Preparation of Ulex europaeus lectin-gliadin nanoparticle conjugates and their interaction with gastrointestinal mucus

Investigation of the mucin-nanoparticle interactions via real-time monitoring by microbalance and kinetic model simulation

Interactions between nanoparticles and the mucus layer are crucial to understand the behaviours in biological environments and design drug delivery systems. In this study, we developed a kinetic deposition model for the dynamic mucin-nanoparticle interactions using quartz crystal microbalance with dissipation (QCM-D). We investigated the effects of the physiochemical properties of several nanoparticles (including size, charge, and shape) and the physiological conditions on the mucin-nanoparticle interaction. Interestingly, layered double hydroxide (LDH) nanoparticles showed stronger interactions with the mucus layer compared to other types of nanoparticles due to their unique plate-like morphology. In specific for sheet-like LDH nanoparticles, our model found that their equilibrium adsorption capacity (Qe) followed the Langmuir adsorption isotherm, and the adsorption rate (k1) increased proportionally with the nanoparticle concentration. In addition, the particle size and thickness affected Qe and the surface coverage. Furthermore, bovine serum albumin (BSA) coating dramatically increased k1 of LDH nanoparticles. We proposed a novel mechanism to elucidate mucin-nanoparticle interactions, shedding light on the synergistic roles of drag force (Fd), repulsive force (Fr), and adsorptive force (Fa). These findings offer valuable insights into the complex mucin-nanoparticle interactions and provide guidance for the design of drug delivery systems.

Gliadin nanoparticles for oral administration of bioactives: Ex vivo and in vivo investigations

This study aims to provide a thorough characterization of Brij O2-stabilized gliadin nanoparticles to be used for the potential oral administration of various compounds. Different techniques were used in order to evaluate their physico-chemical features and then in vivo studies in rats were performed for the investigation of their biodistribution and gastrointestinal transit profiles. The results showed that the gliadin nanoparticles accumulated in the mucus layer of the bowel mucosa and evidenced their ability to move along the digestive systems of the animals. The incubation of the nanosystems with Caenorhabditis elegans, used as an additional in vivo model, confirmed the intake of the particles and evidenced their presence along the entire gastrointestinal tract of these nematodes. The gliadin nanoparticles influenced neither the egg-laying activity of the worms nor their metabolism of lipids up to 10 μg/mL of nanoformulation. The systems decreased the content of the age-related lipofuscin pigment in the nematodes in a dose-dependent manner, demonstrating a certain antioxidant activity. Lastly, dihydroethidium staining showed the absence of oxidative stress upon incubation of the worms together with the formulations, confirming their safe profile. This data paves the way for the future application of the proposed nanosystems regarding the oral delivery of various bioactives.

Alginate Modification and Lectin-Conjugation Approach to Synthesize the Mucoadhesive Matrix

Alginates are natural anionic polyelectrolytes investigated in various biomedical applications, such as drug delivery, tissue engineering, and 3D bioprinting. Functionalization of alginates is one possible way to provide a broad range of requirements for those applications. A range of techniques, including esterification, amidation, acetylation, phosphorylation, sulfation, graft copolymerization, and oxidation and reduction, have been implemented for this purpose. The rationale behind these investigations is often the combination of such modified alginates with different molecules. Particularly promising are lectin conjugate macromolecules for lectin-mediated drug delivery, which enhance the bioavailability of active ingredients on a specific site. Most interesting for such application are alginate derivatives, because these macromolecules are more resistant to acidic and enzymatic degradation. This review will report recent progress in alginate modification and conjugation, focusing on alginate-lectin conjugation, which is proposed as a matrix for mucoadhesive drug delivery and provides a new perspective for future studies with these conjugation methods.

Improved stabilization of coix seed oil in a nanocage-coating framework based on gliadin-carboxymethyl chitosan-Ca2

Coix seed oil (CSO) is easily suffered functional-loss by oxidation and hydrothermal-treatment. The environmental stable nanocage-coating-CSO particles (OGC-Ca) by the frameworks consist of gliadins, carboxymethyl chitosan (CMCS) and Ca²⁺ were investigated. Results showed Ca²⁺ was the key controller for fabricating this nanocage-coating-frameworks, bridging macromolecule-chains with electrostatic interaction and hydrogen bonds, detected by FTIR, CD, DSC and XRD. SEM displayed new-formed velvet-like twigs after cross-linking CMCS to gliadins. Ca²⁺ assisted the nanocage-coating by significant down-sizing conversion OGC to OGC-Ca with consumption of twigs. OGC-Ca displayed a good stability towards heat (60-80 °C, 0-80 min), pH (3-8), NaCl (0-0.5 mM), storage (4/25 °C, 12 days), and a reduce of the pre-oxidation value of CSO in water and the improved controlled release of CSO in simulated GI tract. It illustrated GC-Ca frameworks would be a suitable delivery carrier for the CSO like pharmaceuticals and nutraceuticals for the food or medical use.

Protein-Based Nanoparticles as Drug Delivery Systems

Nanoparticles have been extensively used as carriers for the delivery of chemicals and biomolecular drugs, such as anticancer drugs and therapeutic proteins. Natural biomolecules, such as proteins, are an attractive alternative to synthetic polymers commonly used in nanoparticle formulation because of their safety. In general, protein nanoparticles offer many advantages, such as biocompatibility and biodegradability. Moreover, the preparation of protein nanoparticles and the corresponding encapsulation process involved mild conditions without the use of toxic chemicals or organic solvents. Protein nanoparticles can be generated using proteins, such as fibroins, albumin, gelatin, gliadine, legumin, 30Kc19, lipoprotein, and ferritin proteins, and are prepared through emulsion, electrospray, and desolvation methods. This review introduces the proteins used and methods used in generating protein nanoparticles and compares the corresponding advantages and disadvantages of each.

Biomimetic and bioinspired strategies for oral drug delivery

Oral drug delivery remains the most preferred approach due to its multiple advantages. Recently there has been increasing interest in the development of advanced vehicles for oral delivery of different therapeutics. Among them, biomimetic and bioinspired strategies are emerging as novel approaches that are promising for addressing biological barriers encountered by traditional drug delivery systems. Herein we provide a state-of-the-art review on the current progress of biomimetic particulate oral delivery systems. Different biomimetic nanoparticles used for oral drug delivery are first discussed, mainly including ligand/antibody-functionalized nanoparticles, transporter-mediated nanoplatforms, and nanoscale extracellular vesicles. Then we describe bacteria-derived biomimetic systems, with respect to oral delivery of therapeutic proteins or antigens. Subsequently, yeast-derived oral delivery systems, based on either chemical engineering or bioengineering approaches are discussed, with emphasis on the treatment of inflammatory diseases and cancer as well as oral vaccination. Finally, bioengineered plant cells are introduced for oral delivery of biological agents. A future perspective is also provided to highlight the existing challenges and possible resolution toward clinical translation of currently developed biomimetic oral therapies.

Natural biodegradable polymers based nano-formulations for drug delivery: A review

Nanomedicines are now considered as the new-generation medication in the current era mainly because of their features related to nano size. The efficacy of many drugs in their micro/macro formulations is shown to have poor bioavailability and pharmacokinetics after oral administration. To overcome this predicament, use of natural/synthetic biodegradable polymeric nanoparticles (NPs) have gained prominence in the field of nanomedicine for targeted drug delivery to improve biocompatibility, bioavailability, safety, enhanced permeability, better retention time and lower toxicity. For drug delivery, it is essential to have biodegradable nanoparticle formulations for safe and efficient transport and release of drug at the intended site. Moreover, depending on the target organ, a suitable biodegradable polymer can be selected as the drug-carrier for target specific as well as for sustained drug delivery. The aim of this review is to present the current status and scope of natural biodegradable polymers as well as some emerging polymers with special characteristics as suitable carriers for drug delivery applications. The most widely preferred preparation methods are discussed along with their characterization using different analytical techniques. Further, the review highlights significant features of methods developed using natural polymers for drug entrapment and release studies.

Mucus models to evaluate the diffusion of drugs and particles

Mucus is a complex hydrogel that acts as a natural barrier to drug delivery at different mucosal surfaces including the respiratory, gastrointestinal, and vaginal tracts. To elucidate the role mucus plays in drug delivery, different in vitro, in vivo, and ex vivo mucus models and techniques have been utilized. Drug and drug carrier diffusion can be studied using various techniques in either isolated mucus gels or mucus present on cell cultures and tissues. The species, age, and potential disease state of the animal from which mucus is derived can all impact mucus composition and structure, and therefore impact drug and drug carrier diffusion. This review provides an overview of the techniques used to characterize drug and drug carrier diffusion, and discusses the advantages and disadvantages of the different models available to highlight the information they can afford.

pH responsive biodegradable nanogels for sustained release of bleomycin

Site specific drug delivery with desired therapeutic effect still remains challenging task due to suboptimal release, tissue toxicity, low selectivity and meager therapeutic efficacy in skin cancers. The aim of the current study was to fabricate pH responsive, self-assembled, chemically cross-linked biodegradable chitosan nanogel loaded with bleomycin to target the dermal area of the skin. The nanogel synthesized by ion gelation technique and was characterized for drug loading, swelling and thermal stability followed by in vitro analysis. HaCaT (Human Keratinocyte cell) and HDF (Human dermal fibroblast) cell line were used for the biocompatibility and cytocompatibility evaluation prior to the hemolysis assay and coagulation assessment. The nanogel had a size range of 150nm as determined by TEM and DLS. The nanogel possessed optimum thermal stability as analyzed by thermogravimetry (TG) and differential thermal analysis (DTA). Biodegradation was confirmed by lysozyme enzyme degradation assays. The drug entrapment efficacy was about 55% in the swollen state. The In vitro drug release profile revealed sustained release pattern. The hemolysis of 2.39% and prothrombin time (PT) and activated partial thromboplastin time (APTT) of 12.9 and 31s revealed the biocompatibility of nanogels. The cell uptake and localization profile was validated by fluorescence and confocal microscopy using HDF and HaCaT cell lines. Finally, the MTT assay demonstrated the cytocompatibility of nanogels. In conclusion, the present findings suggest that biodegradable chitosan nanogels with stimuli responsive nature can release the anticancer drug cargo in a sustained and controlled manner and offer promising potentials for treating skin cancers.

STATEMENT OF SIGNIFICANCE

Drug delivery to the targeted site is a major challenge in clinical medicine. The newly constructed pH responsive biodegradable nanogel consisting of bleomycin revealed pH triggered drug release in a sustained manner to the dermal area offering novel approach against skin cancer. The nanogel system is biodegradable in nature possessing high drug entrapment efficiency and offers patient compliance with biocompatible and cytocompatible characteristics. This nanogel system can thus be highly useful for delivery of anticancer drugs to the skin in a controlled and sustained manner.

Targeted Administration of Proteic Drugs. I. Preparation of Polymeric Nanoparticles

The formulation of hybrid nanoparticles based on synthetic polymer-protein hybrid matrices for the targeted release of proteic drugs with antiviral activity such as a-interferon was investigated. Human serum albumin, alone, or in combination with myoglobin, and the hemiesters of alternating copolymers of maleic anhydride/alkyl vinyl ethers of oligo(ethylene glycol) were selected as proteic and synthetic components, respectively. Digalactosyl diacyl gycerol, a natural glycolipid selectively recognized by the asialofetuin receptor was used for the active targeting of liver hepatocytes. Nanoparticle suspensions were prepared either by slow solvent evaporation from biphase and triphase emulsions or by controlled coprecipitation. Nanoparticles, 0.1-0.3 gm in diameter, were obtained by the latter method, whereas the former one afforded heterogeneous micro and nanoparticle mixtures. Several techniques were tested to separate the nanoparticle dispersions from the suspending solution. The best results, in terms of a homogeneous distribution of mostly spherical nanoparticles, were obtained by centrifugation in the presence of modified cyclodextrins. After lyophilization of supernatant, the resulting fluffy powder was easily resuspendable in water.

Surface engineered and ligand anchored nanobioconjugate: an effective therapeutic approach for oral insulin delivery in experimental diabetic rats

The present study was designed to enhance intestinal absorption of insulin by nanobioconjugate formulated with PEGylation and Concanavalin A based targeted synergistic approach. The attempts were aimed at maximizing bioavailability and therapeutic efficacy of insulin by incorporating it in Concanavalin A anchored PEGylated nanoconstructs. The Con A anchored PEGylated PLGA diblock copolymer was synthesized by modified surface functionalization method, and was then characterized by FTIR and 1H NMR spectrum analysis. The nanoparticles from synthesized polymers were prepared and characterized for mean size and distribution by laser diffraction spectroscopy. The physicochemically characterized (by SEM and TEM) formulations were evaluated for optimum particle size, polydispersity index, zeta potential and entrapment efficiency 196.3±4.5 nm, 0.15±0.04, -25.6±1.68 and 44.6±3.5% respectively. The insulin encapsulation efficiency and in vitro release were assessed by bicinchoninic protein assay (BCA). The in vitro results corroborated in vivo studies carried out in experimentally created diabetic albino rats. The nano-encapsulated insulin was discovered to meet the requirements by achieving better stability, improved absorption and enhanced oral bioavailability elucidated by in vivo and in vitro bioassays.

Potential in vitro and in vivo colon specific anticancer activity in a HCT-116 xenograft nude mice model: targeted delivery using enteric coated folate modified nanoparticles

ES–FA–CU–GdNP drug delivery system has been developed for specific targeting in colon cancer and has the promise to address overexpressed FRs.

Fate of paclitaxel lipid nanocapsules in intestinal mucus in view of their oral delivery

The bioavailability of paclitaxel (Ptx) has previously been improved via its encapsulation in lipid nanocapsules (LNCs). In this work, the interactions between LNCs and intestinal mucus are studied because they are viewed as an important barrier to successful oral delivery. The rheological properties of different batches of pig intestinal mucus were studied under different conditions (the effect of hydration and the presence of LNCs). Fluorescence resonance energy transfer (FRET) was used to study the stability of LNCs in mucus at 37°C for at least 3 hours. Diffusion through 223, 446, and 893 μm mucus layers of 8.4, 16.8, and 42 μg/mL Ptx formulated as Taxol® (Bristol-Myers Squibb, Rueil-Malmaison, France) or encapsulated in LNCs (Ptx-LNCs) were investigated. The effect of the size of the LNCs on their diffusion was also investigated (range, 25–110 nm in diameter). Mucus behaves as a non-Newtonian gel with rheofluidifying properties and a flow threshold. The viscous (G″) and elastic (G′) moduli and flow threshold of the two mucus batches varied with water content, but G′ remained below G″. LNCs had no effect on mucus viscosity and flow threshold. The FRET efficiency remained at 78% after 3 hours. Because the destruction of the LNCs would lead to a FRET efficiency below 25%, these results suggest only a slight modification of LNCs after their contact with mucus. The diffusion of Taxol® and Ptx-LNCs in mucus decreases if the mucus layer is thicker. Interestingly, the apparent permeability across mucus is higher for Ptx-LNCs than for Taxol® for drug concentrations of 16.8 and 42 μg/mL Ptx (P<0.05). The diffusion of Ptx-LNCs through mucus is not size-dependent. This study shows that LNCs are stable in mucus, do not change mucus rheological properties, and improve Ptx diffusion at low concentrations, thus making these systems good candidates for Ptx oral delivery. The study of the physicochemical interaction between the LNC surface and its diffusion in mucus is now envisioned.

Nanoparticles for oral delivery: targeted nanoparticles with peptidic ligands for oral protein delivery

As the field of biotechnology has advanced, oral protein delivery has also made significant progress. Oral delivery is the most common method of drug administration with high levels of patient acceptance. Despite the preference of oral delivery, administration of therapeutic proteins has been extremely difficult. Increasing the bioavailability of oral protein drugs to the therapeutically acceptable level is still a challenging goal. Poor membrane permeability, high molecular weight, and enzymatic degradation of protein drugs have remained unsolved issues. Among diverse strategies, nanotechnology has provided a glimpse of hope in oral delivery of protein drugs. Nanoparticles have advantages, such as small size, high surface area, and modification using functional groups for high capacity or selectivity. Nanoparticles with peptidic ligands are especially worthy of notice because they can be used for specific targeting in the gastrointestinal (GI) tract. This article reviews the transport mechanism of the GI tract, barriers to protein absorption, current status and limitations of nanotechnology for oral protein delivery system.

Triggering effect of N-acetylglucosamine on retarded drug release from a lectin-anchored chitosan nanoparticles-in-microparticles system

The aim of this study was to investigate the use of N-acetylglucosamine (NAG) to accelerate drug release from a lectin-modified carrier. A wheat germ agglutinin (WGA)-anchored salmeterol xinafoate (SalX)-loaded nanoparticles-in-microparticles system (NiMS) was prepared with an ionotropic gelation technique combined with a spray drying method. The formulated microparticles were spherical, with diameters ranging mainly from 2 to 8 μm; the drug entrapment efficiency was >70% (w/w), and the loading capacity was approximately 8% (w/w). Drug release from WGA-SalX-NiMS, within the first 4h, was approximately 30% less than that from SalX-NiMS, indicating an effect of lectin-modification to retard drug release from the NiMS. Due to "sugar-lectin" interactions, drug release from WGA-SalX-NiMS was substantially increased after the addition of NAG to the release medium. However, no significant influence of NAG was observed on the drug release profile of SalX-NiMS without WGA anchorage. The characteristics of NAG-WGA interaction may provide valuable insights into the "triggering-effects" of specific sugars on drug release from lectin-anchored carriers. These results suggest that it is possible to control drug release from a lectin-anchored drug delivery system using a specific sugar, and that the designed novel WGA-SalX-NiMS may be a suitable formulation for chronotherapy of asthma.

Anticancer drug-loaded gliadin nanoparticles induce apoptosis in breast cancer cells

Nanoscale drug carriers play an important role in regulating the delivery, permeability, and retention of the drugs. Although various carriers have been used to encapsulate anticancer drugs, natural biomaterials are of great benefit for delivery and controlled release of drugs. We used the electrospray deposition system to synthesize gliadin and gliadin-gelatin composite nanoparticles for delivery and controlled release of an anticancer drug (e.g., cyclophosphamide). The size profile and synthesis of nanoparticles was characterized by dynamic light scattering and X-ray diffractometry. Cyclophosphamide was gradually released from the gliadin nanoparticles for 48 h. In contrast, the gliadin-gelatin composite nanoparticles released cyclophosphamide in a rapid manner. Furthermore, we demonstrated that breast cancer cells cultured with cyclophosphamide-loaded 7% gliadin nanoparticles for 24 h became apoptotic, confirmed by Western blotting analysis. Therefore, the gliadin-based nanoparticle could be a powerful tool for delivery and controlled release of anticancer drugs.

Preparation and investigation of Ulex europaeus agglutinin I-conjugated liposomes as potential oral vaccine carriers

We prepared and optimized Ulex europaeus agglutinin I (UEAI)-modified Bovine serum albumin (BSA)-encapsulating liposomes (UEAI-LIP) as oral vaccine carriers and examined the feasibility of inducing systemic and mucosal immune responses by oral administration of UEAILIP. The prepared systems were characterized in vitro for their average size, zeta potential, encapsulation efficiency (EE%) and conjugation efficiency (CE%). In vitro release studies indicated that the presence of UEAI around the optimized liposomes was able to prevent a burst release of loaded BSA and provide sustained release of the encapsulated protein. In vivo immune-stimulating results in KM mice showed that BSA given intramuscularly generated systemic response only but both systemic and mucosal immune responses could be induced simultaneously in the groups in which BSA-loaded liposomes (LIP) and UEAI-LIP were administered intragastrically. Furthermore, the modification of UEAI on the surface of liposomes could further enhance the IgA and IgG levels obviously. In conclusion, this study demonstrated the high potential of lectin-modified liposomes containing the antigen as carriers for oral vaccine.

Application of Ulex europaeus agglutinin I-modified liposomes for oral vaccine: Ex Vivo bioadhesion and in Vivo immunity

The conjugation of Ulex europaeus agglutinin I (UEAI) onto surface of liposomes has been demonstrated to effectively improve the intestinal absorption of antigen, subsequently induced strong mucosal and systemic immune responses. In this context, we prepared bovine serum albumin (BSA)-encapsulating UEAI-modified liposomes (UEAI-LIP) and unmodified ones (LIP). The specific bioadhesion on mice gastro-intestinal mucosa was studied ex vivo. An important increase of interaction between UEAI-conjugated liposomes and the intestinal segments with Peyer's Patches (PPs) was observed compared with the unconjugated one (p<0.01). However, under the presence of α-L-fucose, which is the reported specific sugar for UEAI, specifically inhibited the activity of these conjugates. The immune-stimulating activity in vivo was studied by measuring immunoglobulin G (IgG) levels in serum and immunoglobulin A (IgA) levels in intestinal mucosal secretions following oral administration of BSA solution, LIP and UEAI-LIP in mice. Results indicate that antigen encapsulated in liposomes, especially the UEAI-modified ones, was favorable for inducing immune response. At 42 d after the first immunization, the highest IgG and IgA antibody levels produced by UEAI-LIP occurred, respectively showing 4.4-fold and 5-fold higher levels compared to those of the groups receiving BSA alone. This data demonstrated high potential of UEAI-modified liposomes for their use as carrier for oral vaccines.

Mucoadhesive curcumin nanospheres: biological activity, adhesion to stomach mucosa and release of curcumin into the circulation

Although mucoadhesive drug carriers for the gastro-intestinal tract (GIT) have been reported, the mucoadhesive property and drug release characteristics have never been evaluated separately, whilst the adherence of the carriers to the surface of GIT has not been directly visualized. Here, a monopolymeric carrier made from ethylcellulose (EC) and a dipolymeric carrier made from a blend of methylcellulose (MC) and EC (ECMC) were easily fabricated through a self-assembling process and yielded the highest reported curcumin loading of ~48-49%. Both curcumin loaded ECMC (C-ECMC) and curcumin loaded EC (C-EC) particles showed an in vitro free radical scavenging activity and a dose-dependent in vitro cytotoxic effect towards MCF-7 human breast adenocarcinoma and HepG2 hepatoblastoma cells in tissue culture. The in vivo evaluation of their adherence to stomach mucosa and their ability to release curcumin into the circulation were carried out through quantification of curcumin levels in the stomach tissue and in blood of mice orally administered with the two spheres. Direct evidence of the adherence of the C-EC and C-ECMC particles along the mucosal epithelia of the stomach is also presented for the first time through SEM images. The mucoadhesive property of self-assembled C-EC nanoparticles is discussed.

Molecular imaging with nanoparticles: giant roles for dwarf actors

Molecular imaging, first developed to localise antigens in light microscopy, now encompasses all imaging modalities including those used in clinical care: optical imaging, nuclear medical imaging, ultrasound imaging, CT, MRI, and photoacoustic imaging. Molecular imaging always requires accumulation of contrast agent in the target site, often achieved most efficiently by steering nanoparticles containing contrast agent into the target. This entails accessing target molecules hidden behind tissue barriers, necessitating the use of targeting groups. For imaging modalities with low sensitivity, nanoparticles bearing multiple contrast groups provide signal amplification. The same nanoparticles can in principle deliver both contrast medium and drug, allowing monitoring of biodistribution and therapeutic activity simultaneously (theranostics). Nanoparticles with multiple bioadhesive sites for target recognition and binding will be larger than 20 nm diameter. They share functionalities with many subcellular organelles (ribosomes, proteasomes, ion channels, and transport vesicles) and are of similar sizes. The materials used to synthesise nanoparticles include natural proteins and polymers, artificial polymers, dendrimers, fullerenes and other carbon-based structures, lipid-water micelles, viral capsids, metals, metal oxides, and ceramics. Signal generators incorporated into nanoparticles include iron oxide, gadolinium, fluorine, iodine, bismuth, radionuclides, quantum dots, and metal nanoclusters. Diagnostic imaging applications, now appearing, include sentinal node localisation and stem cell tracking.

ACL-I, a lectin from the marine sponge Axinella corrugata: isolation, characterization and chemotactic activity

The lectin from the marine sponge Axinella corrugata (ACL-I) was purified by affinity chromatography on rabbit erythrocytic stroma incorporated into a polyacrylamide gel followed by gel filtration on Ultrogel AcA 44 column. Purified ACL-I is a hexameric glycoprotein with a Mr of 82.3 kDa estimated by SDS-PAGE and 78.5 kDa by FPLC on Superose 12 HR column. The pI of lectin is 6.3 and ACL-I is constituted of 13.9 kDa similar subunits some of them linked by disulphide bridges. This lectin agglutinates native rabbit, goat and dog erythrocytes and in less extent human erythrocytes. The hemagglutinating activity is independent of Ca(2+), Mg(2+) and Mn(2+), but it is strongly inhibited by carbohydrates containing N-acetyl groups. ACL-I is stable up to 70 degrees C for 30 min, with optimum pH between 7 and 8, and it is also resistant to enzymatic proteolysis in vitro. In the presence of reducing or denaturant agents, the lectin activity decreases. ACL-I displays chemotactic effect on rat neutrophil in vitro which is inhibited by N-acetyl-d-glucosamine.

Lectin-conjugated PLGA nanoparticles loaded with thymopentin: Ex vivo bioadhesion and in vivo biodistribution

The conjugation of lectins onto PLGA nanoparticles has been demonstrated to effectively improve the intestinal absorption of thymopentin. In this study, thymopentin-loaded nanoparticles made from fluorescein isothiocyanate labeled PLGA were modified with wheat germ agglutinin (WGA). The specific bioadhesion of nanoparticles on rat intestinal mucosa was studied ex vivo. An important increase of interaction between WGA-conjugated nanoparticles and the intestinal segments was observed compared with that of the unconjugated one (p<0.05). Fluorescence photomicrographs confirmed the bioadhesion of WGA-conjugated nanoparticles on intestinal villous epithelium as well as Peyer's patches. Biodistribution of nanoparticles was evaluated using tissues obtained from rats, to which nanoparticles were orally administered. The highest amount of WGA-conjugated nanoparticles was detected in small intestine, suggesting an increase of intestinal bioadhesion and endocytosis. The systemic uptake was as high as 6.48-13.4% of dose at 1 day and 7.32-15.26% at 7 days, which representing an increase of almost 1.4-3.1 fold across the intestine compared to <4.9% of the unconjugated one. The enhanced uptake was related to the increasing of WGA density on nanoparticles. These results further revealed the promising potential of lectin-conjugated nanoparticles on the improvement of intestinal bioadhesion and absorption for oral drug delivery.

Lectin-modified solid lipid nanoparticles as carriers for oral administration of insulin

The aim of this study was to design and characterize lectin-modified solid lipid nanoparticles (SLNs) containing insulin and to evaluate the potential of the lectin-modified colloidal carriers for oral administration of peptide and protein drugs. SLNs were prepared by three different methods. For comparison, some insulin-loaded SLNs were modified with wheat germ agglutinin-N-glutaryl-phosphatidylethanolamine (WGA-N-glut-PE). The particle size, zeta potential and entrapment efficiency of insulin-loaded SLNs were determined. Insulin-loaded SLNs prepared by an appropriate modification of the double dispersion method yielded the highest drug entrapment efficiency, which was more than 60%. In vivo experiments were carried out using insulin-loaded SLNs and WGA-modified SLNs prepared by this method. SLNs and WGA-modified SLNs protected insulin against degradation by digestive enzymes in vitro. The stabilizing effect of WGA-modified SLNs was greater than that observed in SLNs. After oral administration of insulin-loaded SLNs or WGA-modified SLNs to rats, the relative pharmacological bioavailabilities were 4.46% and 6.08%, and the relative bioavailabilities were 4.99% and 7.11%, respectively, in comparison to subcutaneous injection of insulin. These results demonstrated that SLNs and WGA-modified SLNs promoted the oral absorption of insulin.

Preparation and evaluation of lectin-conjugated PLGA nanoparticles for oral delivery of thymopentin

The purpose of this study was to design and evaluate lectin-conjugated PLGA nanoparticles for oral delivery of thymopentin. Thymopentin loaded PLGA nanoparticles (TP5-NPs) were prepared by a double emulsion-solvent evaporation technique. Novel WGA-PLGA conjugates were synthesized by coupling the amino groups of wheat germ agglutinin (WGA) to the carbodiimide-activated carboxylic groups of PLGA, and were incorporated into nanoparticles preparation to take mucoadhesive properties. Important characteristics such as particle size, zeta potential, entrapment efficiency, storage stability, as well as in vitro drug release behavior were investigated. The retention of biorecognitive activity of WGA after covalent coupling was confirmed by haemagglutination test. In vitro experiments with pig mucin (PM) demonstrated that the conjugation of WGA enhanced the interaction about 1.8-4.2 fold compared with that of the non-conjugated nanoparticles, and still exhibited sugar specificity. The pharmacodynamical studies on oral administration of WGA-TP5-NPs were performed in FACScan flow cytometry. The values of CD4(+)/CD8(+) ratios were significantly increased compared with that of TP5-NPs (p<0.01). The enhanced uptake was related to the increasing of WGA content on nanoparticles. These results confirmed that the conjugation of WGA onto PLGA nanoparticles effectively improved the intestinal absorption of TP5 due to specific bioadhesion on GI cell membrane.

Current methods for attaching targeting ligands to liposomes and nanoparticles

Liposomes and nanoparticles have emerged as versatile carrier systems for delivering active molecules in the organism. These colloidal particles have demonstrated enhanced efficacy compared to conventional drugs. However, the design of liposomes and nanoparticles with a prolonged circulation time and ability to deliver active compounds specifically to target sites remains an ongoing research goal. One interesting way to achieve active targeting is to attach ligands, such as monoclonal antibodies or peptides, to the carrier. These surface-bound ligands recognize and bind specifically to target cells. To this end, various techniques have been described, including covalent and noncovalent approaches. Both in vitro and in vivo studies have proved the efficacy of the concept of active targeting. The present review summarizes the most common coupling techniques developed for binding homing moieties to the surface of liposomes and nanoparticles. Various coupling methods, covalent and noncovalent, will be reviewed, with emphasis on the major differences between the coupling reactions, on their advantages and drawbacks, on the coupling efficiency obtained, and on the importance of combining active targeting with long-circulating particles.

Bioadhesive properties of Gantrez nanoparticles

Bioadhesive nanoparticles have been proposed as carriers for the oral delivery of poorly available drugs and facilitate the use of this route. This work summarises some experiments describing the bioadhesive potential of Gantrez nanoparticles fluorescently labeled with rhodamine B isothiocyanate. The adhesive potential of Gantrez was found to be stronger when folded as nanoparticles than in the solubilised form. Conventional nanoparticles displayed a tropism for the upper areas of the gastrointestinal tract, with a maximum of adhesion 30 min post-administration and a decrease in the adhered fraction along the time depending on the given dose. The cross-linkage of nanoparticles with increasing amounts of 1,3-diaminopropane stabilised the resulting carriers and prolonged their half-life in an aqueous environment; although, the adhesive capacity of nanoparticles, the intensity and the relative duration of the adhesive interactions within the gut as a function of the cross-linking degree. Finally, nanoparticles were coated with either gelatin or albumin. In the first case, the presence of gelatin dramatically decreased the initial capacity of these carriers to interact with the gut mucosa and the intensity of these phenomenons. In the latter, bovine serum albumin coated nanoparticles (BSA-NP) showed an important tropism for the stomach mucosa without further significant distribution to other parts of the gut mucosa.

Antioxidant and anti-inflammatory properties of a Cucumis melo LC. extract rich in superoxide dismutase activity

The present study was conducted to evaluate in vitro and in vivo the antioxidant and anti-inflammatory properties of a cantaloupe melon (Cucumis melo LC., Cucurbitaceae) extract (CME) selected for its high superoxide dismutase activity. Peritoneal macrophages were pre-activated in vitro with 300 IU of interferon-gamma (IFN-gamma) and were then challenged in culture with IgGl/anti-IgG1 immune complexes (IgG1IC) in presence of various CME extracts. The subsequent production of free radicals (superoxide anion, nitric oxide, and peroxynitrite) and of pro-(TNF-alpha) and anti-(IL-10) inflammatory cytokines was evaluated. The CME inhibited in a dose-dependent manner the production of superoxide anion with a maximal effect at 100 microg/ml. This inhibitory effect of CME appeared to be closely linked to the SOD activity because it was dramatically decreased after heat inactivation of the SOD activity (HI-CME). In addition, the CME inhibited the production of peroxynitrite strengthening the antioxidant properties of this CME rich in SOD activity. The production of the pro- and anti-inflammatory cytokines, namely TNF-alpha and IL-10, being conditioned by the redox status of macrophages we also evaluated the effect of CME and HI-CME on the IgG1IC-induced cytokine production. When the SOD activity was present in the CME it promoted the IgG1IC-induced production of IL-10 instead of TNF-alpha. These data demonstrated that, in addition to its antioxidant properties, the anti-inflammatory properties of the CME extract were principally related to its capacity to induce the production of IL-10 by peritoneal macrophages. The particular properties of wheat gliadin (Triticum vulgare, Poaceae) for the oral delivery of functional proteins led us to test it in a new nutraceutical formula based on its combination with the CME thus monitoring the SOD activity release during the gastro-intestinal digestive process. In these experiments C57BL/6 mice were supplemented orally everyday during 28 days with: (1) the placebo, (2) the CME extract alone, (3) the gliadin, (4) the CME/gliadin combination, or (5) the HI-CME/gliadin combination (SOD inactivated). At the end of the supplementation period all the animals were injected intra-peritoneal (i.p.) with the pro-inflammatory cytokine IFN-gamma (300 IU) and peritoneal macrophages were harvested 24 h after to test their capacities to produce free radicals, TNF-alpha and IL-10 after triggering with IgG1IC. We demonstrated that animals supplemented during 28 days with the CME/gliadin combination were protected against the pro-inflammatory properties of IFN-gamma while the other products were inefficient. These data did not only indicate that the SOD activity is important for the antioxidant and anti-inflammatory properties of the CME extract, but also demonstrated that when the SOD activity is preserved during the digestive process by its combination with wheat gliadin it is possible to elicit in vivo the pharmacological effects of this antioxidant enzyme.

Lectin-functionalized poly (lactide-co-glycolide) nanoparticles as oral/aerosolized antitubercular drug carriers for treatment of tuberculosis

OBJECTIVES

This study was carried out to explore lectin-functionalized poly (lactide-co-glycolide) nanoparticles (PLG-NPs) as bioadhesive drug carriers against tuberculosis (TB), in order to reduce the drug dosage frequency of antitubercular drugs and thus improve patient compliance in TB chemotherapy.

METHODS

Wheat germ agglutinin (WGA)-coated PLG-NPs were prepared by a two-step carbodiimide procedure. This formulation was administered to guinea pigs through the oral/aerosol route for a detailed pharmacokinetic and chemotherapeutic evaluation. Immunological or hepatotoxic effects of WGA lectin, if any, were also determined.

RESULTS

WGA-functionalized PLG-NPs were in the size range of 350-400 nm, with binding of 3-3.5 microg of WGA/mg of PLG-NPs and drug encapsulation efficiency of 54%-66%. Upon administration of lectin-coated PLG-NPs through the oral/aerosol route, the presence of drugs in plasma was observed for 6-7 days for rifampicin and 13-14 days for isoniazid and pyrazinamide. However, upon administration of uncoated PLG-NPs (oral/aerosolized) rifampicin was detectable in plasma for 4-6 days, whereas isoniazid and pyrazinamide were detectable for 8-9 days. All three drugs were present in lungs, liver and spleen for 15 days. Administration of WGA-coated PLG-NPs caused a significant (P < 0.001) increase in the relative bioavailability of antitubercular drugs. Chemotherapeutic studies revealed that three doses of oral/nebulized lectin-coated nanoparticles fortnightly could yield undetectable mycobacterial colony forming units (cfu); this was achievable with 45 doses of oral free drugs.

CONCLUSION

WGA-functionalized PLG-NPs could be potential drug carriers for antitubercular drugs through the oral as well as aerosol route for effective TB control.

Anti-Helicobacter pylori effect of mucoadhesive nanoparticles bearing amoxicillin in experimental gerbils model

The purpose of the present study was to design mucoadhesive gliadin nanoparticles (GNP) containing amoxicillin and to evaluate their effectiveness in eradicating Helicobacter pylori. GNP-bearing amoxicillin (AGNP) was prepared by desolvation method. The effect of process variables such as gliadin concentration and initial drug loading on particle size, shape, percent payload, percent entrapment efficiency, in vitro release profile, and mucoadhesive property of GNP was assessed. Rhodamine isothiocyanate-entrapped GNP formulations were prepared to evaluate their in vivo gastric mucoadhesive property in albino rats. With increasing gliadin concentration, the mucoadhesive property of GNP increased. Typically, the maximum amount of nanoparticles remaining was 82 +/- 4%, which represented a stronger mucoadhesive propensity and specificity of GNP toward the stomach. In vitro antimicrobial activity of AGNP was evaluated by growth inhibition studies on an isolated H pylori strain. The time required for complete eradication was higher in AGNP than in amoxicillin because of the controlled drug delivery of amoxicillin from AGNP. In vivo clearance of H pylori following oral administration of AGNP to infected Mongolian gerbils was examined. Amoxicillin and AGNP both showed anti-H pylori effects in this experimental model of infection, but the required dose for complete eradication was less in AGNP than in amoxicillin. In conclusion, AGNP eradicated H pylori from the gastrointestinal tract more effectively than amoxicillin because of the prolonged gastrointestinal residence time attributed to mucoadhesion. A dosage form containing mucoadhesive nanoparticles bearing a potential antibiotic should be useful for the complete eradication of H pylori.

Oral insulin delivery using P(MAA-g-EG) hydrogels: effects of network morphology on insulin delivery characteristics

Hydrogels of poly(methacrylic acid-g-ethylene glycol) were prepared using different reaction water contents in order to vary the network mesh size, swelling behavior and insulin loading/release kinetics. Gels prepared with greater reaction solvent contents swelled to a greater degree and had a larger network mesh size. All of the hydrogels were able to incorporate insulin and protected it from release in acidic media. At higher pH (7.4), the release rates increased with reaction solvent content. Using a closed loop animal model, all of the insulin loaded formulations produced significant insulin absorption in the upper small intestine combined with hypoglycemic effects. In these studies, bioavailabilities ranged from 4.6% to 7.2% and were dependent on reaction solvent content.

Novel core(polyester)-shell(polysaccharide) nanoparticles: protein loading and surface modification with lectins

This study describes new lectin-decorated or protein-loaded nanoparticles with a hydrophobic poly(epsilon-caprolactone) (PCL) core and a hydrophilic dextran (Dex) corona. In this view, a family of block Dex-PCLn copolymers was first synthesized, consisting of a Dex backbone to which n preformed PCL blocks were grafted. The ability of these new copolymers to form nanoparticles was evaluated in comparison with a series of PCL homopolymers of various molecular weights (2000, 10,000 and 40,000 g/mole). Two different nanoparticle preparation methods have been developed and tested for their efficacy to incorporate proteins. For this, three proteins were used: a model protein, bovine serum albumin (BSA), a lectin from leaves of Bauhinia monandra (BmoLL) and Lens culinaris (LC) lectin. All these proteins were successfully incorporated in nanoparticles with a mean diameter around 200 nm. Lectins could also be adsorbed onto the surface of Dex-PCLn nanoparticles. Surface-bound BmoLL conserved its hemagglutinating activity, suggesting the possible application of this type of surface-modified nanoparticles for targeted oral administration. Caco-2 cellular viability was higher than 70% when put in contact with Dex-PCLn nanoparticles, even at concentrations as high as 660 microg/ml.

Regional intestinal absorption of FITC-dextran 4,400 with nanoparticles based on beta-sitosterol beta-D-glucoside in rats

Nanoparticles (NP) are potential carriers for drug delivery to the targeted intestine. NP based on beta-sitosterol beta-D-glucoside (Sit-G) enhanced the colon-specific absorption of FITC-dextran 4,400 (FD-4), because the concentration-dependent increase of bioavailability appeared in only the colon. In a permeation study, the absorption enhancement in the colon was suppressed in the following conditions: (1) the addition of Sit-G NP to serosa; (2) a permeation study at 4 degrees C; (3) the addition of endocytosis inhibitor, cytochalasin B. NP based on sitosterol, the aglycon of Sit-G, did not increase the FD-4 colonic permeation. The addition of Sit-G NP to the mucosal side induced a decrease of transepithelial resistance (TEER), but this phenomenon was suppressed by an inhibitor of Na(+)-dependent specific glucose transporter, phrolidzin, which did not affect FD-4 permeation. These findings suggested that absorption enhancement by Sit-G NP may not be due to opening of a tight junction, but might be related to endocytosis via glucose residue of Sit-G.

Surface modification of poly(lactic acid) nanoparticles by covalent attachment of thiol groups by means of three methods

The aim of the present work was to find a suitable method for the introduction of thiol functions on the surface of poly(DL-lactic acid) (PLA) nanoparticles. Three different approaches were investigated. The modification of the surface involves the activation of PLA carboxylic acid groups followed by the attack of a nucleophile such as cysteine (method #1) or cystamine (method #2 and #3) that provide thiol functions via an amide bond. For the conjugation with cystamine, a second reaction step is required to expose the sulfhydryl function of cystamine that is otherwise protected in a disulfide bond. 1,4-Dithio-DL-threitol (DTT) (method #2) or Tris(2-carboxyethyl)-phosphine hydrochloride (method #3) were evaluated for their ability to reduce this linkage. Method #1 allowed a maximum of 8.5+/-2.8 mmol of thiol functions per mol of PLA to be attached on the surface of the nanoparticles. Method #2 allowed the introduction of a greater number of thiol functions (up to 190+/-15 mmol per mol of PLA). However, this latter method has a major drawback: DTT interacts strongly with the nanoparticle matrix during the reduction step. Method #3 has the advantage over method #2 in that it allowed a significant number of thiol functions to be covalently bound to the particles (up to 107.6+/-0.6 mmol per mol of PLA) without the problem of undesired interaction between DTT and the nanoparticle matrix. The introduction of thiol groups onto the surface of PLA nanoparticles is possible with all three suggested methods. The method #3 provides a straight forward approach for the substitution of carboxylic acid groups with a high number of activated sulfhydryl at the surface of PLA nanoparticles.