Chitosan hollow nanospheres fabricated from biodegradable poly-d,l-lactide-poly(ethylene glycol) nanoparticle templates

Sustainable production of porous chitosan microparticles by energy-efficient membrane emulsification

In drug delivery, it is common to use porous particles as carrier media, instead of dense particles, due to their high specific surface area and available entrapment volume, which allows a higher amount of drug to be encapsulated and then released. Chitosan microparticles are extensively used in drug delivery, but porous chitosan microparticles are scarcely reported. In this work, the preparation of porous chitosan microparticles using membrane emulsification is addressed, a technology that involves mild operating conditions and less energy consumption than traditional methods (such as ultrasound), and with higher control of the particle size. The dense structure is obtained by a water-in-oil emulsion. The porous structure is obtained by a gas-in-water-in-oil G/W/O double emulsion, where argon bubbles get entrapped in an aqueous chitosan solution that is further emulsified in a paraffin/petroleum ether mixture. Porous chitosan particles were obtained with sizes of 7.7 ± 1.6 μm, which was comparable with dense chitosan particles (6.2 ± 2.3 μm). The pore structure was optimized by varying the argon flow rate, being optimized at 0.24 L h-1. The impact of drug loading by adsorption or encapsulation, and of the drug release behaviour when using porous and dense particles were assessed, using the protein bovine serum albumin (BSA) as a model drug. The results showed that by encapsulating BSA the loading efficiency was above 95 % for both types of particles, with the release being slightly slower for the dense particles. As for the adsorbed BSA, the loading efficiency was significantly higher for porous particles - 70 % - against the 40 % for dense particles. Porous chitosan particles were successfully obtained using the membrane emulsification technology and showed that these carriers are advantageous regarding drug loading and release.

Chitosan-Coated PLGA Nanoparticles for Enhanced Ocular Anti-Inflammatory Efficacy of Atorvastatin Calcium

Background

Atorvastatin calcium (AT) is an ocular anti-inflammatory with limited bioavailability when taken orally due to its low solubility in low pH and extensive first-pass effect. To overcome these problems, AT was entrapped in polymeric nanoparticles (NPs) to improve surface properties and sustained release, in addition to achieving site-specific action.

Methods

AT was entrapped in chitosan (CS)-coated polylactic-co-glycolic acid (PLGA) NPs to form AT-PLGA-CS-NPs (F1). F1 and free AT were embedded in thermosensitive Pluronic^®127-hydroxypropyl methylcellulose (HPMC) to form thermosensitive gels (F2) and (F3) while F4 is AT suspension in water. F1 was assessed for size, surface charge, polydispersity index (PDI), and morphology. F2 and F3 were examined for gelation temperature, gel strength, pH, and viscosity. In vitro release of the four formulations was also investigated. The ocular irritancy and anti-inflammatory efficacy of formulations against prostaglandin E₁-(PGE₁) induced ocular inflammation in rabbits were investigated by counting the polymorphonuclear leukocytes (PMNs) and protein migrated in tears.

Results

Oval F1 of 80.0–190.0±21.6 nm exhibited a PDI of 0.331 and zeta potential of ‏17.4±5.62 mV with a positive surface charge. F2 and F3 gelation temperatures were 35.17±0.22°C and 36.93±0.31°C, viscosity 12,243±0.64 and 9759±0.22 cP, gel strength 15.56±0.6 and 12.45±0.1 s, and pHs of 7.4±0.02 and 7.4±0.1, respectively. In vitro release of F1, F2, F3, and F4 were 48.21±0.31, 26.48±0.5, 84.76±0.11, and 100% after 24 hrs, respectively. All formulations were non-irritant. F2 significantly inhibited lid closure up to 3 h, PMN counts and proteins in tear fluids up to 5 h compared to other formulations.

Conclusion

AT-PLGA-CS-NP thermosensitive gels proved to be successful ocular anti-inflammatory drug delivery systems.

A CRISPR/Cas9 based polymeric nanoparticles to treat/inhibit microbial infections

The latest breakthrough towards the adequate and decisive methods of gene editing tools provided by CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeat/CRISPR Associated System), has been repurposed into a tool for genetically engineering eukaryotic cells and now considered as the major innovation in gene-related disorders. Nanotechnology has provided an alternate way to overcome the conventional problems where methods to deliver therapeutic agents have failed. The use of nanotechnology has the potential to safe-side the CRISPR/Cas9 components delivery by using customized polymeric nanoparticles for safety and efficacy. The pairing of two (CRISPR/Cas9 and nanotechnology) has the potential for opening new avenues in therapeutic use. In this review, we will discuss the most recent advances in developing nanoparticle-based CRISPR/Cas9 gene editing cargo delivery with a focus on several polymeric nanoparticles including fabrication proposals to combat microbial infections.

Development of drug-loaded chitosan hollow nanoparticles for delivery of paclitaxel to human lung cancer A549 cells

In this study, biodegradable chitosan hollow nanospheres (CHN) were fabricated using polystyrene nanospheres (PS) as templates. CHN were applied to increase the solubility of poorly water-soluble drugs. The lung cancer drug paclitaxel (PTX), which is used as a model drug, was loaded into CHN by the adsorption equilibrium method. The drug-loaded sample (PTX-CHN) offered sustained PTX release and good bioavailability. The state characterization of PTX by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that the PTX absorbed into CHN existed in an amorphous state. An in vitro toxicity experiment indicated that CHN were nontoxic as carriers of poorly water-soluble drugs. The PTX-CHN produced a marked inhibition of lung cancer A549 cells proliferation and encouraged apoptosis. A cell uptake experiment indicated that PTX-CHN was successfully taken up by lung cancer A549 cells. Furthermore, a degradation experiment revealed that CHN were readily biodegradable. These findings state clearly that CHN can be regarded as promising biomaterials for lung cancer treatment.

Template-based syntheses for shape controlled nanostructures

A variety of nanostructured materials are produced through template-based synthesis methods, including zero-dimensional, one-dimensional, and two-dimensional structures. These span different forms such as nanoparticles, nanowires, nanotubes, nanoflakes, and nanosheets. Many physical characteristics of these materials such as the shape and size can be finely controlled through template selection and as a result, their properties as well. Reviewed here are several examples of these nanomaterials, with emphasis specifically on the templates and synthesis routes used to produce the final nanostructures. In the first section, the templates have been discussed while in the second section, their corresponding synthesis methods have been briefly reviewed, and lastly in the third section, applications of the materials themselves are highlighted. Some examples of the templates frequently encountered are organic structure directing agents, surfactants, polymers, carbon frameworks, colloidal sol-gels, inorganic frameworks, and nanoporous membranes. Synthesis methods that adopt these templates include emulsion-based routes and template-filling approaches, such as self-assembly, electrodeposition, electroless deposition, vapor deposition, and other methods including layer-by-layer and lithography. Template-based synthesized nanomaterials are frequently encountered in select fields such as solar energy, thermoelectric materials, catalysis, biomedical applications, and magnetowetting of surfaces.

New acrylate terpolymer-based nanoparticles for the release of nucleic acid: a preliminary study

PURPOSE

Nano-drug delivery systems based on polymeric biomaterials have received considerable interest as drug delivery vehicles. In this work, radical polymerization was carried out in order to obtain nanoparticles based on a new acrylate terpolymer (PBMA-(PEG)MEMA-PDMAEMA).

METHODS

Nanoparticles were developed in the form both of nanospheres and nanocapsules, an innovative kind of hollow nanoparticles with a great potential because of their low effective density and high specific surface area. The ability of the nanoparticles to load and then release a nucleic acid (DNA) to be used in cancer treatment was also investigated.

RESULTS

Scanning electron microscopy analysis showed a spherical shape, nanometric dimensions, and a homogeneous distribution of the nanoparticles, also confirmed by dynamic light scattering measurements. Fourier-transform infrared spectroscopy chemical imaging analysis carried out on the nanocapsules before and after removal of the core demonstrated the presence of the cavity. High-performance liquid chromatography analysis confirmed good encapsulation efficiency of DNA both for nanospheres and nanocapsules. Drug release tests showed controlled release kinetics for both the systems with a high release of DNA in the first hours. In vitro MTT assay showed that the particles do not have cytotoxic effects on the cells.

CONCLUSIONS

The preliminary investigation showed that the terpolymer-based nanoparticles developed in this study could be good candidates to be used as innovative and versatile gene delivery systems.

Core-shell designed scaffolds for drug delivery and tissue engineering

Scaffolds that secure and deliver therapeutic ingredients like signaling molecules and stem cells hold great promise for drug delivery and tissue engineering. Employing a core-shell design for scaffolds provides a promising solution. Some unique methods, such as co-concentric nozzle extrusion, microfluidics generation, and chemical confinement reactions, have been successful in producing core-shelled nano/microfibers and nano/microspheres. Signaling molecules and drugs, spatially allocated to the core and/or shell part, can be delivered in a controllable and sequential manner for optimal therapeutic effects. Stem cells can be loaded within the core part on-demand, safely protected from the environments, which ultimately affords ex vivo culture and in vivo tissue engineering. The encapsulated cells experience three-dimensional tissue-mimic microenvironments in which therapeutic molecules are secreted to the surrounding tissues through the semi-permeable shell. Tuning the material properties of the core and shell, changing the geometrical parameters, and shaping them into proper forms significantly influence the release behaviors of biomolecules and the fate of the cells. This topical issue highlights the immense usefulness of core-shell designs for the therapeutic actions of scaffolds in the delivery of signaling molecules and stem cells for tissue regeneration and disease treatment.

Preparation and application of micro/nanoparticles based on natural polysaccharides

Polysaccharides have attracted more and more attentions and been recognized to be the most promising materials in recent years because of their outstanding merits such as easily available, non-toxic, biocompatible, biodegradable, and easily modified. Considerable research efforts have been directed toward developing polysaccharides-based micro/nanoparticles (PM/NPs). The new major studies of PM/NPs over the past few years are outlined in this review. Methods of preparation, including self-assembly, ionic-gelation, complex coacervation, emulsification, and desolvation method and some others, are summarized. Different applications of PM/NPs in the field of drug-delivery system are highlighted. Besides, another novel application of PM/NPs that are used as emulsifiers to stabilize Pickering emulsion is also introduced. These environmental-friendly particle emulsifiers have received reasonable attention due to their novel applications, especially in food, cosmetics, and pharmaceutics. From literature surveys, we realized that studies on PM/NP systems for different applications have increased rapidly. Hence, the present review is timely.