Surfactant effect on the physicochemical characteristics of γ-oryanol-containing solid lipid nanoparticles

Natural-Origin Betaine Surfactants as Promising Components for the Stabilization of Lipid Carriers

In the present work, we demonstrate studies involving the influence of the formulation composition on the physicochemical properties of nanocarriers: solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs). Novel lipid-origin platforms were prepared using two "green" betaine-based surfactants, cocamidopropyl betaine (ROKAmina K30) and coco betaine (ROKAmina K30B), in combination with three different solid lipids, cetyl palmitate (CRODAMOL CP), trimyristin (Dynasan 114), and tristearin (Dynasan 118). Extensive optimization studies included the selection of the most appropriate lipid and surfactant concentration for effective SLN and NLC stabilization. The control parameters involving the hydrodynamic diameters of the obtained nanocarriers along with the size distribution (polydispersity index) were determined by dynamic light scattering (DLS), while shape and morphology were evaluated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Electrophoretic light scattering (ELS) and turbidimetric method (backscattering profiles) were used to assess colloidal stability. The studied results revealed that both betaine-stabilized SLN and NLC formulations containing CRODAMOL CP as lipid matrix are the most monodisperse and colloidally stable regardless of the other components and their concentrations used, indicating them as the most promising candidates for drug delivery nanosystems with a diverse range of potential uses.

Solid lipid Lyo-Nanosuspension: A promising stabilized oral delivery system for the antihyperglycemic extract of mistletoe Plicosepalus acacia

The antihyperglycemic effect of Plicosepalus acaciae (P. acaciae) extract was proven, but it still needs to be formulated into a suitable dosage form. We aimed at preparing an oral stabilized SLNs for P. acaciae with high payload, to be used as powder for reconstitution, filled into capsule or compressed into tablet. SLNs were prepared by emulsion solvent evaporation technique. Preliminary characterization was performed followed by full assessment of the optimized SLNs suspension and/or its lyophilized form: particle size, zeta potential, surface morphology, percentage entrapment efficiency (% EE), DSC, FTIR and in vitro release studies. The optimized SLNs lyophilized formula (F3_L) exhibited acceptable compressibility and flowability. The reconstituted F3L showed % sedimentation volume of 91.83 %, re-dispersibility of 95%, viscosity of 764.33 cp, uniform particle size of 30.28 nm as shown by TEM, polydispersity index (PDI) of 0.16, zeta potential of -36.4 mV, % EE of 89.64 % and drug content of 97.69 %. The physical mixture and F3_L FTIR spectrum indicated compatibility of components. In vitro release study showed a burst release in lyophilized formulations followed by slow-release, calculated as total phenolic content. Our previously reported work revealed that the total extracts of P. acaciae and SLNs formulations with the greatest lipid content F3_s, demonstrated a considerable blood glucose-lowering effect in diabetic rats. The obtained lyophilized SLNs is promising for preparation of a suitable stable dosage form for P. acaciae extract to be used in treatment of diabetes.

Design, Physical Characterizations, and Biocompatibility of Cationic Solid Lipid Nanoparticles in HCT-116 and 16-HBE Cells: A Preliminary Study

In this study, pEGFP-LUC was used as a model plasmid and three distinct cationic lipids (dioleyloxy-propyl-trimethylammonium chloride [DOTMA], dioleoyl trimethylammonium propane [DOTAP], and cetylpyridinium chloride [CPC]) were tested along with PEG 5000, as a nonionic surfactant, to prepare glyceryl monostearate (GMS)-based cationic solid lipid nanoparticles (cSLNs). Both the type and quantity of surfactant had an impact on the physicochemical characteristics of the cSLNs. Thermal analysis of the greater part of the endothermic peaks of the cSLNs revealed they were noticeably different from the individual pure compounds based on their zeta potential (ZP ranging from +17 to +56 mV) and particle size (PS ranging from 185 to 244 nm). The addition of cationic surfactants was required to produce nanoparticles (NPs) with a positive surface charge. This suggested that the surfactants and extensive entanglement of the lipid matrix GMS provided support for the behavioral diversity of the cSLNs and their capacity to interface with the plasmid DNA. Additionally, hemolytic assays were used to show that the cSLNs were biocompatible with the human colon cancer HCT-116 and human bronchial epithelial 16-HBE cell lines. The DOTMA 6-based cSLN was selected as the lead cSLN for further ex vivo and in vivo investigations. Taken together, these new findings might provide some guidance in selecting surfactants to prepare extremely efficient and non-toxic cSLN-based therapeutic delivery systems (e.g., gene therapy).

Development and Evaluation of Solid Lipid Nanoparticles for the Clearance of Aβ in Alzheimer's Disease

Aggregation of Amyloid-β (Aβ) leads to the formation and deposition of neurofibrillary tangles and plaques which is the main pathological hallmark of Alzheimer's disease (AD). The bioavailability of the drugs and their capability to cross the BBB plays a crucial role in the therapeutics of AD. The present study evaluates the Memantine Hydrochloride (MeHCl) and Tramiprosate (TMPS) loaded solid lipid nanoparticles (SLNs) for the clearance of Aβ on SHSY5Y cells in rat hippocampus. Molecular docking and in vitro Aβ fibrillation were used to ensure the binding of drugs to Aβ. The in vitro cell viability study showed that the M + T SLNs showed enhanced neuroprotection against SHSY5Y cells than the pure drugs (M + T PD) in presence of Aβ (80.35µM ± 0.455 µM) at a 3:1 molar ratio. The Box-Behnken Design (BBD) was employed to optimize the SLNs and the optimized M + T SLNs were further characterized by %drug entrapment efficiency (99.24 ± 3.24 of MeHCl and 89.99 ± 0.95 of TMPS), particle size (159.9 ± 0.569 nm), PDI (0.149 ± 0.08), Zeta potential (-6.4 ± 0.948 mV), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and in vitro drug release. The TEM & AFM analysis showed irregularly spherical morphology. In vitro release of SLNs was noted up to 48 h; whereas the pure drugs released completely within 3 hrs. M + T SLNs revealed an improved pharmacokinetic profile and a 4-fold increase in drug concentration in the brain when compared to the pure drug. Behavioral tests showed enhanced spatial memory and histological studies confirmed reduced Aβ plaques in rat hippocampus. Furthermore, the levels of Aβ decreased in AlCl₃-induced AD. Thus, all these noted results established that the M + T SLNs provide enhanced neuroprotective effects when compared to pure and individual drugs and can be a promising therapeutic strategy for the management of AD.

Solid lipid nanoparticles: a promising tool for insulin delivery

INTRODUCTION

Insulin plays a critical role in metabolism modulation including carbohydrate, lipid, and protein metabolism. There is room to improve insulin delivery but optimizing the best carrier remains challenging. Traditional and conventional approaches for insulin delivery do not emulate the normal fate of insulin release in the body. Despite extensive research attempts to overcome this and other challenges, the goal of achieving optimal insulin delivery that emulates the natural system remains unresolved.

AREAS COVERED

Solid Lipid Nanoparticles (SLNs) may provide a solution, because they are nontoxic, biocompatible, and straightforward to formulate thus providing a promising platform for achieving targeted and controlled delivery of various therapeutic agents. This review aims to provide an overview on the suitability and application of SLNs for insulin delivery. A special emphasis is placed on the biopharmaceutical aspects of insulin loaded SLNs which have not been explored in detail to date.

EXPERT OPINION

SLNs have proven to be safe and versatile drug delivery systems suitable for insulin delivery and capable of improving the efficacy and pharmacokinetic profile of encapsulated insulin. There is still some work to be done to fully explore SLNs' true potential as drug delivery and specifically insulin delivery vehicles suitable for clinical use.

Lipid Nanoparticles for the Posterior Eye Segment

This review highlights the application of lipid nanoparticles (Solid Lipid Nanoparticles, Nanostructured Lipid Carriers, or Lipid Drug Conjugates) as effective drug carriers for pathologies affecting the posterior ocular segment. Eye anatomy and the most relevant diseases affecting the posterior segment will be summarized. Moreover, preparation methods and different types and subtypes of lipid nanoparticles will also be reviewed. Lipid nanoparticles used as carriers to deliver drugs to the posterior eye segment as well as their administration routes, pharmaceutical forms and ocular distribution will be discussed emphasizing the different targeting strategies most recently employed for ocular drug delivery.

Formulation and Pathohistological Study of Mizolastine-Solid Lipid Nanoparticles-Loaded Ocular Hydrogels

Background

Mizolastine (MZL) is a dual-action nonsedating topical antihistamine anti-inflammatory agent that is used to relieve allergic conditions, such as rhinitis and conjunctivitis. Solid lipid nanoparticles (SLNs) are advanced delivery system in ophthalmology, with the merits of increasing the corneal drug absorption and hence improved bioavailability with the objective of ocular drug targeting.

Methods

First, MZL was formulated as MZL-SLNs by hot homogenization/ultrasonication adopting a 3² full factorial design. Solid-state characterization, in vitro release, and stability studies have been performed. Then, the optimized MZL-SLNs formula has been incorporated into ocular hydrogels using 1.5% w/v Na alginate and 5% w/v polyvinylpyrrolidone K₉₀. The gels were evaluated via in vitro release as well as in vivo studies by applying allergic conjunctivitis congestion in a rabbit-eye model.

Results

The optimized formula (F4) was characterized by the highest entrapment efficiency (86.5±1.47%), the smallest mean particle size (202.3±13.59 nm), and reasonable zeta potential (−22.03±3.65 mV). Solid-state characterization of the encapsulation of MZL in SLNs was undertaken. In vitro results showed a sustained release profile from MZL-SLNs up to 30 hours with a non-Fickian Higuchi kinetic model. Stability studies confirmed immutability of freeze-dried MZL-SLNs (F4) upon storage for 6 months. Finally, hydrogel formulations containing MZL-SLNs, proved ocular congestion disappearance with completely repaired conjunctiva after 24 hours. Moreover, pretreatment with MZL-SLNs–loaded hydrogel imparted markedly decreased TNF-α and VEGF-expression levels in rabbits conjunctivae compared with post-treatment with the same formula.

Conclusion

MZL-SLNs could be considered a promising stable sustained-release nanoparticulate system for preparing ocular hydrogel as effective antiallergy ocular delivery systems.

Preparation, Characterization, and Anti-Cancer Activity of Nanostructured Lipid Carriers Containing Imatinib

Breast cancer is the most widespread malignancy in women worldwide. Nanostructured lipid carriers (NLCs) have proven effective in the treatment of cancer. NLCs loaded with imatinib (IMA) (NANIMA) were prepared and evaluated for their in vitro efficacy in MCF-7 breast cancer cells. The hot homogenization method was used for the preparation of NANIMAs. An aqueous solution of surfactants (hot) was mixed with a molten mixture of stearic acid and sesame oil (hot) under homogenization. The prepared NANIMAs were characterized and evaluated for size, polydispersity index, zeta potential, encapsulation efficiency, release studies, stability studies, and MTT assay (cytotoxicity studies). The optimized NANIMAs revealed a particle size of 104.63 ± 9.55 d.nm, PdI of 0.227 ± 0.06, and EE of 99.79 ± 0.03. All of the NANIMAs revealed slow and sustained release behavior. The surfactants used in the preparation of the NANIMAs exhibited their effects on particle size, zeta potential, encapsulation efficiency, stability studies, and release studies. The cytotoxicity studies unveiled an 8.75 times increase in cytotoxicity for the optimized NANIMAs (IC₅₀ = 6 µM) when compared to IMA alone (IC₅₀ = 52.5 µM) on MCF-7 breast cancer cells. In the future, NLCs containing IMA will possibly be employed to cure breast cancer. A small amount of IMA loaded into the NLCs will be better than IMA alone for the treatment of breast cancer. Moreover, patients will likely exhibit less adverse effects than in the case of IMA alone. Consequently, NANIMAs could prove to be useful for effective breast cancer treatment.

Development and Characterization of Stingless Bee Propolis Properties for the Development of Solid Lipid Nanoparticles for Loading Lipophilic Substances

Stingless bees are insects which are popularly bred by agriculturists in the eastern region of Thailand for the pollination of their orchards. The products from stingless bee breeding include bee honey and bee propolis. The objective of this experiment is to study the possibility of developing stingless bee propolis wax into solid lipid nanoparticles (SLN) by the comparison of five surfactants (Brij 721, Cremophor WO 7, Myrj 52, Poloxamer 188, and Tween 80). Each surfactant is used at three concentrations: 10%, 20%, and 30%. A master formula is selected according to the following: physical features, particle size, zeta potential, and entrapment. The results showed that Brij 721 and Myri 52 at 20% can be used in preparing SLN and have good preservation properties for vitamin E (size: 451.2 nm and 416.8 nm, zeta potential: - 24.0 and - 32.7; % EE: 92.32% and 92.00%, resp.). Therefore, they are further developed by adding the following drugs at low solubility: curcumin, ibuprofen, and astaxanthin. It is found that a formula using the surfactants Brij 721 and Myrj 52 at 20% have similar drug entrapment. The entrapment study involves curcumin 82%, ibuprofen 40%, and astaxanthin 67%. Moreover, the cytotoxicity test of blank solid lipid nanoparticle found no toxicty in fibroblast cell line (CRL-2522). Therefore, from this study, it is determined that stingless bee propolis wax has the potential to be developed to provide more efficient SLN in the future.

Solid Lipid Nanoparticles for Drug Delivery: Pharmacological and Biopharmaceutical Aspects

In the golden age of pharmaceutical nanocarriers, we are witnessing a maturation stage of the original concepts and ideas. There is no doubt that nanoformulations are extremely valuable tools for drug delivery applications; the current challenge is how to optimize them to ensure that they are safe, effective and scalable, so that they can be manufactured at an industrial level and advance to clinical use. In this context, lipid nanoparticles have gained ground, since they are generally regarded as non-toxic, biocompatible and easy-to-produce formulations. Pharmaceutical applications of lipid nanocarriers are a burgeoning field for the transport and delivery of a diversity of therapeutic agents, from biotechnological products to small drug molecules. This review starts with a brief overview of the characteristics of solid lipid nanoparticles and discusses the relevancy of performing systematic preformulation studies. The main applications, as well as the advantages that this type of nanovehicles offers in certain therapeutic scenarios are discussed. Next, pharmacokinetic aspects are described, such as routes of administration, absorption after oral administration, distribution in the organism (including brain penetration) and elimination processes. Safety and toxicity issues are also addressed. Our work presents an original point of view, addressing the biopharmaceutical aspects of these nanovehicles by means of descriptive statistics of the state-of-the-art of solid lipid nanoparticles research. All the presented results, trends, graphs and discussions are based in a systematic (and reproducible) bibliographic search that considered only original papers in the subject, covering a 7 years range (2013-today), a period that accounts for more than 60% of the total number of publications in the topic in the main bibliographic databases and search engines. Focus was placed on the therapeutic fields of application, absorption and distribution processes and current efforts for the translation into the clinical practice of lipid-based nanoparticles. For this, the currently active clinical trials on lipid nanoparticles were reviewed, with a brief discussion on what achievements or milestones are still to be reached, as a way of understanding the reasons for the scarce number of solid lipid nanoparticles undergoing clinical trials.

Improved synthesis and characterization of cholesteryl oleate-loaded cationic solid lipid nanoparticles with high transfection efficiency for gene therapy applications

The development of new nanoparticle formulations that are capable of high transfection efficiency without toxicity is essential to provide new tools for gene therapy. However, the issues of complex, poorly reproducible manufacturing methods, and low efficiencies during in vivo testing have prevented translation to the clinic. We have previously reported the use of cholesteryl oleate as a novel excipient for solid lipid nanoparticles (SLNs) for the development of highly efficient and nontoxic nucleic acid delivery carriers. Here, we performed an extensive characterization of this novel formulation to make the scale up under Good Manufacturing Practice (GMP) possible. We also describe the complete physicochemical and biological characterization of cholesteryl oleate-loaded SLNs to ensure the reproducibility of this formula and the preservation of its characteristics before and after the lyophilization process. We defined the best manufacturing method and studied the influence of some parameters on the obtained nanoparticles using the Quality by Design (ICH Q8) guideline to obtain cholesteryl oleate-loaded SLNs that remain stable during storage and guarantee in vitro nucleic acid delivery efficacy. Our results indicate that this improved formulation is suitable for gene therapy with the possibility of scale-up the manufacturing of nanoparticles under GMP conditions.

Comparison of different chemometric methods to extract chemical and physical information from Raman images of homogeneous and heterogeneous semi-solid pharmaceutical formulations

In formulations of nanostructured lipid carriers, lipid solid dispersions and self-emulsifying drug delivery systems, it is common that a solid or semi-solid lipid excipient is mixed with a liquid solvent or liquid lipid. Even when the excipients are visually miscible upon melting, they might have microscopic non-homogeneities which could lead to instability over time and future phase separation. Raman mapping associated with chemometric methods can be useful to evaluate spatial distribution of compounds, however it has not been extensively applied to the formulations mentioned above. The aim of this work was to compare the outcomes of three different chemometric methods - principal components analysis (PCA), multivariate curve resolution with alternating least squares (MCR-ALS) and independent components analysis (ICA) - to study two systems of very different degrees of microscopic miscibility: cetyl palmitate + Transcutol^© (heterogeneous) and polyethylene glycol 6000 (PEG 6000) + Tween 80^© (homogeneous). These two samples were chosen due to large differences in spatial distribution of the compounds over the pixels which could require different approaches for data treatment. The three methods were compared regarding recovered concentrations (or scores), signals (or loadings) and the need for matrix augmentation to obtain reliable results. Results showed that PCA loadings were the mathematical differences of the spectra of pure compounds for both samples, and therefore only 'contrast images' could be generated. MCR and ICA provided signals that could be related to the chemical components, however MCR presented rotational ambiguities even for the very heterogeneous sample, a situation in which ICA performed better as a blind search method. For the homogeneous sample, both methods showed rank deficiency and therefore the use of a matrix augmentation was necessary. ICA and PCA allowed identifying physical modifications in the homogeneous semi-solid PEG 6000/Tween 80^® sample over the time, probably due to the folding/unfolding of the crystalline chains of PEG 6000. Therefore, this work discusses the ability of the three chemometrics methods to extract information from Raman spectra in order to characterize the chemical, spatial and even physical aspects of semi-solid pharmaceutical formulations, which could be of much use for stability studies of different drug delivery systems.

Topical phenytoin nanostructured lipid carriers: design and development

Phenytoin (PHT) is an antiepileptic drug that was reported to exhibit high wound healing activity. Nevertheless, its limited solubility, bioavailability, and inefficient distribution during topical administration limit its use. Therefore, this study aims to develop, characterize nanostructured lipid carriers (NLCs), and evaluate their potential in topical delivery of PHT to improve the drug entrapment efficiency and sustained release. The NLCs were prepared by hot homogenization followed by ultra sonication method using 2³ factorial design. NLC formulations were characterized regarding their particle size (PS), zeta potential (ZP), entrapment efficiency percent (%EE), surface morphology, physicochemical stability, and in vitro release studies. The optimized NLC (F7) was further incorporated in 1%w/v carbopol gel and then characterized for appearance, pH, viscosity, stability, and in vitro drug release. The prepared NLCs were spherical in shape and possessed an average PS of 121.4-258.2 nm, ZP of (-15.4)-(-32.2) mV, and 55.24-88.80 %EE. Solid-state characterization revealed that the drug is dispersed in an amorphous state with hydrogen bond interaction between the drug and the NLC components. NLC formulations were found to be stable at 25 °C for six months. The stored F7-hydrogel showed insignificant changes in viscosity and drug content (p>.05) up to six months at 25 °C that pave a way for industrial fabrication of efficient PHT products. In vitro release studies showed a sustained release from NLC up to 48 h at pH 7.4 following non-Fickian Higuchi kinetics model. These promising findings encourage the potential use of phenytoin loaded lipid nanoparticles for future topical application.