Bioactive Hybrid Particles from Poly(D,L-lactide-co-glycolide) Nanoparticle Stabilized Lipid Droplets

Tailoring the release of drugs having different water solubility by hybrid polymer-lipid microparticles with a biphasic structure

The aim of this study is to investigate the potential of hybrid polymer-lipid microparticles with a biphasic structure (b-MPs) as drug delivery system. Hybrid b-MPs of Compritol®888 ATO as main lipid constituent of the shell and polyethylene glycol 400 as core material were produced by an innovative solvent-free approach based on spray congealing. To assess the suitability of hybrid b-MPs to encapsulate various types of APIs, three model drugs (fluconazole, tolbutamide and nimesulide) with extremely different water solubility were loaded into the polymeric core. The hybrid systems were characterized in terms of particle size, morphology and physical state. Various techniques (e.g. optical, Confocal Raman and Scanning Electron Microscopy) were used to investigate the influence of the drugs on different aspects of the b-MPs, including external and internal morphology, properties at the lipid/polymer interface and drug distribution. Hybrid b-MPs were suitable for the encapsulation of all drugs (encapsulation efficiency > 90 %) regardless the drug hydrophobic/hydrophilic properties. Finally, the drug release behaviors from hybrid b-MPs were studied and compared with traditional solid lipid MPs (consisting of only the lipid carrier). Due to the combination of lipid and polymeric materials, hybrid b-MPs showed a wide array of release profiles that depends on their composition, the type of loaded drug, the drug loading amount and location, providing a versatile platform and allowing the formulators to finely balance the release performance of drugs intended for oral administration. Overall, the study demonstrates that hybrid, solvent-free b-MPs produced by spray congealing are an extremely versatile delivery platform able to efficiently encapsulate and release very different types of drug compounds.

Inulin-lipid hybrid (ILH) microparticles promote pH-triggered release of rifampicin within infected macrophages

Intracellular bacteria serve as a problematic source of infection due to their ability to evade biological immune responses and the inability for conventional antibiotics to efficiently penetrate cellular membranes. Subsequently, new treatment approaches are urgently required to effectively eradicate intracellular pathogens residing within immune cells (e.g. macrophages). In this study, the poorly soluble and poorly permeable antibiotic, rifampicin, was re-purposed via micro-encapsulation within inulin-lipid hybrid (ILH) particles for the treatment of macrophages infected with small colony variants of Staphylococcus aureus (SCV S. aureus). Rifampicin-encapsulated ILH (Rif-ILH) microparticles were synthesized by spray drying a lipid nano-emulsion, with inulin dissolved throughout the aqueous phase and rifampicin pre-loaded within the lipid phase. Rif-ILH were strategically designed and engineered with pH-responsive properties to promote lysosomal drug release upon cellular internalization, while preventing premature rifampicin release in plasma-simulating media. The pH-responsiveness of Rif-ILH was controlled by the acid-mediated hydrolysis of the inulin coating, where exposure to acidic media simulating the lysosomal environment of macrophages triggered hydrolysis of the oligofructose chain and the subsequent diffusion of rifampicin from Rif-ILH. This pH-provoked release mechanism, as well as the ability for ILH microparticles to be more readily internalized by macrophages, was found to be influential in triggering a 2.9-fold increase in intracellular rifampicin concentration within infected macrophages, compared to the pure drug. The subsequent increase in exposure of intracellular pathogens to rifampicin leads to a ~ 2-log improvement in antibacterial activity for Rif-ILH, at a rifampicin dose of 2.5 µg/mL. Thus, the reduction in viability of intracellular SCV S. aureus, in the absence of cellular toxicity, is indicative of ILH microparticles serving as a unique approach for the safe and efficacious delivery of antibiotics to phagocytic cells for the treatment of intracellular infections.

Self-emulsifying drug delivery systems: a novel approach to deliver drugs

Self-emulsifying drug delivery systems (SEDDS) are a proven method for poorly soluble substances works by increasing the solubility and bioavailability. SEDDS and isotropic mixtures, are composed of oils, surfactants, and occasionally cosolvents. The ability of these formulations and methods to produce microemulsions or fine oil-in-water (o/w) emulsions after moderate stirring and dilution by water phase along the GI tract might be a promising technique for lipophilic agents with dissolution rate-limited absorption. This review provides an outline of SEDDS's numerous advances and biopharmaceutical elements, types, manufacturing, characterization, limitations, and future prospects. The evaluation of SEDDS and its applications are also discussed, focusing on the advances of SEDDS's solid self-emulsifying delivery mechanism and dosage form. By integrating suitable polymer into the formulation, SEDDS may be studied for the creation of a formulation with sustained drug release. This technology's improvement might lead to a new application in the field of medicine delivery. SEDDS has been demonstrated to be quite efficient in increasing oral bioavailability of lipophilic products. SEDDS is one of the promising methods for controlling the characteristics of medications that are not great choices for oral delivery. It is also worth mentioning that SEDDS may be made in variety of solid dosage forms that are acceptable for both oral and parenteral administration.

In Vitro Performance and Chemical Stability of Lipid-Based Formulations Encapsulated in a Mesoporous Magnesium Carbonate Carrier

Lipid-based formulations can circumvent the low aqueous solubility of problematic drug compounds and increase their oral absorption. As these formulations are often physically unstable and costly to manufacture, solidification has been suggested as a way to minimize these issues. This study evaluated the physicochemical stability and in vitro performance of lipid-loaded mesoporous magnesium carbonate (MMC) particles with an average pore size of 20 nm. A medium chain lipid was loaded onto the MMC carrier via physical adsorption. A modified in vitro lipolysis setup was then used to study lipid release and digestion with ¹H nuclear magnetic resonance spectroscopy. The lipid loading efficiency with different solidification techniques was also evaluated. The MMC, unlike more commonly used porous silicate carriers, dissolved during the lipolysis assay, providing a rapid release of encapsulated lipids into solution. The digestion of the dispersed lipid-loaded MMC therefore resembled that of a coarse dispersion of the lipid. The stability data demonstrated minor degradation of the lipid within the pores of the MMC particles, but storage for three months did not reveal extensive degradation. To conclude, lipids can be adsorbed onto MMC, creating a solid powder from which the lipid is readily released into the solution during in vitro digestion. The chemical stability of the formulation does however merit further attention.

Current Status of Supersaturable Self-Emulsifying Drug Delivery Systems

Self-emulsifying drug delivery systems (SEDDSs) are a vital strategy to enhance the bioavailability (BA) of formulations of poorly water-soluble compounds. However, these formulations have certain limitations, including in vivo drug precipitation, poor in vitro in vivo correlation due to a lack of predictive in vitro tests, issues in handling of liquid formulation, and physico-chemical instability of drug and/or vehicle components. To overcome these limitations, which restrict the potential usage of such systems, the supersaturable SEDDSs (su-SEDDSs) have gained attention based on the fact that the inclusion of precipitation inhibitors (PIs) within SEDDSs helps maintain drug supersaturation after dispersion and digestion in the gastrointestinal tract. This improves the BA of drugs and reduces the variability of exposure. In addition, the formulation of solid su-SEDDSs has helped to overcome disadvantages of liquid or capsule dosage form. This review article discusses, in detail, the current status of su-SEDDSs that overcome the limitations of conventional SEDDSs. It discusses the definition and range of su-SEDDSs, the principle mechanisms underlying precipitation inhibition and enhanced in vivo absorption, drug application cases, biorelevance in vitro digestion models, and the development of liquid su-SEDDSs to solid dosage forms. This review also describes the effects of various physiological factors and the potential interactions between PIs and lipid, lipase or lipid digested products on the in vivo performance of su-SEDDSs. In particular, several considerations relating to the properties of PIs are discussed from various perspectives.

Poly(lactic-co-glycolic) Acid-Lipid Hybrid Microparticles Enhance the Intracellular Uptake and Antibacterial Activity of Rifampicin

An urgent demand exists for the development of effective carrier systems that systematically enhance the cellular uptake and localization of antibiotic drugs for the treatment of intracellular pathogens. Commercially available antibiotics suffer from poor cellular penetration, restricting their efficacy against pathogens hosted and protected within phagocytic cells. In this study, the potency of the antibiotic rifampicin against intracellular small colony variants of Staphylococcus aureus was improved through encapsulation within a strategically engineered cell-penetrant delivery system, composed of lipid nanoparticles encapsulated within a poly(lactic-co-glycolic) acid (PLGA) nanoparticle matrix. PLGA-lipid hybrid (PLH) microparticles were synthesized through the process of spray drying, whereby rifampicin was loaded within both the polymer and lipid phases, to create a nanoparticle-in-microparticle system capable of efficient redispersion in aqueous biorelevant media and with programmable release kinetics. The ability of PLH particles to disintegrate into nanoscale agglomerates of the precursor nanoparticles was shown to be instrumental in optimizing rifampicin uptake in RAW264.7 macrophages, with a 7.2- and 1.6-fold increase in cellular uptake, when compared to the pure drug and PLGA microparticles (of an equivalent initial particle size), respectively. The enhanced phagocytosis and extended drug release mechanism (under the acidic macrophage environment) associated with PLH particles induced a 2.5-log reduction in colony forming units compared to initial colonies at 2.50 μg/mL rifampicin dose. Thus, the ability of PLH particles to reduce the intracellular viability of S. aureus, without demonstrating significant cellular toxicity, satisfies the requirements necessary for the safe and efficacious delivery of antibiotics to macrophages for the treatment of intracellular infections.

An update on polymer-lipid hybrid systems for improving oral drug delivery

INTRODUCTION

A promising approach that has recently emerged to overcome the complex biobarriers and interrelated challenges associated with oral drug absorption is to combine the benefits of polymeric and lipid-based nanocarriers within one hybrid system. This multifaceted formulation strategy has given rise to a plethora of polymer-lipid hybrid (PLH) systems with varying nanostructures and biological activities, all of which have demonstrated the ability to improve the biopharmaceutical performance of a wide range of challenging therapeutics.

AREAS COVERED

The multitude of polymers that can be combined with lipids to exert a synergistic effect for oral drug delivery have been identified, reviewed and critically evaluated. Specific focus is attributed to preclinical studies performed within the past 5 years that have elucidated the role and mechanism of the polymer phase in altering the oral absorption of encapsulated therapeutics.

EXPERT OPINION

The potential of PLH systems has been clearly identified; however, improved understanding of the structure-activity relationship between PLH systems and oral absorption is fundamental for translating this promising delivery approach into a clinically relevant formulation. Advancing research within this field to identify optimal polymer, lipid combinations and engineering conditions for specific therapeutics are therefore encouraged.

Solidification to improve the biopharmaceutical performance of SEDDS: Opportunities and challenges

Self-emulsifying drug delivery systems (SEDDS) offer potential for overcoming the inherent slow dissolution and poor oral absorption of hydrophobic drugs by retaining them in a solubilised state during gastrointestinal transit. However, the promising biopharmaceutical benefits of liquid lipid formulations has not translated into widespread commercial success, due to their susceptibility to long term storage and in vivo precipitation issues. One strategy that has emerged to overcome such limitations, is to combine the solubilisation and dissolution enhancing properties of lipids with the stabilising effects of solid carrier materials. The development of intelligent hybrid drug formulations has presented new opportunities to harness the potential of emulsified lipids in optimising oral bioavailability for lipophilic therapeutics. Specific emphasis of this review is placed on the impact of solidification approaches and excipients on the biopharmaceutical performance of self-emulsifying lipids, with findings highlighting the key design considerations that should be implemented when developing hybrid lipid-based formulations.

Engineering intelligent particle-lipid composites that control lipase-mediated digestion

Nanostructured particle-lipid composites have emerged as state-of-the-art carrier systems for poorly water-soluble bioactive molecules due to their ability to control and enhance the lipase-mediated hydrolysis of encapsulated triglycerides, leading to a subsequent improvement in the solubilisation and absorption of encapsulated species. The first generation of particle-lipid composites (i.e. silica-lipid hybrid (SLH) microparticles) were designed and fabricated by spray drying a silica nanoparticle-stabilised Pickering emulsion, to create a novel three-dimensional architecture, whereby lipid droplets were encapsulated within a porous matrix support. The development of SLH microparticles has acted as a solid foundation for the synthesis of several next generation particle-lipid composites, including polymer-lipid hybrid (PLH) and clay-lipid hybrid systems (CLH), which present lipase with unique lipid microenvironments for optimised lipolysis. This review details the methods utilised to engineer lipid hybrid particles and the strategic investigations that have been performed to determine the influence of key material characteristics on digestion enzyme activity. In doing so, this provides insight into manipulating the mechanism of lipase action through the intelligent design of lipid-based biomaterials for their use in drug delivery formulations and novel functional foods.

Novel core-shell dextran hybrid nanosystem for anti-viral drug delivery

Zidovudine (AZT) is an antiviral drug extensively used for combating the global pandemic- HIV/AIDS. However, its uses are overshadowed by its short half -life, poor aqueous solubility and inability to cross physiological barriers. This study highlights a nanosystem consisting of dextran and stearic acid for AZT delivery. This hybrid nanoparticle was prepared by double emulsion solvent evaporation method. The morphological analysis of the prepared nanoparticles was carried out by transmission electron microscopy (TEM) and structural analysis through FTIR spectroscopy. Haemolysis, blood cell aggregation and cytotoxicity evaluations were also performed. These biological evaluations indicated that the nanoparticles were compatible and fluorescence microscopy studies demonstrated increased cellular internalization of drug loaded hybrid nanoparticles when compared with free drug molecules. The experimental outcomes indicate that the prepared nanoparticles are highly biocompatible haemocompatible and effective in getting internalized into cells of neural origin. These results highlight the feasibility and efficacy of the hybrid nanoparticles for effective delivery of zidovudine.

Emulsion Microgel Particles as High-Performance Bio-Lubricants

Starch-based emulsion microgel particles with different starch (15 and 20 wt %) and oil contents (0-15 wt %) were synthesized, and their lubrication performance under physiological conditions was investigated. Emulsion microgels were subjected to skin mimicking or oral cavity mimicking conditions, i.e., smooth hydrophobic polydimethylsiloxane ball-on-disc tribological tests, in the absence or presence of salivary enzyme (α-amylase). In the absence of enzyme, emulsion microgel particles (30-60 vol % particle content) conserved the lubricating properties of emulsion droplets, providing considerably lower friction coefficients (μ ≤ 0.1) in the mixed lubrication regime compared to plain microgel particles (0 wt % oil). Upon addition of enzyme, the lubrication performance of emulsion microgel particles became strongly dependent on the particles' oil content. Microgel particles encapsulating 5-10 wt % oil showed a double plateau mixed lubrication regime having a lowest friction coefficient μ ∼ 0.03 and highest μ ∼ 0.1, the latter higher than with plain microgel particles. An oil content of 15 wt % was necessary for the microgel particles to lubricate similarly to the emulsion droplets, where both systems showed a normal mixed lubrication regime with μ ≤ 0.03. The observed trends in tribology, theoretical considerations, and the combined results of rheology, light scattering, and confocal fluorescence microscopy suggested that the mechanism behind the low friction coefficients was a synergistic enzyme- and shear-triggered release of the emulsion droplets, improving lubrication. The present work thus demonstrates experimentally and theoretically a novel biolubricant additive with stimuli-responsive properties capable of providing efficient boundary lubrication between soft polymeric surfaces. At the same time, the additive should provide an effective delivery vehicle for oil soluble ingredients in aqueous media. These findings demonstrate that emulsion microgel particles can be developed into multifunctional biolubricant additives for future use in numerous soft matter applications where both lubrication and controlled release of bioactives are essential.

Graphene Oxide Quantum Dots as Novel Nanozymes for Alcohol Intoxication

Alcohol overconsumption as a worldwide issue results in alcoholic liver disease (ALD), such as steatosis, alcoholic hepatitis, and cirrhosis. The treatment of ALD has been widely investigated but remains challenging. In this work, the protective effects of graphene oxide quantum dots (GOQDs) as novel nanozymes against alcohol overconsumption are discovered, and the specific mechanisms underlying these effects are elucidated via omics analysis. GOQDs dramatically alleviate the reduction of cell viability induced by ethanol and can act as nanozymes to accelerate ethanol metabolism and avoid the accumulation of toxic intermediates in cells. Mitochondrial damage and the excessive generation of free radicals were mitigated by GOQDs. The mechanisms underlying the cellular protective effects were also related to alterations in metabolic and protein signals, especially those involved in lipid metabolism. The moderately increased autophagy induced by GOQDs explained the removal of accumulated lipids and the subsequent elimination of excessive GOQDs. These findings suggest that GOQDs have an antagonistic capacity against the adverse effects caused by ethanol and provide new insights into the direct applications of GOQDs. In addition to traditional antioxidation, this work also establishes metabolomics and proteomics techniques as effective tools to discover the multiple functions of nanozymes.

Nanostructured Montmorillonite Clay for Controlling the Lipase-Mediated Digestion of Medium Chain Triglycerides

Biocompatible lipid hybrid particles composed of montmorillonite and medium chain triglycerides were engineered for the first time by spray drying oil-in-water emulsions stabilized by montmorillonite platelets to form montmorillonite-lipid hybrid (MLH) microparticles containing up to 75% w/w lipid. In vitro lipolysis studies under simulated intestinal conditions indicated that the specific porous nanoarchitecture and surface chemistry of MLH particles significantly increased the rate (>10-fold) and extent of lipase-mediated digestion compared to that of coarse and homogenized submicrometer triglyceride emulsions. Proton nuclear magnetic resonance studies verified the rapid and enhanced production of fatty acids for MLH particles; these are electrostatically repelled by the negatively charged montmorillonite platelet faces and avoid the "interfacial poisoning" caused by incomplete digestion that retards lipid droplet digestion. MLH particles are a novel biomaterial and encapsulation system that optimize lipase enzyme efficiency and have excellent potential as a smart delivery system for lipophilic biomolecules owing to their exceptional physicochemical and biologically active properties. These particles can be readily fabricated with varying lipid loads and thus may be tailored to optimize the solubilization of specific bioactive molecules requiring reformulation.

Nanostructuring Biomaterials with Specific Activities towards Digestive Enzymes for Controlled Gastrointestinal Absorption of Lipophilic Bioactive Molecules

This review describes the development of novel lipid-based biomaterials that modulate fat digestion for the enhanced uptake of encapsulated lipophilic bioactive compounds (e.g. drugs and vitamins). Specific focus is directed towards analysing how key material characteristics affect the biological function of digestive lipases and manipulate lipolytic digestion. The mechanism of lipase action is a complex, interfacial process, whereby hydrolysis can be controlled by the ability for lipase to access and adsorb to the lipid-in-water interface. However, significant conjecture exists within the literature regarding parameters that influence the activities of digestive lipases. Important findings from recent investigations that strategically examined the interplay between the interfacial composition of the lipid microenvironment and lipolysis kinetics in simulated biophysical environments are presented. The correlation between lipolysis and the rate of solubilisation and absorption of lipophilic compounds in the gastrointestinal tract (GIT) is detailed. Greater insights into the mechanism of lipase action have provided a new approach for designing colloidal carriers that orally deliver poorly soluble compounds, directly impacting the pharmaceutical and food industries.

Improving the Intracellular Drug Concentration in Lung Cancer Treatment through the Codelivery of Doxorubicin and miR-519c Mediated by Porous PLGA Microparticle

Porous PLGA microparticle for the coencapsulation of doxorubicin and miR-519c was successfully constructed through the water-oil-water emulsion solvent evaporation method, using ammonium bicarbonate as a porogen. It has been characterized with high porous surface, adaptive aerodynamic diameter (<10 μm), favorable drug loading, and sustained release profile. The release supernatant exhibited a higher inhibition of cell proliferation than those from porous PLGA microparticles harboring a single component (doxorubicin or miR-519c), attributing to the enhanced induction of cell apoptosis and cell cycle arrest at S phase. Finally, the improved intracellular concentration of doxorubicin was elucidated by flow cytometry and liquid chromatography with tandem mass spectrometry, owing to the knockdown of drug transporter ABCG2 by miR-519c. Overall, the porous PLGA microparticle combining chemotherapy and gene therapy could facilitate the antitumor efficacy and reduce the side effects, and thus, it is potential to be used as a sustained release system for lung cancer treatment via pulmonary administration.

Lysozyme-loaded lipid-polymer hybrid nanoparticles: preparation, characterization and colloidal stability evaluation

CONTEXT

Lipid-polymer hybrid nanoparticles (LPNPs) are polymeric nanoparticles enveloped by lipid layers, which have emerged as a potent therapeutic nanocarrier alternative to liposomes and polymeric nanoparticles.

OBJECTIVE

The aim of this work was to develop, characterize and evaluate LPNPs to deliver a model protein, lysozyme.

MATERIALS AND METHODS

Lysozyme-loaded LPNPs were prepared by using the modified w/o/w double-emulsion-solvent-evaporation method. Poly-ɛ-caprolactone (PCL) was used as polymeric core material and tripalmitin:lechitin mixture was used to form a lipid shell around the LPNPs. LPNPs were evaluated for particle size distribution, zeta potential, morphology, encapsulation efficiency, in vitro drug release, stability and cytotoxicity.

RESULTS

The DLS measurement results showed that the particle size of LPNPs ranged from 58.04 ± 1.95 nm to 2009.00 ± 0.52 nm. The AFM and TEM images of LPNPs demonstrate that LPNPs are spherical in shape. The protein-loading capacity of LPNPs ranged from 5.81% to 60.32%, depending on the formulation parameters. LPNPs displayed a biphasic drug release pattern with a burst release within 1 h, followed by sustained release afterward. Colloidal stability results of LPNPs in different media showed that particle size and zeta potential values of particles did not change significantly in all media except of FBS 100% for 120 h. Finally, the results of a cellular uptake study showed that LPNPs were significantly taken up by 83.3% in L929 cells.

CONCLUSION

We concluded that the LPNPs prepared with PCL as polymeric core material and tripalmitin:lechitin mixture as lipid shell should be a promising choice for protein delivery.

Polymer-lipid hybrid systems: merging the benefits of polymeric and lipid-based nanocarriers to improve oral drug delivery

INTRODUCTION

A number of biobarriers limit efficient oral drug absorption; both polymer-based and lipid-based nanocarriers have demonstrated properties and delivery mechanisms to overcome these biobarriers in preclinical settings. Moreover, in order to address the multifaceted oral drug delivery challenges, polymer-lipid hybrid systems are now being designed to merge the beneficial features of both polymeric and lipid-based nanocarriers.

AREAS COVERED

Recent advances in the development of polymer-lipid hybrids with a specific focus on their viability in oral delivery are reviewed. Three classes of polymer-lipid hybrids have been identified, i.e. lipid-core polymer-shell systems, polymer-core lipid-shell systems, and matrix-type polymer-lipid hybrids. We focus on their application to overcome the various biological barriers to oral drug absorption, as exemplified by selected preclinical studies.

EXPERT OPINION

Numerous studies have demonstrated the superiority of polymer-lipid hybrid systems to their non-hybrid counterparts in providing improved drug encapsulation, modulated drug release, and improved cellular uptake. These features have encouraged their applications in the delivery of chemotherapeutics, proteins, peptides, and vaccines. With further research expected to optimize the manufacturing and scaling up processes and in-depth pre-clinical pharmacological and toxicological assessments, these multifaceted drug delivery systems will have significant clinical impact on the oral delivery of pharmaceuticals and biopharmaceuticals.

Interfacial processes that modulate the kinetics of lipase-mediated catalysis using porous silica host particles

Surface immobilised lipases are important bioactive materials that have a wide range of applications in the biotechnology, chemical and pharmaceutical industries.