Altered chemical and biological activities of all-trans retinoic acid incorporated in solid lipid nanoparticle powders

Preparation and evaluation the effects of retinoic acid loaded proliposomal nanofibers on microbial biofilm inhibition

The electrospinning method involves the production of different drug delivery applications using various polymers. The production of proliposomes with electrospinning provides the hybridization of two novel drug delivery systems. Retinoic acid, also known as all-trans retinoic acid (ATRA), is a common and effective drug for acne therapy. This study aimed to prepare ATRA-loaded proliposomal nanofibers and evaluate their effectiveness on biofilm inhibition. Blank and ATRA-loaded proliposomal nanofiber formulations were fabricated in various polyvinylpyrrolidone, phosphatidylcholine and cholesterol ratios. TEM images verified the rapid formation of the liposomes after the hydration of nanofibers. The vesicle size, polydispersity index and zeta potential values of self-assembled liposomes were measured. The vesicle size values were found to be 321.9-363.8nm with PDI values varying between 0.332-0.511 and zeta potential values of (-16.8)-(-20.5)mV. ATRA-loaded proliposomal nanofibers provided higher bioadhesion (0.25mJ/cm2) than the commercial cream (0.07mJ/cm2). The short-term stability results showed that the initial characteristics remained for three months at 4 °C. The proposed ATRA-loaded self-assembled proliposomal system provided antibacterial, fungistatic or fungicidal effects superior to retinoic acid itself and inhibited biofilm formation in lower concentrations. This approach can combine the stability advantage of nanofibers in the dry state with the high effectiveness of liposomes in acne treatment presenting antibacterial and anti-biofilm-forming activity against Candida albicans and Cutibacterium acnes.

An Insight into Advances in Developing Nanotechnology Based Therapeutics, Drug Delivery, Diagnostics and Vaccines: Multidimensional Applications in Tuberculosis Disease Management

Tuberculosis (TB), one of the deadliest contagious diseases, is a major concern worldwide. Long-term treatment, a high pill burden, limited compliance, and strict administration schedules are all variables that contribute to the development of MDR and XDR tuberculosis patients. The rise of multidrug-resistant strains and a scarcity of anti-TB medications pose a threat to TB control in the future. As a result, a strong and effective system is required to overcome technological limitations and improve the efficacy of therapeutic medications, which is still a huge problem for pharmacological technology. Nanotechnology offers an interesting opportunity for accurate identification of mycobacterial strains and improved medication treatment possibilities for tuberculosis. Nano medicine in tuberculosis is an emerging research field that provides the possibility of efficient medication delivery using nanoparticles and a decrease in drug dosages and adverse effects to boost patient compliance with therapy and recovery. Due to their fascinating characteristics, this strategy is useful in overcoming the abnormalities associated with traditional therapy and leads to some optimization of the therapeutic impact. It also decreases the dosing frequency and eliminates the problem of low compliance. To develop modern diagnosis techniques, upgraded treatment, and possible prevention of tuberculosis, the nanoparticle-based tests have demonstrated considerable advances. The literature search was conducted using Scopus, PubMed, Google Scholar, and Elsevier databases only. This article examines the possibility of employing nanotechnology for TB diagnosis, nanotechnology-based medicine delivery systems, and prevention for the successful elimination of TB illnesses.

Ultrasonically Fabricated Beta-Carotene Nanoemulsion: Optimization, Characterization and Evaluation of Combinatorial Effect with Quercetin on Streptozotocin-Induced Diabetic Rat Model

Diabetes mellitus (D.M.) is a metabolic disease that has affected over 500 million people globally. Bioactive compounds such as β-carotene and Quercetin have gained research interest for their potential antidiabetic properties, and bioactives have reported superior combinatorial effects in several ailments, including D.M. However, poor oral bioavailability has limited their potential application. Thus, the present study was focused on developing ultrasonically fabricated β-Carotene nanoemulsion (βC-NE) by employing capmul as the oil phase, Gelucire 44/14 as surfactant and Acconon MCM C8 as co-surfactant. The 3 factor- 3 level Box-Behnken design (BBD) was applied to optimise the βC-NE and study the impact of selected independent variables such as % Smix (5 to 9%), amplitude (20-30%) and sonication time (2.5-7.5 min) on responses including globule size (G.S.), poly dispersibility Index (PDI) and entrapment efficiency (E.E.). Further, the combinatorial effect of βC-NE with Quercetin Nanoemulsion (QU-NE) in the streptozotocin-induced diabetic rat model was evaluated. The results exhibited that 7% Smix at 25% amplitude for 5 min produced βC-NE with a droplet size of 153.1 ± 12.25 nm, 0.200 ± 0.04 PDI, and 73.25 ± 3.25% E.E. The βC-NE showed superior in-vivo bioavailability by 5.38 folds. The βC-NE, combined with QU-NE, exhibited potential therapeutic benefits in controlling body weight, blood sugar level, lipid levels, and tissue damage markers. Additionally, the pancreatic cells and hepatic cells were well protected. These results demonstrate the potential benefits of βC-NE and QU-NE in combination and recommend them as a substitute strategy for diabetes.

Formulation, Optimization and Evaluation of Cytarabine-Loaded Iron Oxide Nanoparticles: From In Vitro to In Vivo Evaluation of Anticancer Activity

Innovative drug delivery systems based on iron oxide nanoparticles (INPs) has generated a lot of interest worldwide and have prime biomedical benefits in anticancer therapy. There are still issues reported regarding the stability, absorption, and toxicity of iron oxide nanoparticles (INPs) when administered due to its rapid surface oxidation and agglomeration with blood proteins. To solve this problem, we have synthesized trehalose-coated stabilized iron oxide nanoparticles (TINPs) by a co-precipitation technique. The surface coating of INPs with trehalose helps to improve the stability, prevents protein binding, and increase absorption uptake inside the body. Developed TINPs was then loaded with anticancer drug cytarabine by chemical crosslinking encapsulation method using suitable solvent. Engineered cytarabine-loaded trehalose-coated stabilized iron oxide nanoparticles (CY-TINPs) were optimized for particle size, zeta potential (-13.03 mV), and solid-state characterization such as differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and transmission electron microscope (TEM) studies. The particle size of 50 nm was achieved for developed CY-TINPs. The developed CY-TINPs was further evaluated for in vitro cell line investigations which confirmed potential cytotoxic activity. Developed CY-TINPs show remarkable enhancement in in vivo pharmacokinetic parameters Cmax as 425.26 ± 2.11 and AUC0-72 as 11,546.64 ± 139.82 as compared to pure drug. Compared to traditional drug delivery, the CY-TINPs formulation can effectively delay release, improve bioavailability, and boost cytotoxic activity against tumors.

Fabrication and Evaluation of Quercetin Nanoemulsion: A Delivery System with Improved Bioavailability and Therapeutic Efficacy in Diabetes Mellitus

The current study was intended to fabricate and evaluate ultrasonically assisted quercetin nanoemulsion (Que-NE) for improved bioavailability and therapeutic effectiveness against diabetes mellitus in rats. Ethyl oleate, Tween 20, and Labrasol were chosen as oil, surfactant, and cosurfactant, respectively. Box–Behnken design (BBD) was employed to study the influence of process variables such as % surfactant and cosurfactant mixture (Smix) (5 to 7%), % amplitude (20–30%) and sonication time (2.5–7.5 min) on droplet size, polydispersibility index (PDI), and % entrapment efficiency (%EE) were studied. The optimization predicted that 9% Smix at 25% amplitude for 2.5 min would produce Que-NE with a droplet size of 125.51 nm, 0.215 PDI, and 87.04% EE. Moreover, the optimized Que-NE exhibited appreciable droplet size and PDI when stored at 5, 30, and 40 °C for 45 days. Also, the morphological characterization by transmission electron microscope (TEM) indicated the spherical shape of the optimized nanoemulsion. Furthermore, the Que-NE compared to pure quercetin exhibited superior release and enhanced oral bioavailability. The streptozocin-induced antidiabetic study in rats revealed that the Que-NE had remarkable protective and therapeutic properties in managing body weight, blood glucose level, lipid profile, and tissue injury markers, alongside the structure of pancreatic β-cells and hepatocytes being protected. Thus, the developed Que-NE could be of potential use as a substitute strategy for diabetes.

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

Ellagic Acid Containing Nanostructured Lipid Carriers for Topical Application: A Preliminary Study

Ellagic acid (EA) is a potent antioxidant substance of natural origin characterized by poor biopharmaceutical properties and low solubility in water that limit its use. The aim of the present study was to develop lipid-based nanoparticle formulations able to encapsulate EA for dermal delivery. The EA-loaded nanoparticles were prepared using two different lipid compositions, namely tristearin/tricaprylin (NLC-EA1) and tristearin/labrasol (NLC-EA2). The influence of formulations on size, entrapment efficiency, and stability of EA-loaded nanoparticles was investigated. Cryo-TEM and small-angle X-ray scattering (SAXS) analyses showed that no morphological differences are evident among all the types of loaded and unloaded nanostructured lipid carriers (NLCs). The macroscopic aspect of both NLC-EA1 and NLC-EA2 did not change with time. No difference in size was appreciable between empty and drug-containing NLC, thus the nanoparticle diameter was not affected by the presence of EA and in general no variations of the diameters occurred during this time. The entrapment efficiency of both EA-loaded nanoparticles was almost quantitative. In addition, NLC-EA1 maintained EA stability for almost two months, while NLC-EA2 up to 40 days. FRAP (Ferric reducing ability of plasma) assay showed an antioxidant activity around 60% for both the loaded NLC, as compared to the solution. Although both types of NLC are characterized by some toxicity on HaCaT cells, NLC-EA1 are less cytotoxic than NLC-EA2. Taken together these results demonstrated that the inclusion of EA within NLC could improve the water solubility, allowing for a reduction of the dosage. Moreover, both types of NLC-EA maintained a high antioxidant effect and low toxicity.

Formulation and Intracellular Trafficking of Lipid-Drug Conjugate Nanoparticles Containing a Hydrophilic Antitubercular Drug for Improved Intracellular Delivery to Human Macrophages

Isoniazid is an important first-line antitubercular drug used in the treatment of all major clinical manifestations of tuberculosis, including both pulmonary and cerebral diseases. However, it is associated with significant drawbacks due to its inherent hydrophilic nature, including poor gut permeability and an inability to cross the lipophilic blood-brain barrier, which, in turn, limit its clinical efficacy. We hypothesized that the addition of a hydrophobic moiety to this molecule would help overcome these limitations and improve its bioavailability in the bloodstream. Therefore, we designed a stable, covalently linked lipid-drug conjugate of isoniazid with a short lipid chain of stearoyl chloride. Further, lipid-drug conjugate nanoparticles were synthesized from the bulk lipid-drug conjugate by a cold high-pressure homogenization method enabled by the optimized use of aqueous surfactants. The nanoparticle formulation was characterized systematically using in vitro physicochemical analytical methods, including atomic force microscopy, transmission electron microscopy, differential scanning calorimetry, X-ray diffraction, attenuated total reflectance, particle size, ζ-potential, and drug release studies, and the mechanism of drug release kinetics. These investigations revealed that the lipid-drug conjugate nanoparticles were loaded with an appreciable amount of isoniazid conjugate (92.73 ± 6.31% w/w). The prepared lipid-drug conjugate nanoparticles displayed a uniform shape with a smooth surface having a particle size of 124.60 ± 5.56 nm. In vitro drug release studies showed sustained release up to 72 h in a phosphate-buffered solution at pH 7.4. The release profile fitted to various known models of release kinetics revealed that the Higuchi model of diffusion kinetics was the best-fitting model (R 2 = 0.9929). In addition, confocal studies showed efficient uptake of lipid-drug conjugate nanoparticles by THP-1 macrophages presumably because of increased lipophilicity and anionic surface charge. This was followed by progressive intracellular trafficking into endosomal and lysosomal vesicles and colocalization with intravesicular compartmental proteins associated with mycobacterium tuberculosis pathogenesis, including CD63, LAMP-2, EEA1, and Rab11. The developed lipid-drug conjugate nanoparticles, therefore, displayed significant ability to improve the intracellular delivery of a highly water-soluble drug such as isoniazid.

Effect of a Solid Lipid Nanoparticle Formulation on the Bioavailability of 4-(N)-Docosahexaenoyl 2', 2'-Difluorodeoxycytidine After Oral Administration

Previously, we developed a solid lipid nanoparticle (SLN) formulation of 4-(N)-docosahexaenoyl 2', 2'-difluorodeoxycytidine (DHA-dFdC), a compound with promising antitumor activity. Herein, we studied the feasibility of administering the DHA-dFdC by the oral route using the solid lipid nanoparticles (i.e., DHA-dFdC-SLNs). In simulated gastrointestinal fluids, the DHA-dFdC-SLNs did not aggregate. The release of the DHA-dFdC from the solid lipid nanoparticles in simulated gastrointestinal fluid was slow, but was slightly faster in simulated intestinal fluid than in simulated gastric fluid. In mice orally administered with DHA-dFdC-SLNs, plasma DHA-dFdC concentration vs. time curve has a T_max of ~ 1.7 h and a C_max of 17.01 μg/mL. The absolute oral bioavailability of DHA-dFdC when given as DHA-dFdC-SLNs was ~ 68% (based on AUC_{0-24 h} values), while the relative oral bioavailability DHA-dFdC (compared with DHA-dFdC in a Tween 80/ethanol-in-water solution) was 126%. Finally, in mice with pre-establish B16-F10 murine melanoma, oral DHA-dFdC-SLNs increased their survival significantly, as compared with oral administration of the DHA-dFdC solution. It is concluded that the solid lipid nanoparticle formulation increased the bioavailability of the DHA-dFdC upon oral administration, as compared with the DHA-dFdC solution.

Characterization and Absorption Kinetics of a Novel Multifunctional Nanoliposome Stabilized by Sea Cucumber Saponins Instead of Cholesterol

Cholesterol was usually used to stabilize liposome, although there have been controversies on the relationship between dietary cholesterol and health. The present study aimed to prepare a novel multifunctional nanoliposomes stabilized by sea cucumber-derived saponins using ultrasound-assisted film dispersion method. A novel uniform liposome with a mass ratio of egg yolk lecithin/sea cucumber saponins at 75:25 was successfully prepared to encapsulate saponin, and the particle size was 164.8 ± 1.70 nm with a PDI value of 0.214 ± 0.022 and zeta potential of -15.97 ± 1.23 mV. The digestion and absorption results in vivo showed that the dietary saponins in liposome form could delay the peak time of saponins and prolong their residence time in the serum. Moreover, saponins were more easily converted into their corresponding metabolites after administration with saponins in the liposome form. The novel liposome as an efficient carrier with multiple functions had great potential in the development of functional food and biomedical applications.

Engineered Polymeric Materials for Biological Applications: Overcoming Challenges of the Bio-Nano Interface

Nanomedicine has generated significant interest as an alternative to conventional cancertherapy due to the ability for nanoparticles to tune cargo release. However, while nanoparticletechnology has promised significant benefit, there are still limited examples of nanoparticles inclinical practice. The low translational success of nanoparticle research is due to the series ofbiological roadblocks that nanoparticles must migrate to be effective, including blood and plasmainteractions, clearance, extravasation, and tumor penetration, through to cellular targeting,internalization, and endosomal escape. It is important to consider these roadblocks holistically inorder to design more effective delivery systems. This perspective will discuss how nanoparticlescan be designed to migrate each of these biological challenges and thus improve nanoparticledelivery systems in the future. In this review, we have limited the literature discussed to studiesinvestigating the impact of polymer nanoparticle structure or composition on therapeutic deliveryand associated advancements. The focus of this review is to highlight the impact of nanoparticlecharacteristics on the interaction with different biological barriers. More specific studies/reviewshave been referenced where possible.

A solid lipid nanoparticle formulation of 4-(N)-docosahexaenoyl 2', 2'-difluorodeoxycytidine with increased solubility, stability, and antitumor activity

Previously, we synthesized 4-(N)-docosahexaenoyl 2', 2'-difluorodeoxycytidine (DHA-dFdC), a novel lipophilic compound with a potent, broad-spectrum antitumor activity. Herein, we report a solid lipid nanoparticle (SLN) formulation of DHA-dFdC with improved apparent aqueous solubility, chemical stability, as well as efficacy in a mouse model. The SLNs were prepared from lecithin/glycerol monostearate-in-water emulsions emulsified with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and Tween 20. The resultant DHA-dFdC-SLNs were 102.2 ± 7.3 nm in diameter and increased the apparent solubility of DHA-dFdC in water to at least 5.2 mg/mL, more than 200-fold higher than its intrinsic water solubility. DHA-dFdC in a lyophilized powder of DHA-dFdC-SLNs was significantly more stable than the waxy solid of pure DHA-dFdC. DHA-dFdC-SLNs also showed an increased cytotoxicity against certain tumor cells than DHA-dFdC. The plasma concentration of DHA-dFdC in mice intravenously injected with DHA-dFdC-SLNs in dispersion followed a bi-exponential model, with a half-life of ~44 h. In mice bearing B16-F10 murine melanoma, DHA-dFdC-SLNs were significantly more effective than DHA-dFdC in controlling the tumor growth. In addition, histology evaluation revealed a high level of apoptosis and tumor encapsulation in tumors in mice treated with DHA-dFdC-SLNs. DHA-dFdC-SLNs represents a new DHA-dFdC formulation with improved antitumor activity.

Solid Lipid Nanoparticles Surface Modification Modulates Cell Internalization and Improves Chemotoxic Treatment in an Oral Carcinoma Cell Line

Solid lipid nanoparticles (SLN) present low toxicity, versatility to incorporate both lipophilic and hydrophilic drugs, controlled drug release and they are easy to scale-up. It is well known that the endocytosis pathway by which SLN are taken up and the subsequent subcellular distribution are crucial for the biological effect of the incorporated drug. In addition, interactions between SLN and cells depend on many factors, such as, the composition of nanoparticle surface. In this work different amounts of phosphatidylethanolamine polyethylene glycol (PE–PEG) were added to SLN composed of stearic acid, Epikuron 200 and sodium taurodeoxycholate. Characterization of obtained nanoparticle suspensions were performed by the analysis of particle size, polydispersity index, ζ-potential, cell toxicity and cell internalization pathway. We have observed that the presence of PE–PEG improves active cell internalization of the nanoparticles in an oral adenocarcinoma cell line, reducing non-specific internalization mechanisms. Finally, we have tested the effect of surface coating on the efficiency of incorporated drugs using all-trans retinoic acid as a model drug. We have observed that delivery of this drug into PE–PEG coated SLN increases its chemotoxic effect compared to non-coated SLN. Therefore, it can be concluded that surface modification with PE–PEG improves the efficiency and the specificity of the SLN-loaded drug.

Formulation and characterization of chitosan encapsulated phytoconstituents of curcumin and rutin nanoparticles

Curcumin and Rutin are natural polyphenolic molecules exhibits several pharmacological actives like antibacterial, anticancer, antioxidant, chemo-preventive and anti-inflammatory properties. However till date, no studies have been reported on their combination efficacy, especially in treating multi-drug resistance of cancers because of their poor solubility and bioavailability. Hence in the present study, an attempt has been made to load both these drugs into a single nanoparticlulate system to enhance their bioavailability and efficacy. This novel formulation was prepared by solvent evaporation technique and was evaluated for particle size and shape using Zeta Sizer, Scanning Electron Microscopy (SEM) and Fourier Transform Infra Red (FT-IR) Spectroscopy. The optimized formulation was further subjected to in vitro and in vivo evaluations. The prepared nanoparticles were in the size range of 25-100nm and the release profile was found to be Non -Fickian transport. In-vivo pharmacokinetic studies were carried in rabbits and the pharmacokinetic profile was studied. The results indicate that oral bioavailability of Curcumin and Rutin has been increased to 3.06 and 4.24 folds respectively when compared to their pure drugs. This data suggest that the present novel nanoparticles loaded with these combinational drugs may have better therapeutic potential in treating drug resistant cancers.

HPMA copolymer-based polymer conjugates for the delivery and controlled release of retinoids

In this paper, we describe the synthesis, physicochemical characterization, drug release kinetics and preliminary biological evaluation of several N-(2-hydroxypropyl)methacrylamide (HPMA)-based polymer-retinoid conjugates designed for solid tumor immunotherapy. The conjugates are supposed to inhibit the immunosuppressive activity of myeloid-derived suppressor cells (MDSC) accumulated in the solid tumor microenvironment. All-trans retinoic acid (ATRA) was derivatized to hydrazide (AtrHy) and then attached to the polymer backbone via a spacer that is stable at the normal pH of blood (7.4) and hydrolytically degradable in mildly acidic environments (e.g. in endosomes or lysosomes, pH~5.0-6.5). Polymer-AtrHy conjugates were designed to achieve prolonged blood circulation and release of the immunomodulator intracellularly or extracellularly in solid tumor tissue. Three types of polymer precursors, differing in the structure of the keto acid-containing side chains, were synthesized. A linkage susceptible to hydrolytic cleavage was formed by the conjugation reaction of the carbonyl group-terminated side chains of the polymer precursors with the hydrazide group of a drug derivative. In vitro incubation of the conjugates in buffers resulted in much faster release of the drugs or their derivatives from the polymer at pH 5.0 than at pH 7.4, with the rate depending on the detailed structure of the spacer. Both the AtrHy derivative and its polymer conjugates showed the ability to induce the differentiation of retinoid-responsive HL-60 cells, thus demonstrating the required biological activity.

Biomaterials to suppress cancer stem cells and disrupt their tumoral niche

Lack of improvement in the treatment options of several types of cancer can largely be attributed to the presence of a subpopulation of cancer cells with stem cell signatures and to the tumoral niche that supports and protects these cells. This review analyses the main strategies that specifically modulate or suppress cancer stem cells (CSCs) and the tumoral niche (TN), focusing on the role of biomaterials (i.e. implants, nanomedicines, etc.) in these therapies. In the case of CSCs, we discuss differentiation therapies and the disruption of critical cellular signaling networks. For the TN, we analyze diverse strategies to modulate tumor hypervascularization and hypoxia, tumor extracellular matrix, and the inflammatory and tumor immunosuppressive environment. Due to their capacity to control drug disposition and integrate diverse functionalities, biomaterial-based therapies can provide important benefits in these strategies. We illustrate this by providing case studies where biomaterial-based therapies either show CSC suppression and TN disruption or improved delivery of major modulators of these features. Finally, we discuss the future of these technologies in the framework of these emerging therapeutic concepts.

Development of paclitaxel-loaded liposomal nanocarrier stabilized by triglyceride incorporation

Studies have highlighted the challenge of developing injectable liposomes as a paclitaxel (PTX) carrier, a challenge attributable to the limitations in liposomal stability caused by PTX loading. Poor stability of PTX-loaded liposomes is caused by PTX-triggered aggregation or fusion of liposomal membranes and is exacerbated in the presence of PEGylated lipid. In the present study, the effect of triglyceride incorporation on the stability of PTX-loaded/PEGylated liposomes was explored. Incorporation of a medium chain triglyceride Captex 300 into saturated phosphatidylcholine (PC)-based liposomes (1,2-dimyristoyl-sn-glycero-3-phosphocholine [DMPC]:cholesterol [CHOL]:N-(Carbonyl-methoxypolyethyleneglycol 2000)-1, 2-distearoyl-sn-glycero-3-phospho-ethanolamine [PE-PEG]), produced a fine, homogeneous, and membrane-filterable PTX-loaded liposomes fulfilling the requirement of an injectable lipid formulation. Triglyceride incorporation also greatly inhibited the time-dependent leakage of PTX from saturated PC-based liposomes, which appears to be mediated by the inhibition of liposome fusion. In contrast, triglyceride incorporation induced the destabilization and PTX leakage of unsaturated PC-based liposomes, indicating the opposite effect of triglyceride depending on the fluidity status of PC constituting the liposomal membrane. PTX release profile and the in vitro and in vivo anticancer efficacy of triglyceride-incorporated DMPC:CHOL:PE-PEG liposomes were similar to Taxol^® while the toxicity of liposomal PTX was significantly lower than that of Taxol. Taken together, triglyceride incorporation provided an injectable PTX formulation by functioning as a formulation stabilizer of PEGylated/saturated PC-based liposomes.

Lipid-Based Drug Delivery Systems in Cancer Therapy: What Is Available and What Is Yet to Come

Cancer is a leading cause of death in many countries around the world. However, the efficacy of current standard treatments for a variety of cancers is suboptimal. First, most cancer treatments lack specificity, meaning that these treatments affect both cancer cells and their normal counterparts. Second, many anticancer agents are highly toxic, and thus, limit their use in treatment. Third, a number of cytotoxic chemotherapeutics are highly hydrophobic, which limits their utility in cancer therapy. Finally, many chemotherapeutic agents exhibit short half-lives that curtail their efficacy. As a result of these deficiencies, many current treatments lead to side effects, noncompliance, and patient inconvenience due to difficulties in administration. However, the application of nanotechnology has led to the development of effective nanosized drug delivery systems known commonly as nanoparticles. Among these delivery systems, lipid-based nanoparticles, particularly liposomes, have shown to be quite effective at exhibiting the ability to: 1) improve the selectivity of cancer chemotherapeutic agents; 2) lower the cytotoxicity of anticancer drugs to normal tissues, and thus, reduce their toxic side effects; 3) increase the solubility of hydrophobic drugs; and 4) offer a prolonged and controlled release of agents. This review will discuss the current state of lipid-based nanoparticle research, including the development of liposomes for cancer therapy, different strategies for tumor targeting, liposomal formulation of various anticancer drugs that are commercially available, recent progress in liposome technology for the treatment of cancer, and the next generation of lipid-based nanoparticles.

Shape-Related Toxicity of Titanium Dioxide Nanofibres

Titanium dioxide (TiO₂) nanofibres are a novel fibrous nanomaterial with increasing applications in a variety of fields. While the biological effects of TiO₂ nanoparticles have been extensively studied, the toxicological characterization of TiO₂ nanofibres is far from being complete. In this study, we evaluated the toxicity of commercially available anatase TiO₂ nanofibres using TiO₂ nanoparticles (NP) and crocidolite asbestos as non-fibrous or fibrous benchmark materials. The evaluated endpoints were cell viability, haemolysis, macrophage activation, trans-epithelial electrical resistance (an indicator of the epithelial barrier competence), ROS production and oxidative stress as well as the morphology of exposed cells. The results showed that TiO₂ nanofibres caused a cell-specific, dose-dependent decrease of cell viability, with larger effects on alveolar epithelial cells than on macrophages. The observed effects were comparable to those of crocidolite, while TiO₂ NP did not decrease cell viability. TiO₂ nanofibres were also found endowed with a marked haemolytic activity, at levels significantly higher than those observed with TiO₂ nanoparticles or crocidolite. Moreover, TiO₂ nanofibres and crocidolite, but not TiO₂ nanoparticles, caused a significant decrease of the trans-epithelial electrical resistance of airway cell monolayers. SEM images demonstrated that the interaction with nanofibres and crocidolite caused cell shape perturbation with the longest fibres incompletely or not phagocytosed. The expression of several pro-inflammatory markers, such as NO production and the induction of Nos2 and Ptgs2, was significantly increased by TiO₂ nanofibres, as well as by TiO₂ nanoparticles and crocidolite. This study indicates that TiO₂ nanofibres had significant toxic effects and, for most endpoints with the exception of pro-inflammatory changes, are more bio-active than TiO₂ nanoparticles, showing the relevance of shape in determining the toxicity of nanomaterials. Given that several toxic effects of TiO₂ nanofibres appear comparable to those observed with crocidolite, the possibility that they exert length dependent toxicity in vivo seems worthy of further investigation.

Skin Delivery and in Vitro Biological Evaluation of Trans-Resveratrol-Loaded Solid Lipid Nanoparticles for Skin Disorder Therapies

The aim of this study was to evaluate the skin delivery and in vitro biological activity of trans-resveratrol (RES)-loaded solid lipid nanoparticles (SLNs). The SLNs were composed of stearic acid, poloxamer 407, soy phosphatidylcholine (SPC), an aqueous phase and 0.1% RES. The particle size, polydispersity index (PdI) and zeta potential were analyzed by dynamic light scattering (DLS). The SLNs were analyzed by scanning electron microscopy (SEM-FEG) and differential scanning calorimetry (DSC). In vitro RES-SLN skin permeation/retention assays were conducted, and their tyrosinase inhibitory activity was evaluated. An MTT reduction assay was performed on HaCat keratinocytes to determine in vitro cytotoxicity. The formulations had average diameter lower than 200 nm, the addition of SPC promoted increases in PdI in the RES-SLNs, but decreases PdI in the RES-free SLNs and the formulations exhibited zeta potentials smaller than −3 mV. The DSC analysis of the SLNs showed no endothermic peak attributable to RES. Microscopic analysis suggests that the materials formed had nanometric size distribution. Up to 45% of the RES permeated through the skin after 24 h. The RES-loaded SLNs were more effective than kojic acid at inhibiting tyrosinase and proved to be non-toxic in HaCat keratinocytes. The results suggest that the investigated RES-loaded SLNs have potential use in skin disorder therapies.

Preparation and characterization of solid lipid nanoparticles loaded with cytarabine via a micellar composition for leukemia

The present investigation reports the fabrication, optimization and characterization of tristearin based cytarabine solid lipid nanoparticles (SLN). Higher sensitivity of the cytarabine SLN than drug solution on cell line demonstrated the potential of this developed carrier.

Nanostructured lipid carriers loaded with tributyrin as an alternative to improve anticancer activity of all-trans retinoic acid

OBJECTIVES

All-trans retinoic acid (ATRA) is one of the most successful examples of differentiation agents and histone deacetylase inhibitors, such as tributyrin (TB), are known for their antitumor activity and potentiating action of drugs, such as ATRA. Nanostructured lipid carriers (NLC) represent a promising alternative to the encapsulation of lipophilic drugs such as ATRA. This study aims to develop, characterize and evaluate the cytotoxicity of ATRA-TB-loaded NLC for cancer treatment.

METHODS

The influence of in situ formation of an ion pairing between ATRA and a lipophilic amine (benethamine) on the characteristics of NLC (size, zeta potential, encapsulation efficiency) was evaluated. TB, a butyric acid donor, was used as a component of the lipid matrix. In vitro activity on cell viability and distribution of cell cycle phases were evaluated for MCF-7, MDA-MB-231, HL-60 and Jurkat cell lines.

RESULTS

The presence of the amine significantly increased the encapsulation efficiency of ATRA in NLC. Inhibition of cell viability by TB-ATRA-loaded NLC was more pronounced than the free drug. Analysis of the distribution of cell cycle phases also showed increased activity for TB-ATRA-loaded NLC, with the clear effect of cell cycle arrest in G0/G1 phase transition. The presence of TB played an important role in the activity of the formulation.

CONCLUSION

Taken together, these findings suggest that TB-ATRA-loaded NLC represents a promising alternative to intravenous administration of ATRA in cancer treatment.

Formulation of solid lipid nanoparticles (SLN): the value of different alkyl polyglucoside surfactants

Alkyl polyglycosides (APGs) represent a group of nonionic tensides with excellent skin compatibility. Thus they seem to be excellent stabilizers for lipid nanoparticles for dermal application. To investigate this, different APGs were selected to evaluate their influence on the formation and characteristics of solid lipid nanoparticles (SLN). Contact angle analysis of the aqueous solutions/dispersions of the APGs on cetyl palmitate films revealed good wettability for all APG surfactants. Cetyl palmitate based SLN were prepared by hot high pressure homogenization and subjected to particle size, charge and inner structure analysis. 1% of each APG was sufficient to obtain SLN with a mean size between 150 nm and 175 nm and a narrow size distribution. The zeta potential in water was ∼ -50 mV; the values in the original medium were distinctly lower, but still sufficient high to provide good physical stability. Physical stability at different temperatures (5°C, 25°C and 40°C) was confirmed by a constant particle size over an observation period of 90 days in all dispersions. In comparison to SLN stabilized with classical surfactants, e.g., Polysorbate, APG stabilized SLN possess a smaller size, improved physical stability and contain less surfactant. Therefore, the use of APGs for the stabilization of lipid nanoparticles is superior in comparison to classical stabilizers. Further, the results indicate that the length of the alkyl chain of the APG influences the diminution efficacy, the final particle size and the crystallinity of the particles. APGs with short alkyl chain led to a faster reduction in size during high pressure homogenization, to a smaller particle size of the SLN and to a lower recrystallization index, i.e., to a lower crystallinity of the SLN. The crystallinity of the SLN increased with an increase in the alkyl chain length of APGs. Therefore, by using the tested APGs differing in the alkyl chain length, not only small sized and physically stable but also SLN with different sizes and crystallinity can be obtained. An optimized selection of these stabilizers might therefore enable the production of lipid nanoparticles with "tailor-made" properties.

Nanocarrier for poorly water-soluble anticancer drugs--barriers of translation and solutions

Many existing chemotherapeutic drugs, repurposed drugs and newly developed small-molecule anticancer compounds have high lipophilicity and low water-solubility. Currently, these poorly water-soluble anticancer drugs (PWSAD) are generally solubilized using high concentrations of surfactants and co-solvents, which frequently lead to adverse side effects. In recent years, researchers have been actively exploring the use of nanotechnology as an alternative to the solvent-based drug solubilization approach. Several classes of nanocarrier systems (lipid-based, polymer-based and albumin-based) are widely studied for encapsulation and delivery of the existing and new PWSAD. These nanocarriers were also shown to offer several additional advantages such as enhanced tumour accumulation, reduced systemic toxicity and improved therapeutic effectiveness. In this article, the recent nanotechnological advances in PWSAD delivery will be reviewed. The barriers commonly encountered in the development of PWSAD nanoformulations (e.g. formulation issues and nanotoxicity issues) and the strategies to overcome these barriers will also be discussed. It is our goal to provide the pharmaceutical scientists and clinicians with more in-depth information about the nanodelivery approach, thus, more efficacious and safe PWSAD nanoformulations can be developed with improved translational success.

A retinyl palmitate-loaded solid lipid nanoparticle system: effect of surface modification with dicetyl phosphate on skin permeation in vitro and anti-wrinkle effect in vivo

Surface-modified solid lipid nanoparticles (SLNs) containing retinyl palmitate (Rpal) were prepared by the hot-melt method using Gelucire 50/13(®) and Precirol ATO5(®). Dicetyl phosphate (DCP) was added to negatively charge the surfaces of the SLNs and thereby enhance the skin distribution properties of Rpal. In vitro skin permeation and in vivo anti-aging studies were performed using SLNs dispersed in a hydrogel. The SLNs were under 100 nm in size with an even polydispersity index (PDI), and the high absolute zeta-potential value was sufficient to maintain the colloidal stability of the SLNs. DCP-modified negative SLNs (DCPmod-SLNs) enhanced the skin distribution of Rpal 4.8-fold and delivered Rpal to a greater depth than did neutral SLNs. The in vivo anti-wrinkle effect of the DCPmod-SLN formulation was Rpal dose-dependent. However, the anti-wrinkle effects of the DCPmod-SLN formulations were significantly different from that of the negative control and effectively prevented the reduction of elastin and superoxide dismutase by UV irradiation. In conclusion, the DCPmod-SLN system presented is a good candidate for topical Rpal delivery.

Liquid proliposomes of nimodipine drug delivery system: preparation, characterization, and pharmacokinetics

To investigate the possibility of liquid proliposomes being carriers for oral delivery, nimodipine liquid proliposomes-based soft capsules (NPSC) were prepared. Nimodipine proliposomes were characterized by transmission electron microscopy (TEM), conversion rate from proliposomes to liposomes, entrapment efficiency, particle size, and zeta potential. Accelerated stability testing of NPSC was carried out for 3 months at 40±2°C, 75±5% RH. The concentration of nimodipine in plasma of New Zealand rabbits of NPSC, nimodipine soft capsules, and hydrated liposomes was studied. Results showed that nimodipine proliposomes were automatically converted into liposomes when exposed to a water phase in 30 s. The average diameter was 378.6±26.5 nm in distilled water with entrapment efficiency (EE%) of 84.7±5.9%, while the average diameter was 316.9±34.6 nm in 0.1 M hydrochloric acid solution with EE% of 72.8±4.7%. Accelerated stability test showed that there was no change in drug content, particle size, and EE% except for a decrease in dissolution of nimodipine. In vivo experiments, areas under the plasma level-time curve of NPSC and nimodipine-hydrated liposomes increased 2.41 and 2.34 times more than that of nimodipine soft capsules, peak concentration increased 2.87 and 2.92 times, time of peak concentration from 0.75 to 2 and 1 h, respectively. Nimodipine-hydrated liposomes presented similar pharmacokinetic parameters compared with NPSC. Results suggested that NPSC offered a potential way to improve oral delivery of nimodipine.

Formation of ion pairing as an alternative to improve encapsulation and anticancer activity of all-trans retinoic acid loaded in solid lipid nanoparticles

This work aims to develop solid lipid nanoparticles (SLNs) loaded with retinoic acid (RA) to evaluate the influence of two lipophilic amines, stearylamine (SA) and benethamine (BA), and one hydrophilic, triethylamine (TA), on drug-encapsulation efficiency (EE) and cytotoxicity in cancer cell lines. The SLNs were characterized for EE, size, and zeta potential. The mean particle size decreased from 155 ± 1 nm (SLNs without amine) to 104 ± 4, 95 ± 1, and 96 ± 1 nm for SLNs prepared with SA, BA, and TA, respectively. SA-RA-loaded SLNs resulted in positively charged particles, whereas those with TA and BA were negatively charged. The EEs were significantly improved with the addition of the amines, and they increased from 36% ± 6% (without amine) to 97% ± 2%, 90% ± 2%, and 100% ± 1% for SA, TA, and BA, respectively. However, stability studies showed higher EE for BA-RA-loaded SLNs than TA-RA-loaded SLNs after 30 days. The formulations containing SA loaded or unloaded (blank SLNs) with RA were cytotoxic in normal and cancer cell lines. In contrast, the blank SLNs containing TA or BA did not show cytotoxicity in human breast adenocarcinoma cells (MCF-7), while RA-loaded SLNs with the respective amines were significantly more cytotoxic than free RA. Furthermore, the cytotoxicity of BA-RA-loaded SLNs was significantly higher than TA-RA-loaded SLNs. These findings are in agreement with the data obtained in the evaluation of subdiploid DNA content and cell-cycle analysis, which showed better anticancer activity for BA-RA-loaded SLNs than TA-RA-loaded SLNs and free RA. Taken together, these findings suggest that the BA-RA-loaded SLN formulation is a promising alternative for the intravenous administration of RA in the treatment of cancer.

Pharmacokinetics, tissue distribution and relative bioavailability of isoniazid-solid lipid nanoparticles

Low levels of isoniazid gain access into plasma following oral administration due to its high aqueous solubility, poor permeability and rapid and extensive hepatic metabolism. Further, a small t(1/2) of 1-4 h indicates its short stay in plasma and the need for repetitive or high doses which may subsequently result in hepatotoxicity and neurotoxicity associated with its use. Isoniazid-solid lipid nanoparticles (SLNs) were prepared to achieve improved bioavailability and prolonged effect, thus minimizing pulsatile plasma concentrations (and associated side effects at peak plasma concentrations). Developed SLNs showed high entrapment efficiency (69%) and small size (d(90) 48.4 nm) such that they are expected to bypass reticulo-endothelial system (RES) pickup resulting in prolonged circulation times and since liver is the major site of metabolism of isoniazid, RES avoidance will reduce its elimination from the body. Single dose (25 mg/kg BW) oral pharmacokinetic studies were performed in plasma and various tissues of rats. A significant improvement (p<0.001) in relative bioavailability in plasma (6 times) and brain (4 times) was observed after administration of isoniazid-SLNs with respect to the free drug solution at the same dose. Insignificant changes in liver concentration coupled with bypass of first pass metabolism and slow release of isoniazid (60%, in 24 h) indicate low incidence of hepatotoxicity. Isoniazid-SLNs showed a 3 times higher LD50.

A novel hybrid delivery system: polymer-oil nanostructured carrier for controlled delivery of highly lipophilic drug all-trans-retinoic acid (ATRA)

Many recently developed drugs encounter delivery issues due to their high lipophilicity and poor aqueous solubility. This study reports the development of a novel hybrid nanocarrier known as polymer-oil nanostructured carrier (PONC), in which highly lipophilic drugs such as all-trans-retinoic acid (ATRA) and indomethacin pre-solubilized in oil phase were dispersed in a polymeric matrix of poly(D,L-lactic-co-glycolic acid) (PLGA). In comparison to the standard PLGA only nanoparticles, PONC substantially increased the encapsulation efficiency of ATRA and indomethacin by up to 259% and 124%, respectively. Differential scanning calorimetry analysis revealed that the inclusion of oil introduced nanostructure into the polymeric matrix of the carrier. This feature facilitated more uniform distribution of the drug molecules which subsequently led to improved drug release kinetics with significantly reduced burst release effects (p<0.05). PONC was lyophilizable, remained physically stable when stored at low temperatures, and demonstrated low non-specific carrier toxicity. Delivery of ATRA by PONC also significantly improved its anticancer activity over the standard PLGA only nanoparticles (p<0.05). Our findings have therefore validated a promising delivery system that integrates the advantages of lipid-based (e.g. efficient encapsulation of highly lipophilic drugs) and polymeric colloidal carriers (e.g. uniform size, good stability), plus potential therapeutic benefits for delivery of poorly water-soluble anticancer drugs like ATRA.

A critical review of lipid-based nanoparticles for taxane delivery

Nano-based delivery systems have attracted a great deal of attention in the past two decades as a strategy to overcome the low therapeutic index of conventional anticancer drugs and delivery barriers in solid tumors. Myriads of preclinical studies have been focused on developing nano-based formulations to effectively deliver taxanes, one of the most important and most prescribed anticancer drug types in the clinic. Given the hydrophobic property of taxanes, lipid-based NPs, serve as a viable alternative delivery system. This critical review will provide an overview and perspective of the advancement of lipid-based nanoparticles for taxane delivery. Currently available formulations of taxanes and their drawbacks as well as criteria for idea taxane delivery system will be discussed.

Improvement of drug safety by the use of lipid-based nanocarriers

Drug toxicity is an important factor that contributes significantly to adverse drug events in current healthcare practice. Application of lipid-based nanocarriers in drug formulation is one approach to improve drug safety. Lipid-based delivery systems include micelles, liposomes, solid lipid nanoparticles, nanoemulsions and nanosuspensions. These carriers are generally composed of physiological lipids well tolerated by human body. Delivery of water-insoluble drugs in these formulations increases their solubility and stability in aqueous media and eliminates the need for toxic co-solvents or pH adjustment to solubilize hydrophobic drugs. Association or encapsulation of peptides/proteins within lipid-based carriers protects the labile biologics against enzymatic degradation, hence reducing the therapeutic dose required and risk of dose-dependent toxicity. Most importantly, lipid-based nanocarriers alter the pharmacokinetics and biodistribution of drugs through passive and active targeting, leading to increased drug accumulation at target sites while significantly decreasing non-specific distribution to other tissues. Furthermore, surface modification of these nanocarriers reduces immunogenicity of drug-carrier complexes, imparts stealth by preventing opsonization and removal by phagocytes and minimizes interaction with circulating blood components. In view of heightening attention on drug safety in patient treatment, lipid-based nanocarrier is therefore an important and promising option for formulation of pharmaceutical products to improve treatment safety and efficacy.

Nanostructured lipid carriers (NLC) for parenteral delivery of an anticancer drug

The purpose of this research was to formulate nanostructured lipid carriers (NLC) for the parenteral delivery of an anticancer drug, all-trans retinoic acid (ATRA). The ATRA was incorporated into NLC by the de novo emulsification method. The effect of the formulation factor, i.e., type and oil ratio, initial ATRA concentration on physicochemical properties was determined. The anticancer efficacy of ATRA-loaded NLC on HL-60 and HepG2 cells was also studied. NLC was formulated using a blend of solid lipids (cetyl palmitate) and liquid lipids (soybean oil (S), medium-chain triglyceride (M), S/oleic acid (O; 3:1) and M/O (3:1)) at a weight ratio of 1:1. ATRA-loaded NLC had an average size of less than 200 nm (141.80 to 172.95 nm) with a narrow PDI and negative zeta potential that was within an acceptable range for intravenous injection. The results indicated that oleic acid enhanced the ATRA-loading capacity of NLC. In vitro ATRA release was only approximately 4.06% to 4.34% for 48 h, and no significant difference in ATRA release rate from all NLC formulations in accordance with the composition of the oil phase. Moreover, no burst release of the drug was observed, indicating that NLC could prolong the release of ATRA. The initial drug concentration affected the photodegradation rate but did not affect the release rate. All ATRA-loaded NLC formulations exhibited the photoprotective property. The cytotoxicity results showed that all ATRA-loaded NLC had higher cytotoxicity than the free drug and HL-60 cells were more sensitive to ATRA than HepG2 cells.