Pickering emulsion hydrogel based on alginate-gellan gum with carboxymethyl chitosan as a pH-responsive controlled release delivery system

Pickering emulsion hydrogels (PEHs) were developed as a pH-responsive, controlled-release delivery system to address the limitations of Pickering emulsions in some harsh processing or gastrointestinal conditions. Specifically, the PEHs were fabricated based on alginate and various concentrations of gellan gum (GG) with carboxymethyl chitosan (CMCS) matrix. The encapsulation efficiency (EE), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results proved the successful encapsulation. Furthermore, the hydrogels remained stable in the presence of destabilizing ions (Na⁺ or phosphate ions) and high osmotic pressure mediums. The texture profile analysis (TPA) characteristics and Young's modulus of the 0.8 % GG (w/v) PEHs were superior to the others. The PEHs prevented the emulsions from being released at pH 2.0, while the emulsions were entirely released at pH 7.4 in vitro, with the rate of release controlled by CMCS and the degree by GG concentration. This work facilitates the delivery of Pickering emulsions with excellent stability and pH-responsive controlled release for hydrophobic actives in food applications.

Leaky gut model of the human intestinal mucosa for testing siRNA-based nanomedicine targeting JAK1

Complex in vitro models of human immune cells and intestinal mucosa may have a translation-assisting role in the assessment of anti-inflammatory compounds. Chronic inflammation of the gastrointestinal tract is a hallmark of inflammatory bowel diseases (IBD). In both IBD entities, Crohn's disease and ulcerative colitis, impaired immune cell activation and dysfunctional epithelial barrier are the common pathophysiology. Current therapeutic approaches are targeting single immune modulator molecules to stop disease progression and reduce adverse effects. Such molecular targets can be difficult to assess in experimental animal models of colitis, due to the disease complexity and species differences. Previously, a co-culture model based on human epithelial cells and monocytes arranged in a physiological microenvironment was used to mimic inflamed mucosa for toxicological and permeability studies. The leaky gut model described here, a co-culture of Caco-2, THP-1 and MUTZ-3 cells, was used to mimic IBD-related pathophysiology and for combined investigations of permeability and target engagement of two Janus kinase (JAK) inhibitors, tofacitinib (TOFA) and a JAK1-targeting siRNA nanomedicine. The co-culture just before reaching confluency of the epithelium was used to mimic the compromised intestinal barrier. Delivery efficacy and target engagement against JAK1 was quantified via downstream analysis of STAT1 protein phosphorylation after IFN-γ stimulation. Compared to a tight barrier, the leaky gut model showed 92 ± 5% confluence, a barrier function below 200 Ω*cm², and enhanced immune response to bacteria-derived lipopolysaccharides. By confocal microscopy we observed an increased accumulation of siJAK1-nanoparticles within the sub-confluent regions leading to uptake into immune cells near the epithelium. A concentration-dependent downregulation of JAK/STAT pathway was observed for siJAK1-nanoparticles (10 ± 12% to 16 ± 12%), whereas TOFA inhibition was 86 ± 2%, compared to untreated cells. By mimicking the status of severely damaged epithelium, like in IBD, the leaky gut model holds promise as a human in vitro system to evaluate the efficacy of anti-inflammatory drugs and nanomedicines.

Zinc Triggered Release of Encapsulated Cargo from Liposomes via a Synthetic Lipid Switch

Liposomes are effective nanocarriers due to their ability to encapsulate and deliver a wide variety of therapeutics. However, therapeutic potential would be improved by enhanced control over the release of drug cargo. Zinc ions provide exciting new targets for stimuli-responsive lipid design due to their overly abundant concentrations associated with diseased cells. Herein, we report zinc-triggered release of liposomal contents exploiting synthetic lipid switches designed to undergo conformational changes in the presence of this ion. Initially, Nile red leakage assays were conducted that validated successful dose-dependent triggering of release using zinc-responsive lipids (ZRLs). In addition, dynamic light scattering and confocal microscopy experiments showed that zinc treatment led to morphological changes in lipid nanoparticles only when ZRLs were present in formulations. Next, zinc-binding experiments conducted in a solution (NMR, MS) or membrane (zeta potential) context confirmed ZRL-Zn complexation. Finally, polar cargo release from liposomes was achieved. The results from these wide-ranging experiments using four different compounds indicated that zinc-responsive properties varied based on ZRL structure, providing insights into the structural requirements for activity. This work has established zinc-responsive liposomal platforms toward the development of clinical triggered release formulations.

One-photon red light-triggered disassembly of small-molecule nanoparticles for drug delivery

BACKGROUND

Photoresponsive drug delivery can achieve spatiotemporal control of drug accumulation at desired sites. Long-wavelength light is preferable owing to its deep tissue penetration and low toxicity. One-photon upconversion-like photolysis via triplet-triplet energy transfer (TTET) between photosensitizer and photoresponsive group enables the use of long-wavelength light to activate short-wavelength light-responsive groups. However, such process requires oxygen-free environment to achieve efficient photolysis due to the oxygen quenching of triplet excited states.

RESULTS

Herein, we report a strategy that uses red light to trigger disassembly of small-molecule nanoparticles by one-photon upconversion-like photolysis for cancer therapy. A photocleavable trigonal molecule, BTAEA, self-assembled into nanoparticles and enclosed photosensitizer, PtTPBP. Such nanoparticles protected TTET-based photolysis from oxygen quenching in normoxia aqueous solutions, resulting in efficient red light-triggered BTAEA cleavage, dissociation of nanoparticles and subsequent cargo release. With paclitaxel as the model drug, the red light-triggered drug release system demonstrated promising anti-tumor efficacy both in vitro and in vivo.

CONCLUSIONS

This study provides a practical reference for constructing photoresponsive nanocarriers based on the one-photon upconversion-like photolysis.

Antibody conjugated lipid nanoparticles as a targeted drug delivery system for hydrophobic pharmaceuticals

Cancer remains a significant health issue worldwide. The most common group of chemotherapeutic agents are small-molecule drugs, which often are associated with toxic side-effects and non-specific delivery, leading to limited therapeutic effect. This paper describes the development of a targeted drug delivery system based on lipid nanoparticles for cancer therapy. The lipid nanoparticles consist of a lipid core conjugated to an albumin stealth coating and targeting antibodies through thiol chemistry synthesized utilizing a one-step method. Applying the developed method, lipid nanoparticles with diameters down to 87 nm, capable of encapsulating small molecule compounds were synthesized. Cellular uptake studies of the lipid nanoparticles loaded with the model drug Nile red demonstrated that stealth-coating reduced non-specific cell uptake by up to a 1000-fold compared to free drug. Moreover, antibody-conjugation led to a significant cellular retargeting. Finally, it was shown that the lipid nanoparticles undergo cellular uptake through the endocytic pathway. The lipid nanoparticles are simple to synthesize, stabile in serum and have the potential to be versatile targeted towards receptors selectively expressed by diseased cells using antibodies. Thus, the system may reduce the toxic side-effects of cancer drugs while improving their delivery to cancer cells, increasing the therapeutic effect.

Comparing microfluidics and ultrasonication as formulation methods for developing hempseed oil nanoemulsions for oral delivery applications

Emerging formulation technologies aimed to produce nanoemulsions with improved characteristics, such as stability are attractive endeavors; however, comparisons between competing technologies are lacking. In this study, two formulation techniques that employed ultrasound and microfluidic approaches, respectively, were examined for relative capacity to produce serviceable oil in water nanoemulsions, based on hempseed oil (HSO). The ultrasound method reached > 99.5% entrapment efficiency with nanoemulsions that had an average droplet size (Z-Ave) < 180 nm and polydispersity index (PDI) of 0.15 ± 0.04. Surfactant concentration (% w/v) was found to be a significant factor (p < 0.05) controlling the Z-Ave, PDI and zeta potential of these nanoparticles. On the other hand, the microfluidic approach produced smaller particles compared to ultrasonication, with good stability observed during storage at room temperature. The Z-Ave of < 62.0 nm was achieved for microfluidic nanoemulsions by adjusting the aqueous : organic flow rate ratio and total flow rate at 4:1 and 12 mL/min, respectively. Further analyses including a morphology examination, a simulated gastrointestinal release behavior study, transepithelial transport evaluations and a toxicity test, using a Caco2-cell model, were performed to assess the functionality of the prepared formulations. The results of this study conclude that both approaches of ultrasound and microfluidics have the capability to prepare an HSO-nanoemulsion formulation, with acceptable characteristics and stability for oral delivery applications.

Redox-Responsive Nanocarrier for Controlled Release of Drugs in Inflammatory Skin Diseases

A synthetic route for redox-sensitive and non-sensitive core multi-shell (CMS) carriers with sizes below 20 nm and narrow molecular weight distributions was established. Cyclic voltammetric measurements were conducted characterizing the redox potentials of reduction-sensitive CMS while showcasing its reducibility through glutathione and tris(2-carboxyethyl)-phosphine as a proof of concept. Measurements of reduction-initiated release of the model dye Nile red by time-dependent fluorescence spectroscopy showed a pronounced release for the redox-sensitive CMS nanocarrier (up to 90% within 24 h) while the non-sensitive nanocarriers showed no release in PBS. Penetration experiments using ex vivo human skin showed that the redox-sensitive CMS nanocarrier could deliver higher percentages of the loaded macrocyclic dye meso-tetra (m-hydroxyphenyl) porphyrin (mTHPP) to the skin as compared to the non-sensitive CMS nanocarrier. Encapsulation experiments showed that these CMS nanocarriers can encapsulate dyes or drugs with different molecular weights and hydrophobicity. A drug content of 1 to 6 wt% was achieved for the anti-inflammatory drugs dexamethasone and rapamycin as well as fluorescent dyes such as Nile red and porphyrins. These results show that redox-initiated drug release is a promising strategy to improve the topical drug delivery of macrolide drugs.

Nanostructured lipid carriers accumulate in atherosclerotic plaques of ApoE-/- mice

Nanostructured lipid carriers (NLC) might represent an interesting approach for the identification and targeting of rupture-prone atherosclerotic plaques. In this study, we evaluated the biodistribution, targeting ability and safety of ⁶⁴Cu-fonctionalized NLC in atherosclerotic mice. ⁶⁴Cu-chelating-NLC (51.8±3.1 nm diameter) with low dispersity index (0.066±0.016) were produced by high pressure homogenization at tens-of-grams scale. 24 h after injection of ⁶⁴Cu-chelated particles in ApoE^-/- mice, focal regions of the aorta showed accumulation of particles on autoradiography that colocalized with Oil Red O lipid mapping. Signal intensity was significantly greater in aortas isolated from ApoE^-/- mice compared to wild type (WT) control (8.95 [7.58, 10.16]×10⁸ vs 4.59 [3.11, 5.03]×10⁸ QL/mm², P < 0.05). Moreover, NLC seemed safe in relevant biocompatibility studies. NLC could constitute an interesting platform with high clinical translation potential for targeted delivery and imaging purposes in atherosclerosis.

Quantification of Surface GalNAc Ligands Decorating Nanostructured Lipid Carriers by UPLC-ELSD

Nanoparticles have been extensively studied for drug delivery and targeting to specific organs. The functionalization of the nanoparticle surface by site-specific ligands (antibodies, peptides, saccharides) can ensure efficient recognition and binding with relevant biological targets. One of the main challenges in the development of these decorated nanocarriers is the accurate quantification of the amount of ligands on the nanoparticle surface. In this study, nanostructured lipid carriers (NLC) were functionalized with N-acetyl-D-galactosamine (GalNAc) units, known to target the asialoglycoprotein receptor (ASGPR). Different molar percentages of GalNAc-functionalized surfactant (0%, 2%, 5%, and 14%) were used in the formulation. Based on ultra-high-performance liquid chromatography separation and evaporative light-scattering detection (UPLC-ELSD), an analytical method was developed to specifically quantify the amount of GalNAc units present at the NLC surface. This method allowed the accurate quantification of GalNAc surfactant and therefore gave some insights into the structural parameters of these multivalent ligand systems. Our data show that the GalNAc decorated NLC possess large numbers of ligands at their surface and suitable distances between them for efficient multivalent interaction with the ASGPR, and therefore promising liver-targeting efficiency.

Biodistribution of Nanostructured Lipid Carriers in Mice Atherosclerotic Model

Atherosclerosis is a major cardiovascular disease worldwide, that could benefit from innovative nanomedicine imaging tools and treatments. In this perspective, we here studied, by fluorescence imaging in ApoE^-/- mice, the biodistribution of non-functionalized and RXP470.1-targeted nanostructured lipid carriers (NLC) loaded with DiD dye. RXP470.1 specifically binds to MMP12, a metalloprotease that is over-expressed by macrophages residing in atherosclerotic plaques. Physico-chemical characterizations showed that RXP-NLC (about 105 RXP470.1 moieties/particle) displayed similar features as non-functionalized NLC in terms of particle diameter (about 60-65 nm), surface charge (about −5 — −10 mV), and colloidal stability. In vitro inhibition assays demonstrated that RXP-NLC conserved a selectivity and affinity profile, which favored MMP-12. In vivo data indicated that NLC and RXP-NLC presented prolonged blood circulation and accumulation in atherosclerotic lesions in a few hours. Twenty-four hours after injection, particle uptake in atherosclerotic plaques of the brachiocephalic artery was similar for both nanoparticles, as assessed by ex vivo imaging. This suggests that the RXP470.1 coating did not significantly induce an active targeting of the nanoparticles within the plaques. Overall, NLCs appeared to be very promising nanovectors to efficiently and specifically deliver imaging agents or drugs in atherosclerotic lesions, opening avenues for new nanomedicine strategies for cardiovascular diseases.

Measuring Particle Size Distribution by Asymmetric Flow Field Flow Fractionation: A Powerful Method for the Preclinical Characterization of Lipid-Based Nanoparticles

Particle size distribution and stability are key attributes for the evaluation of the safety and efficacy profile of medical nanoparticles (Med-NPs). Measuring particle average size and particle size distribution is a challenging task which requires the combination of orthogonal high-resolution sizing techniques, especially in complex biological media. Unfortunately, despite its limitations, due to its accessibility, low cost, and easy handling, batch mode dynamic light scattering (DLS) is still very often used as the only approach to measure particle size distribution in the nanomedicine field. In this work the use of asymmetric flow field flow fractionation coupled to multiangle light scattering and dynamic light scattering detectors (AF4-MALS-DLS) was evaluated as an alternative to batch mode DLS to measure the physical properties of lipid-based nanoparticles. A robust standard operating procedure (SOPs) developed by the Nanomedicine Characterization Laboratory (EUNCL) was presented and tested to assess size stability, batch to batch consistency, and the behavior of the lipid-based nanoparticles in plasma. Orthogonal sizing techniques, such as transmission electron microscopy (TEM) and particle tracking analysis (PTA) measurements, were performed to support the results. While batch mode DLS could be applied as a fast and simple method to provide a preliminary insight into the integrity and polydispersity of samples, it was unsuitable to resolve small modifications of the particle size distribution. The introduction of nanoparticle sorting by field-flow fractionation coupled to online DLS and MALS allowed assessment of batch to batch variability and changes in the size of the lipid nanoparticles induced by the interaction with serum proteins, which are critical for quality control and regulatory aspects. In conclusion, if a robust SOP is followed, AF4-MALS-DLS is a powerful method for the preclinical characterization of lipid-based nanoparticles.

Lipid Nanoparticles and Their Hydrogel Composites for Drug Delivery: A Review

Several drug delivery systems already exist for the encapsulation and subsequent release of lipophilic drugs that are well described in the scientific literature. Among these, lipid nanoparticles (LNP) have specifically come up for dermal, transdermal, mucosal, intramuscular and ocular drug administration routes in the last twenty years. However, for some of them (especially dermal, transdermal, mucosal), the LNP aqueous dispersions display unsuitable rheological properties. They therefore need to be processed as semi-solid formulations such as LNP-hydrogel composites to turn into versatile drug delivery systems able to provide precise spatial and temporal control of active ingredient release. In the present review, recent developments in the formulation of lipid nanoparticle-hydrogel composites are highlighted, including examples of successful encapsulation and release of lipophilic drugs through the skin, the eyes and by intramuscular injections. In relation to lipid nanoparticles, a specific emphasis has been put on the LNP key properties and how they influence their inclusion in the hydrogel. Polymer matrices include synthetic polymers such as poly(acrylic acid)-based materials, environment responsive (especially thermo-sensitive) polymers, and innovative polysaccharide-based hydrogels. The composite materials constitute smart, tunable drug delivery systems with a wide range of features, suitable for dermal, transdermal, and intramuscular controlled drug release.

Microgels of silylated HPMC as a multimodal system for drug co-encapsulation

Combined therapy is a global strategy developed to prevent drug resistance in cancer and infectious diseases. In this field, there is a need of multifunctional drug delivery systems able to co-encapsulate small drug molecules, peptides, proteins, associated to targeting functions, nanoparticles. Silylated hydrogels are alkoxysilane hybrid polymers that can be engaged in a sol-gel process, providing chemical cross linking in physiological conditions, and functionalized biocompatible hybrid materials. In the present work, microgels were prepared with silylated (hydroxypropyl)methyl cellulose (Si-HPMC) that was chemically cross linked in soft conditions of pH and temperature. They were prepared by an emulsion templating process, water in oil (W/O), as microreactors where the condensation reaction took place. The ability to functionalize the microgels, so-called FMGs, in a one-pot process, was evaluated by grafting a silylated hydrophilic model drug, fluorescein (Si-Fluor), using the same reaction of condensation. Biphasic microgels (BPMGs) were prepared to evaluate their potential to encapsulate lipophilic model drug (Nile red). They were composed of two separate compartments, one oily phase (sesame oil) trapped in the cross linked Si-HPMC hydrophilic phase. The FMGs and BPMGs were characterized by different microscopic techniques (optic, epi-fluorescence, Confocal Laser Scanning Microscopy and scanning electronic microscopy), the mechanical properties were monitored using nano indentation by Atomic Force Microscopy (AFM), and different preliminary tests were performed to evaluate their chemical and physical stability. Finally, it was demonstrated that it is possible to co-encapsulate both hydrophilic and hydrophobic drugs, in silylated microgels, that were physically and chemically stable. They were obtained by chemical cross linking in soft conditions, and without surfactant addition during the emulsification process. The amount of drug loaded was in favor of further biological activity. Mechanical stimulations should be necessary to trigger drug release.

Multicomponent Supramolecular Polymers as a Modular Platform for Intracellular Delivery

Supramolecular polymers are an emerging family of nanosized structures with potential use in materials chemistry and medicine. Surprisingly, application of supramolecular polymers in the field of drug delivery has received only limited attention. Here, we explore the potential of PEGylated 1,3,5-benzenetricarboxamide (BTA) supramolecular polymers for intracellular delivery. Exploiting the unique modular approach of supramolecular chemistry, we can coassemble neutral and cationic BTAs and control the overall properties of the polymer by simple monomer mixing. Moreover, this platform offers a versatile approach toward functionalization. The core can be efficiently loaded with a hydrophobic guest molecule, while the exterior can be electrostatically complexed with siRNA. It is demonstrated that both compounds can be delivered in living cells, and that they can be combined to enable a dual delivery strategy. These results show the advantages of employing a modular system and pave the way for application of supramolecular polymers in intracellular delivery.

Phase-0/phase-I study of dye-loaded lipid nanoparticles for near-infrared fluorescence imaging in healthy dogs

Near-infrared (NIR) fluorescence imaging using FDA-approved indocyanine green (ICG) has been the subject of numerous studies during the past few years. It could constitute a potentially exciting new paradigm shift in veterinary oncology, especially to develop in vivo fluorescence imaging diagnostics and surgery guidance methods. The objective of this study was to evaluate the pharmacologic and toxicological characteristics in healthy beagle dogs of LipImage™ 815, a formulation made of NIR-dye-loaded lipid nanoparticles. The initial dosage for the evaluation of biodistribution was extrapolated from data in mice and then adapted to define the more adapted dose (MAD) according to the fluorescence results obtained in 5 dogs using a Fluobeam® 800 imaging device (phase 0 study). A single dose acute toxicity study was then performed (3 dogs, phase I study). Before the systemic administration of LipImage™ 815, the dogs presented a very mild residual fluorescence, particularly in the liver and kidneys. After injection, the plasma fluorescence continuously decreased, and the signal was relatively homogeneously distributed throughout the different organs, though more pronounced in the liver and to a lesser extent in the steroid-rich organs (adrenal, ovaries), intestines, lymph nodes and kidneys. A MAD of 2.0μg/kg was found. No evidence of acute or delayed general, hepatic, renal or hematologic toxicity was observed at 1-fold, 5-fold or 10-fold MAD. The results of this phase-0/phase-I study showed that an optimal dosage of LipImage™ 815 of 2.0μg/kg allowed the achievement of a fluorescence signal suitable for surgery guidance application without any acute side effects.

Self-assembly of isomannide-based monoesters of C18-fatty acids and their cellular uptake studies

The self-assembling behavior of oleic, elaidic and stearic acid-isomannide glycolipids is revealed.

Formulation and nebulization of fluticasone propionate-loaded lipid nanocarriers

Inhaled fluticasone propionate (FP) is often prescribed as a first-line therapy for the effective management of pulmonary diseases such as asthma. As nanocarriers offer many advantages over other drug delivery systems, this study investigated the suitability of lipid nanocapsules (LNCs) as a carrier for fluticasone propionate, examining the drug-related factors that should be considered in the formulation design and the behaviour of LNCs with different compositions and properties suspended within aerosol droplets under the relatively hostile conditions of nebulization. By adjusting the formulation conditions, particularly the nanocarrier composition, FP was efficiently encapsulated within the LNCs with a yield of up to 97%, and a concentration comparable to commercially available preparations was achieved. Moreover, testing the solubility of the drug in oil and water and determining the oil/water partition coefficient proved to be useful when assessing the encapsulation of the FP in the LNC formulation. Nebulization did not cause the FP to leak from the formulation, and no phase separation was observed after nebulization. LNCs with a diameter of 100 nm containing a smaller amount of surfactant and a larger amount of oil provided a better FP-loading capacity and better stability during nebulization than 30 or 60 nm LNCs.

Tumor-Targeting Co-Delivery of Drug and Gene from Temperature-Triggered Micelles

Co-delivery strategy using multifunctional nanocarriers is an attractive option for the synergistic and enhanced effects in cancer treatment, but one system integrating multiple functions for controlled release at the target is still challenging. Herein, this study shows the synthesis and characterization of our stimulus-responsive co-delivery system for the controlled release into tumors, which is composed of polyethylenimine (PEI)-linked Pluronic F127 (PF127) and folic acid (FA), called PF127-PEI-FA. PF127-PEI-FA system facilitated drug loading and gene complex formation, and showed controlled release behaviors in response to hitting temperature to hyperthermia. PF127-PEI-FA system was demonstrated to be biocompatible and showed receptor-mediated gene delivery. The results of our multifunctional nanocarrier system that enabled co-delivery suggest a promising potential for controlled drug release at targeted areas. However, further in-depth studies on the use of therapeutic drugs and genes in multiple cell types and the animal response are required.

Comparative biodistribution in mice of cyanine dyes loaded in lipid nanoparticles

Two near infrared cyanine dyes, DiD (1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine perchlorate) and ICG (Indocyanine Green) were loaded in lipid nanoparticles (LNP). DiD-LNP and ICG-LNP presented similar physicochemical characteristics (hydrodynamic diameter, polydispersity, zeta potential), encapsulation efficiency, and colloidal stability when stored in PBS buffer. However, whereas DiD had similar biodistribution than cholesteryl-1-(14)C-oleate ([(14)C]CHO, a constituent of the nanoparticle used as a reference radiotracer), ICG displayed a different biodistribution pattern, similar to that of the free dye, indicative of its immediate leakage from the nanovector after blood injection. NMR spectroscopy using Proton NOE (Nuclear Overhauser Effect) measurements showed that the localization of the dye in the lipid nanoparticles was slightly different: ICG, more amphiphilic than DiD, was found both inside the lipid core and at particle interface, whereas DiD, more hydrophobic, appeared exclusively located inside the particle core. The ICG release rate from the particles was 7% per 1 month under storage conditions (4 °C, dark, 10% of lipids), whereas no leakage could be detected for DiD. ICG leakage increased considerably in the presence of BSA 40 g/L (45% leakage in 24h at 100 mg/mL of lipids), because of the high affinity of the fluorophore for plasma proteins. On the contrary, no DiD leakage was observed, until high dilution of the nanoparticles which triggered their dissociation (45% leakage in 24h at 1 mg/mL of lipids). Altogether, the subtle difference in dye localization into the nanoparticles, the partial dissociation of the LNP in diluted media, and more importantly the high ICG affinity for plasma proteins, accounted for the differences observed in the fluorescence biodistribution after tail vein injection of the dye-loaded nanoparticles.

Potential of Nanomaterials as Movers and Packers for Drug Molecules

As the development of nanotechnology has extended to the world of biomolecules, a revolution has occurred in the design and assembly of nanomaterials for drug delivery with a significant potential to impact drug efficacy and patient outcomes. Currently a number of nanomaterials are under investigation for their suitability as sustained, controlled and targeted drug carriers. Leading edge of the rapidly developing nanosciences is the development and assessment of these nanomaterials, with specific physicochemical properties different from their larger/ bulk counterparts, as vehicles for transport of small and large drug molecules. The characteristics such as size, shape, chemical composition, surface structure and charge, aggregation and agglomeration, and solubility, can greatly influence interactions of these nanostructured systems or carriers with biomembranes and cells. The selectivity and reactivity achieved due to the very small size assigns these systems with a wide spectrum of applications. In this review, nanomaterials are considered in terms of the physical attributes or pharmaceutical effects allocated by them to the all-inclusive carrier or vehicle system (s). However we will limit our discussion to lipidic and polymeric nanomaterials, the two most commonly promoted, and safe nanosystems for delivery of both, the chemical or small molecular entities (SME) and the macromolecules including genes and siRNA.Contents of Paper

Lipid-based carriers for pulmonary products: preclinical development and case studies in humans

A number of lipid-based technologies have been applied to pharmaceuticals to modify their drug release characteristics, and additionally, to improve the drug loading for poorly soluble drugs. These technologies, including solid-state lipid microparticles, many of which are porous in nature, liposomes, solid lipid nanoparticles and nanostructured lipid carriers, are increasingly being developed for inhalation applications. This article provides a review of the rationale for the use of these technologies in the pulmonary delivery of drugs, and summarizes the manufacturing processes and their limitations, the in vitro and in vivo performance of these systems, the safety of these lipid-based systems in the lung, and their promise for commercialization.

Shell cross-linked polyethylenimine-modified micelles for temperature-triggered drug release and gene delivery

Stimuli-responsiveness is an important characteristic of nanocarriers that can deliver therapeutic molecules in a controlled and on-demand manner.

Gene therapy and DNA delivery systems

Gene therapy is a promising new technique for treating many serious incurable diseases, such as cancer and genetic disorders. The main problem limiting the application of this strategy in vivo is the difficulty of transporting large, fragile and negatively charged molecules like DNA into the nucleus of the cell without degradation. The key to success of gene therapy is to create safe and efficient gene delivery vehicles. Ideally, the vehicle must be able to remain in the bloodstream for a long time and avoid uptake by the mononuclear phagocyte system, in order to ensure its arrival at the desired targets. Moreover, this carrier must also be able to transport the DNA efficiently into the cell cytoplasm, avoiding lysosomal degradation. Viral vehicles are the most commonly used carriers for delivering DNA and have long been used for their high efficiency. However, these vehicles can trigger dangerous immunological responses. Scientists need to find safer and cheaper alternatives. Consequently, the non-viral carriers are being prepared and developed until techniques for encapsulating DNA can be found. This review highlights gene therapy as a new promising technique used to treat many incurable diseases and the different strategies used to transfer DNA, taking into account that introducing DNA into the cell nucleus without degradation is essential for the success of this therapeutic technique.

Aerosol generation using nanometer liposome suspensions for pulmonary drug delivery applications

Pulmonary lung targeting finds applications in drug delivery to the lung itself and to other body organs, via blood circulation following transfer across alveolar membranes. Understanding pulmonary drug delivery systems towards improving their efficacy needs identification of particle sizes of relevance and elucidation of links between suspension properties, techniques of atomisation and properties of the generated aerosols. This review article is focussed on understanding the elements of pulmonary drug delivery, specifically related to suspensions of small liposomes. Specific objectives of this review include (a) understanding aerosol particle deposition and absorption on pulmonary surface, (b) links between properties of aerosol generation and colloidal drug carriers used for drug encapsulation, and (c) investigation on the controlled properties of liposome aerosols generated using different atomisation techniques for efficacious aerosol therapy.

Composition influence on pulmonary delivery of rifampicin liposomes

The effects of lipid concentration and composition on the physicochemical properties, aerosol performance and in vitro toxicity activity of several rifampicin-loaded liposomes were investigated. To this purpose, six liposome formulations containing different amounts of soy phosphatidylcholine and hydrogenated soy phosphatidylcholine, with and without cholesterol and oleic acid, were prepared and fully characterized. Uni- or oligo-lamellar, small (~100 nm), negatively charged (~60 mV) vesicles were obtained. Lipid composition affected aerosol delivery features of liposomal rifampicin; in particular, the highest phospholipid concentration led to a better packing of the vesicular bilayers with a consequent higher nebulization stability. The retention of drug in nebulized vesicles (NER%) was higher for oleic acid containing vesicles (55% ± 1.4%) than for the other samples (~47%). A549 cells were used to evaluate intracellular drug uptake and in vitro toxicity activity of rifampicin-loaded liposomes in comparison with the free drug. Cell toxicity was more evident when oleic acid containing liposomes were used.