Characterization Methods for Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC)

Linoleate-pazopanib conjugation as active pharmacological ingredient to abolish hepatocellular carcinoma growth

Small molecule compounds targeting multiple kinases involved in neoangiogenesis have shown survival benefits in patients with unresectable hepatocellular carcinoma (HCC). Nonetheless, despite the beneficial effects of multikinase inhibitors (MKIs), a lack of boosting adjuvant limits their objective response rate. Lipid conjugates have been used to improve delivery efficacy or pharmaceutical benefits for decades. However, the feasibility of utilizing lipid-drug conjugates (LDCs) in HCC regimens remains untested. In this study, oral feeding of linoleate-fluorescein isothiocyanate conjugates showed that the compound was well distributed in a spontaneous HCC mouse model. Therefore, a rationale design was developed for chemically synthesizing a linoleate-pazopanib conjugate (LAPC). The LAPC showed a significantly improved cytotoxicity compared to the parental drug pazopanib. Pazopanib's angiogenic suppressing signals were not observed in LAPC-treated HCC cells, potentially suggesting an altered mechanism of action (MOA). In an efficacy trial comparing placebo, oral pazopanib, and LAPC treatments in the hepatitis B virus transgene-related spontaneous HCC mouse model (HBVtg-HCC), the LAPC treatment demonstrated superior tumor ablating capacity in comparison to both placebo and pazopanib treatments, without any discernible systemic toxicity. The LAPC exposure is associated with an apoptosis marker (Terminal deoxynucleotidyl transferase dUTP nick end labeling [TUNEL]) and an enhanced ferroptosis (glutathione peroxidase 4 [GPX4]) potential in HBVtg-HCC tumors. Therefore, the LAPC showed excellent HCC ablative efficacy with altered MOA. The molecular mechanisms of the LAPC and LDCs for HCC therapeutics are of great academic interest. Further comprehensive preclinical trials (e.g., chemical-manufacture-control, toxicity, distribution, and pharmacokinetics/pharmacodynamics) are expected.

Characterization and stability of solid lipid nanoparticles produced from different fully hydrogenated oils

The use of lipids from conventional oils and fats to produce solid lipid nanoparticles (SLN) attracting interest from the food industry, since due their varying compositions directly affects crystallization behavior, stability, and particle sizes (PS) of SLN. Thus, this study aimed evaluate the potential of fully hydrogenated oils (hardfats) with different hydrocarbon chain lengths to produce SLN using different emulsifiers. For that, fully hydrogenated palm kern (FHPkO), palm (FHPO), soybean (FHSO), microalgae (FHMO) and crambe (FHCO) oils were used. Span 60 (S60), soybean lecithin (SL), and whey protein isolate (WPI) were used as emulsifiers. The physicochemical characteristics and crystallization properties of SLN were evaluated during 60 days. Results indicates that the crystallization properties were more influenced by the hardfat used. SLN formulated with FHPkO was more unstable than the others, and hardfats FHPO, FHSO, FHMO, and FHCO exhibited the appropriate characteristics for use to produce SLN. Concerning emulsifiers, S60- based SLN showed high instability, despite the hardfat used. SL-based and WPI-based SLN formulations, showed a great stability, with crystallinity properties suitable for food incorporation.

Validation of an Innovative Chromatographic Method for Hypericin Quantification in Nanostructured Lipid Carriers

BACKGROUND

Hypericin (HYP) is a natural compound widely used as a food supplement. The encapsulation of HYP into nanosystems, such as nanostructured lipid carriers (NLC), is a promising strategy for delivering this lipophilic molecule and protecting it from degradation.

OBJECTIVE

This study aims to develop and validate an analytical method to quantify the encapsulation efficiency of HYP in NLC.

METHOD

A reverse-phase high-performance liquid chromatography (HPLC) method was developed and validated according to the International Conference on Harmonization (ICH) guide Q2 (R1). NLC was prepared through the ultrasonication method, and HYP encapsulation efficiency was evaluated using the validated method.

RESULTS

Separation was achieved using an isocratic mobile phase composed of acetonitrile, methanol, and ammonium acetate buffer (10 mM, pH 5.0) (54:36:10, v/v/v) and a reverse stationary phase. The specificity, linearity, precision, accuracy, and robustness of the method were assessed and confirmed during the validation. Furthermore, the validated method was able to determine the encapsulation efficiency of HYP in NLC.

CONCLUSIONS

The HPLC method was validated, and the results indicated the ability of NLC to deliver HYP compounds for further application as a food supplement.

HIGHLIGHTS

HYP is used as a food supplement and for photodynamic therapy (PDT). The developed method was specific, linear, precise, accurate, and robust. NLCs showed a high ability to encapsulate HYP.

Design, Synthesis, Characterization, and Evaluation of the Anti-HT-29 Colorectal Cell Line Activity of Novel 8-Oxyquinolinate-Platinum(II)-Loaded Nanostructured Lipid Carriers Targeted with Riboflavin

Colorectal cancer is occasionally called colon or rectal cancer, depending on where cancer begins to form, and is the second leading cause of cancer death among both men and women. The platinum-based [PtCl(8-O-quinolinate)(dmso)] (8-QO-Pt) compound has demonstrated encouraging anticancer activity. Three different systems of 8-QO-Pt-encapsulated nanostructured lipid carriers (NLCs) with riboflavin (RFV) were investigated. NLCs of myristyl myristate were synthesized by ultrasonication in the presence of RFV. RFV-decorated nanoparticles displayed a spherical shape and a narrow size dispersion in the range of 144-175 nm mean particle diameter. The 8-QO-Pt-loaded formulations of NLC/RFV with more than 70% encapsulation efficiency showed sustained in vitro release for 24 h. Cytotoxicity, cell uptake, and apoptosis were evaluated in the HT-29 human colorectal adenocarcinoma cell line. The results revealed that 8-QO-Pt-loaded formulations of NLC/RFV showed higher cytotoxicity than the free 8-QO-Pt compound at 5.0 µM. All three systems exhibited different levels of cellular internalization. Moreover, the hemotoxicity assay showed the safety profile of the formulations (less than 3.7%). Taken together, RFV-targeted NLC systems for drug delivery have been investigated for the first time in our study and the results are promising for the future of chemotherapy in colon cancer treatment.

Solid Lipid Nanoparticles Based on Monosubstituted Pillar[5]arenes: Chemoselective Synthesis of Macrocycles and Their Supramolecular Self-Assembly

Novel monosubstituted pillar[5]arenes with one or two terminal carboxyl groups were synthesized by the reaction of succinic anhydride with pillar[5]arene derivative containing a diethylenetriamine function. The ability for non-covalent self-assembly in chloroform, dimethyl sulfoxide, as well as in tetrahydrofuran-water system was studied. The ability of the synthesized macrocycles to form different types of associates depending on the substituent nature was established. The formation of stable particles with average diameter of 192 nm in chloroform and of 439 nm in DMSO was shown for pillar[5]arene containing two carboxyl fragments. Solid lipid nanoparticles (SLN) based on monosubstituted pillar[5]arenes were synthesized by nanoprecipitation in THF-water system. Minor changes in the structure of the macrocycle substituent can dramatically influence the stability and shape of SLN (spherical and rod-like structures) accordingly to DLS and TEM. The presence of two carboxyl groups in the macrocycle substituent leads to the formation of stable spherical SLN with an average hydrodynamic diameter of 364-454 nm. Rod-like structures are formed by pillar[5]arene containing one carboxyl fragment, which diameter is about of 50-80 nm and length of 700-1000 nm. The synthesized stable SLN open up great prospects for their use as drug storage systems.

Distribution of Drug Substances in Solid Lipid Microparticles (SLM)—Methods of Analysis and Interpretation

The incorporation of drug substances into the matrix of solid lipid microparticles (SLM) is critical to providing effects such as prolonged release, taste masking, and protection of the labile API. Currently, a commonly used method of characterizing multi-compartment lipid systems, such as SLM, is to determine entrapment efficiency (EE) and drug loading (DL) parameters, but this is not sufficient for understanding the localization of API either in the core or on the surface of the microspheres. The main objective of the research was to study the distribution of API in an aqueous dispersion of SLM in order to distinguish between the API incorporated in the lipid matrix and localized in the superficial region (interphase) and to refer the obtained results to the EE and DL parameters. SLM dispersions (10–30% of the lipid) with four model drug substances, i.e., cyclosporine, clotrimazole, diclofenac sodium and hydrocortisone, were prepared and investigated. In the first stage, the experiments were designed to optimize the method of extracting the API fraction localized on the SLM surface by shaking the dispersions with methanol. The fraction dissolved in the aqueous phase was obtained by ultrafiltration of SLM dispersions. Total drug content and the concentration in the separated phases were determined by the HPLC method. The obtained results were compared with the EE and DL parameters. Selected SLM dispersions were tested both before and after thermal sterilization. Short-term shaking of SLM dispersion with methanol does not damage the lipid matrix and allows the API fraction localized on the SLM surface to be extracted, the result of which was the determination of API distribution between lipid matrix, interphase and aqueous phase. It was found that the majority of API represented by EE value was localized on the surface of SLM. Only for cyclosporine was the incorporation of drug molecules in the lipid core very effective (up to 48%), while for other drug substances only 1–21% was found in the lipid core of SLM. A clear influence of the sterilization process on the distribution of API within the microparticles was found. The presented studies showed that the characterization of multi-compartment SLM dispersions solely on the basis of EE and DL values, is insufficient. The proposed new distribution test method enables the localization of API to be demonstrated within the microspheres, with the quantitative characteristics of the drug fraction incorporated in the lipid matrix and the fraction associated with the surface of the lipid matrix. The proposed new method allows the influence of the sterilization process on the changes in the API distribution within the lipospheres to be evaluated. Such characteristics provide new opportunities for the development and use of this dosage form as a carrier providing prolonged release and other aforementioned advantages.

Oral Efficacy of a Diselenide Compound Loaded in Nanostructured Lipid Carriers in a Murine Model of Visceral Leishmaniasis

Leishmaniasis urgently needs new oral treatments, as it is one of the most important neglected tropical diseases that affects people with poor resources. The drug discovery pipeline for oral administration currently discards entities with poor aqueous solubility and permeability (class IV compounds in the Biopharmaceutical Classification System, BCS) such as the diselenide 2m, a trypanothione reductase (TR) inhibitor. This work was assisted by glyceryl palmitostearate and diethylene glycol monoethyl ether-based nanostructured lipid carriers (NLC) to render 2m bioavailable and effective after its oral administration. The loading of 2m in NLC drastically enhanced its intestinal permeability and provided plasmatic levels higher than its effective concentration (IC50). In L. infantum-infected BALB/c mice, 2m-NLC reduced the parasite burden in the spleen, liver, and bone marrow by at least 95% after 5 doses, demonstrating similar efficacy as intravenous Fungizone. Overall, compound 2m and its formulation merit further investigation as an oral treatment for visceral leishmaniasis.

Smart biomaterials to enhance the efficiency of immunotherapy in glioblastoma: State of the art and future perspectives

Glioblastoma multiform (GBM) is considered as the most lethal tumor among CNS malignancies. Although immunotherapy has achieved remarkable advances in cancer treatment, it has not shown satisfactory results in GBM patients. Biomaterial science, along with nanobiotechnology, is able to optimize the efficiency of immunotherapy in these patients. They can be employed to provide the specific activation of immune cells in tumor tissue and combinational therapy as well as preventing systemic adverse effects resulting from hyperactivation of immune responses and off-targeting effect. Advance biomaterials in this field are classified into targeting nanocarriers and localized delivery systems. This review will offer an overview of immunotherapy strategies for glioblastoma and advance delivery systems for immunotherapeutics that may have a high potential in glioblastoma treatment.

Lipid nanostructures for targeting brain cancer

Advancements in both material science and bionanotechnology are transforming the health care sector. To this end, nanoparticles are increasingly used to improve diagnosis, monitoring, and therapy. Huge research is being carried out to improve the design, efficiency, and performance of these nanoparticles. Nanoparticles are also considered as a major area of research and development to meet the essential requirements for use in nanomedicine where safety, compatibility, biodegradability, biodistribution, stability, and effectiveness are requirements towards the desired application. In this regard, lipids have been used in pharmaceuticals and medical formulations for a long time. The present work focuses on the use of lipid nanostructures to combat brain tumors. In addition, this review summarizes the literature pertaining to solid lipid nanoparticles (SLN) and nanostructured lipid carriers (LNC), methods of preparation and characterization, developments achieved to overcome blood brain barrier (BBB), and modifications used to increase their effectiveness.

Assessment of a Novel Vitamin D3 Formulation with Nanostructured Lipid Carriers for Transdermal Delivery

OBJECTIVE

Develop and assess a transdermal emulsion loaded with nanostructured lipid carriers for vitamin D3 supplementation.

METHODS

Vitamin D3 loaded nanostructured lipid carriers, produced via high shear homogenization and ultrasonication, were assessed for their particle size, distribution, morphology, zeta potential, entrapment efficiency, and cytotoxicity. They were incorporated into a transdermal vehicle, and the stability and ex vivo permeation were evaluated.

RESULTS

Spherical nanoparticles were developed with a particle size of 192.5 nm, a polydispersity index of 0.13, a zeta potential of -29.0 mV, and an entrapment efficiency of 99.75%. They were stable (particle size and distribution) for 15 days when stored in a refrigerator and for 30 days at room temperature and 32 °C. The nanoparticles decreased the drug cytotoxicity against fibroblasts, as shown by IC50 (nanoparticle: 32.48 μg mL-1; vitamin D3: 16.73 μg mL-1). The emulsion loaded with nanoparticles minimized the degradation of vitamin D3 when compared with the nanoparticle dispersion. Additionally, the emulsion provided the skin permeation of vitamin D3 following the recommended daily allowance.

CONCLUSION

To the best of our knowledge, this is the first study to use nanostructured lipid carriers for transdermal delivery of vitamin D. The developed formulation is a promising strategy to overcome the vitamin D3 variable oral bioavailability. It also represents a comfortable route of administrationd. Thus it could be beneficial for patients and clinicians. However, further studies are needed to allow the permeation of larger amounts of vitamin D3, and the combination of these nanoparticles with microneedles would be interesting.

Preclinical Assessment of Ursolic Acid Loaded into Nanostructured Lipid Carriers in Experimental Visceral Leishmaniasis

Ursolic acid, a triterpene produced by plants, displayed leishmanicidal activity in vitro and in vivo; however, the low solubility of this triterpene limits its efficacy. To increase the activity of ursolic acid (UA), this triterpene was entrapped in nanostructured lipid carriers (UA-NLC), physical-chemical parameters were estimated, the toxicity was assayed in healthy golden hamsters, and the efficacy of UA-NLC was studied in experimental visceral leishmanisis. UA-NLC exhibited a spherical shape with a smooth surface with a size of 266 nm. UA-NLC displayed low polydispersity (PDI = 0.18) and good colloidal stability (-29.26 mV). Hamsters treated with UA-NLC did not present morphological changes in visceral organs, and the levels of AST, ALT, urea and creatinine were normal. Animals infected with Leishmania (Leishmania) infantum and treated with UA-NLC showed lower parasitism than the infected controls, animals treated with UA or Amphotericin B (AmB). The therapeutic activity of UA-NLC was associated with the increase in a protective immune response, and it was associated with a high degree of spleen and liver preservation, and the normalization of hepatic and renal functions. These data indicate that the use of lipid nanoparticles as UA carriers can be an interesting strategy for the treatment of leishmaniasis.

Lipid, polymeric, inorganic-based drug delivery applications for platinum-based anticancer drugs

The three main FDA-approved platinum drugs in chemotherapy such as carboplatin, cisplatin, and oxaliplatin are extensively applied in cancer treatments. Although the clinical applications of platinum-based drugs are extremely effective, their toxicity profile restricts their extensive application. Therefore, recent studies focus on developing new platinum drug formulations, expanding the therapeutic aspect. In this sense, recent advances in the development of novel drug delivery carriers will help with the increase of drug stability and biodisponibility, concomitantly with the reduction of drug efflux and undesirable secondary toxic effects of platinum compounds. The present review describes the state of the art of platinum drugs with their biological effects, pre- and clinical studies, and novel drug delivery nanodevices based on lipids, polymers, and inorganic.

Natural Lipids as Structural Components of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers for Topical Delivery

BACKGROUND

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) are useful drug delivery systems for dermal application. Thanks to their biocompatible and biodegradable profile, these carriers offer many advantages such as enhanced bioavailability, low toxicity, viable drug targeting and controlled release. SLN and NLC are composed of well-tolerated lipids, including natural fats and oils that are successfully used in the pharmaceutical and cosmetic dermal formulation.

OBJECTIVE

This article presents an overview of the benefits of selecting natural fats and oils as structural components of SLN and NLC for topical application.

METHODS

This review is based on data published over the past 20 years about the development of stable and nontoxic lipid nanoparticles with natural lipids. We shed light on the role of natural fats in skin restoration, as well as on the contributed penetration and occlusive properties of SLN and NLC.

RESULTS

The deliberate selection of excipients (type and lipid ratio) influences the quality of the final dermal formulation. Natural lipids show good compatibility with different active molecules and are able to create stable lipid matrices that facilitate the biopharmaceutical properties of lipid nanoparticles. Patents involving natural fats and oils in SLN and NLC composition are listed, yet it is important to note that the approved marketed formulations are mainly cosmetic, not pharmaceutical, products.

CONCLUSION

Natural lipids can enhance topical drug delivery by adding their ability of improving skin penetration and hydration to the permeation and occlusion properties of SLN and NLC.

Polymeric microfluidic continuous flow mixer combined with hyperspectral FT-IR imaging for studying rapid biomolecular events

Early reaction intermediates in protein folding, such as those resulting in β-amyloid formation due to transient misfolding, emerge within a few hundred microseconds. Here, we report a method to obtain sub-millisecond temporal resolution and molecular structural information of protein (mis-)folding events by using a microfluidic continuous-flow mixer (MCFM) in combination with Fourier transform infrared (FT-IR) imaging. The MCFMs are made out of cyclic olefin copolymer (COC) films, because this approach allows for rapid prototyping of different mixer designs. Furthermore, COC offers high IR transparency between 1500 and 2500 cm^-1, thus maximizing the signal to noise ratio of the IR data obtained from a sample of interest. By combining narrow and wide channel widths in MCFM design, the platform provides fast mixing (460 μs) to induce protein (mis-)folding, and it maximizes the residence time in the observing area, so a wide range of reaction timescales can be captured in a single image. We validated the platform for its ability to induce and observe sub-millisecond processes by studying two systems: (i) the mixing of H₂O and D₂O and (ii) the mixing induced deprotonation of carboxylic acid. First, we observed excellent agreement between simulated and experimental data of the on-chip mixing of H₂O and D₂O, which verifies the distance-reaction time relationships based on simulation. Second, deprotonation of carboxylic acid by on-chip mixing with sodium hydroxide solution validates the ability of the platform to induce rapid pH jump that is needed for some biomolecular reactions. Finally, we studied the methanol-induced partial-unfolding of ubiquitin to show that our platform can be used to study biomolecular events 'on-pathway' using FT-IR imaging. We successfully extracted kinetic and structural details of the conformational changes along the channel. Our results are in agreement with prior studies that required more elaborate stopped flow approaches to acquire data for different time points. In summary, the reported method uses an easy-to-fabricate microfluidic mixer platform integrated with hyperspectral FT-IR imaging for rapid acquisition of structural details and kinetic parameters of biomolecular reactions. This approach does not need stopped flow or molecular imaging probes, as required respectively for alternative FT-IR spectroscopy and fluorescence approaches.

Drug-Phospholipid Complex-a Go Through Strategy for Enhanced Oral Bioavailability

Among many, the oral route of delivery is considered to be the most favorable route with the highest patient compliance. The main issue with oral delivery is the environmental vulnerability of gastro intestinal tract (G.I.T). The bioavailability could further decrease when drug has poor aqueous solubility and permeability through biological membrane. This drawback could be resolved by employing drug-phospholipid complex strategy, as they utilize mechanism which is similar to the absorption mechanism of nutritional constituents form G.I.T. The drug-phospholipid complexes are considered ideal for oral delivery as they are biodegradable and non-toxic, which enable them to be employed as solubilizer, emulsifier, and as a matrix forming excipient for dugs with poor solubility and/or permeability. The present review compiles the basic know how about the phospholipids and the mechanism through which it improves the bioavailability of drugs. Further, it also compiles the crucial formulation aspects and methods of preparations of drug-phospholipid complex along with its physical and in silico characterization techniques. The increase in number of recent reports involving the utilization of drug-phospholipid complex to improve oral bioavailability of drugs thus explains how vital the strategy is for a successful oral delivery.