α-Tocopherol succinate improves encapsulation and anticancer activity of doxorubicin loaded in solid lipid nanoparticles

"Characterization and stability of α-tocopherol loaded solid lipid nanoparticles formulated with different fully hydrogenated vegetable oils"

Solid lipid nanoparticles can be compatible with several bioactive compounds and confer a differentiated crystalline structure. This study aimed to produce α-tocopherol loaded solid lipid nanoparticles with fully hydrogenated oils and fats from palm oil, soybean oil, and crambe oil, by high-pressure homogenization, using lecithin as an emulsifier. After recrystallization of solid lipid nanoparticles, dispersions were evaluated until 60 days of storage for particle size, polydispersity index, zeta potential, microstructure, dispersion stability and α-tocopherol quantification. α-tocopherol loaded solid lipid nanoparticles showed particle sizes and zeta potential values considered adequate for this type of particle. Presence of α-tocopherol altered thermal behavior of the particles, leading to increased crystallinity, with no changes in polymorphism, when compared to the unloaded solid lipid nanoparticles. All α-tocopherol loaded solid lipid nanoparticles dispersions showed stability with no losses of α-tocopherol, indicating their potential as a carrier for this compound in fortified foods.

Anticancer and Chemosensitizing Effects of Menadione-Containing Peptide-Targeted Solid Lipid Nanoparticles

Vitamin K derivatives such as menadione (MD) have been recognized as promising redox-modulating and chemosensitizing agents for anticancer therapy, however, their cellular activities in peptide-targeted nanocarriers have not been elucidated to date. This study provides the guidelines for developing MD-loaded solid lipid nanoparticles (SLN) modified with extracellular matrix (ECM)-derived peptides. Relationships between RGD peptide concentration and changes in DLS characteristics as well as accumulation of SLN in cancer cells were revealed to adjust the peptide-lipid ratio. SLN system maintained adequate nanoparticle concentration and low dispersity after introduction of MD and MD/RGD, whereas formulated MD was protected from immediate conjugation with reduced glutathione (GSH). RGD-modified MD-containing SLN showed enhanced prooxidant, GSH-depleting and cytotoxic activities toward PC-3 prostate cancer cells attributed to improved cellular pharmacokinetics of the targeted formulation. Furthermore, this formulation effectively sensitized PC-3 cells and OVCAR-4 ovarian cancer cells to free doxorubicin and cisplatin so that cell growth was inhibited by MD-drug composition at nontoxic concentrations of the ingredients. These results provide an important background for further improving chemotherapeutic methods based on combination of conventional cytostatics with peptide-targeted SLN formulations of MD.

Natural Compounds: Co-Delivery Strategies with Chemotherapeutic Agents or Nucleic Acids Using Lipid-Based Nanocarriers

Cancer is one of the leading causes of death, and latest predictions indicate that cancer- related deaths will increase over the next few decades. Despite significant advances in conventional therapies, treatments remain far from ideal due to limitations such as lack of selectivity, non-specific distribution, and multidrug resistance. Current research is focusing on the development of several strategies to improve the efficiency of chemotherapeutic agents and, as a result, overcome the challenges associated with conventional therapies. In this regard, combined therapy with natural compounds and other therapeutic agents, such as chemotherapeutics or nucleic acids, has recently emerged as a new strategy for tackling the drawbacks of conventional therapies. Taking this strategy into consideration, the co-delivery of the above-mentioned agents in lipid-based nanocarriers provides some advantages by improving the potential of the therapeutic agents carried. In this review, we present an analysis of the synergistic anticancer outcomes resulting from the combination of natural compounds and chemotherapeutics or nucleic acids. We also emphasize the importance of these co-delivery strategies when reducing multidrug resistance and adverse toxic effects. Furthermore, the review delves into the challenges and opportunities surrounding the application of these co-delivery strategies towards tangible clinical translation for cancer treatment.

Long-Circulating and Fusogenic Liposomes Loaded with Paclitaxel and Doxorubicin: Effect of Excipient, Freezing, and Freeze-Drying on Quality Attributes

Liposomes can increase plasma half-life, enhance targeting, and diminish the side-effects of loaded drugs. On the downside, physical and chemical instabilities of dispersions often result in a reduced lifespan, which limits their availability on the market. Solid formulations obtained by freeze-drying can immobilize vesicles and provide extended shelf life. For both processes, the choice of excipients and process parameters are crucial to protect the carrier layers against tension caused by freezing and/or dehydration. The aim of this work is to evaluate the influence of freezing and drying parameters, besides excipient choice, to obtain solid long-circulating and fusogenic liposomes (LCFL-PTX/DXR) co-encapsulating paclitaxel (PTX) and doxorubicin (DXR) at a synergistic ratio (1:10).

METHODS

LCFL-PTX/DXR was evaluated by freeze-drying microscopy (glass transition, Tg'), differential scanning calorimetry (collapse temperature, Tc), freeze-thawing and freeze-drying processes. Freeze-dried samples were evaluated by thermogravimetry (residual moisture) and the resuspended liposomes were characterized in terms of size, polydispersity index (PI), zeta potential (ZP), and drug content. Liposomes morphology was evaluated by cryomicroscopy.

RESULTS

Trehalose protected PTX cargo upon freeze-thawing and more than 80% of the original DXR retention. The formulations with trehalose resulted in a cake with 5-7% of moisture content (200-240 nm); 44-60% of PTX retention, and 25-35% of DXR retention, with the variations caused by cryoprotector concentration and process changes.

CONCLUSIONS

Trehalose protected liposome integrity, maintaining PTX retention and most of DXR upon freeze-thawing. Freeze-drying reduced the retention of both drugs inside all liposomes, whereas formulation with trehalose presented minor losses. Therefore, this frozen formulation is an alternative product option, with no need for manipulation before use.

Preparation and evaluation of liposome with ropivacaine ion-pairing in local pain management

Local analgesia is one of the most desirable methods for postoperative pain control, while the existing local anesthetics have a short duration of analgesic effect. Nano-drug carriers have been widely used in various fields and provide an excellent strategy for traditional drugs. Although the existing liposomes for local anesthetics have certain advantages, their instability and complexity of the preparation process still cannot be ignored. Here, we developed novel ropivacaine hydrochloride liposomes with improved stability and sustained release performance by combining ropivacaine hydrochloride with sodium oleate in liposomes via hydrophobic ion-pairing (HIP). The liposomes are easy to prepare, inexpensive, and suitable for mass production. The infrared (IR), particle size, and Zeta potential measurements adequately characterized the complex, which showed a diameter of 81.09 nm and a zeta potential of -83.3 mV. Animal behavioral experiments, including the hot plate test and von Frey fiber test, demonstrated that the liposome system had a prolonged analgesic effect of 2 h versus conventional liposome preparations, consistent with the results of in vitro release experiments. In addition, in vitro cytotoxicity evaluations in RAW264.7 cells and in vivo evaluations revealed the biocompatibility and safety of the ropivacaine-sodium oleate ion-paired liposome (Rop-Ole-Lipo) system as a suitable local anesthetic for local pain management. Our findings provide a new idea for the preparation of local anesthetics.

Fabrication, physicochemical characterization and In vitro anticancer activity of nerolidol encapsulated solid lipid nanoparticles in human colorectal cell line

Nerolidol is a sesquiterpene that occurs naturally and possesses a diverse set of biological characteristics including anticancer activity but has limited solubility, bioavailability, and fast hepatic metabolism. The goal of this study was to develop a nanocarrier system encapsulating a bioactive as well as to evaluate its efficacy in Human Colorectal Cell Line. Solid lipid nanoparticles were fabricated by the emulsion solvent evaporation method and determined the particle size, polydispersity index (PDI), zeta potential, % entrapment efficiency, scanning electron microscopy (SEM), transmission electron microscopy (TEM), drug-excipient interaction study of developed nanoparticles. MTT assay was used to assess the cytotoxicity of formulations in vitro. Nerolidol loaded solid lipid nanoparticles (NR-LNPs) have presented satisfactory properties: mean particles diameter of 159 ± 4.89 nm, PDI of 0.32 ± 0.01, the zeta potential value was found to be -10 ± 1.97 and % entrapment efficiency 71.3% ± 6.11. The formulations demonstrated enhanced biological activity due to enhanced solubility and stability of the bioactive after loading into a nanoformulation along with the better internalization inside the cells.

Development of α-Tocopherol Succinate-Based Nanostructured Lipid Carriers for Delivery of Paclitaxel

The management of retinoblastoma (RB) involves the use of invasive treatment regimens. Paclitaxel (PTX), an effective antineoplastic compound used in the treatment of a wide range of malignant tumors, poses treatment challenges due to systemic toxicity, rapid elimination, and development of resistance. The goal of this work was to develop PTX-loaded, α-tocopherol succinate (αTS)-based, nanostructured lipid carrier (NLCs; αTS-PTX-NLC) and PEGylated αTS-PTX-NLC (αTS-PTX-PEG-NLC) to improve ocular bioavailability. The hot homogenization method was used to prepare the NLCs, and repeated measures ANOVA analysis was used for formulation optimization. αTS-PTX-NLC and αTS-PTX-PEG-NLC had a mean particle size, polydispersity index and zeta potential of 186.2 ± 3.9 nm, 0.17 ± 0.03, −33.2 ± 1.3 mV and 96.2 ± 3.9 nm, 0.27 ± 0.03, −39.15 ± 3.2 mV, respectively. The assay and entrapment efficiency of both formulations was >95.0%. The NLC exhibited a spherical shape, as seen from TEM images. Sterilized (autoclaved) formulations were stable for up to 60 days (last time point checked) under refrigerated conditions. PTX-NLC formulations exhibited an initial burst release and 40% drug release, overall, in 48 h. The formulations exhibited desirable physicochemical properties and could lead to an effective therapeutic option in the management of RB.

Self-assembled tocopherol-albumin nanoparticles with full biocompatibility for chemo-photothermal therapy against breast cancer

BACKGROUND

The combination of photothermal therapy (PTT) and chemotherapy has proven to be a promising strategy for cancer treatment. Various nanomaterials have shown great potential in combination therapy, including gold, graphene oxide, iron oxide, and other nanoparticles. However, their undefinable toxicity in vivo greatly slowed down their development for clinical applications.

OBJECTIVE

The present work aimed to develop a multifunctional nanoparticle for chemo-photothermal therapy composed of acknowledged biocompatible materials.

METHODS

A novel biocompatible nanoparticle (HIT-NPs) was self-assembled through the intrinsic interaction between D-α-tocopherol Succinate (TOS), human serum albumin (HSA) and indocyanine green (ICG). Doxorubicin (DOX) was then loaded due to the ion pairing between DOX and TOS. The feasibility of combined chemo-photothermal therapy induced by DOX-loaded HIT-NPs was carefully evaluated.

RESULTS

In vitro, HIT-NPs showed no cytotoxicity on human normal liver cells (HL-7702 cells) but obvious killing effects murine breast cancer cells (4T1 cells). The combined chemo-photothermal therapeutic effect on 4T1 cells was successfully obtained. DOX-loaded HIT-NPs could effectively accumulate in 4T1 subcutaneous tumors after intravenous injection, and the tumor temperature rapidly increased under laser exposure, indicating the feasibility of PTT in vivo.

CONCLUSION

The self-assembled HIT-NPs could provide a promising platform for combined chemo-photothermal cancer therapy with full biocompatibility.

Preclinical toxicological study of long-circulating and fusogenic liposomes co-encapsulating paclitaxel and doxorubicin in synergic ratio

Combination therapy between paclitaxel (PTX) and doxorubicin (DXR) is applied as the first-line treatment of breast cancer. Co-administration of drugs at synergistic ratio for treatment is facilitated with the use of nanocarriers, such as liposomes. However, despite the high response rate of solid tumors to this combination, a synergism of cardiotoxicity may limit the use. Thus, the objective of this work was to investigate the toxicity of long-circulating and fusogenic liposomes co-encapsulating PTX and DXR at the synergistic molar ratio (1:10) (LCFL-PTX/DXR). For this, clinical chemistry, histopathological analysis and electrocardiographic exams were performed on female Balb/c mice that received a single intravenous dose of LCFL-PTX/DXR. The results of the study indicated that the LD50 dose range (lethal dose for 50% of animals) of the LCFL-PTX/DXR treatment (28.9-34.7 mg/kg) is much higher than that found for free PTX/DXR treatment (20.8-23.1 mg/kg). In addition, liposomes promoted cardiac protection by not raising CK-MB levels in animals, keeping cardiomyocytes without injury or electrocardiographic changes. After 14 days of treatment, free PTX/DXR caused prolongation of the QRS interval when compared to LCFL-PTX/DXR treatment at the same dose (37.0 ± 5.01 ms and 30.83 ± 2.62 ms, respectively, with p = 0.017). The survival rate of animals treated with LCFL-PTX/DXR was three times higher than that of those treated with free drugs. Thus, it was established that the toxicity of LCFL-PTX/DXR is reduced compared to the combination of free PTX/DXR and this platform has advantages for the clinical treatment of breast cancer.

pH-sensitive doxorubicin-tocopherol succinate prodrug encapsulated in docosahexaenoic acid-based nanostructured lipid carriers: An effective strategy to improve pharmacokinetics and reduce toxic effects

Side effects often limit the use of doxorubicin (DOX) in cancer treatment. We have recently developed a nanostructured lipid carrier (NLC) formulation for synergistic chemotherapy, encapsulating DOX and the anticancer adjuvants docosahexaenoic acid (DHA) and α-tocopherol succinate (TS). Hydrophobic ion-pairing with TS allowed a high DOX entrapment in the nanocarrier. In this work, we investigated the pharmacokinetics of this formulation after intravenous administration in mice. The first data obtained led us to propose synthesizing covalent DOX-TS conjugates to increase DOX retention in the NLC. We successfully conjugated DOX to TS via an amide or hydrazone bond. In vitro studies in 4T1 tumor cells indicated low cytotoxicity of the amide derivative, while the hydrazone conjugate was effective in killing cancer cells. We encapsulated the hydrazone derivative in a DHA-based nanocarrier (DOX-hyd-TS/NLC), which had reduced particle size and high drug encapsulation efficiency. The pH-sensitive hydrazone bond allowed controlled DOX release from the NLC, with increased drug release at acidic conditions. In vivo studies revealed that DOX-hyd-TS/NLC had a better pharmacokinetic profile than free DOX and attenuated the short-term cardiotoxic effects caused by DOX, such as QT prolongation and impaired left ventricular systolic function. Moreover, this formulation showed excellent therapeutic performance by reducing tumor growth in 4T1 tumor-bearing mice and decreasing DOX-induced toxicity to the heart and liver, demonstrated by hematologic, biochemical, and histologic analyses. These results indicate that DOX-hyd-TS/NLC may be a promising nanocarrier for breast cancer treatment.

PEGylated phospholipid micelles containing D-α-tocopheryl succinate as multifunctional nanocarriers for enhancing the antitumor efficacy of doxorubicin

The aim of this investigation is to clarify the effect of D-α-tocopheryl succinate (vitamin E succinate, VES) and distearoylphosphatidyl ethanolamine-poly(ethylene glycol) (DSPE-PEG) on the encapsulation and controlled release of doxorubicin (DOX) in nano-assemblies and their consequences on the anti-tumor efficacy of DOX. DOX molecules were successfully loaded into the hybrid micelles with VES and DSPE-PEG (VDPM) via thin-film hydration method, exhibiting a small hydrodynamic particle size (~30 nm) and a weak negative zeta potential of around -5 mv. The obtained DOX-loaded VDPM2 displayed retarded DOX release at pH of 7.4, while substantially accelerated drug release at acidic pH of 5.0. Furthermore, the DOX-loaded VDPM2 exhibited substantially slower drug release rate at pH 7.4 compared with the drug-loaded VDPM1 or DPM preparation, benefiting for decreasing the premature DOX release during blood circulation. In vitro cell experiment indicated that DOX-loaded micelles (DPM, VDPM1 and VDPM2) improved the cellular uptake of DOX in 4T1 and MDA-MB-231 cells. The existence of VES component in the structure of DOX-loaded micelles had no obvious influence on the subcellular distribution of the encapsulated DOX molecules. Furthermore, the DOX-loaded VDPM2 exhibited more pronounced cytotoxicity to 4T1 and MDA-MB-231 cancerous cells compared with DOX-loaded DPM and free DOX solution. The hybrid nanocarriers including VES and DSPE-PEG selectively induced intracellular ROS accumulation and increased level of cytoplasmic calcium ion in cancerous cells by interacting with mitochondria and endoplasmic reticulum, bringing about the improved cytotoxicity of DOX. In vivo antitumor efficacy investigation of DOX-loaded VDPM2 against 4T1 xenograft-bearing mice displayed satisfied therapeutic activity with negligible systemic toxicity, as evidenced by the histological analysis and change of body weight. The proposed DOX-loaded VDPM preparation, as a mulifunctional chemotherapeutic nanomedicine system, holds great potential and bright prospect for clinical tumor therapy.

Mitochondria-acting carrier-free nanoplatform self-assembled by α-tocopheryl succinate carrying cisplatin for combinational tumor therapy

Unsatisfactory drug loading capability, potential toxicity of the inert carrier and the limited therapeutic effect of a single chemotherapy drug are all vital inhibitory factors of carrier-assisted drug delivery systems for chemotherapy. To address the above obstacles, a series of carrier-free nanoplatforms self-assembled by dual-drug conjugates was constructed to reinforce chemotherapy against tumors by simultaneously disrupting intratumoral DNA activity and inhibiting mitochondria function. In this nanoplatform, the mitochondria-targeting small-molecular drug, α-tocopheryl succinate (TOS), firstly self-assembled into nanoparticles, which then were used as the carrier to conjugate cisplatin (CDDP). Systematic characterization results showed that this nanoplatform exhibited suitable particle size and a negative surface charge with good stability in physicochemical environments, as well as pH-sensitive drug release and efficient cellular uptake. Due to the combined effects of reactive oxygen species (ROS) generation by TOS and DNA damage by CDDP, the developed nanoplatform could induce mitochondrial dysfunction and elevated cell apoptosis, resulting in highly efficient anti-tumor outcomes in vitro. Collectively, the combined design principles adopted for carrier-free nanodrugs construction in this study aimed at targeting different intracellular organelles for facilitating ROS production and DNA disruption can be extended to other carrier-free nanodrugs-dependent therapeutic systems.

Nanoencapsulated Doxorubicin Prevents Mucositis Development in Mice

Doxorubicin (DOX), a chemotherapy drug successfully used in the therapy of various types of cancer, is currently associated with the mucositis development, an inflammation that can cause ulcerative lesions in the mucosa of the gastrointestinal tract, abdominal pain and secondary infections. To increase the safety of the chemotherapy, we loaded DOX into nanostructured lipid carriers (NLCs). The NLC-DOX was characterized by HPLC, DLS, NTA, Zeta potential, FTIR, DSC, TEM and cryogenic-TEM. The ability of NLC-DOX to control the DOX release was evaluated through in vitro release studies. Moreover, the effect of NLC-DOX on intestinal mucosa was compared to a free DOX solution in C57BL/6 mice. The NLC-DOX showed spherical shape, high drug encapsulation efficiency (84.8 ± 4.6%), high drug loading (55.2 ± 3.4 mg/g) and low average diameter (66.0-78.8 nm). The DSC and FTIR analyses showed high interaction between the NLC components, resulting in controlled drug release. Treatment with NLC-DOX attenuated DOX-induced mucositis in mice, improving shortening on villus height and crypt depth, decreased inflammatory parameters, preserved intestinal permeability and increased expression of tight junctions (ZO-1 and Ocludin). These results indicated that encapsulation of DOX in NLCs is viable and reduces the drug toxicity to mucosal structures.

Co-delivery of doxorubicin, docosahexaenoic acid, and α-tocopherol succinate by nanostructured lipid carriers has a synergistic effect to enhance antitumor activity and reduce toxicity

Doxorubicin (DOX) is widely used in cancer treatment, however, its use is often limited due to its side effects. To avoid these shortcomings, the encapsulation of DOX into nanocarriers has been suggested. Herein, we proposed a novel nanostructured lipid carrier (NLC) formulation loading DOX, docosahexaenoic acid (DHA), and α-tocopherol succinate (TS) for cancer treatment. DHA is an omega-3 fatty acid and TS is a vitamin E derivative. It has been proposed that these compounds can enhance the antitumor activity of chemotherapeutics. Thus, we hypothesized that the combination of DOX, DHA, and TS in NLC (NLC-DHA-DOX-TS) could increase antitumor efficacy and also reduce toxicity. NLC-DHA-DOX-TS was prepared using emulsification-ultrasound. DOX was incorporated after preparing the NLC, which prevented its degradation during manufacture. High DOX encapsulation efficiency was obtained due to the ion-pairing with TS. This ion-pairing increases lipophilicity of DOX and reduces its crystallinity, contributing to its encapsulation in the lipid matrix. Controlled DOX release from the NLC was observed in vitro, with increased drug release at the acidic environment. In vitro cell studies indicated that DOX, DHA, and TS have synergistic effects against 4T1 tumor cells. The in vivo study showed that NLC-DHA-DOX-TS exhibited the greatest antitumor efficacy by reducing tumor growth in 4T1 tumor-bearing mice. In addition, this formulation reduced mice mortality, prevented lung metastasis, and decreased DOX-induced toxicity to the heart and liver, which was demonstrated by hematologic, biochemical, and histologic analyses. These results indicate that NLC-DHA-DOX-TS may be a promising carrier for breast cancer treatment.

Tocopheryl Succinate-Induced Structural Changes in DPPC Liposomes: DSC and ANS Fluorescence Studies

Recent studies show that alpha-tocopheryl succinate (TS) exhibits selective toxicity against cancer cells. In this study, we investigated the effect of TS's presence on the physico-chemical and structural properties of DPPC liposomes using fluorescence parameters (intensity, lifetime, and position of emission maximum) of 1-anilino-8-naphtalene sulphonate (ANS), differential scanning calorimetry (DSC) and zeta potential methods. Increasing the TS presence in the DPPC gel phase produced ANS fluorescence enhancement with a hypsochromic shift of the maximum. The zeta potential measurements show an increase in the negative surface charge and confirmed that this process is connected with the hydrophobic properties of dye, which becomes located deeper into the interphase region with a progressing membrane disorder. Temperature dependence studies showed that an increase in temperature increases the ANS fluorescence and shifts the ANS maximum emission from 464 to 475 nm indicating a shift from hydrophobic to a more aqueous environment. In the liquid crystalline phase, the quenching of ANS fluorescence occurs due to the increased accessibility of water to the ANS located in the glycerol region. The DSC results revealed that increasing the presence of TS led to the formation of multicomponent DSC traces, indicating the formation of intermediate structures during melting. The present results confirmed that TS embedded into the DPPC membrane led to its disruption due to destabilisation of its structure, which confirmed the measured biophysical parameters of the membrane.

Alpha-tocopheryl succinate improves encapsulation, pH-sensitivity, antitumor activity and reduces toxicity of doxorubicin-loaded liposomes

Doxorubicin (DOX) plays an important role in cancer treatment; however, high cardiotoxicity and low penetration in solid tumors are the main limitations of its use. Liposomal formulations have been developed to attenuate the DOX toxicity, but the technological enhancement of the liposomal formulation as well as the addition of another agent with antitumor properties, like alpha-tocopheryl succinate (TS), a semi-synthetic analog of vitamin E, could certainly bring benefits. Thus, in this study, it was proposed the development of liposomes composed of DOX and TS (pHSL-TS-DOX). A new DOX encapsulation method, without using the classic ammonium sulfate gradient with high encapsulation percentage was developed. Analysis of Small Angle X-ray Scattering (SAXS) and release study proved the pH-sensitivity of the developed formulation. It was observed stabilization of tumor growth using pHSL-TS-DOX when compared to free DOX. The toxicity tests showed the safety of this formulation since it allowed body weight initial recovery after the treatment and harmless to heart and liver, main target organs of DOX toxicity. The developed formulation also avoided the occurrence of myelosuppression, a typical adverse effect of DOX. Therefore, pHSL-TS-DOX is a promising alternative for the treatment of breast cancer since it has adequate antitumor activity and a safe toxicity profile.

Development of Long-Circulating and Fusogenic Liposomes Co-encapsulating Paclitaxel and Doxorubicin in Synergistic Ratio for the Treatment of Breast Cancer

Background:

The co-encapsulation of paclitaxel (PTX) and doxorubicin (DXR) in liposomes has the potential to offer pharmacokinetic and pharmacodynamic advantages, providing delivery of both drugs to the tumor at the ratio required for synergism.

Objective:

To prepare and characterize long-circulating and fusogenic liposomes co-encapsulating PTX and DXR in the 1:10 molar ratio (LCFL-PTX/DXR).

Methods:

LCFL-PTX/DXR was prepared by the lipid film formation method. The release of PTX and DXR from liposomes was performed using a dialysis method. Studies of cytotoxicity, synergism, and cellular uptake were also carried out.

Results:

The encapsulation percentage of PTX and DXR was 74.1 ± 1.8 % and 89.6 ± 12.3%, respectively, and the mean diameter of the liposomes was 244.4 ± 28.1 nm. The vesicles remained stable for 30 days after their preparation. The drugs were simultaneously released from vesicles during 36 hours, maintaining the drugs combination in the previously established ratio. Cytotoxicity studies using 4T1 breast cancer cells showed lower inhibitory concentration 50% (IC50) value for LCFL-PTX/DXR treatment (0.27 ± 0.11 µm) compared to the values of free drugs treatment. In addition, the combination index (CI) assessed for treatment with LCFL-PTX/DXR was equal to 0.11 ± 0.04, showing strong synergism between the drugs. Cell uptake studies have confirmed that the molar ratio between PTX and DXR is maintained when the drugs are administered in liposomes.

Conclusion:

It was possible to obtain LCFL-PTX/DXR suitable for intravenous administration, capable of releasing the drugs in a fixed synergistic molar ratio in the tumor region.

Hydrophobic ion pairing: encapsulating small molecules, peptides, and proteins into nanocarriers

Hydrophobic ion pairing has emerged as a method to modulate the solubility of charged hydrophilic molecules ranging in class from small molecules to large enzymes. Charged hydrophilic molecules are ionically paired with oppositely-charged molecules that include hydrophobic moieties; the resulting uncharged complex is water-insoluble and will precipitate in aqueous media. Here we review one of the most prominent applications of hydrophobic ion pairing: efficient encapsulation of charged hydrophilic molecules into nano-scale delivery vehicles - nanoparticles or nanocarriers. Hydrophobic complexes are formed and then encapsulated using techniques developed for poorly-water-soluble therapeutics. With this approach, researchers have reported encapsulation efficiencies up to 100% and drug loadings up to 30%. This review covers the fundamentals of hydrophobic ion pairing, including nomenclature, drug eligibility for the technique, commonly-used counterions, and drug release of encapsulated ion paired complexes. We then focus on nanoformulation techniques used in concert with hydrophobic ion pairing and note strengths and weaknesses specific to each. The penultimate section bridges hydrophobic ion pairing with the related fields of polyelectrolyte coacervation and polyelectrolyte-surfactant complexation. We then discuss the state of the art and anticipated future challenges. The review ends with comprehensive tables of reported hydrophobic ion pairing and encapsulation from the literature.

Sclareol is a potent enhancer of doxorubicin: Evaluation of the free combination and co-loaded nanostructured lipid carriers against breast cancer

AIMS

In this work, it was sought to determine if there was synergism between doxorubicin (DOX), a well-known antineoplastic, and sclareol (SC), a diterpene from natural origin, in breast cancer treatment. Moreover, it was investigated if their co-loading in the same nanocarrier would result in a gain of activity and/or a toxicity diminishment.

MAIN METHODS

The synergism of the DOX:SC combination was evaluated in MDA-MB-231 and 4T1 cells. A nanostructured lipid carrier (NLC) co-encapsulating DOX and SC in their synergistic molar ratio was prepared and characterised, in terms of mean diameter, zeta potential, DOX encapsulation efficiency, small angle X-ray scattering, differential scanning calorimetry, and polarised light microscopy for further intravenous administration. The anticancer activity of the combination, free and encapsulated, was evaluated in 4T1-tumour bearing mice.

KEY FINDINGS

It was determined that DOX:SC combination at the molar ratio 1:1.9 presents better synergistic anticancer activity than the molar ratio 1:7.5 in vitro. DOX:SC-loaded NLC (NLC-DOX-SC) improved in vitro cytotoxic and in vivo antitumour activity compared to free DOX. Although NLC-DOX-SC and free DOX:SC, at the synergistic molar ratio, showed similar activity in the in vivo study, the free combination provoked body weight loss, behaviour alterations and haematological toxicity in the animals, while this was not observed for NLC-DOX-SC.

SIGNIFICANCE

This work shows that SC and DOX present synergistic anticancer activity for breast cancer treatment whereas NLC-DOX-SC was a feasible alternative to attain the benefits posed by DOX:SC combination but with none to fewer side effects.

Preparation and evaluation of tacrolimus-loaded thermosensitive solid lipid nanoparticles for improved dermal distribution

Background: Tacrolimus (TCR), also known as FK-506, is a biopharmaceutics classification system (BCS) class II drug that is insoluble in water because of its high log P values. After dermal application, TCR remains in the stratum corneum and passes through the skin layers with difficulty.

Purpose: The objectives of this study were to develop and evaluate solid lipid nanoparticles (SLNs) with thermosensitive properties to improve penetration and retention.

Methods: We prepared TCR-loaded thermosensitive solid lipid nanoparticles (TCR-SLNs) with different types of surfactants on the shell of the particle, which conferred the advantages of enhancing skin permeation and distribution. We also characterized them from a physic point of view and performed in vitro and in vivo evaluations.

Results: The TCR contained in the prepared TCR-SLN was in an amorphous state and entrapped in the particles with a high loading efficiency. The assessment of ex vivo skin penetration using excised rat dorsal skin showed that the TCR-SLNs penetrated to a deeper layer than the reference product (0.1% Protopic^®). In addition, the in vivo skin penetration test demonstrated that TCR-SLNs delivered more drug into deeper skin layers than the reference product. FT-IR images also confirmed drug distribution of TCR-SLNs into deeper layers of the skin.

Conclusion: These results revealed the potential application of thermosensitive SLNs for the delivery of difficult-to-permeate, poorly water-soluble drugs into deep skin layers.

99mTc-Radiolabeled TPGS Nanomicelles Outperform 99mTc-Sestamibi as Breast Cancer Imaging Agent

D-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS) is a Food and Drug Administration (FDA) approved biomaterial that can form nanosized micelles in aqueous solution. TPGS micelles stand as an interesting system to perform drug delivery as they can carry lipophilic drugs and overcome P glycoprotein efflux as well. Therefore, TPGS micelles combined with other copolymers have been reported in many cancer research studies as a carrier for therapeutic drugs. Their ability to reach tumoral tissue can also be exploited to develop imaging agents with diagnostic application. A radiolabeling method with ^99mTc for TPGS nanosized micelles and their biodistribution in a healthy animal model as well as their pharmacokinetics and radiolabeling stability in vivo was previously reported. The aim of this work was to evaluate the performance of this radioactive probe as a diagnostic imaging agent compared to routinely available SPECT radiopharmaceutical, ^99mTc-sestamibi. A small field of view gamma camera was used for scintigraphy studies using radiolabeled TPGS micelles in two animal models of breast cancer: syngeneic 4T1 murine cell line (injected in BALB/c mice) and chemically NMU-induced (Sprague-Dawley rats). Ex vivo radioactivity accumulation in organs of interest was measured by a solid scintillation counter, and a semiquantitative analysis was performed over acquired images as well. Results showed an absence of tumoral visualization in 4T1 model for both radioactive probes by gamma camera imaging. On the contrary, NMU-induced tumors had a clear tumor visualization by scintigraphy. A higher tumor/background ratio and more homogeneous uptake were found for radiolabeled TPGS micelles compared to ^99mTc-sestamibi. In conclusion, ^99mTc-radiolabeled TPGS micelles might be a potential SPECT imaging probe for diagnostic purposes.

α- Tocopherol succinate loaded nano-structed lipid carriers improves antitumor activity of doxorubicin in breast cancer models in vivo

Combination-based chemotherapies have been the standard treatment for multiple solid tumors since the 1960s. Combined therapies where both agents have toxicity results in dose-limiting effects. α- tocopherol succinate (TS) is an analogue of vitamin E that exhibits antitumor properties in the absence of toxicity. Hence, its combination with a frontline chemotherapy, doxorubicin (DOX) is an alternative to increase antitumor efficacy. Therefore, the aim of this work was to evaluate the antitumor activity of nanostructed lipid carriers (NLC) loaded with TS and DOX. The NLC-TS-DOX were prepared, characterized and radiolabeled with technetium-99m. Cytotoxicity studies were performed in vitro, using two breast cancer cell lines, MDA-MB-231 and 4T1. Biodistribution and antitumor activity were evaluated in 4T1 tumor-bearing mice. The results showed that NLC-TS-DOX had a small diameter (85 nm) and a long blood clearance (T_1/2β = 1107.71 min) that consequently resulted in a higher tumor uptake compared to contralateral muscle for up to 48 h. Drug combination studies in MDA-MB-231 and 4T1 cells showed a combination index below 0.8 at ED_50-90 for both cell lines. Interestingly, a high synergism was found at ED_90. Antitumor activity showed a better control of tumor growth for animals treated with NLC-ST-DOX. The small particle size, along with the EPR effect and the controlled release of DOX from the particle, associated with the synergic combination between TS and DOX led to an increase of the antitumor efficacy. Therefore, NLC-TS-DOX can be considered a plausible alternative to improve antitumor efficacy in DOX therapeutic regimens.

High payload nanostructured lipid carriers fabricated with alendronate/polyethyleneimine ion complexes

Oral bioavailability of the anti-osteoporotic drug alendronate (AL) is limited to ≤ 1% due to unfavorable physicochemical properties. To augment absorption across the gastrointestinal mucosa, an ion pair complex between AL and polyethyleneimine (PEI) was formed and incorporated into nanostructured lipid carriers (NLCs) using a modified solvent injection method. When compared to free AL, ion pairing with PEI increased drug encapsulation efficiency in NLCs from 10% to 87%. Drug release from NLCs measured in vitro using fasted state simulated intestinal fluid, pH 6.5 (FaSSIF-V2) was significantly delayed after PEI complexation. Stability of AL/PEI was pH-dependent resulting in 10-fold faster dissociation of AL in FaSSIF-V2 than measured at pH 7.4. Intestinal permeation properties estimated in vitro across Caco-2 cell monolayers revealed a 3-fold greater flux of AL encapsulated as hydrophobic ion complex in NLCs when compared to AL solution (P_app = 8.43 ± 0.14 × 10^-6 cm/s and vs. 2.76 ± 0.42 × 10^-6 cm/s). Cellular safety of AL/PEI-containing NLCs was demonstrated up to an equivalent AL concentration of 2.5 mM. These results suggest that encapsulation of AL/PEI in NLCs appears a viable drug delivery strategy for augmenting oral bioavailability of this clinically relevant bisphosphonate drug and, simultaneously, increase gastrointestinal safety.

In vitro evaluation of antisense oligonucleotide functionalized core-shell nanoparticles loaded with α-tocopherol succinate

Antisense oligonucleotide (ASO)-conjugated-α-tocopherol succinate (TCS)-loaded-poly(lactic acid)-g-poly(ethylene glycol) nanoparticles (ASO-TCS-PLA-PEG NPs), with the ratio of polymer/TCS of 10:2.5, 10:5, 10:7 (w/w) were prepared for targeting cancer therapy. The amphiphilic PLA, amino terminated PEG graft copolymers were synthesized by ring opening polymerization reaction. Nanoparticles were produced by using double emulsion (w/o/w) solvent evaporation method. ASO-TCS-PLA-PEG NPs demonstrated satisfactory encapsulation and loading efficiency and size distribution. The short-term stability studies were carried out at 4 and 25 °C for 30 days to assess their mean particle size, polydispersity index and zeta potential. The cellular uptake and extended cytoplasmic retention of the NPs in A549 human lung carcinoma and L929 mouse fibroblast cells were examined by fluorescence and confocal microscopy. In human lung cancer cells, ASO-TCS-PLA-PEG NPs exhibited better cellular internalization, cytotoxicity and apoptotic and necrotic effects compared to healthy cell line, L929. These findings showed that ASO-modified nanoparticles could serve as a promising nanocarrier for targeted tumor cells.

Enhanced antitumor activity of epigallocatechin gallate–conjugated dual-drug-loaded polystyrene–polysoyaoil–diethanol amine nanoparticles for breast cancer therapy

The development of novel combination anticancer drug delivery systems is an important step to improve the effectiveness of anticancer treatment in metastatic breast cancer and to overcome increased toxicity of the currently used combination treatments. The aim of this study was to assess efficient targeting, therapeutic efficacy, and bioavailability of a combination of drugs (curcumin and α-tocopheryl succinate) loaded polystyrene–polysoyaoil–diethanol amine nanoparticles. Polystyrene–polysoyaoil–diethanol amine nanoparticles encapsulating two drugs, individually or in combination, were prepared by double-emulsion solvent evaporation method, resulting in particle size smaller than 250 nm with a surface negative charge between −30 and −40 mV. Entrapment efficiency of curcumin and α-tocopheryl succinate in the epigallocatechin gallate–conjugated dual-drug-loaded nanoparticles was found to be 68% and 80%, respectively. The release kinetics of curcumin and α-tocopheryl succinate from the nanoparticles exhibited a gradual and continuous profile followed by an initial burst behavior with a release over 20 days in vitro. Next, we have investigated the anticancer activity of nanoparticles encapsulating both the drugs and individually drug in human breast cancer cells (MDA-MB-231) using double-staining-based cell death analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assessment of cytotoxicity and flow cytometer. In vitro cytotoxicity studies revealed that epigallocatechin gallate–α-tocopheryl succinate/curcumin–polystyrene–polysoyaoil–diethanol amine nanoparticles are more potent than the corresponding α-tocopheryl succinate/curcumin–polystyrene–polysoyaoil–diethanol amine nanoparticles and their single-drug-loaded forms and show a synergistic and breast tumor targeting function. Thus, here, we propose epigallocatechin gallate–conjugated curcumin and α-tocopheryl succinate–loaded polystyrene–polysoyaoil–diethanol amine nanoparticles which effectively inhibit tumor growth and reduce toxicity compared to single-drug chemotherapy.

Hydrophilically modified self-assembling α-tocopherol derivative as niosomal nanocarrier for improving clarithromycin oral bioavailability

Synthesis of biocompatible and cost-effective novel nonionic surfactants from renewable resources has been the subject of greater scientific interest for enhancing the bioavailability of less water-soluble drugs. The present study focuses on the synthesis of α-tocopherol-based novel biocompatible nonionic surfactant and its evaluation for forming clarithromycin-loaded niosomal drug delivery system. α-tocopherol was hydrophilically modified through multistep reactions and characterized using mass and ¹H NMR spectroscopic techniques. Drug-loaded niosomal vesicles were investigated for entrapment efficiency (%EE), size, polydispersity index (PDI), zeta potential (ζ) and morphology using LC-MS, dynamic light scattering (DLS) and atomic force microscopy (AFM). Blood haemolysis, cell culture and acute toxicity tests were performed to investigate its biocompatibility. In vivo oral bioavailability of clarithromycin loaded in niosomal formulation was studied in rabbits. The vesicles were spherical in shape and entrapped up to 75 ± 2.57% of the drug. They exhibited a homogeneous size distribution with a mean diameter of 245 ± 4.66 nm. The surfactant was quite haemocompatible, low cytotoxic and safe in mice. Improved oral bioavailability of clarithromycin was achieved when carried in α-tocopherol-based niosomes. Results obtained showed that the synthesized amphiphile is biocompatible and has excellent capability for formation of niosomal vesicles and enhancing oral bioavailability of less water-soluble drugs like clarithromycin.

Novel transferrin modified and doxorubicin loaded Pluronic 85/lipid-polymeric nanoparticles for the treatment of leukemia: In vitro and in vivo therapeutic effect evaluation

PURPOSE

Childhood leukemia is a common malignant disease in children. Doxorubicin (DOX) was widely used for the treatment of leukemia. However, severe toxic side effects and drug resistance are the major limitations of DOX. Nanocarriers offer the opportunity to overcome these drawbacks, there are many attempts to enhance the activity of DOX against drug resistance. This study aimed to develop a novel transferrin (Tf) modified and doxorubicin (DOX) loaded Pluronic 85/lipid-polymeric nanoparticles for the treatment of leukemia.

METHODS

In this study, a novel targeted ligand: transferrin-polyethylene glycol-oleic acid (Tf-PEG-OA) was synthesized. Tf modified and DOX loaded Pluronic 85/lipid-polymeric nanoparticles (Tf-DOX P85/LPNs) were prepared via the self-assembly of PLGA, P85, stearic acid and Tf-PEG-OA using the nanoprecipitation method. The physicochemical properties of LPNs were characterized. In vitro and in vivo anti-tumor efficacy of LPNs was evaluated in human promyelocytic leukemia cell line (HL-60 cells) and DOX resistance HL-60 cell line (HL-60/DOX cells) including the relevant animal models.

RESULTS

Tf-DOX P85/LPNs displayed strong anti-tumor ability on both HL-60 cells and HL-60/DOX cells than other formulations used as contrast. Also, in HL-60/DOX bearing animal models, Tf-DOX P85/LPNs exhibited the highest efficiency as well as the lowest systemic toxicity.

CONCLUSION

The results indicated that Tf P85/LPNs is a promising platform to enhance efficacy, reduce toxicity and overcome drug resistance of DOX for the treatment of leukemia.

Solid lipid nanoparticles co-loaded with doxorubicin and α-tocopherol succinate are effective against drug-resistant cancer cells in monolayer and 3-D spheroid cancer cell models

This work aimed to develop solid lipid nanoparticles (SLN) co-loaded with doxorubicin and α-tocopherol succinate (TS) and to evaluate its potential to overcome drug resistance and to increase antitumoral effect in MCF-7/Adr and NCI/Adr cancer cell lines. The SLN were prepared by a hot homogenization method and characterized for size, zeta potential, entrapment efficiency (EE), and drug loading (DL). The cytotoxicity of SLN or penetration was evaluated in MCF-7/Adr and NCI/adr as a monolayer or spheroid cancer cell model. The SLN showed a size in the range of 74-80nm, negative zeta potential, EE of 99%, and DL of 67mg/g. The SLN co-loaded with Dox and TS showed a stronger cytotoxicity against MCF-7/Adr and NCI/Adr cells. In the monolayer model, the doxorubicin co-localization as a free and encapsulated form was higher for the encapsulated drug in MCF-7/Adr and NCI/adr, suggesting a bypassing of P-glycoprotein bomb efflux. For cancer cell spheroids, the SLN co-loaded with doxorubicin and TS showed a prominent cytotoxicity and a greater penetration of doxorubicin.