Porous hydrophilic core/hydrophobic shell nanoparticles for particle size and drug release control

Increased radical scavenging activity of thymoquinone and l-ascorbic acid dual encapsulated in palmitoyl-chitosan nanoparticles in a human normal lung fibroblast, MRC-5 due to synergistic antioxidative effects

Less effective antioxidant supplementation in combating free radicals is often related to the lack of the formulation of carriers. The antioxidant may be one of the most powerful substances but is marred by poor uptake by cells when the carrier degraded and dissolved too rapidly. Nanoparticle (NP) systems are promising in overcoming the problem since they provide high surface area to enhance encapsulation and release efficiency. With the right selection of material, NP carriers could function as constructive antioxidant cargos. Generally, NPs carry only one active ingredient; this study, however, utilized chitosan nanoparticles (CNPs) and hydrophobically modified palmitoyl-chitosan nanoparticles (PCNPs) that were dual encapsulated with antioxidants of different polarities, namely, hydrophobic thymoquinone (TQ) and hydrophilic l-ascorbic acid (LAA) to evaluate their combination effects in scavenging free radicals. The antioxidants followed zero-order release kinetics with a controlled release manner for about 48 h. The interaction effects between TQ and LAA loaded in the NP systems were determined by classical isobologram (CI) values. The CI values were derived by a diphenyl picrylhydrazyl (DPPH) assay, a radical scavenging activity assay. Combined TQ and LAA had CI values of less than one, with a lower value in the PCNP system than in the CNP system. This indicates that the interaction between those antioxidants showed higher synergistic effects in PCNPs, which enhanced the DPPH radical scavenging activities. The antioxidative potential of compound(s) encapsulated in the PCNP carrier was further experimented by a reactive oxygen species (ROS) assay on a human normal lung fibroblast cell line (MRC-5) as lung is one of the organs with high accumulation of free radicals. About 48 h post treatment, the dual-loaded TQ and LAA in PCNPs showed the lowest ROS level in comparison to single-loaded antioxidants and bare antioxidant delivery. The hydrogen peroxide (H2O2) radical scavenging was influenced by both the controlled release property of the PCNP system and the synergy between TQ and LAA. In short, dual-loaded TQ and LAA in the hydrophobically modified PCNP had effectively depicted the capability of a single CS-based nanocarrier to hold more than one compound at a time to function as a potent radical scavenger.

Core-shell microparticles: From rational engineering to diverse applications

Core-shell microparticles, composed of solid, liquid, or gas bubbles surrounded by a protective shell, are gaining considerable attention as intelligent and versatile carriers that show great potential in biomedical fields. In this review, an overview is given of recent developments in design and applications of biodegradable core-shell systems. Several emerging methodologies including self-assembly, gas-shearing, and coaxial electrospray are discussed and microfluidics technology is emphasized in detail. Furthermore, the characteristics of core-shell microparticles in artificial cells, drug release and cell culture applications are discussed and the superiority of these advanced multi-core microparticles for the generation of artificial cells is highlighted. Finally, the respective developing orientations and limitations inherent to these systems are addressed. It is hoped that this review can inspire researchers to propel the development of this field with new ideas.

Electrospraying as a novel process for the synthesis of particles/nanoparticles loaded with poorly water-soluble bioactive molecules

Hydrophobicity and low aqueous-solubility of different drugs/nutraceuticals remain a persistent challenge for their development and clinical/food applications. A range of nanotechnology strategies have been implemented to address this issue, and amongst which a particular emphasis has been made on those that afford an improved biological performance and tunable release kinetic of bioactives through a one-step process. More recently, the technique of electrospraying (or electrohydrodynamic atomization) has attained notable impulse in virtue of its potential to tune attributes of nano/micro-structured particles (e.g., porosity, particle size, etc.), rendering a near zero-order release kinetics, diminished burst release manner, as well as its simplicity, reproducibility, and applicability to a broad spectrum of hydrophobic and poorly water-soluble bioactives. Controlled morphology or monodispersity of designed particles could be properly obtained via electrospraying, with a high encapsulation efficiency and without unfavorable denaturation of thermosensitive bioactives upon encapsulation. This paper overviews the recent technological advances in electrospraying for the encapsulation of low queues-soluble bioactive agents. State-of-the-art, advantages, applications, and challenges for its implementation in pharmaceutical/food researches are also discussed.

l-Ascorbic Acid and Thymoquinone Dual-Loaded Palmitoyl-Chitosan Nanoparticles: Improved Preparation Method, Encapsulation and Release Efficiency

Encapsulation of dual compounds of different characters (hydrophilic and hydrophobic) in single nanoparticles carrier could reach the site of action more accurately with the synergistic effect but it is less investigated. In our previous findings, combined-compounds encapsulation and delivery from chitosan nanoparticles were impaired by the hydrophilicity of chitosan. Therefore, hydrophobic modification on chitosan with palmitic acid was conducted in this study to provide an amphiphilic environment for better encapsulation of antioxidants; hydrophobic thymoquinone (TQ) and hydrophilic l-ascorbic acid (LAA). Palmitoyl chitosan nanoparticles (PCNPs) co-loaded with TQ and LAA (PCNP-TQ-LAA) were synthesized via the ionic gelation method. Few characterizations were conducted involving nanosizer, Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). UV–VIS spectrophotometry was used to analyze the encapsulation and release efficiency of the compounds in PCNPs. Successfully modified PCNP-TQ-LAA had an average particle size of 247.7 ± 24.0 nm, polydispersity index (PDI) of 0.348 ± 0.043 and zeta potential of 19.60 ± 1.27 mV. Encapsulation efficiency of TQ and LAA in PCNP-TQ-LAA increased to 64.9 ± 5.3% and 90.0 ± 0%, respectively. TQ and LAA in PCNP-TQ-LAA system showed zero-order release kinetics, with a release percentage of 97.5% and 36.1%, respectively. Improved preparation method, encapsulation and release efficiency in this study are anticipated to be beneficial for polymeric nanocarrier development.

Combination of microfluidic chip and electrostatic atomization for the preparation of drug-loaded core-shell nanoparticles

To overcome the shortcoming of drug-loaded nanoparticles, such as high initial burst release and wide size distribution, a novel manufacturing technique for core-shell structure nanoparticle was developed by combining microfluidic chip and electrohydrodynamic atomization. In this study, the mixture solution of the surfactant 1, 2- dipalmitoyl-sn-glycero-3-phosphoglycerol and the polymeric coating material polylactic-glycolic-acid was introduced into the outer microchannel of the microfluidic chip as the particle's shell. And the encapsulated drug paclitaxel was pumped into the inner microchannel as the core. Then, the particles with a nanoscale-size core-shell structure were generated by applying an electric field on the laminar flow which was formed in the microfluidic chip. Operation parameters, including working voltage, carrier material and surfactant concentration as well as liquid flow rates were optimized for nanoparticles generation. The properties of drug-loaded nanoparticles in terms of their particle size, zeta potential and encapsulation efficiency were investigated. Under the optimal experimental conditions, the particle size was approximately 145 nm and encapsulation efficiency reached 92%. Moreover, the drug release of these nanoparticles could be prolonged over a significant period for more than ten days. It can be expected that this innovative approach could provide a useful platform for drug-loaded core-shell nanoparticles developing.

Electrospun nanofibers as versatile platform in antimicrobial delivery: current state and perspectives

Nanotechnology has attracted increasing interest in different aspects of biotechnology. The fabrication of electrospun nanofibers (NFs) containing antibacterial agents for antimicrobial applications has been significantly enhanced in recent years. In the current review, various electrospun NFs with antimicrobial properties were introduced and evaluated. The main focus was on the recent developments and applications of antimicrobial electrospun NFs incorporated with different antimicrobial agents, including metal nanoparticles (NPs), antibiotics, quaternized ammonium compounds, triclosan, herbal extracts, carbon nanomaterials, and antimicrobial biopolymers with inherent antimicrobial properties. The search results revealed that antimicrobial containing electrospun NFs had enhanced antimicrobial performance with various biomedical applications compared to the traditional antimicrobial materials. According to the reported results, most of the studies were of an investigative nature and were mostly based on in vitro tests. Hence, further examination on in vivo clinical performance of these antimicrobial NFs seems necessary. However, these antimicrobial NFs appear to have the potential to achieve clinical usefulness and commercial production in the near future.

Bioactive injectable polymethylmethacrylate/silicate bioceramic hybrid cements for percutaneous vertebroplasty and kyphoplasty

Polymethylmethacrylate (PMMA) cement has been widely used to fill and stabilize hard tissue defects in clinical surgery, especially in percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP). However, the dense body of pure PMMA in defects has no ability to promote bone regeneration. We herein aim to fabricate novel PMMA/silicate bioceramic hybrid cements by adding bioactive calcium silicate (CS) particles into PMMA to endow PMMA/CS hybrid cements with bioactivity and biodegradability without losing the excellent mechanical strength and injectability. Following comprehensive characterization of the physicochemical properties and in vitro bioactivity study, our results showed compared with PMMA cement, the constructed PMMA/CS hybrid cements possessed significantly lower curing temperatures and simultaneously retained the acceptable mechanical strength and injectability. Moreover, obvious bioactive ion release and hydroxyapatite formation could be detected and observed after the PMMA/CS hybrid cements were soaked in simulated body fluid, indicating their pronounced bioactivity. A further in vivo study of the PMMA/CS hybrid cements on goat vertebral body defect models reflected that the PMMA/CS hybrid cements could be biodegraded well and could significantly promote new bone formation in defects 6 months of post-injection. Our results suggest that PMMA/CS hybrid cements may be promising candidates for PVP and PKP in clinic.

All-Natural Food-Grade Hydrophilic-Hydrophobic Core-Shell Microparticles: Facile Fabrication Based on Gel-Network-Restricted Antisolvent Method

Hydrophilic-hydrophobic core-shell microparticles are highly appealing for a variety of industrial applications (foods, pharmaceutics, cosmetics, biomedicines, etc.) owing to their unique properties of moisture resistance and controlled release. However, the fabrication of such structured microparticles proves to be nontrivial due to the difficulty in assembling two materials of distinctly different hydrophilicities and hydrophobicities. This paper reports a facile method to fabricate hydrophilic-hydrophobic core-shell microparticles using all-natural food-grade polysaccharides and proteins, based on a novel principle of gel-network-restricted antisolvent precipitation. Immersion of microgel beads prepared from hydrophilic polysaccharides (i.e., alginates, κ-carrageenan, agarose) into a hydrophobic protein solution (i.e., zein in 70% aqueous ethanol) enables slow and controllable antisolvent precipitation of a protein layer around the microbead surface, leading to the formation of a hydrophilic-hydrophobic core-shell structure. The method applies to various gelling systems and can easily tailor the particle size and shell thickness. The resulting freeze-dried microparticles demonstrate restricted swelling in water, improved moisture resistance, and sustained release of encapsulants, with great potential in applications such as protection of unstable and/or hygroscopic compounds and delivery and controlled release of drugs, bioactives, flavors, etc. The method is rather universal and can be extended to prepare more versatile core-shell structures using a large variety of hydrophilic and hydrophobic materials.

Coaxial Electrohydrodynamic Atomization for the Production of Drug-Loaded Micro/Nanoparticles

Coaxial electrohydrodynamic atomization (CEHDA) presents a promising technology for preparing drug-loaded micro/nanoparticles with core-shell structures. Recently, CEHDA has attracted tremendous attention based on its specific advantages, including precise control over particle size and size distribution, reduced initial burst release and mild preparation conditions. Moreover, with different needles, CEHDA can produce a variety of drug-loaded micro/nanoparticles for drug delivery systems. In this review, we summarize recent advances in using double-layer structure, multilayer structure and multicomponent encapsulation strategies for developing micro/nanoparticles. The merits of applying multiplexed electrospray sources for high-throughput production are also highlighted.

Approaches in topical ocular drug delivery and developments in the use of contact lenses as drug-delivery devices

Drug-delivery approaches have diversified over the last two decades with the emergence of nanotechnologies, smart polymeric systems and multimodal functionalities. The intended target for specific treatment of disease is the key defining developing parameter. One such area which has undergone significant advancements relates to ocular delivery. This has been expedited by the development of material advancement, mechanistic concepts and through the deployment of advanced process technologies. This review will focus on the developments within lens-based drug delivery while touching on conventional and current methods of topical ocular drug delivery. A summary table will provide quick reference to note the key findings in this area. In addition, the review also elucidates current theranostic and diagnostic approaches based on ocular lenses.

Intracellular responsive dual delivery by endosomolytic polyplexes carrying DNA anchored porous silicon nanoparticles

Bioresponsive cytosolic nanobased multidelivery has been emerging as an enormously challenging novel concept due to the intrinsic protective barriers of the cells and hardly controllable performances of nanomaterials. Here, we present a new paradigm to advance nano-in-nano integration technology amenable to create multifunctional nanovehicles showing considerable promise to overcome restrictions of intracellular delivery, solve impediments of endosomal localization and aid effectual tracking of nanoparticles. A redox responsive intercalator chemistry comprised of cystine and 9-aminoacridine is designed as a cross-linker to cap carboxylated porous silicon nanoparticles with DNA. These intelligent nanocarriers are then encapsulated within novel one-pot electrostatically complexed nano-networks made of a zwitterionic amino acid (cysteine), an anionic bioadhesive polymer (poly(methyl vinyl ether-alt-maleic acid)) and a cationic endosomolytic polymer (polyethyleneimine). This combined nanocomposite is successfully tested for the co-delivery of hydrophobic (sorafenib) or hydrophilic (calcein) molecules loaded within the porous core, and an imaging agent covalently integrated into the polyplex shell by click chemistry. High loading capacity, low cyto- and hemo-toxicity, glutathione responsive on-command drug release, and superior cytosolic delivery are shown as achievable key features of the proposed formulation. Overall, formulating drug molecules, DNA and imaging agents, without any interference, in a physico-chemically optimized carrier may open a path towards broad applicability of these cost-effective multivalent nanocomposites for treating different diseases.