Lipid nanoparticles for brain targeting II. Technological characterization

Small-angle X-ray scattering unveils the internal structure of lipid nanoparticles

Lipid nanoparticles own a remarkable potential in nanomedicine, only partially disclosed. While the clinical use of liposomes and cationic lipid-nucleic acid complexes is well-established, liquid lipid nanoparticles (nanoemulsions), solid lipid nanoparticles, and nanostructured lipid carriers have even greater possibilities. However, they face obstacles in being used in clinics due to a lack of understanding about the molecular mechanisms controlling their drug loading and release, interactions with the biological environment (such as the protein corona), and shelf-life stability. To create effective drug delivery carriers and successfully translate bench research to clinical settings, it is crucial to have a thorough understanding of the internal structure of lipid nanoparticles. Through synchrotron small-angle X-ray scattering experiments, we determined the spatial distribution and internal structure of the nanoparticles' lipid, surfactant, and the bound water in them. The nanoparticles themselves have a barrel-like shape that consists of coplanar lipid platelets (specifically cetyl palmitate) that are covered by loosely spaced polysorbate 80 surfactant molecules, whose polar heads retain a large amount of bound water. To reduce the interface cost of bound water with unbound water without stacking, the platelets collapse onto each other. This internal structure challenges the classical core-shell model typically used to describe solid lipid nanoparticles and could play a significant role in drug loading and release, biological fluid interaction, and nanoparticle stability, making our findings valuable for the rational design of lipid-based nanoparticles.

Engineered Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as New Generations of Blood-Brain Barrier Transmitters

The blood-brain barrier (BBB) is considered as the most challenging barrier in brain drug delivery. Indeed, there is a definite link between the BBB integrity defects and central nervous systems (CNS) disorders, such as neurodegenerative diseases and brain cancers, increasing concerns in the contemporary era because of the inability of most therapeutic approaches. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have already been identified as having several advantages in facilitating the transportation of hydrophilic and hydrophobic agents across the BBB. This review first explains BBB functions and its challenges in brain drug delivery, followed by a brief description of nanoparticle-based drug delivery for brain diseases. A detailed presentation of recent progressions in optimizing SLNs and NLCs for controlled release drug delivery, gene therapy, targeted drug delivery, and diagnosis of neurodegenerative diseases and brain cancers is approached. Finally, the problems, challenges, and future perspectives in optimizing these carriers for potential clinical application were described briefly.

Essential Oil-Loaded NLC for Potential Intranasal Administration

Complementary and alternative medicines represent an interesting field of research on which worldwide academics are focusing many efforts. In particular, the possibility to exploit pharmaceutical technology strategies, such as the nanoencapsulation, for the delivery of essential oils is emerging as a promising strategy not only in Italy but also all over the world. The aim of this work was the development of nanostructured lipid carriers (NLC) for the delivery of essential oils (Lavandula, Mentha, and Rosmarinus) by intranasal administration, an interesting topic in which Italian contributions have recently increased. Essential oil-loaded NLC, projected as a possible add-on strategy in the treatment of neurodegenerative diseases, were characterized in comparison to control formulations prepared with Tegosoft CT and Neem oil. Homogeneous (polydispersity index, PDI < 0.2) nanoparticles with a small size (<200 nm) and good stability were obtained. Morphological and physical-chemical studies showed the formation of different structures depending on the nature of the liquid oil component. In particular, NLC prepared with Lavandula or Rosmarinus showed the formation of a more ordered structure with higher cytocompatibility on two cell lines, murine and human fibroblasts. Taken together, our preliminary results show that optimized positively charged NLC containing Lavandula or Rosmarinus can be proposed as a potential add-on strategy in the treatment of neurodegenerative diseases through intranasal administration, due to the well-known beneficial effects of essential oils and the mucoadhesive properties of NLC.

Application of computational tools for the designing of Oleuropein loaded nanostructured lipid carrier for brain targeting through nasal route

PURPOSE

Meningitis is an inflammation of meninges encircled the brain and spinal cord. Currently it can be treated with second generation cephalosporins which were ended up with an unresolvable problem called Multi Drug Resistance (MDR). Hence, there is a need to develop a better herbal molecule to conflict the MDR.

METHODS

Hot Blanching technique followed by ultra sound assisted extraction using bio-solvent aqueous glycerol was used to extract OLE from olive leaves. QbD tool was applied to predict the interactions between Critical Material Attributes (Ratio of solid Lipid X₁, Concentration of Surfactant X₂) and Critical Process Parameters (Homogenization Time X₃) on Critical Quality Attributes (CQA, Particle Size Y₁, Zeta Potential Y₂, and Entrapment Efficiency Y₃). Particulate characteristics were evaluated and Invivo pharmacokinetic study was done in albino Wistar rats by IV and IN route of administration.

RESULTS

Thermal studies reflect the formation of low ordered crystalline structure of lipid matrix which offers higher encapsulation of drug in NLC than physical mixture. CMA and CPP show significant effect on CQA and method operable design range was developed. Histo-pathological studies confirms that there is no signs of toxicity and in-vitro drug release studies reveals a rapid release of a drug initially followed by prolonged release of oleuropein upto 24 h. The absolute bioavailability of drug loaded NLC in brain was higher in IN route compared to NLC administered by IV route.

CONCLUSIONS

In a nutshell, challenges offered by the hydrophilic OLE for brain targeting can be minimized through lipidic nature of NLC. Graphical Abstract.

Brain Delivery of Curcumin Using Solid Lipid Nanoparticles and Nanostructured Lipid Carriers: Preparation, Optimization, and Pharmacokinetic Evaluation

Curcumin is a multitherapeutic agent with great therapeutic potential in central nervous system (CNS) diseases. In the current study, curcumin was encapsulated in solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) for the purpose of increasing brain accumulation. The preparation processes have been optimized using experimental design and multiobjective optimization methods. Entrapment efficiency of curcumin in SLNs and NLCs was found to be 82% ± 0.49 and 94% ± 0.74, respectively. The pharmacokinetic studies showed that the amount of curcumin available in the brain was significantly higher in curcumin-loaded NLCs (AUC_0-t = 505.76 ng/g h) compared to free curcumin (AUC_0-t = 0.00 ng/g h) and curcumin-loaded SLNs (AUC_0-t = 116.31 ng/g h) ( P < 0.005), after intravenous (IV) administration of 4 mg/kg dose of curcumin in rat. The results of differential scanning calorimetry and X-ray diffraction showed that curcumin has been dispersed as amorphous in the nanocarriers. Scanning electron microscopy images confirmed the nanoscale size and spherical shape of the nanoparticles. The DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging study indicated that preparation processes do not have any significant effect on the antioxidant activity of curcumin. The results of this study are promising for the use of curcumin-loaded NLCs in more studies and using curcumin in the treatment of CNS diseases.

Facile development, characterization, and optimization of new metformin-loaded nanocarrier system for efficient colon cancer adjunct therapy

PURPOSE

Metformin hydrochloride (MF) repurposing as adjuvant anticancer therapy for colorectal cancer (CRC) proved effective. Several studies attempted to develop MF-loaded nanoparticles (NPs), however the entrapment efficiency (EE%) was poor. Thus, the present study aimed at the facile development of a new series of chitosan (CS)-based semi-interpenetrating network (semi-IPN) NPs incorporating Pluronic^® nanomicelles as nanocarriers for enhanced entrapment and sustained release of MF for efficient treatment of CRC.

METHODS

The NPs were prepared by ionic gelation and subsequently characterized using FTIR, DSC, TEM, and DLS. A full factorial design was also adopted to study the effect of various formulation variables on EE%, particle size, and zeta-potential of NPs.

RESULTS

NPs had a spherical shape and a mean particle size ranging between 135 and 220 nm. FTIR and DSC studies results were indicative of successful ionic gelation with the drug being dispersed in its amorphous form within CS-Pluronic^® matrix. Maximum EE% reaching 57.00 ± 12.90% was achieved using Pluronic^®-123 based NPs. NPs exhibited a sustained release profile over 48 h. The MF-loaded NPs sensitized RKO CRC cells relative to drug alone.

CONCLUSION

The reported results highlighted the novel utility of the developed NPs in the arena of colon cancer treatment.

Solid lipid nanoparticles and nanostructured lipid carriers as novel drug delivery systems: applications, advantages and disadvantages

During the recent years, more attentions have been focused on lipid base drug delivery system to overcome some limitations of conventional formulations. Among these delivery systems solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) are promising delivery systems due to the ease of manufacturing processes, scale up capability, biocompatibility, and also biodegradability of formulation constituents and many other advantages which could be related to specific route of administration or nature of the materials are to be loaded to these delivery systems. The aim of this article is to review the advantages and limitations of these delivery systems based on the route of administration and to emphasis the effectiveness of such formulations.

How can lipid nanocarriers improve transdermal delivery of olanzapine?

The development of a transdermal nanocarrier drug delivery system with potential for the treatment of psychiatric disorders, such as schizophrenia and bipolar disorder, is described. Lipid nanocarriers (LN), encompassing various solid:liquid lipid compositions were formulated and assessed as potential nanosystems for transdermal delivery of olanzapine. A previously optimized method of hot high pressure homogenization (HPH) was adopted for the production of the LN, which comprised solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and nanoemulsions (NE). Precirol^® was selected as the solid lipid for progression of studies. SLN exhibited the best performance for transdermal delivery of olanzapine, based on in vitro release and permeation studies, coupled with results from physicochemical characterization of several solid:liquid lipid formulations. Stability tests, performed to give an indication of long-term storage behavior of the formulations, were in good agreement with previous studies for the best choice of solid:liquid lipid ratio. Overall, these findings highlight the SLN-based formulation as promising for the further inclusion in and production of transdermal patches, representing an innovative therapeutic approach.

Injectable gellan gum-based nanoparticles-loaded system for the local delivery of vancomycin in osteomyelitis treatment

Infection spreading in the skeletal system leading to osteomyelitis can be prevented by the prolonged administration of antibiotics in high doses. However systemic antibiotherapy, besides its inconvenience and often low efficacy, provokes numerous side effects. Thus, we formulated a new injectable nanoparticle-loaded system for the local delivery of vancomycin (Vanc) applied in a minimally-invasive way. Vanc was encapsulated in poly(L-lactide-co-glycolide) nanoparticles (NPs) by double-emulsification. The size (258 ± 11 nm), polydispersity index (0.240 ± 0.003) and surface potential (-25.9 ± 0.2 mV) of NPs were determined by dynamic light scattering and capillary electrophoresis measurements. They have a spherical morphology and a smooth topography as observed using atomic force microscopy. Vanc loading and encapsulation efficiencies were 8.8 ± 0.1 and 55.2 ± 0.5 %, respectively, based on fluorescence spectroscopy assays. In order to ensure injectability, NPs were suspended in gellan gum and cross-linked with Ca(2+); also a portion of dissolved antibiotic was added to the system. The resulting system was found to be injectable (extrusion force 11.3 ± 1.1 N), reassembled its structure after breaking as shown by rheology tests and ensured required burst release followed by sustained Vanc delivery. The system was cytocompatible with osteoblast-like MG-63 cells (no significant impact on cells' viability was detected). Growth of Staphylococcus spp. reference strains and also those isolated from osteomyelitic joints was inhibited in contact with the injectable system. As a result we obtained a biocompatible system displaying ease of application (low extrusion force), self-healing ability after disruption, adjustable drug release and antimicrobial properties.