrome type 1 is a severe form of congenital ichthyosis. Patients have severe itch and generalized peeling of the skin. Current therapeutic approaches are very unsatisfactory. The disease is the result of mutations (mistakes) in the CDSN gene, which cause a lack of the protein corneodesmosin (CDSN) in the skin. We wanted to develop the first steps towards a specific protein replacement therapy for CDSN deficiency. The aim is to improve the cell–cell connection in two layers of the epidermis (the granular and corneal layers). Human CDSN was produced in bacterial cells. A liposomal carrier system was developed to transport the CDSN to the outer membrane of the epidermal cells. The liposomal carrier system was checked for stability and toxicity. Also, the effect on epidermal cells and artificial skin models was investigated. The liposomes were found to be successfully present at the epidermal cell membranes. The CDSN-deficient skin models were treated with liposomal CDSN and demonstrated the presence of the replaced protein within the granular layer. Finally, the skin barrier test and microscopy showed improved skin integrity (skin that functioned better), if the skin models were treated with liposomal CDSN. We believe that this study presents helpful laboratory results to develop a protein replacement therapy for patients with peeling skin syndrome and other diseases where there is also a lack of CDSN. Volume184, Issue6June 2021Pages e197-e197 RelatedInformation

Development of a pathogenesis-based therapy for peeling skin syndrome type 1.

Peeling skin syndrome type 1 (PSS1) is a rare and severe autosomal recessive form of congenital ichthyosis. Patients are affected by pronounced erythroderma accompanied by pruritus and superficial generalized peeling of the skin. The disease is caused by nonsense mutations or complete deletion of the CDSN gene encoding for corneodesmosin (CDSN). PSS1 severely impairs quality of life and therapeutic approaches are totally unsatisfactory. The objective of this study was to develop the first steps towards a specific protein replacement therapy for CDSN deficiency. Using this approach, we aimed to restore the lack of CDSN and improve cell-cell cohesion in the transition area of the stratum granulosum (SG) to the stratum corneum. Human CDSN was recombinantly expressed in Escherichia coli. A liposome-based carrier system, prepared with a cationic lipopeptide to mediate the transport to the outer membrane of keratinocytes, was developed. This formulation was chosen for CDSN delivery into the skin. The liposomal carrier system was characterized with respect to size, stability and toxicity. Furthermore, the interaction with primary keratinocytes and human epidermal equivalents was investigated. The liposomes showed an accumulation at the membranes of keratinocytes. CDSN-deficient epidermal equivalents that were treated with liposomal encapsulated CDSN demonstrated presence of CDSN in the SG. Finally, the penetration assay and histological examinations revealed an improved epidermal integrity for CDSN-deficient epidermal equivalents, if they were treated with liposomal encapsulated CDSN. This study presents the first preclinical in vitro experiments for a future specific protein replacement therapy for patients affected by PSS1.

Functionally engineered 'hepato-liposomes': Combating liver-stage malaria in a single prophylactic dose.

Primaquine continues to remain the gold standard molecule with an incumbent toxicity profile, as far as radical treatment of malaria is concerned. Better molecules are available at experimental level but their targeted delivery is a challenge. The present work identifies 'Decoquinate (DQN)' as a repurposed, safer drug molecule with a potential to function as an appealing replacement for primaquine active against liver-stage malaria. The work focuses on delivering the highly lipophilic DQN (log P~5) in a liposomal carrier system to 'sporozoite infested hepatocytes' using two different in-house synthesized hepatotropic ligands. Functionally engineered 'hepato-liposomes' exhibit differences in their DQN loading capacities but no significant change in morphology or particle size and are also not affected by freeze drying. Two ligands, targeting different receptors on hepatocytes, have been compared for their in vitro and in vivo drug delivery efficiency in liver stage malaria. The studies reveal superior antimalarial efficacy of differently designed DQN loaded liposomes and demonstrate antimalarial efficacy at a low dose of 0.5mg/kg for a repurposed molecule like DQN. The in vivo studies successfully discriminate the functional efficiency of the carriers and establish the importance of design in liposomal drug delivery for malarial prophylaxis.

Targeted mitochondrial delivery of antisense RNA-containing nanoparticles by a MITO-Porter for safe and efficient mitochondrial gene silencing

Mitochondrial gene therapy will be needed to treat mitochondrial diseases. We previously demonstrated mitochondrial gene silencing by the mitochondrial delivery of antisense RNA oligonucleotide (ASO) targeting mtDNA-encoded mRNA using a MITO-Porter, a liposomal nano carrier system designed for mitochondrial delivery. Here, we report on the efficient packaging of ASO in the MITO-Porter via a nanoparticle packaging method, which showed a 10-fold higher packaging efficiency than the conventional method. The constructed carrier showed a decrease in the target mRNA levels and ATP production. These results indicate that such a MITO-Porter has potential for use in therapies designed to regulate mitochondrial function.

Stefin A-functionalized liposomes as a system for cathepsins S and L-targeted drug delivery

Proteolytic activity in the tumor microenvironment is one of the key elements supporting tumor development and metastasis. One of the key families of proteases that are overexpressed in various types of cancer and implicated in different stages of tumor progression are cysteine cathepsins. Among them, cathepsins S and L can be secreted into the tumor microenvironment by tumor and/or immune cells, making them promising drug delivery targets. Here we present a new system for cathepsin S/L targeting using a liposomal drug carrier system functionalized with the endogenous cysteine cathepsin inhibitor, stefin A. The selective targeting of cathepsins by stefin A-conjugated liposomes was confirmed in vitro and in vivo, demonstrating the potential of this approach for cancer diagnosis and treatment.

Stimuli-responsive liposomes for drug delivery.

The ultimate goal of drug delivery is to increase the bioavailability and reduce the toxic side effects of the active pharmaceutical ingredient (API) by releasing them at a specific site of action. In the case of antitumor therapy, association of the therapeutic agent with a carrier system can minimize damage to healthy, nontarget tissues, while limit systemic release and promoting long circulation to enhance uptake at the cancerous site due to the enhanced permeation and retention effect (EPR). Stimuli-responsive systems have become a promising way to deliver and release payloads in a site-selective manner. Potential carrier systems have been derived from a wide variety of materials, including inorganic nanoparticles, lipids, and polymers that have been imbued with stimuli-sensitive properties to accomplish triggered release based on an environmental cue. The unique features in the tumor microenvironment can serve as an endogenous stimulus (pH, redox potential, or unique enzymatic activity) or the locus of an applied external stimulus (heat or light) to trigger the controlled release of API. In liposomal carrier systems triggered release is generally based on the principle of membrane destabilization from local defects within bilayer membranes to effect release of liposome-entrapped drugs. This review focuses on the literature appearing between November 2008-February 2016 that reports new developments in stimuli-sensitive liposomal drug delivery strategies using pH change, enzyme transformation, redox reactions, and photochemical mechanisms of activation. WIREs Nanomed Nanobiotechnol 2017, 9:e1450. doi: 10.1002/wnan.1450 For further resources related to this article, please visit the WIREs website.

Encapsulation of two different TLR ligands into liposomes confer protective immunity and prevent tumor development

Nucleic acid-based Toll-like receptor (TLR) ligands are promising adjuvants and immunotherapeutic agents. Combination of TLR ligands potentiates immune response by providing synergistic immune activity via triggering different signaling pathways and may impact antigen dependent T-cell immune memory. However, their short circulation time due to nuclease attack hampers their clinical performance. Liposomes offer inclusion of protein and nucleic acid-based drugs with high encapsulation efficiency and drug loading. Furthermore, they protect cargo from enzymatic cleavage while providing stability, and enhancing biological activity. Herein, we aimed to develop a liposomal carrier system co-encapsulating TLR3 (polyinosinic-polycytidylic acid; poly(I:C)) and TLR9 (oligodeoxynucleotides (ODN) expressing unmethylated CpG motifs; CpG ODN) ligands as immunoadjuvants together with protein antigen. To demonstrate that this depot system not only induce synergistic innate immune activation but also boost antigen-dependent immune response, we analyzed the potency of dual ligand encapsulated liposomes in long-term cancer protection assay. Data revealed that CpG ODN and poly(I:C) co-encapsulation significantly enhanced cytokine production from spleen cells. Activation and maturation of dendritic cells as well as bactericidal potency of macrophages along with internalization capacity of ligands were elevated upon incubation with liposomes co-encapsulating CpG ODN and poly(I:C). Immunization with co-encapsulated liposomes induced OVA-specific Th1-biased immunity which persisted for eight months post-booster injection. Subsequent challenge with OVA-expressing tumor cell line, E.G7, demonstrated that mice immunized with liposomes co-encapsulating dual ligands had significantly slower tumor progression. Tumor clearance was dependent on OVA-specific cytotoxic memory T-cells. These results suggest that liposomes co-encapsulating TLR3 and TLR9 ligands and a specific cancer antigen could be developed as a preventive cancer vaccine.

Identification of a Nucleoporin358-Specific RNA Aptamer for Use as a Nucleus-Targeting Liposomal Delivery System.

An active targeting drug delivery system that targets the nucleus could solve the problem of the treatment of genetic disorders through gene delivery, but it has met with limited success. The purpose of this study was to establish an RNA aptamer-modified nucleus-targeting liposomal carrier system referred to as NupApt-liposomes. RNA aptamers against the Nup358 protein are prepared using a newly established Protein SELEX method. After confirming aptamer binding to the recombinant protein, an aptamer-lipid conjugate (Apt-PEG-DSPE) was prepared. Aptamer-modified liposomes and simple polyethylene glycol (PEG) liposomes were prepared to check its ability to bind to isolated nuclei. Confocal studies indicated that the aptamer-modified liposomes had the ability to bind to isolated nuclei, whereas PEG-liposomes showed only weak binding. Confocal laser scanning microscopy studies of inhibition assays also supported the above conclusion. The dissociation constant of the Nucleoporin358-specific aptamer referred to as NupApt01 and NupApt02 were 36 and 70 nM, respectively. Finally, with aptamer-modified liposomes, gene expression studies showed a two times better gene expression in NupApt-liposome-treated nuclei in comparison to that of PEG-liposomes. This represents the first artificial RNA aptamer-modified liposomes promoting the specific binding of a nanocarrier to the nucleus, thus improving gene expression in comparison to PEG-liposomes.

Abstract 2161: Development of radiolabelled drug carrier systems for molecularly targeted radiotherapy

Abstract Introduction Tagging of radioisotopes to targeting moieties such as peptides, antibodies and nucleotides aids in more precise delivery of these isotopes to cancer cells for treatment. However some of the obstacles to successful delivery of these radiolabelled molecules include poor circulation half-life and inefficient tumour extravasation and penetration. Liposomal drug carrier systems have extended circulation profiles but would benefit from enhanced binding and entry into target cancer cells. To address some of these challenges, liposomes encapsulating a chemotherapeutic agent (doxorubicin) and tagged with radiolabelled targeting moieties were designed, formulated and then tested for specific binding to and killing of cancer cell lines. Experimental Procedures Distearoylphosphatidylethanolamine-poly ethylene glycol (DSPE-PEG) based liposomes were developed and surface modified with epidermal growth factor-diethylenetriamine pentaacetate (EGF-DTPA) followed by 111In radiolabelling. The EGF-tagged liposomes were characterised using zetasizer and transmission electron microscopy (TEM). Direct particle cytotoxicity was assessed using the MTT assay and uptake kinetics was determined by treating EGF+ve MDA-MB-468 (1.3 × 10⁁6 EGFR/cell) and EGFR-ve MCF7 cells (1.5 × 10⁁4 EGFR/cell) with Nile red-containing liposomes and quantifying Nile red fluorescence in the cell lysates. Payload delivery capabilities were studied by exposing EGFR+ve luciferase-expressing MDA-MB-231 or EGFR-ve luciferase expressing MCF7 breast cancer cells to EGF-tagged or non-tagged particles containing the model drug luciferin. Therapeutic efficacy of Doxorubicin-containing EGF-tagged liposomes to MDA-MB-468 and MCF7 cells was then assessed by the MTT assay. Results The particles were spherical in morphology with a diameter of 140-160 nm. More than 95% of the 111In added was tagged to the particles. The liposomes did not show intrinsic cytotoxicity and were taken up by cells in a dose-dependent manner with greater uptake observed in MDA-MB-468 than in MCF7s. Greater delivery (2-fold increase, p<0.05) of EGF-tagged luciferin-containing particles was observed in MDA-MB-231 cells than in MCF7 cells, this was not the case for non-tagged particles. EGF-tagged particles also gave better delivery (3.5-fold increase, p<0.05) than non-tagged particles in MDA-MB-231 cells, this was not the case in MCF7 cells. Doxorubicin-loaded EGF-tagged liposomes had an IC50 of 0.02 mg/ml with MDA-MB-468 and 0.04 mg/ml with MCF7s. Conclusions This work, using 111In- and EGF-tagged liposomes has shown promising in vitro targeted cellular uptake and drug delivery. Receptor binding kinetics and the feasibility of using these systems in vivo for ultrasound-assisted radiopharmaceutical delivery will follow. Citation Format: Jyothi U. Menon, Joshua Owen, Robert Carlisle, Katherine A. Vallis. Development of radiolabelled drug carrier systems for molecularly targeted radiotherapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2161.

A New Type of Liquid Silymarin Proliposome Containing Bile Salts: Its Preparation and Improved Hepatoprotective Effects.

Silymarin, a known extract, is used in the treatment of liver diseases with various origins, but its current administration form cannot target the liver because of its poor oral bioavailability. A new type of oral silymarin proliposome aimed at improving silymarin’s poor bioavailability and hepatoprotective effects, is introduced in this work. Silymarin-loaded liquid proliposome were prepared using a simple dissolving process. The morphology, particle size, zeta potential, and entrapment efficiency of the silymarin liposomes were analysed. The everted gut sac transport model was used to measure the intestinal transport of liposomes. The liposomal hepatoprotective activity was evaluated in three types of experimental hepatitis animal models. After staining with haematoxylin and eosin, the livers were microscopically examined to analyse any pathological changes. The prepared silymarin proliposome formed silymarin liposomes with a multilayer liposome structure and improved intestinal transport. In an injured liver, the silymarin liposomes produced a stronger hepatoprotective effect through a significant decrease in both the aminotransferase and MDA levels and a significant increase in the SOD and GSH-PX levels compared to orally administered silymarin tablets. This effect was also confirmed histopathologically. In a word, incorporation of silymarin into a liposomal carrier system increased intestinal absorption and showed better hepatoprotective effects compared to silymarin tablets.

Liposomal systems as carriers for bioactive compounds.

Since the revolutionary discovery that phospholipids can form closed bilayered structures in aqueous systems, the study of liposomes has become a very interesting area of research. The versatility and amazing biocompatibility of liposomes has resulted in their wide-spread use in many scientific fields, and many of their applications, especially in medicine, have yielded breakthroughs in recent decades. Specifically, their easy preparation and various structural aspects have given rise to broadly usable methodologies to internalize different compounds, with either lipophilic or hydrophilic properties. The study of compounds with potential biotechnological application(s) is generally related to evaluation and risk assessment of the possible cytotoxic or therapeutic effects of the compound under study. In most cases, undesirable side-effects are associated with an interaction of the liposome with the cell membrane and/or its absorption and subsequent interaction with a cellular biomolecule. Liposomal carrier systems have an unprecedented potential for delivering bioactive substances to specific molecular targets due to their biocompatibility, biodegradability and low toxicity. Liposomes are therefore considered to be an invaluable asset in applied biotechnology studies due to their potential for interaction with both hydrophilic and lipophilic compounds.

A photo-responsive peptide- and asparagine–glycine–arginine (NGR) peptide-mediated liposomal delivery system

The conjugation of tunable peptides or materials with nanocarriers represents a promising approach for drug delivery to tumor cells. In this study, we report the development of a novel liposomal carrier system that exploits the cell surface binding synergism between photo-sensitive peptides (PSPs) and targeting ligands. The positive charges of the lysine residues on the cell-penetrating peptides (CPPs) were temporarily caged by the photolabile-protective groups (PG), thereby forming a PSP. Furthermore, this PSP enhances specific uptake into cancer cells after rapidly uncaging the PG via near-infrared (NIR) light illumination. In the circulatory system, the cell penetrability of PSP was hindered. In contrast, the asparagine–glycine–arginine (NGR) peptide moieties, selectively bind to CD13-positive tumors, were attached to the nanocarrier to facilitate the active accumulation of this liposomal carrier in tumor tissue. The dual-modified liposomes (PSP/NGR-L) were prepared by emulsification method, and the concentrations of DSPE-PEG2000-psCPP and DSPE-PEG5000-NGR in the liposomes were chosen to be 4% and 1% (molar ratio), respectively. The mean particle size of the PSP/NGR-L was about 95 nm, and the drug entrapment efficiency was more than 90%. Cellular uptake results demonstrated that the proposed PSP/NGR-L had an enhancement of cancer cell recognition and specific uptake. Furthermore, the PSP/NGR-L demonstrated a stronger antitumor efficacy in the HT-1080 tumor model in nude mice with the aid of NIR illumination.

Matrix liposomes: A solid liposomal formulation for oral administration

Liposomes can be used as oral dosage form to improve the bioavailability of both hydrophilic drugs, such as peptides and proteins and lipophilic drugs. But liposome dispersions are not very stable under the harsh conditions of the GI‐tract. Also a controlled release of embedded compounds is not possible. Therefore we developed a lipid based liposomal carrier system for peroral delivery of peptides. The lipid bilayer of standard egg‐PC/cholesterol liposomes were stabilized by gelatine. The gelatine also works as a thickening agent by forming a matrix in which liposomes are embedded. Liposomes were prepared by dual asymmetric centrifugation with the addition of gelatine. Size and size distribution of prepared liposomes with up to 20% gelatine achieved the same quality compared to conventional liposomes. Size and size distribution, encapsulation efficiency of different compounds and the dissolution behaviour of the solid dosage form in simulated intestinal fluid were examined. Matrix liposomes containing 20% gelatine showed an approximately linear release of liposomes. Moreover, the dissolution rate could be adjusted by modification of the gelatine concentration and the absolute amount of liposomes released at a certain time was found to be dose dependent.Practical applications: The new liposomal solid formulation can be useful for a controlled release of hydrophilic macromolecules as peptides and proteins after peroral administration. Liposomes embedded in a solid dosage form offer the possibility of a simple administration and exhibit higher storage stability compared to liposomes in dispersion.A composition of phospholidpids and gelatine leads to matrix liposomes prepared by dual asymmetric centrifugation. Dissolution of the solid liposomal formulation leads to a liposome release out of the dosage form. The dissolution rate can be adjusted by the concentration of gelatine.

Investigation of Drug-Excipients Compatibility of Ellagic Acid for Development of Formulation Containing Lipososmes

The aim of the present study was tochecked the compatibility between drug: lipid and drug: excipients. Ellagic acid was selected as model drug while phospholipid and Cholesterol were considered excipients. The study was performed by Fourier transform infrared spectroscopy (FTIR), Diffraction scanning calorimetric (DSC) and High performance liquid chromatography (HPLC). The spectrophotometric graphs revealed that there was no significant changes in the position of functional groups of ellagic acid, phospholipid and Cholesterol (O-H, C=O, C-H str.) in pure drugs and excipients with respect to their physical mixtures. Further the samples werecharacterized by using DSC and HPLC methods and found no any interaction between drug excipients. Combination of synthetic herbal drug and pharmaceutical excipients are compatible with each other and shows no interaction. Thus this suitable combination can be employed for the successful development of novel liposomal carrier system.

Development of a gradient high performance liquid chromatography assay for simultaneous analysis of hydrophilic gemcitabine and lipophilic curcumin using a central composite design and its application in liposome development

A rapid and reliable gradient high performance liquid chromatography (HPLC) method was developed for the simultaneous analysis of a hydrophilic anticancer drug, gemcitabine, and a lipophilic phytochemical, curcumin. A central composite design (CCD) was employed to optimize the gradient elution programme to obtain an acceptable retention time and peak width for curcumin with the aid of the desirability function (DF). Dual wavelengths (gemcitabine, 270nm; curcumin, 420nm) were selected to give maximal specific detection using a diode-array detector. The optimized DF was obtained with a mobile phase (water:acetonitrile) of 95:5 for 4.5min, followed by 30:70 for 5min, which gave retention times within 11min with peak widths <0.10min, respectively. No interference from the formulation ingredients was detected. The method was linear over the range of 0.125–5μM for gemcitabine, and 1.25–50μM for curcumin. The intra-day and inter-day variability were less than 5%, with accuracies between 90 and 110% of the true values. The limit of detection (LOD) for gemcitabine and curcumin was 0.04μM and 0.03μM, respectively. Using this method, release study for a dual-drug loaded formulation revealed a Fickian diffusion process for both. The stability of curcumin was pH dependent in aqueous solutions with a half-life of 3h at 25°C and pH 7.4. This was significantly improved after incorporation into the liposomes with no degradation for at least 3 months. In conclusion, the combination of CCD and DF offers a new approach to optimize a gradient HPLC method with high efficiency. A liposomal carrier system may provide an option for tumour dual-drug therapy with the additional advantage of chemical stabilization of the encapsulated compound.