Core–shell-type lipid–polymer hybrid nanoparticles as a drug delivery platform

Bioactive Hybrid Particles from Poly(D,L-lactide-co-glycolide) Nanoparticle Stabilized Lipid Droplets

Biodegradable and bioactive hybrid particles composed of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles and medium-chain triglycerides were prepared by spray drying lipid-in-water emulsions stabilized by PLGA nanoparticles, to form PLGA-lipid hybrid (PLH) microparticles approximately 5 μm in mean diameter. The nanoparticle stabilizer was varied and mannitol was also incorporated during the preparation to investigate the effect of stabilizer charge and cryoprotectant content on the particle microstructure. An in vitro lipolysis model was used to demonstrate the particles' bioactivity by manipulating the digestion kinetics of encapsulated lipid by pancreatic lipase in simulated gastrointestinal fluid. Lipid digestion kinetics were enhanced in PLH and PLGA-lipid-mannitol hybrid (PLMH) microparticles for both stabilizers, compared to a coarse emulsion, in biorelevant media. An optimal digestion rate was observed for the negatively charged PLMH system, evidenced by a 2-fold increase in the pseudo-first-order rate constant compared to a coarse emulsion. Improved microparticle redispersion, probed by dual dye confocal fluorescence microscopy, increased the available surface area of lipid for lipase adsorption, enhancing digestion kinetics. Thereby, lipase action was controlled in hybrid microparticles by altering the surface charge and carbohydrate content. Our results demonstrate that bioactive microparticles composed of versatile and biodegradable polymeric particles and oil droplets have great potential for use in smart food and nutrient delivery, as well as safer and more efficacious oral delivery of drugs and drug combinations.

Gated mesoporous silica nanoparticles for the controlled delivery of drugs in cancer cells

In recent years, mesoporous silica nanoparticles (MSNs) have been used as effective supports for the development of controlled-release nanodevices that are able to act as multifunctional delivery platforms for the encapsulation of therapeutic agents, enhancing their bioavailability and overcoming common issues such as poor water solubility and poor stability of some drugs. In particular, redox-responsive delivery systems have attracted the attention of scientists because of the intracellular reductive environment related to a high concentration of glutathione (GSH). In this context, we describe herein the development of a GSH-responsive delivery system based on poly(ethylene glycol)- (PEG-) capped MSNs that are able to deliver safranin O and doxorubicin in a controlled manner. The results showed that the PEG-capped systems designed in this work can be maintained closed at low GSH concentrations, yet the cargo can be delivered when the concentration of GSH is increased. Moreover, the efficacy of the PEG-capped system in delivering the cytotoxic agent doxorubicin in cells was also demonstrated.

Folate-modified lipid-polymer hybrid nanoparticles for targeted paclitaxel delivery

The purpose of this study was to develop a novel lipid-polymer hybrid drug carrier comprised of folate (FA) modified lipid-shell and polymer-core nanoparticles (FLPNPs) for sustained, controlled, and targeted delivery of paclitaxel (PTX). The core-shell NPs consist of 1) a poly(ε-caprolactone) hydrophobic core based on self-assembly of poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL) amphiphilic copolymers, 2) a lipid monolayer formed with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol)-2000] (DSPE-PEG2000), 3) a targeting ligand (FA) on the surface, and were prepared using a thin-film hydration and ultrasonic dispersion method. Transmission electron microscopy and dynamic light scattering analysis confirmed the coating of the lipid monolayer on the hydrophobic polymer core. Physicochemical characterizations of PTX-loaded FLPNPs, such as particle size and size distribution, zeta potential, morphology, drug loading content, encapsulation efficiency, and in vitro drug release, were also evaluated. Fluorescent microscopy proved the internalization efficiency and targeting ability of the folate conjugated on the lipid monolayer for the EMT6 cancer cells which overexpress folate receptor. In vitro cytotoxicity assay demonstrated that the cytotoxic effect of PTX-loaded FLPNPs was lower than that of Taxol(®), but higher than that of PTX-loaded LPNPs (without folate conjugation). In EMT6 breast tumor model, intratumoral administration of PTX-loaded FLPNPs showed similar antitumor efficacy but low toxicity compared to Taxol(®). More importantly, PTX-loaded FLPNPs showed greater tumor growth inhibition (65.78%) than the nontargeted PTX-loaded LPNPs (48.38%) (P<0.05). These findings indicated that the PTX loaded-FLPNPs with mixed lipid monolayer shell and biodegradable polymer core would be a promising nanosized drug formulation for tumor-targeted therapy.

Engineering of a hybrid polymer-lipid nanocarrier for the nasal delivery of tenofovir disoproxil fumarate: physicochemical, molecular, microstructural, and stability evaluation

PURPOSE

To engineer a hybrid nanocarrier system based on lipid and polymer for the nasal delivery of tenofovir disoproxil fumarate (TDF), and further to investigate its physicochemical, molecular, microstructural, and stability aspects.

METHODS

Nanoparticles were prepared by melt emulsification-probe sonication technique. A 3(2) factorial design was used to identify key formulation variables influencing the characteristics of drug-loaded carrier. FT-IR, mass spectroscopy (MS) and (1)H NMR was used to probe molecular interactions among the components of the system, while the surface morphology was imagined through electron microscopy (TEM and SEM). Thermal analysis and powder X-ray diffraction (PXRD) was used to explore melting and crystallization behavior of drug and the carrier lipid. PLN-9 GEL was studied for its rheology, drug release, ex-vivo permeation, histopathology, and stability.

RESULTS

Batch PLN-9 had size of 239 nm, drug encapsulation of 87.14% and revealed spherical morphology. MS, FT-IR and (1)H NMR established compatibility between the drug (TDF) and the carrier lipid (Lauric acid), while, a strong H-bonding was identified between the amino (-NH2) group of drug and the carboxyl (-COOH) group of pemulen polymer. Thermal analysis confirmed an amorphous TDF within the carrier matrix. PXRD analysis indicated substantial change in the molecular packing and subcell structure of carrier lipid during the PLN processing. PLN-9 GEL had shear thinning rheology, an anomalous type (n>0.5) of drug release and possessed potential to transport TDF across the nasal mucosa with an average flux of 135.36 μg/cm(2)/h.

CONCLUSION

The designed carrier can encapsulate TDF and accentuates its transnasal flux, thus could be used as a carrier for an effective nasal delivery of TDF.

Co-delivery of HIF1α siRNA and gemcitabine via biocompatible lipid-polymer hybrid nanoparticles for effective treatment of pancreatic cancer

Hypoxia-inducible factor 1α (HIF1α) has emerged as a promising new target for pancreatic cancer treatment over the past decade. High expression of HIF-1α increases the drug resistance of the current first line chemotherapeutic drug, gemcitabine (Gem). Here we employed biocompatible lipid-polymer hybrid nanoparticles to co-deliver HIF1α siRNA (si-HIF1α) and Gem for pancreatic cancer treatment in subcutaneous and orthotopic tumor models. The cationic ε-polylysine co-polymer (ENPs) can effectively absorb negatively charged si-HIF1α on the surface and encapsulate Gem to the hydrophilic core. Further coating of ENPs with PEGylated lipid bilayer resulted formation of LENPs, with reversed surface charge. The lipid bilayer of LENPs prevented nanoparticle aggregation and si-HIF1α degradation in serum, as well as Gem leakage. Those characteristics endow LENPs encapsulating drug prolonged lifetime in bloodstream and improved drug release via the enhanced tumor vasculature effect in tumor tissues. LENPs can co-deliver Gem and si-HIF1α (LENP-Gem-si-HIF1α) into tumor cells and effectively suppress the HIF1α expression both in vitro and in vivo. LENP-Gem-siHIF1α exhibited significant synergistic antitumor effects. Furthermore, LENP-Gem-si-HIF1α showed excellent capability to inhibit tumor metastasis in orthotopic tumor model.

Receptor-mediated membrane adhesion of lipid-polymer hybrid (LPH) nanoparticles studied by dissipative particle dynamics simulations

Lipid-polymer hybrid (LPH) nanoparticles represent a novel class of targeted drug delivery platforms that combine the advantages of liposomes and biodegradable polymeric nanoparticles. However, the molecular details of the interaction between LPHs and their target cell membranes remain poorly understood. We have investigated the receptor-mediated membrane adhesion process of a ligand-tethered LPH nanoparticle using extensive dissipative particle dynamics (DPD) simulations. We found that the spontaneous adhesion process follows a first-order kinetics characterized by two distinct stages: a rapid nanoparticle-membrane engagement, followed by a slow growth in the number of ligand-receptor pairs coupled with structural re-organization of both the nanoparticle and the membrane. The number of ligand-receptor pairs increases with the dynamic segregation of ligands and receptors toward the adhesion zone causing an out-of-plane deformation of the membrane. Moreover, the fluidity of the lipid shell allows for strong nanoparticle-membrane interactions to occur even when the ligand density is low. The LPH-membrane avidity is enhanced by the increased stability of each receptor-ligand pair due to the geometric confinement and the cooperative effect arising from multiple binding events. Thus, our results reveal the unique advantages of LPH nanoparticles as active cell-targeting nanocarriers and provide some general principles governing nanoparticle-cell interactions that may aid future design of LPHs with improved affinity and specificity for a given target of interest.

Aptamer density dependent cellular uptake of lipid-capped polymer nanoparticles for polyvalent targeted delivery of vinorelbine to cancer cells

In this work, MUC1 aptamer (designated S2.2) modified and vinorelbine (VRL) loaded lipid-polymer hybrid nanoparticles (Apt-VRL-NPs) were prepared.

Nanoengineered drug delivery systems for enhancing antibiotic therapy

Formulation scientists are recognizing nanoengineered drug delivery systems as an effective strategy to overcome limitations associated with antibiotic drug therapy. Antibiotics encapsulated into nanodelivery systems will contribute to improved management of patients with various infectious diseases and to overcoming the serious global burden of antibiotic resistance. An extensive review of several antibiotic-loaded nanocarriers that have been formulated to target drugs to infectious sites, achieve controlled drug release profiles, and address formulation challenges, such as low-drug entrapment efficiencies, poor solubility and stability is presented in this paper. The physicochemical properties and the in vitro/in vivo performances of various antibiotic-loaded delivery systems, such as polymeric nanoparticles, micelles, dendrimers, liposomes, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles, nanohybirds, nanofibers/scaffolds, nanosheets, nanoplexes, and nanotubes/horn/rods and nanoemulsions, are highlighted and evaluated. Future studies that will be essential to optimize formulation and commercialization of these antibiotic-loaded nanosystems are also identified. The review presented emphasizes the significant formulation progress achieved and potential that novel nanoengineered antibiotic drug delivery systems have for enhancing the treatment of patients with a range of infections.

Therapeutic effect of folate-targeted and PEGylated phytosomes loaded with a mitomycin C-soybean phosphatidyhlcholine complex

A mitomycin C (MMC)-soybean phosphatidyhlcholine complex loaded in phytosomes was previously reported for the purpose of developing a MMC drug delivery system (Mol. Pharmaceutics 2013, 10, 90-101), but this approach was limited by rapid elimination from the body and lack of target specificity. In this article, to overcome these limitations, MMC-soybean phosphatidyhlcholine complex-loaded phytosomes (MMC-loaded phytosomes) as drug carriers were surface-functionalized with folate-PEG (FA-PEG) to achieve reduced toxicity and a superior MMC-mediated therapeutic effect. For this purpose, FA was conjugated to DSPE-PEG-NH2, and the resultant DSPE-PEG-FA was introduced into the lipid moiety of the phytosomes via a postinsertion technique. The prepared FA-PEG-functionalized MMC-loaded phytosomes (FA-PEG-MMC-loaded phytosomes) have a particle size of 201.9 ± 2.4 nm, a PDI of 0.143 ± 0.010, a zeta potential of -27.50 ± 1.67 mV, a spherical shape, and sustained drug release. The remarkable features of FA-PEG-MMC-loaded phytosomes included increased cellular uptake in HeLa cells and higher accumulation in H22 tumor-bearing mice over that of the PEG-MMC-loaded phytosomes. Furthermore, FA-PEG-MMC-loaded phytosomes were associated with enhanced cytotoxic activity in vitro and an improved antitumor effect in vivo compared to that resulting from free MMC injection. These results suggest that FA-PEG-MMC-loaded phytosomes may be useful drug delivery systems for widening the therapeutic window of MMC in clinical trials.

Surface modification of nonviral nanocarriers for enhanced gene delivery

Biomedical nanotechnology has given a new lease of life to gene therapy with the ever-developing and ever-diversifying nonviral gene delivery nanocarriers. These are designed to pass a series of barriers in order to bring their nucleic acid cargo to the right subcellular location of particular cells. For a given application, each barrier has its dedicated strategy, which translates into a physicochemical, biological and temporal identity of the nanocarrier surface. Different strategies have thus been explored to implement adequate surface identities on nanocarriers over time for systemic delivery. In that context, this review will mainly focus on organic nanocarriers, for which these strategies will be described and discussed.

Biomaterials for nanoparticle vaccine delivery systems

Subunit vaccination benefits from improved safety over attenuated or inactivated vaccines, but their limited capability to elicit long-lasting, concerted cellular and humoral immune responses is a major challenge. Recent studies have demonstrated that antigen delivery via nanoparticle formulations can significantly improve immunogenicity of vaccines due to either intrinsic immunostimulatory properties of the materials or by co-entrapment of molecular adjuvants such as Toll-like receptor agonists. These studies have collectively shown that nanoparticles designed to mimic biophysical and biochemical cues of pathogens offer new exciting opportunities to enhance activation of innate immunity and elicit potent cellular and humoral immune responses with minimal cytotoxicity. In this review, we present key research advances that were made within the last 5 years in the field of nanoparticle vaccine delivery systems. In particular, we focus on the impact of biomaterials composition, size, and surface charge of nanoparticles on modulation of particle biodistribution, delivery of antigens and immunostimulatory molecules, trafficking and targeting of antigen presenting cells, and overall immune responses in systemic and mucosal tissues. This review describes recent progresses in the design of nanoparticle vaccine delivery carriers, including liposomes, lipid-based particles, micelles and nanostructures composed of natural or synthetic polymers, and lipid-polymer hybrid nanoparticles.

Drug targeting using solid lipid nanoparticles

The present review aims to show the features of solid lipid nanoparticles (SLNs) which are at the forefront of the rapidly developing field of nanotechnology with several potential applications in drug delivery and research. Because of some unique features of SLNs such as their unique size dependent properties it offers possibility to develop new therapeutics. A common denominator of all these SLN-based platforms is to deliver drugs into specific tissues or cells in a pathological setting with minimal adverse effects on bystander cells. SLNs are capable to incorporate drugs into nanocarriers which lead to a new prototype in drug delivery which maybe used for drug targeting. Hence solid lipid nanoparticles hold great promise for reaching the goal of controlled and site specific drug delivery and hence attracted wide attention of researchers. This review presents a broad treatment of targeted solid lipid nanoparticles discussing their types such as antibody SLN, magnetic SLN, pH sensitive SLN and cationic SLN.

In vitro performance of lipid-PLGA hybrid nanoparticles as an antigen delivery system: lipid composition matters

Due to the many beneficial properties combined from both poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) and liposomes, lipid-PLGA hybrid NPs have been intensively studied as cancer drug delivery systems, bio-imaging agent carriers, as well as antigen delivery vehicles. However, the impact of lipid composition on the performance of lipid-PLGA hybrid NPs as a delivery system has not been well investigated. In this study, the influence of lipid composition on the stability of the hybrid NPs and in vitro antigen release from NPs under different conditions was examined. The uptake of hybrid NPs with various surface charges by dendritic cells (DCs) was carefully studied. The results showed that PLGA NPs enveloped by a lipid shell with more positive surface charges could improve the stability of the hybrid NPs, enable better controlled release of antigens encapsulated in PLGA NPs, as well as enhance uptake of NPs by DC.

Liposome-like Nanostructures for Drug Delivery

Liposomes are a class of well-established drug carriers that have found numerous therapeutic applications. The success of liposomes, together with recent advancements in nanotechnology, has motivated the development of various novel liposome-like nanostructures with improved drug delivery performance. These nanostructures can be categorized into five major varieties, namely: (1) polymer-stabilized liposomes, (2) nanoparticle-stabilized liposomes, (3) core-shell lipid-polymer hybrid nanoparticles, (4) natural membrane-derived vesicles, and (5) natural membrane coated nanoparticles. They have received significant attention and have become popular drug delivery platforms. Herein, we discuss the unique strengths of these liposome-like platforms in drug delivery, with a particular emphasis on how liposome-inspired novel designs have led to improved therapeutic efficacy, and review recent progress made by each platform in advancing healthcare.

Emerging targets and novel approaches to Ebola virus prophylaxis and treatment

Ebola is a highly virulent pathogen causing severe hemorrhagic fever with a high case fatality rate in humans and non-human primates (NHPs). Although safe and effective vaccines or other medicinal agents to block Ebola infection are currently unavailable, a significant effort has been put forth to identify several promising candidates for the treatment and prevention of Ebola hemorrhagic fever. Among these, recombinant adenovirus-based vectors have been identified as potent vaccine candidates, with some affording both pre- and post-exposure protection from the virus. Recently, Investigational New Drug (IND) applications have been approved by the US Food and Drug Administration (FDA) and phase I clinical trials have been initiated for two small-molecule therapeutics: anti-sense phosphorodiamidate morpholino oligomers (PMOs: AVI-6002, AVI-6003) and lipid nanoparticle/small interfering RNA (LNP/siRNA: TKM-Ebola). These potential alternatives to vector-based vaccines require multiple doses to achieve therapeutic efficacy, which is not ideal with regard to patient compliance and outbreak scenarios. These concerns have fueled a quest for even better vaccination and treatment strategies. Here, we summarize recent advances in vaccines or post-exposure therapeutics for prevention of Ebola hemorrhagic fever. The utility of novel pharmaceutical approaches to refine and overcome barriers associated with the most promising therapeutic platforms are also discussed.

Mechanistic evaluation of the transfection barriers involved in lipid-mediated gene delivery: interplay between nanostructure and composition

Here we present a quantitative mechanism-based investigation aimed at comparing the cell uptake, intracellular trafficking, endosomal escape and final fate of lipoplexes and lipid-protamine/deoxyribonucleic acid (DNA) (LPD) nanoparticles (NPs) in living Chinese hamster ovary (CHO) cells. As a model, two lipid formulations were used for comparison. The first formulation is made of the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and the zwitterionic lipid dioleoylphosphocholine (DOPC), while the second mixture is made of the cationic 3β-[N-(N,N-dimethylaminoethane)-carbamoyl] cholesterol (DC-Chol) and the zwitterionic helper lipid dioleoylphosphatidylethanolamine (DOPE). Our findings indicate that lipoplexes are efficiently taken up through fluid-phase macropinocytosis, while a less efficient uptake of LPD NPs occurs through a combination of both macropinocytosis and clathrin-dependent pathways. Inside the cell, both lipoplexes and LPD NPs are actively transported towards the cell nucleus, as quantitatively addressed by spatio-temporal image correlation spectroscopy (STICS). For each lipid formulation, LPD NPs escape from endosomes more efficiently than lipoplexes. When cells were treated with DOTAP-DOPC-containing systems the majority of the DNA was trapped in the lysosome compartment, suggesting that extensive lysosomal degradation was the rate-limiting factors in DOTAP-DOPC-mediated transfection. On the other side, escape from endosomes is large for DC-Chol-DOPE-containing systems most likely due to DOPE and cholesterol-like molecules, which are able to destabilize the endosomal membrane. The lipid-dependent and structure-dependent enhancement of transfection activity suggests that DNA is delivered to the nucleus synergistically: the process requires both the membrane-fusogenic activity of the nanocarrier envelope and the employment of lipid species with intrinsic endosomal rupture ability.

Mechanistic understanding of gene delivery mediated by highly efficient multicomponent envelope-type nanoparticle systems

We packaged condensed DNA/protamine particles in multicomponent envelope-type nanoparticle systems (MENS) combining different molar fractions of the cationic lipids 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and 3β-[N-(N,N-dimethylaminoethane)-carbamoyl] cholesterol (DC-Chol) and the zwitterionic lipids dioleoylphosphocholine (DOPC) and dioleoylphosphatidylethanolamine (DOPE). Dynamic light scattering (DLS) and microelectrophoresis allowed us to identify the cationic lipid/DNA charge ratio at which MENS are small sized and positively charged, while synchrotron small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) revealed that MENS are well-shaped DNA/protamine particles covered by a lipid monobilayer. Transfection efficiency (TE) experiments indicate that a nanoparticle formulation, termed MENS-3, was not cytotoxic and highly efficient to transfect Chinese hamster ovary (CHO) cells. To rationalize TE, we performed a quantitative investigation of cell uptake, intracellular trafficking, endosomal escape, and final fate by laser scanning confocal microscopy (LSCM). We found that fluid-phase macropinocytosis is the only endocytosis pathway used by MENS-3. Once taken up by the cell, complexes that are actively transported by microtubules frequently fuse with lysosomes, while purely diffusing systems do not. Indeed, spatiotemporal image correlation spectroscopy (STICS) clarified that MENS-3 mostly exploit diffusion to move in the cytosol of CHO cells, thus explaining the high TE levels observed. Also, MENS-3 exhibited a marked endosomal rupture ability resulting in extraordinary DNA release. The lipid-dependent and structure-dependent TE boost suggests that efficient transfection requires both the membrane-fusogenic activity of the nanocarrier envelope and the employment of lipid species with intrinsic endosomal rupture ability.

Merging the best of both worlds: hybrid lipid-enveloped matrix nanocomposites in drug delivery

The advent of nanotechnology has revolutionized drug delivery in terms of improving drug efficacy and safety. Both polymer-based and lipid-based drug-loaded nanocarriers have demonstrated clinical benefit to date. However, to address the multifaceted drug delivery challenges ahead and further expand the spectrum of therapeutic applications, hybrid lipid-polymer nanocomposites have been designed to merge the beneficial features of both polymeric drug delivery systems and liposomes in a single nanocarrier. This review focuses on different classes of nanohybrids characterized by a drug-loaded polymeric matrix core enclosed in a lipid shell. Various nanoengineering approaches to obtain lipid-polymer nanocomposites with a core-shell nanoarchitecture will be discussed as well as their predominant applications in drug delivery.