Targeted Drug Delivery and Treatment of Endoparasites with Biocompatible Particles of pH-Responsive Structure

Discovery of a Digenean (Cryptogonimidae) Living in a Cleft-Lipped Goby, Sicyopterus cynocephalus (Teleostei: Gobiidae) from Ranongga Island, Solomon Islands: Analysis of Multiple Ribosomal DNA Regions

This study results from a continued investigation of the occurrence and diversity of parasites of freshwater fish in the Solomon Islands. Thus, we revealed a new host as well as a new site of infection and a new geographical area for the cryptogonimid parasite, Stemmatostoma cribbi (Digenea: Cryptogonimidae). The cryptogonimid species was identified based on general morphology and on molecular data of metacercariae found in the gills of the cleft-lipped goby, Sicyopterus cynocephalus, from Ranongga Island, Western Province of the Solomon Islands. This is the first report of a Stemmatostoma sp. digenean parasitizing fish of the genus Sicyopterus in the Indo-Pacific region and the first report of S. cribbi infection in a fish from the Solomon Islands. Phylogenetic analysis performed by Bayesian inference and maximum likelihood confirmed the presence of the cryptogonimid in a well-supported subclade of Stemmatostoma spp.

Interaction of polyelectrolyte-shell cubosomes with serum albumin for triggering drug release in gastrointestinal cancer

Nano-structured and functionalized materials for encapsulation, transport, targeting and controlled release of drugs are of high interest to overcome low bioavailability in oral administration. We develop lipid-based cubosomes, which are surface-functionalized with biocompatible chitosan-N-arginine and alginate, displaying internal liquid crystalline structures. Polyelectrolyte-shell (PS) cubosomes have pH-responsive characteristics profitable for oral delivery. The obtained PScubosomes can strongly interact with serum albumin, a protein which is released in the stomach under gastric cancer conditions. An effective thermodynamic PScubosome-protein interaction was characterized at pH 2.0 and 7.4 by isothermal titration calorimetry at 37 °C. A high increment of the albumin conformation transition temperature was evidenced by differential scanning calorimetry upon incubation with PScubosomes. The performed structural studies by synchrotron small-angle X-ray scattering (SAXS) revealed essential alterations in the internal liquid crystalline topology of the nanocarriers including an Im3m to Pn3m transition and a reduction of the cubic lattice parameters. The PScubosome nanoparticle interaction with serum albumin, leading to inner structural changes in a range of temperatures, promoted the release of water from the cubosomal nanochannels. Altogether, the results revealed effective interactions of the PScubosomes with albumin under simulated gastrointestinal pH conditions and suggested promising nanocarrier characteristics for triggered oral drug release.

Complexation of a Polypeptide-Polyelectrolytes Bioparticle as a Biomaterial of Antibacterial Activity

The development of biomaterials to enable application of antimicrobial peptides represents a strategy of high and current interest. In this study, a bioparticle was produced by the complexation between an antimicrobial polypeptide and the biocompatible and biodegradable polysaccharides chitosan-N-arginine and alginate, giving rise to a colloidal polyelectrolytic complex of pH-responsive properties. The inclusion of the polypeptide in the bioparticle structure largely increases the binding sites of complexation during the bioparticles production, leading to its effective incorporation. After lyophilization, detailed evaluation of colloidal structure of redispersed bioparticles evidenced nano or microparticles with size, polydispersity and zeta potential dependent on pH and ionic strength, and the dependence was not withdrawn with the polypeptide inclusion. Significant increase of pore edge tension in giant vesicles evidenced effective interaction of the polypeptide-bioparticle with lipid model membrane. Antibacterial activity against Aeromonas dhakensis was effective at 0.1% and equal for the isolated polypeptide and the same complexed in bioparticle, which opens perspectives to the composite material as an applicable antibacterial system.

Ivermectin: recent approaches in the design of novel veterinary and human medicines

Ivermectin (IVM) is a drug widely used in veterinary and human medicine for the management of parasitic diseases. Its repositioning potential has been recently considered for the treatment of different diseases, such as cancer and viral infections. However, IVM faces some limitations to its formulations due to its low water solubility and bioavailability, along with reports of drug resistance. In this sense, novel technological approaches have been explored to optimize its formulations and/or to develop innovative medicines. Therefore, this review discusses the strategies proposed in the last decade to improve the safety and efficacy of IVM and to explore its novel therapeutic applications. Among these technologies, the use of micro/nano-drug delivery systems is the most used approach, followed by long-acting formulations. In general, the development of these novel formulations seems to run side by side in veterinary and human health, showing a shared interface between the two areas. Although the technologies proposed indicate a promising future in the development of innovative dosage forms containing IVM, its safety and therapeutic targets must be further evaluated. Overall, these approaches comprise tailoring drug delivery profiles, decreasing the risks of developing drug resistance, and supporting the application of IVM for reaching different therapeutic targets.

Charge reversal nano-systems for tumor therapy

Surface charge of biological and medical nanocarriers has been demonstrated to play an important role in cellular uptake. Owing to the unique physicochemical properties, charge-reversal delivery strategy has rapidly developed as a promising approach for drug delivery application, especially for cancer treatment. Charge-reversal nanocarriers are neutral/negatively charged at physiological conditions while could be triggered to positively charged by specific stimuli (i.e., pH, redox, ROS, enzyme, light or temperature) to achieve the prolonged blood circulation and enhanced tumor cellular uptake, thus to potentiate the antitumor effects of delivered therapeutic agents. In this review, we comprehensively summarized the recent advances of charge-reversal nanocarriers, including: (i) the effect of surface charge on cellular uptake; (ii) charge-conversion mechanisms responding to several specific stimuli; (iii) relation between the chemical structure and charge reversal activity; and (iv) polymeric materials that are commonly applied in the charge-reversal delivery systems.

Efficient Treatment of Fish Intestinal Parasites Applying a Membrane-Penetrating Oral Drug Delivery Nanoparticle

Nanodelivery of drugs aims to ensure drug stability in the face of adverse biochemical conditions in the course of administration, concomitant with appropriate pharmacological action provided by delivery at the targeted site. In this study, the application potential of a nanoparticle produced with biopolymers chitosan-N-arginine and alginate as an oral drug delivery material is evaluated. Both macromolecules being weak polyelectrolytes, the nanoparticle presents strong thermodynamic interactions with a biological model membrane consisting of a charged lipid liposome bilayer, leading to membrane disruption and membrane penetration of the nanoparticles in ideal conditions of pH corresponding to the oral route. The powder form of the nanoparticle was obtained by lyophilization and with a high percentage of entrapment of the anthelmintic drug praziquantel. In vivo studies were conducted with oral administration to Corydoras schwartzi fish with high intensity of intestinal parasites infection. The in vivo experiments confirmed the mucoadhesive and revealed membrane-penetrating properties of the nanoparticle by translocating the parasite cyst, which provided target drug release and reduction of over 97% of the fish intestinal parasites. Thus, it was evidenced that the nanoparticle was effective in transporting and releasing the drug to the target, providing an efficient treatment.

High compliance and effective treatment of fish endoparasitic infections with oral drug delivery nanobioparticles: Safety of intestinal tissue and blood parameters

Parasite infections in fish require constant surveillance and strategies for efficient treatments which guarantee the fish health, their sale value and the non-propagation of pathogens in new environments. Fish treatments based on nanotechnology become of increasing interest since nanoparticles have been shown as efficient materials for optimizing administration of bioactives. In this study a chitosan derivative, alginate and praziquantel conjugated nanobioparticle of effective action for oral treatment of digenetic trematodes in highly infected Corydoras schwartzi was evaluated in terms of histological and hematological safety. The inherent absence of alterations in intestinal tissue and the reversible blood cells counting during a period up to 35 days showed the safety of the drug delivery nanobioparticles, which thus represent a promising strategy for effective applications in pathogens treatments by oral administration.

Cubosomal lipid nanoassemblies with pH-sensitive shells created by biopolymer complexes: A synchrotron SAXS study

We report a strategy for sustainable development of pH-responsive cubic liquid crystalline nanoparticles (cubosomes), in which the structure-defining lyotropic nonlamellar lipid and the eventually encapsulated guest molecules can be protected by pH-sensitive polyelectrolyte shells with mucoadhesive properties. Bulk non-lamellar phases as well as pH-responsive polyelectrolyte-modified nanocarriers were formed by spontaneous assembly of the nonlamellar lipid monoolein and two biopolymers tailored in nanocomplexes with pH-dependent net charge. The mesophase particles involved positively charged N-arginine-modified chitosan (CHarg) and negatively charged alginate (ALG) chains assembled at different biopolymer concentrations and charge ratios into a series of pH-responsive complexes. The roles of Pluronic F127 as a dispersing agent and a stabilizer of the nanoscale dispersions were examined. Synchrotron small-angle X-ray scattering (SAXS) investigations were performed at several N-arginine-modified chitosan/alginate ratios (CHarg/ALG with 10, 15 and 20 wt% ALG relative to CHarg) and varying pH values mimicking the pH conditions of the gastrointestinal route. The structural parameters characterizing the inner cubic liquid crystalline organizations of the nanocarriers were determined as well as the particle sizes and stability on storage. The surface charge variations, influencing the measured zeta-potentials, evidenced the inclusion of the CHarg/ALG biopolymer complexes into the lipid nanoassemblies. The polyelectrolyte shells rendered the hybrid cubosome nanocarriers pH-sensitive and influenced the swelling of their lipid-phase core as revealed by the acquired SAXS patterns. The pH-responsiveness and the mucoadhesive features of the cubosomal lipid/polyelectrolyte nanocomplexes may be of interest for in vivo drug delivery applications.

Safety of oral administration of high doses of ivermectin by means of biocompatible polyelectrolytes formulation

The FDA-approved drug ivermectin is applied for treatments of onchocerciasis and lymphatic filariasis. The anti-cancer and anti-viral activities have been demonstrated stressing possibilities for the drug repurposing and therefore new information on high dosage safety is on demand. We analyzed in vivo tissue responses for high doses of ivermectin using Corydoras fish as animal model. We made intestinal histology and hematologic assays after oral administration of ivermectin transported with polyelectrolytes formulation. Histology showed any apparent damage of intestinal tissues at 0.22–170 mg of ivermectin/kg body weight. Immunofluorescence evidenced delocalization of Myosin-Vb at enterocytes only for the higher dose. Hematology parameters showed random variations after 7 days from administration, but a later apparent recover after 14 and 21 days. The study evaluated the potential of high doses of oral administration of ivermectin formulation, which could be an alternative with benefits in high compliance therapies.

Advances in the Design of pH-Sensitive Cubosome Liquid Crystalline Nanocarriers for Drug Delivery Applications

Nanostructure bicontinuous cubic phase self-assembled materials are receiving expanding applications as biocompatible delivery systems in various therapeutic fields. The functionalization of cubosome, spongosome, hexosome and liposome nanocarriers by pH-sensitive lipids and/or pH-sensitive polymer shells offers new opportunities for oral and topical drug delivery towards a new generation of cancer therapies. The electrochemical behavior of drug compounds may favor pH-triggered drug release as well. Here, we highlight recent investigations, which explore the phase behavior of mixed nonlamellar lipid/fatty acid or phospholipid systems for the design of pH-responsive and mucoadhesive drug delivery systems with sustained-release properties. X-ray diffraction and small-angle X-ray scattering (SAXS) techniques are widely used in the development of innovative delivery assemblies through detailed structural analyses of multiple amphiphilic compositions from the lipid/co-lipid/water phase diagrams. pH-responsive nanoscale materials and nanoparticles are required for challenging therapeutic applications such as oral delivery of therapeutic proteins and peptides as well as of poorly water-soluble substances. Perspective nanomedicine developments with smart cubosome nanocarriers may exploit compositions elaborated to overcome the intestinal obstacles, dual-drug loaded pH-sensitive liquid crystalline architectures aiming at enhanced therapeutic efficacy, as well as composite (lipid/polyelectrolyte) types of mucoadhesive controlled release colloidal cubosomal formulations for the improvement of the drugs' bioavailability.

Ionically crosslinked polyelectrolyte nanoparticle formation mechanisms: the significance of mixing

Mixing oppositely charged polyelectrolytes and multivalent counterion solutions at low concentrations leads to the formation of colloidal ionically crosslinked polyelectrolyte particles. Due to the rapid reaction kinetics, the complexation processes and the final product could vary significantly when changing the mixing efficiency, which was often overlooked in previous studies. To investigate the effect of mixing on the polyelectrolyte-based colloid formation, we use chitosan/tripolyphosphate mixtures as a model system and compare the particle formation under flash nano-complexation (FNC, representing rapid and efficient mixing) and conventional dropwise mixing. It turns out that the non-uniform mixing and rapid complex formation during conventional mixing lead to particle formation at a low tripolyphosphate : chitosan ratio, which could be avoided by FNC. When mixing using FNC, the particle formation started at a critical tripolyphosphate : glucosamine ratio, below which only soluble complexes exist, and such a critical ratio is independent of the chitosan molecular weight and charge density. Homogeneous mixing also leads to the formation of a large amount of small primary particles without further aggregation due to the rapid consumption of free crosslinking counterions. Such a strong dependency of ionically crosslinked polyelectrolyte colloid formation on the mixing efficiency was also demonstrated using other polyelectrolytes and counterions. Thus, the mixing efficiency could have a significant impact on the interpretation of the complexation process and the mechanisms and should be carefully discussed when studying ionically crosslinked polyelectrolyte colloids.

Biotin-functionalized copolymeric PEG-PCL micelles for in vivo tumour-targeted delivery of artemisinin

Artemisinin is used as an antimalarial and anticancer agent with minimal toxic effects on the host body. Biotin-PEG-PCL polymers have been used for targeted drug delivery to cancer, as well as to improve the pharmacokinetics of the drug and reduce its effects. In this study, biotin-conjugated copolymers were fabricated with polymerization of the ring opening method and the properties of copolymer and nanoparticles were investigated using various techniques. The toxicity of artemisinin and its nanoparticles have been investigated on MCF-7 and normal HFF2 cells. The results showed that the encapsulation efficacy of artemisinin in nanoparticles was 45.5 ± 0.41%. The release profile of the drug indicates that the release is slow and controlled and is approximately pH dependent. The results of artemisinin cell culture on human breast cancer cells showed that biotin-PEG-PCL nanoparticles had an inhibitory effect on MCF-7 cells and had no toxic effects on HFF2 cells. Anticancer activity in vivo in the 4T1 breast cancer model showed that tumour volumes were decreased up 40 mm³ by ART-loaded micelles and 76 mm³ by free ART, compared to the control group (2150 mm). In vivo results showed that this formulation significantly increases the accumulation of substances in the tumours. Therefore, the molecular formulation of ART-based copolymers can be a desirable process for cancer treatment purposes.

Chitosan-Based Nanomaterials for Drug Delivery

This review discusses different forms of nanomaterials generated from chitosan and its derivatives for controlled drug delivery. Nanomaterials are drug carriers with multiple features, including target delivery triggered by environmental, pH, thermal responses, enhanced biocompatibility, and the ability to cross the blood-brain barrier. Chitosan (CS), a natural polysaccharide largely obtained from marine crustaceans, is a promising drug delivery vector for therapeutics and diagnostics, owing to its biocompatibility, biodegradability, low toxicity, and structural variability. This review describes various approaches to obtain novel CS derivatives, including their distinct advantages, as well as different forms of nanomaterials recently developed from CS. The advanced applications of CS-based nanomaterials are presented here in terms of their specific functions. Recent studies have proven that nanotechnology combined with CS and its derivatives could potentially circumvent obstacles in the transport of drugs thereby improving the drug efficacy. CS-based nanomaterials have been shown to be highly effective in targeted drug therapy.