Cationic Solid Lipid Nanoparticles Research Articles

A promising approach to develop nanostructured lipid carriers from solid lipid nanoparticles: preparation, characterization, cytotoxicity and nucleic acid binding ability

We aimed to develop nanostructured lipid carriers (NLCs) displaying similar characteristics – particle size, polydispersity index, and zeta potential – with the model solid lipid nanoparticles (SLNs) for better comparability. By considering the hydrophilic-lipophilic balance values of solid and liquid lipids, five out of six NLCs and eight out of eight cationic NLCs (cNLCs) were successfully prepared with similar characteristics to their precursor SLN and cationic SLNs (cSLNs), respectively. Among cationic formulations, two cSLNs containing different surfactant/co-surfactant concentrations (4% and 8% S/CoS; w/w) and their cNLC versions prepared with Labrafac lipophile WL 1349 (LWL) or Labrafac PG were selected to compare cytotoxicity, stability, and nucleic acid binding ability. All formulations are well-tolerated by L-929 cells, cSLNs being least toxic. The formulations containing 4% S/CoS had higher stability after 24-months. All nanoparticles formed complexes with pDNA (Binding ability: cNLCs > cSLNs). cSLN and LWL-cNLC containing 4% S/CoS showed the highest pDNA binding capacity in each group, and their spherical/oval shape was revealed by electron microscopy. However, they did not form complexes with siRNA. The developed approach has the potential to simplify the production of (c)NLCs having similar physicochemical properties with the optimum (c)SLN and may provide better insight for (c)SLN vs. (c)NLC comparison studies.

New Folate-Modified Human Serum Albumin Conjugated to Cationic Lipid Carriers for Dual Targeting of Mitoxantrone against Breast Cancer.

In the present work, folic acid-modified human serum albumin conjugated to cationic solid lipid nanoparticles were synthesized as nanocarriers of mitoxantrone for the treatment of breast cancer. Dual-targeted drug delivery is a new drug dosing strategy that is frequently used to enhance the therapeutic efficacy of anticancer drugs. Dual targeting of the cancer cells was achieved by dual tagging of human serum albumin and folic acid on the surface of the lipid nanoparticles. The targeted drug-loaded nanocomplexes were synthesized and characterized using transmission electron microscopy along with photon-correlation and Fourier-transform infrared spectroscopic techniques. The anti-cancer activity of the nanocomplexes was screened against an in-vitro model of MCF-7 and MDA-MB-231 breast cancer cell lines to examine drug efficacy. The entrapment efficiency and drug loading values for mitoxantrone were calculated to be 97 and 8.84%, respectively. The data from the drug release studies for the system indicated the release profile did not significantly change within a pH range of 5.5-7.4. The hemolysis ratio of the hybrid carrier was less than 5% even at the upper doses of 3 mg/mL, demonstrating its safety for intravenous injection with limited hemolysis and a long blood circulation time. The cell cytotoxicity results confirmed that the drug hybrid nanocomplex was more toxic to breast cancer cells compared with the free drug. Furthermore, the weakly cationic and small size particles prevented opsonin binding of nanocomplexes, improving blood circulation time and cancer tissue uptake.

Perillaldehyde 1,2-epoxide Loaded SLN-Tailored mAb: Production, Physicochemical Characterization and In Vitro Cytotoxicity Profile in MCF-7 Cell Lines.

We have developed a new cationic solid lipid nanoparticle (SLN) formulation, composed of Compritol ATO 888, poloxamer 188 and cetyltrimethylammonium bromide (CTAB), to load perillaldehyde 1,2-epoxide, and surface-tailored with a monoclonal antibody for site-specific targeting of human epithelial growth receptor 2 (HER2). Perillaldehyde 1,2-epoxide-loaded cationic SLN (cPa-SLN), with a mean particle size (z-Ave) of 275.31 ± 4.78 nm and polydispersity index (PI) of 0.303 ± 0.081, were produced by high shear homogenization. An encapsulation efficiency of cPa-SLN above 80% was achieved. The release of perillaldehyde 1,2-epoxide from cationic SLN followed the Korsemeyer–Peppas kinetic model, which is typically seen in nanoparticle formulations. The lipid peroxidation of cPa-SLN was assessed by the capacity to produce thiobarbituric acid-reactive substances, while the antioxidant activity was determined by the capacity to scavenge the stable radical DPPH. The surface functionalization of cPa-SLN with the antibody was done via streptavidin-biotin interaction, monitoring z-Ave, PI and ZP of the obtained assembly (cPa-SLN-SAb), as well as its stability in phosphate buffer. The effect of plain cationic SLN (c-SLN, monoterpene free), cPa-SLN and cPa-SLN-SAb onto the MCF-7 cell lines was evaluated in a concentration range from 0.01 to 0.1 mg/mL, confirming that streptavidin adsorption onto cPa-SLN-SAb improved the cell viability in comparison to the cationic cPa-SLN.

Biocompatible cationic solid lipid nanoparticles as adjuvants effectively improve humoral and T cell immune response of foot and mouth disease vaccines

In this work, we explored the potential of cationic solid lipid nanoparticles (cSLN) as efficient adjuvants for inactivated foot and mouth disease virus (iFMDV) vaccine. The cSLN were prepared by O/W emulsion method with Compritol 888 ATO as lipid matrix, and were modified by cationic lipid Didodecyldimethylammonium bromide (DDAB). The content of cationic lipid was optimized to produce cSLN with appropriate particle size, surface morphology, zeta potential, and polydispersity. Loading iFMDV onto cSLN by electrostatic attraction did not destruct iFMDV particle structure as measured by high performance size exclusion chromatography (HPSEC). Differential scanning fluorimetry (DSF) showed the transition temperature, Tm, related to iFMDV dissociation increased for 1.2 °C after loading on cSLN, indicating an enhanced stability of this unstable antigen. The cSLN loaded iFMDV enhanced in vitro antigen uptake and activation of bone-marrow-derived dendritic cells (BMDCs) with augmented expression of CD86, CD40, and MHC I. In animal trials, BALB/c mice were immunized with free iFMDV, antigen adjuvanted with the cSLN, and antigen adjuvanted with Montanide ISA 206 emulsion. Specific antibody titers showed cSLN could stimulate similar FMDV-specific IgG and IgG subclasses antibody level compared with the widely used ISA 206. In addition, cSLN significantly enhanced memory immune response including effector-memory T cells and central-memory T cells compared to free iFMDV antigen and antigen adjuvanted with ISA 206. Taken together the enhanced humoral and T cell immune responses and the antigen structure friendly properties, cSLN can be a potential adjuvant for iFMDV vaccines.

Comparison of Protective Potency of DNA and Live Vaccines Expressing A2-CPA-CPB-CTE Antigens against Visceral Leishmaniasis in Syrian Hamster as Preliminary Study.

Background:Visceral leishmaniasis is the most severe form of leishmaniasis caused by Leishmania (L.) donovani complex. Drug-resistant strains have been developed as a consequence of the current chemotherapeutic interventions, which has increased the need for advanced preventive and therapeutic strategies. A2-CPA-CPB-CTE-recombinant strain of L. tarentolae, which is non-pathogenic to humans, was shown protective in live vaccine as well as its DNA vaccine counterpart in both murine and canine models.Methods:We evaluated the effectiveness of these DNA and live vaccination harboring A2-CPA-CPB-CTE in protecting hamsters against L. infantum infection using prime-boost regimens, namely DNA/DNA and Live/Live (n=9 hamsters per group). Cationic solid lipid nanoparticles (cSLN) were utilized as an adjuvant for DNA priming and electroporation for boosting DNA. At different time points post-challenge, parasite burden and body weight as well as humoral immune responses were measured.Results:Both immunization strategies partially protect hamsters against L. infantum challenge. This protective immunity is associated with remarkable decrease in parasite load in liver and spleen of vaccinated hamsters eight weeks after challenge compared to control group.Conclusion:Both test groups (DNA/DNA and Live/Live) elicited high levels of IgG2 and total IgG as humoral immune responses and lower level of parasite propagation in both liver and spleen.

Soft Cationic Nanoparticles for Drug Delivery: Production and Cytotoxicity of Solid Lipid Nanoparticles (SLNs)

The surface properties of nanoparticles have decisive influence on their interaction with biological barriers (i.e., living cells), being the concentration and type of surfactant factors to have into account. As a result of different molecular structure, charge, and degree of lipophilicity, different surfactants may interact differently with the cell membrane exhibiting different degrees of cytotoxicity. In this work, the cytotoxicity of two cationic solid lipid nanoparticles (SLNs), differing in the cationic lipids used as surfactants CTAB (cetyltrimethylammonium bromide) or DDAB (dimethyldioctadecylammonium bromide), referred as CTAB-SLNs and DDAB-SLNs, respectively, was assessed against five different human cell lines (Caco-2, HepG2, MCF-7, SV-80, and Y-79). Results showed that the cationic lipids used in SLN production highly influenced the cytotoxic profile of the particles, with CTAB-SLNs being highly cytotoxic even at low concentrations (IC50 < 10 µg/mL, expressed as CTAB amount). DDAB-SLNs produced much lower cytotoxicity, even at longer exposure time (IC50 from 284.06 ± 17.01 µg/mL (SV-80) to 869.88 ± 62.45 µg/mL (MCF-7), at 48 h). To the best of our knowledge, this is the first report that compares the cytotoxic profile of CTAB-SLNs and DDAB-SLNs based on the concentration and time of exposure, using different cell lines. In conclusion, the choice of the right surfactant for biological applications influences the biocompatibility of the nanoparticles. Regardless the type of drug delivery system, not only the cytotoxicity of the drug-loaded nanoparticles should be assessed, but also the blank (non-loaded) nanoparticles as their surface properties play a decisive role both in vitro and in vivo.

Toxicity of cationic solid lipid nanoparticles in rats

Cationic solid lipid nanoparticles (cSLNs) represent one alternative to deliver poorly water-soluble drugs and oligonucleotides (e.g., DNA, siRNA, miRNA) based on well-known biocompatible and safe excipients. However, to guarantee the translation of cSLNs from the bench to bedside it is necessary to confirm that the formulation is safe. Hence, we investigate the toxicity of cSLNs formulation in adult male Wistar rats 24 h and 72 h after single intravenous injection (5 mL/kg b.w.). Hematological, biochemical and histopathological evaluation of the reticuloendothelial system and clearance organs indicated short-lived alterations including neutrophilia, a decrease in blood urea nitrogen levels, and an increase of the marginated pools of neutrophils and macrophages located in the lungs, liver, and spleen. These findings were transient as none of them were observed in treated animals after 72 h. We also observed the ability of cSLNs to enter the brain parenchyma without disrupting the blood-brain barrier. Few minor and acute transient alterations were found, but overall, cSLNs showed to be highly biocompatible under the experimental conditions of this study, including the capability of delivering into the central nervous system. The mechanistic understanding of biocompatibility and toxicity of cSLNs is needed for providing a safe clinical translation.

Development and characterization of an improved formulation of cholesteryl oleate-loaded cationic solid-lipid nanoparticles as an efficient non-viral gene delivery system

Nanoparticle-mediated plasmid delivery is considered a useful tool to introduce foreign DNA into the cells for the purpose of DNA vaccination and/or gene therapy. Cationic solid-lipid nanoparticles (cSLNs) are considered one of the most promising non-viral vectors for nucleic acid delivery. Based on the idea that the optimization of the components is required to improve transfection efficiency, the present study aimed to formulate and characterize cholesteryl oleate-containing solid-lipid nanoparticles (CO-SLNs) incorporating protamine (P) to condense DNA to produce P:DNA:CO-SLN complexes as non-viral vectors for gene delivery with reduced cytotoxicity and high cellular uptake efficiency. For this purpose, CO-SLNs were used to prepare DNA complexes with and without protamine as DNA condenser and nuclear transfer enhancer. The main physicochemical characteristics, binding capabilities, cytotoxicity and cellular uptake of these novel CO-SLNs were analyzed.Positively charged spherical P:DNA:CO-SLN complexes with a particle size ranging from 330.1 ± 14.8 nm to 347.0 ± 18.5 nm were obtained. Positive results were obtained in the DNase I protection assay with a protective effect of the genetic material and 100% loading efficiency was achieved at a P:DNA:CO-SLN ratio of 2:1:7. Transfection studies in human embryonic kidney (HEK293T) cells showed the versatility of adding protamine to efficiently transfect cells, widening the potential applications of CO-SLN-based vectors, since the incorporation of protamine induced almost a 200-fold increase in the transfection capacity of CO-SLNs without toxicity.These results indicate that CO-SLNs with protamine are a safe and effective platform for non-viral nucleic acid delivery.

Comparison of antiproliferative effect of epigallocatechin gallate when loaded into cationic solid lipid nanoparticles against different cell lines

Several therapeutic properties have been attributed to epigallocatechin gallate (EGCG), a phytopharmaceutical polyphenol with antioxidant and antiproliferative activity. EGCG is, however, very prone to oxidation in aqueous solutions which changes its bioactive properties. Its loading in nanoparticles has been proposed to reduce its degradation while increasing its in vivo efficacy. The aim of this study was to compare the antiproliferative effect of EGCG before and after its loading in solid lipid nanoparticles (SLNs), against five different cell lines (Caco-2, HepG2, MCF-7, SV-80 and Y-79). EGCG produced concentration- and time-dependent antiproliferative effect, with efficacy dependent on the cell line. The order of potency was: MCF-7>SV-80>HepG2>Y-79>Caco-2, for 24 h exposure (MCF-7 IC50=58.60 ± 3.29 µg/mL; Caco-2 IC50>500.00 µg/mL). To the best of our knowledge this is the first study reporting EGCG antiproliferative effect in SV-80 and Y-79 cells. DDAB-SLN physicochemical properties (size ∼134 nm; PI∼0.179; ZP ∼+28mV) were only slightly modified with EGCG loading (EGCG-DDAB-SLN: ∼144 nm; PI∼0.160; ZP ∼+26mV). EGCG loading in SLN, only slightly increases the EGCG antiproliferative effect in MCF-7 and SV-80 cells. SLN exhibited intrinsic toxicity, attributed to the surfactant used in its production. From the obtained results, the biocompatibility of blank SLN must be also considered when testing the efficacy of loaded phytopharmaceutics.

Immune-triggered cancer treatment by intestinal lymphatic delivery of docetaxel-loaded nanoparticle

The maximally tolerated dose (MTD) approach in conventional chemotherapy accompanies adverse effects, primarily due to high drug concentrations in the blood after intravenous administration and non-specific damages to highly proliferating cells, including immune cells. This causes the immune system to dysfunction. To rather boost intrinsic tumor-fighting immune capacity, we demonstrate a new oral route treatment regimen of docetaxel (DTX) without apparent toxicity. The DTX-loaded cationic solid lipid nanoparticles (DSLN-CSG) were coated with an anionic polymer conjugated with glycocholic acid. The resulting nanoparticles (DSLN-CSG, ~120 nm in diameter) were actively absorbed in the distal ileum mediated by interactions with the apical sodium bile acid transporter. The plasma DTX profile was sustained up to 24 h after a single oral dose and did not impair the functions of the immune system. In mouse models, daily oral DSLN-CSG administration inhibited the growth of existing tumors and tumor formation by medication prior to cancer cell inoculation. The extent of effects depended on the cancer cell lines of melanoma, colorectal adenocarcinoma, and breast carcinoma. It was most effective for melanoma in growth inhibition and in preventing tumor formation in mice. During the medication, the cytotoxic T cell population increased while the populations of tumor-associated macrophage and regulatory T cell declined. The low dose daily oral treatment may help patients with intermittent maintenance therapy between MTD cycles and prevent tumor recurrence after completing remission for certain tumors.

The in vivo toxicological profile of cationic solid lipid nanoparticles.

Cationic solid lipid nanoparticles (cSLNs) are considered as one of the most effective lipid nanocarriers for delivery of low water-solubility compounds and genetic materials. As the excipients used in the cSLN production are generally regarded as safe (GRAS), the formulations are granted as non-toxic. However, the toxicological profile of new SLN-based formulations should always be performed to confirm that the delivery systems themselves may not impose risks to the human health. Therefore, in this study, we delineate the toxicological profile of the cSLN formulation at 24 and 72h after single intravenous injection to male Wistar rats. Hematological, biochemical, and histopathological evaluations of the spleen, lungs, liver, and kidneys indicated short-lived alterations including neutrophilia. We found increases in the population of macrophages in the lungs, liver, and spleen and also migration of circulating neutrophils into inflamed tissue and a decrease in blood urea nitrogen. We also observed the presence of cSLNs within the brain parenchyma without any sign of damage to the blood-brain barrier. These side effects appeared to be mild and transitory (< 72h). These findings reinforce the importance of investigating the toxicity of SLN-based formulations before the incorporation of drugs/genetic material to the formulation and its translation to the clinic.

Nutlin3a-Loaded Nanoparticles Show Enhanced Apoptotic Activity on Prostate Cancer Cells.

Escape from apoptosis, one of the characteristic features of cancer cells, is a case that reduces the therapeutic efficacy of apoptosis-inducing molecules used in the cancer treatment. Stabilization of the P53 protein, which is responsible for the regulation of apoptosis mechanism in the cell, is therefore an important therapeutic goal. Nutlin3a inhibits the degradation of the P53 protein, triggers P53-mediated apoptosis in cancer cells and enhances the effectiveness of chemotherapeutics. However, its low aqueous solubility is the major disadvantage when it comes to in vivo administration. In order to facilitate an aqueous formulation of Nutlin3a and to enhance its apoptotic activity on cancer cells, Nutlin3a was encapsulated in solid lipid nanoparticles (SLNs) prepared by Ouzo method. Physicochemical characterization was performed and activity of apoptosis induction on wild-type P53 expressing LNCaP prostate cancer cell line was evaluated. Nutlin3a-loaded cationic solid lipid nanoparticles were found to stabilize functional P53 at protein level. In addition, induction rate of apoptosis by nanoparticles was higher than Nutlin3a solution in DMSO, proving this nanoparticle formulation is a promising candidate for increasing the efficiency of Nutlin3a for P53(+) cancer cases. Thus, it is anticipated that the results will contribute to evaluate the use of lipid-based nanocarriers to enhance the therapeutic potential of small molecules that are important in cancer cure.

Cost Comparison of Integrative and Complementary Practices Specialized Unit In SUS

CAB51, a compact antibody against human epithelial growth receptor 2 (HER2, ErbB2), has been linked to cationic Solid Lipid Nanoparticles (SLN) via streptavidin-biotin interaction and their targeting potential evaluated against breast cancer cells. The amount of streptavidin and biotinylated antibody was optimised by monitoring the mean complex size (intensity weighed average diameter), polydispersity index and immediate stability in phosphate buffer saline (PBS). The effect on MCF-7 and BT-474 cells was evaluated at concentrations of 0.01 mg/mL and 0.1 mg/mL (counted as solid lipid). Streptavidin adsorption onto SLN surface had no influence on cell viability. Linking the antibody showed a synergistic effect on cell viability at lowest concentration tested (0.01 mg/mL) which was lower than that observed after exposure to SLN alone or antibody alone. At the higher tested concentration (0.1 mg/mL), the observed toxicity was entirely governed by the inherent toxicity of the SLN themselves. Streptavidin adsorption had no effect on accumulation in cells, while the antibody-containing complexes showed clearly increased internalisation in both cell lines. In HER2/neu positive BT-474 higher internalisation was observed than in HER2/neu negative MCF-7.

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.

Surface-tailored anti-HER2/neu-solid lipid nanoparticles for site-specific targeting MCF-7 and BT-474 breast cancer cells

CAB51, a compact antibody against human epithelial growth receptor 2 (HER2, ErbB2), has been linked to cationic Solid Lipid Nanoparticles (SLN) via streptavidin-biotin interaction and their targeting potential evaluated against breast cancer cells. The amount of streptavidin and biotinylated antibody was optimised by monitoring the mean complex size (intensity weighed average diameter), polydispersity index and immediate stability in phosphate buffer saline (PBS). The effect on MCF-7 and BT-474 cells was evaluated at concentrations of 0.01 mg/mL and 0.1 mg/mL (counted as solid lipid). Streptavidin adsorption onto SLN surface had no influence on cell viability. Linking the antibody showed a synergistic effect on cell viability at lowest concentration tested (0.01 mg/mL) which was lower than that observed after exposure to SLN alone or antibody alone. At the higher tested concentration (0.1 mg/mL), the observed toxicity was entirely governed by the inherent toxicity of the SLN themselves. Streptavidin adsorption had no effect on accumulation in cells, while the antibody-containing complexes showed clearly increased internalisation in both cell lines. In HER2/neu positive BT-474 higher internalisation was observed than in HER2/neu negative MCF-7.

A Method for Efficient Loading of Ciprofloxacin Hydrochloride in Cationic Solid Lipid Nanoparticles: Formulation and Microbiological Evaluation.

The aim of the study was the production of solid lipid nanoparticles (SLN) loaded with ciprofloxacin (CIP) through two different production techniques, quasi-emulsion solvent diffusion (QESD) and solvent injection (SI). In order to efficaciously entrap the commercial salt form (hydrochloride) of the antibiotic in these lipid systems, a conversion of CIP hydrochloride to the free base was realized in situ, through the addition of triethylamine. To ensure physical stability to the carriers over time and ameliorate the interaction with bacterial cell membranes, positively charged SLN were produced by addition of the cationic lipid didecyldimethylammonium bromide (DDAB). Homogeneous SLN populations with a mean particle sizes of 250–350 nm were produced by both methods; drug encapsulation was over 85% for most samples. The SLN were physically stable for up to nine months both at 4 °C and 25 °C, although the former condition appears more suitable to guarantee the maintenance of the initial particle size distribution. As expected, CIP encapsulation efficiency underwent a slight reduction after nine months of storage, although the initial high drug content values would ensure a residual concentration of the antibiotic in the SLN still appropriate to exert an acceptable antibacterial activity. Selected SLN formulations were subjected to an in vitro microbiological assay against different bacterial strains, to verify the effect of nanoencapsulation on the cell growth inhibitory activity of CIP. In general, CIP-SLN produced without DDAB showed MIC values for CIP comparable to those of the free drug. Conversely, addition of increasing percentages of the cationic lipid, reflected by a progressive increase of the positive value of the Zeta potential, showed a variety of MIC values against the various bacterial strains, but with values 2–4 order of dilution lower than free CIP. An hypothesis of the effect of the cationic lipid upon the increased antibacterial activity of CIP in the nanocarriers is also formulated.

Cationic Solid Lipid Nanoparticles as Non Viral Vectors for the Inhibition of Hepatocellular Carcinoma Growth by RNA Interference.

Hepatocellular carcinoma (HCC) is one of the most important causes of cancer deaths worldwide. Gene therapy is a novel approach for treating HCC. A safe and efficient gene delivery method, using viral or non-viral vectors, is a crucial factor for developing a successful HCC gene therapy. Among non-viral vectors, cationic solid lipid nanoparticles (cSLN) have advantages such as biocompatibility and transfection efficiency. In this study, novel cSLN were prepared, characterized and complexed with a plasmid (shNUPR1) capable of inhibiting the expression of the NUPR1 gene, which is involved in HCC growth and chemoresistance. The particles resulted biocompatible, as confirmed by haemolysis and cytotoxicity assays, and was able to protect the shNUPR1 plasmid from degradation by DNase I. We also demonstrated, by carrying out transfection and immunofluorescence studies, that the particles efficiently delivered the shNUPR1 plasmid into HCC cells, causing the downregulation of NUPR1-regulated genes and NUPR1 protein expression. These results suggest that the cSLN obtained could be proposed for further in vivo studies as novel transfection vectors for HCC gene therapy, having shown excellent in vitro transfection efficiency and biocompatibility.

Cholesteryl oleate-loaded cationic solid lipid nanoparticles as carriers for efficient gene-silencing therapy.

BackgroundCationic solid lipid nanoparticles (SLNs) have been given considerable attention for therapeutic nucleic acid delivery owing to their advantages over viral and other nanoparticle delivery systems. However, poor delivery efficiency and complex formulations hinder the clinical translation of SLNs.AimThe aim of this study was to formulate and characterize SLNs incorporating the cholesterol derivative cholesteryl oleate to produce SLN–nucleic acid complexes with reduced cytotoxicity and more efficient cellular uptake.MethodsFive cholesteryl oleate-containing formulations were prepared. Laser diffraction and laser Doppler microelectrophoresis were used to evaluate particle size and zeta potential, respectively. Nanoparticle morphology was analyzed using electron microscopy. Cytotoxicity and cellular uptake of lipoplexes were evaluated using flow cytometry and fluorescence microscopy. The gene inhibition capacity of the lipoplexes was assessed using siRNAs to block constitutive luciferase expression.ResultsWe obtained nanoparticles with a mean diameter of approximately 150–200 nm in size and zeta potential values of 25–40 mV. SLN formulations with intermediate concentrations of cholesteryl oleate exhibited good stability and spherical structures with no aggregation. No cell toxicity of any reference SLN was observed. Finally, cellular uptake experiments with DNA-and RNA-SLNs were performed to select one reference with superior transient transfection efficiency that significantly decreased gene activity upon siRNA complexation.ConclusionThe results indicate that cholesteryl oleate-loaded SLNs are a safe and effective platform for nonviral nucleic acid delivery.

Inhibition of intrinsic coagulation improves immune checkpoint-targeted gene delivery of cationic solid lipid nanoparticles

Abstract Tumor-targeted delivery of CRISPR/Cas9 plasmid or siRNA to inhibit immune checkpoint protein expression in tumor cells has the potential to improve anticancer immune responses. Cationic solid lipid nanoparticles (cSLNs) are promising carrier for the delivery of negatively charged nucleic acids. cSLNs with high surface charge and low PEG density have been demonstrated to enhance transfection efficiency in vitro, but for unknown reasons fail to improve gene delivery in vivo. We prepared 9 kinds of cSLNs with varying surface charge and PEG density and detected the interactions of these cSLNs with blood cells. We found that increasing surface charge and/or reducing PEG density present a risk for systemic platelet aggregation and activation. Thrombosis was clearly detected in liver, lung and kidney from mice treated with cSLNs with high surface charge and low PEG density. Mechanistic studies revealed that the intrinsic coagulation pathway was responsible for cSLN-induced thrombus formation. Furthermore, pretreatment of recipient mice with heparin, a clinically-approved intrinsic coagulation inhibitor, was highly effective in preventing toxicity, prolonging the circulation time, improving tumor accumulation and enhancing the tumor cell uptake in tumor-bearing mice. These results indicate that the thrombotic toxicity of cSLNs is an important factor affecting their drug delivery efficiency in vivo, and that heparin treatment offers a useful strategy for improving cSLN-based cancer immunotherapies.

Curcumin-loaded cationic solid lipid nanoparticles as a potential platform for the treatment of skin disorders.

Curcumin (CUM) possesses therapeutic activity against diverse skin disorders (SD); however, its clinical use faces many challenges related to physicochemical and bioavailability characteristics, that can be solve designing a new drug delivery system for CUM to treat SD. Cationic solid lipid nanoparticles (CSLN) were developed and physicochemically analyzed. The ingredients and methods adopted in this study promoted the successful preparation of CSLN with a monodispersed particle size of 218.4-238.6 nm and a polydispersity index of 0.156-0.350. A differential scanning calorimetric assay demonstrated that CUM was incorporated. The atomic force microscopy images showed uniform spherical particles, and light scattering technique confirmed the size of the particles. The zeta potential of the CSLN was +23.1 to +30.1 mV, which is important in targeting the drug to the diseased tissue that presents unregulated apoptosis. All formulations behaved as controlled drug delivery systems of CUM, as demonstrated by an in vitro drug release study, which delayed the start of drug release from formulations. At the end of the experiment, the formulations had released 14.74-21.23% of the incorporated CUM. In conclusion, the results suggest the potential of this CSLN as a controlled CUM delivery system for the treatment of SD.