High melting lipid based approach for drug delivery: Solid lipid nanoparticles

Experimental approaches to evaluate solid lipid nanoparticle-based drug delivery systems

Solid lipid nanoparticles (SLNs) are potential drug carriers due to the several advantages they offer. The physicochemical stability of lipid carriers varies significantly due to their diverse compositions and structures. Appropriate analytical methods are required for the complete characterization of SLNs. Physicochemical characterization includes analysis of bulk properties like particle size, size distribution, zeta potential, morphology, stability, polymorphism, crystallinity, and molecular level properties like microenvironments within nanoparticles and their interactions with drugs. Moreover, drug loading, drug entrapment efficiency, and drug release kinetics are essential parameters to evaluate the efficacy of SLNs as drug delivery systems. In addition to testing the physicochemical stability and functionality of SLN formulations, it is essential to investigate their desired actions through in vivo studies, which are beyond the scope of this article. This review briefly discusses the different experimental techniques and their applications in the field of solid lipid nanoparticles. These techniques can also be used to characterize nanostructure lipid carriers, which are second-generation lipid nanoparticles.

Formulation optimization of chitosan surface coated solid lipid nanoparticles of griseofulvin: A Box-Behnken design and in vivo pharmacokinetic study

Solid lipid nanoparticles (SLNs) are becoming increasingly favored for their robust biocompatibility and their capacity to enhance drug solubility, particularly for drugs with limited water solubility. This study delves into the effectiveness of the hot melt sonication technique in fabricating SLNs with high drug loading capabilities and sustained release characteristics. Griseofulvin (GF), chosen as a representative drug due to its poor water solubility, was encapsulated into SLNs composed of stearic acid. Optimization of chitosan-coated GF-loaded SLNs (CS-GF-SLN) was conducted using a Box-Behnken design. Utilizing the desirability approach, optimal parameters were determined, including a lipid quantity of 450.593 mg, chitosan content of 268.67 mg, and sonication duration of 2.14 h. These parameters resulted in a zeta potential of -34.8 mV and a particle size (PS) of 56.87 nm. Following optimization, the refined formulation underwent comprehensive assessment across various parameters. Notably, the drug encapsulated within SLNs exhibited sustained release over three days, as illustrated by the in-vitro drug release profile. The optimized formulation demonstrated a bioavailability enhancement by approximately 1.7 to 2.0 times compared to the conventional formulation. Furthermore, administration of drug-loaded SLNs to a macrophage cell line demonstrated no cytotoxicity, affirming their suitability as conventional drug delivery platforms for GF.

Lipid-based Non-viral Vector: Promising Approach for Gene Delivery

OBJECTIVES

The present review aims to discuss various strategies to overcome intracellular and extracellular barriers involved in gene delivery as well as the advantages, challenges, and mechanisms of gene delivery using non-viral vectors. Additionally, patents, clinical studies, and various formulation approaches related to lipid-based carrier systems are discussed.

METHODS

Data were searched and collected from Google Scholar, ScienceDirect, PubMed, and Springer.

RESULTS

In this review, we have investigated the advantages of non-viral vectors over viral vectors. The advantage of using non-viral vectors are that they seek more attention in different fields. They play an important role in delivering the genetic materials. However, few non-viral vector-based carrier systems have been found in clinical settings. Challenges are developing more stable, site-specific gene delivery and conducting thorough safety assessments to minimize the undesired effects.

CONCLUSION

In comparison to viral vectors, non-viral vector-based lipid nanocarriers have more advantages for gene delivery. Gene therapy research shows promise in addressing health concerns. Lipid-based nanocarriers can overcome intracellular and extracellular barriers, allowing efficient delivery of genetic materials. Nonviral vectors are more attractive due to their biocompatibility, ease of synthesis, and cost-effectiveness. They can deliver various nucleic acids and have improved gene delivery efficacy by avoiding degradation steps. Despite limited clinical use, many patents have been filed for mRNA vaccine delivery using non-viral vectors.

Doxorubicin and 4-nitrochalcone loaded in beeswax-based nanostructured lipid carriers: In vitro antitumoral screening and evaluation of synergistic effect on HepG-2 cells

Cancer is the second most deadly disease worldwide, and the most traditional approaches such as chemotherapy still face limitations associated to drug dosage and off-target side effects. To address these issues, we propose the simultaneous administration of 4-Nitrochalcone (4NC) and Doxorubicin (DOX) using beeswax based nanostructured lipid carriers (NLCs). The co-encapsulation of 4NC and DOX in the beeswax based NLCs was performed using the water/oil/water double emulsion technique in association with the melt dispersion approach. The system composed by semi-spherical NLCs with an average diameter around 200 nm and narrow size distribution, displayed colloidal stability before and after redispersion, keeping the zeta potential below -30 mV. The antitumor activity of the nanoparticles was screened on different tumor cell lines, and the induced cellular death and internal ROS levels were analyzed on hepatocarcinoma cells, which were found to be more affected by the combination of 4NC and DOX. The results indicated that 4NC + DOX-NCLs could promote cytotoxicity and oxidative damage-mediated apoptosis in a HepG-2 cell line.

Engineered urolithin A-laden functional polymer-lipid hybrid nanoparticles prevent cisplatin-induced proximal tubular injury in vitro

Functional polymer-lipid hybrid nanoparticles (H-NPs) are a promising class of nanocarriers that combine the benefits of polymer and lipid nanoparticles, offering biocompatibility, structural stability, high loading capacity, and, most importantly, superior surface functionalization. Here, we report the synthesis and design of highly functional H-NPs with specificity toward the transferrin receptor (TfR), using a small molecule ligand, gambogic acid (GA). A fluorescence study revealed the molecular orientation of H-NPs, where the lipid-dense core is surrounded by a polymer exterior, functionalized with GA. Urolithin A, an immunomodulator and anti-inflammatory agent, served as a model drug-like compound to prepare H-NPs via traditional emulsion-based techniques, where H-NPs led to smaller particles (132 nm) and superior entrapment efficiencies (70 % at 10 % drug loading) compared to GA-conjugated polymeric nanoparticles (P-NPs) (157 nm and 52 % entrapment efficiency) and solid lipid nanoparticles (L-NPs) (186 nm and 29 % entrapment efficiency). H-NPs showed superior intracellular accumulation compared to individual NPs using human small intestinal epithelial (FHs 74) cells. The in vitro efficacy was demonstrated by flow cytometry analysis, in which UA-laden H-NPs showed excellent anti-inflammatory properties in cisplatin-induced injury in healthy human proximal tubular cell (HK2) model by decreasing the TLR4, NF-κβ, and IL-β expression. This preliminary work highlights the potential of H-NPs as a novel functional polymer-lipid drug delivery system, establishing the foundation for future research on its therapeutic potential in addressing chemotherapy-induced acute kidney injury in cancer patients.

Solid lipid nanoparticles: a versatile approach for controlled release and targeted drug delivery

Solid Lipid Nanoparticles (SLN), the first type of lipid-based solid carrier systems in the nanometer range, were introduced as a replacement for liposomes. SLN are aqueous colloidal dispersions with solid biodegradable lipids as their matrix. SLN is produced using processes like solvent diffusion method and high-pressure homogenization, among others. Major benefits include regulated release, increased bioavailability, preservation of peptides and chemically labile compounds like retinol against degradation, cost-effective excipients, better drug integration, and a broad range of applications. Solid lipid nanoparticles can be administered via different routes, such as oral, parenteral, pulmonary, etc. SLN can be prepared by using high shear mixing as well as low shear mixing. The next generation of solid lipids, nanostructured lipid carriers (NLC), can reduce some of the drawbacks of SLN, such as its restricted capacity for drug loading and drug expulsion during storage. NLC are controlled nanostructured lipid particles that enhance drug loading. This review covers a brief introduction of solid lipid nanoparticles, manufacturing techniques, benefits, limitations, and their characterization tests.

Co-encapsulation of omega-3 and vitamin D3 in beeswax solid lipid nanoparticles to evaluate physicochemical and in vitro release properties

In recent years, lipophilic bioactive compounds have gained much attention due to their wide range of health-benefiting effects. However, their low solubility and susceptibility to harsh conditions such as high temperatures and oxidation stress have limited their potential application for the development of functional foods and nutraceutical products in the food industry. Nanoencapsulation can help to improve the stability of hydrophobic bioactive compounds and protect these sensitive compounds during food processing conditions, thus overcoming the limitation of their pure use in food products. The objective of this work was to co-entrap vitamin D3 (VD3) and omega 3 (ω3) as hydrophobic bioactive compounds providing significant health benefits in beeswax solid lipid nanoparticles (BW. SLNs) for the first time and to investigate the effect of different concentrations of VD3 (5 and 10 mg/mL) and ω3 (8 and 10 mg) on encapsulation efficiency (EE). Our findings revealed that the highest EE was obtained for VD3 and ω3 at concentrations of 5 mg/mL and 10 mg, respectively. VD3/ω3 loaded BW. SLNs (VD3/ω3-BW. SLNs) were prepared with zeta potential and size of-32 mV and 63.5 nm, respectively. Results obtained by in-vitro release study indicated that VD3 release was lower compared to ω3 in the buffer solution. VD3 and ω3 incorporated in BW. SLNs demonstrated excellent stability under alkaline and acidic conditions. At highly oxidizing conditions, 96.2 and 90.4% of entrapped VD3 and ω3 remained stable in nanoparticles. Moreover, nanoparticles were stable during 1 month of storage, and no aggregation was observed. In conclusion, co-loaded VD3 and ω3 in BW. SLNs have the great potential to be used as bioactive compounds in food fortification and production of functional foods.

Design Optimization and Evaluation of Solid Lipid Nanoparticles of Azelnidipine for the Treatment of Hypertension

BACKGROUND

Solid lipid nanoparticles (SLN) are the most promising lipid-based drug delivery to enhance poorly water-soluble molecules' solubility, bioavailability, and therapeutic efficacy. Azelnidipine (AZN) is a calcium channel blocker widely recommended for treating high blood pressure, but its activity is restricted due to high lipophilicity and poor solubility in the GIT. The current research focused on developing the SLN of AZN and thereby improving the absorption, bioavailability, and therapeutic efficacy in hypertension which is a leading cause of death worldwide. Recent patents on SLN were available as U.S. Patent,10,973,798B2, U.S. Patent 10,251,960B2, U.S. Patent 2021/0069121A1, U.S. Patent 2022/0151945A1.

METHODS

SLN was developed by hot melt emulsification and ultrasonication method using glyceryl monostearate (GMS) as solid lipid and Poloxamer 188 as a surfactant to stabilize colloidal dispersion.

RESULTS

Box-Behnken model was utilized, which predicted 13 batches in which concentration of GMS (X1), Poloxamer 188 (X2) and sonication time (X3) were considered independent parameters. The particle size (Y1) and entrapment efficiency (Y2) were dependable parameters, and optimized batch F2 showed a particle size of 166.4 nm, polydispersity index of 0.40 and zeta potential of -13.7 mV. The entrapment efficiency was observed at 86.21%. FTIR spectra confirm the identity and compatibility with the formulation components. The differential scanning calorimetry (DSC) confirmed the absence of melting point and interpreted that AZN was entirely incorporated in the lipid matrix and transformed from crystalline to amorphous. The ANOVA for the particle size (p-value: 0.0203), % EE (p-value: 0.0271) was found significant. The in-vitro drug release showed a sustained release pattern for about 12 h. The AZN-loaded SLN was lyophilized and intended for oral delivery.

CONCLUSION

AZN-loaded SLN was developed by the hot melt emulsification method, which accelerated the solubility and bioavailability and was released sustainably for treating hypertension.

The Astonishing Accomplishment of Biological Drug Delivery using Lipid Nanoparticles: An Ubiquitous Review

Biotech drugs, including proteins, hormones, enzymes, DNA/RNA therapies, and cell-based treatments, are gaining popularity due to their effectiveness. However, effective delivery systems are needed to overcome administration challenges. Lipid nanoparticles (LNPs) have emerged as promising carriers for various therapies. LNPs are biocompatible, less likely to cause adverse reactions, and can stabilize delicate biological drugs, enhancing their stability and solubility. Scalable and cost-effective manufacturing processes make LNPs suitable for largescale production. Despite recent research efforts, challenges in stability, toxicity, and regulatory concerns have limited the commercial availability of LNP-based products. This review explores the applications, administration routes, challenges, and future directions of LNPs in delivering biopharmaceuticals.

M6P-modified solid lipid nanoparticles loaded with matrine for the treatment of fibrotic liver

Liver fibrosis is a key pathological process shared by the progression of various chronic liver diseases. Treatment of liver fibrosis can effectively block the occurrence and development of hepatic cirrhosis or even carcinoma. Currently, there is no effective drug delivery vehicle for curing liver fibrosis. In this study, we designed matrine (MT)-loaded mannose 6-phosphate (M6P) modified human serum albumin (HSA) conjugated solid lipid nanoparticles (SLN), named M6P-HSA-MT-SLN for treatment of hepatic fibrosis. We demonstrated that M6P-HSA-MT-SLN exhibited controlled and sustained release properties and good stability over 7 days. The drug release experiments showed that M6P-HSA-MT-SLN exhibited slow and controlled drug release characteristics. In addition, M6P-HSA-MT-SLN showed a significant targeted ability to fibrotic liver. Importantly, in vivo studies indicated that M6P-HSA-MT-SLN could significantly improve histopathological morphology and inhibit the fibrotic phenotype. In addition, in vivo experiments demonstrate that M6P-HSA-MT-SLN could reduce the expression of fibrosis markers and alleviate the damage of liver structure. Hence, the M6P-HSA-MT-SLN provide a promising strategy to deliver therapeutic agents to fibrotic liver to prevent liver fibrosis.

Design and Optimization of Solid Lipid Nanoparticles Loaded with Triamcinolone Acetonide

Principles of quality by design and design of experiments are acquiring more importance in the discovery and application of new drug carriers, such as solid lipid nanoparticles. In this work, an optimized synthesis of solid lipid nanoparticles loaded with Triamcinolone Acetonide is presented using an approach that involves Stearic Acid as a lipid, soy PC as an ionic surfactant, and Tween 80 as a nonionic surfactant. The constructed circumscribed Central Composite Design considers the lipid and nonionic surfactant quantities and the sonication amplitude in order to optimize particle size and Zeta potential, both measured by means of Dynamic Light Scattering, while the separation of unentrapped drug from the optimized Triamcinolone Acetonide-loaded solid lipid nanoparticles formulation is performed by Size Exclusion Chromatography and, subsequently, the encapsulation efficiency is determined by HPLC-DAD. The proposed optimized formulation-with the goal of maximizing Zeta potential and minimizing particle size-has shown good accordance with predicted values of Zeta potential and dimensions, as well as a high value of encapsulated Triamcinolone Acetonide. Experimental values obtained from the optimized synthesis reports a dimension of 683 ± 5 nm, which differs by 3% from the predicted value, and a Zeta potential of -38.0 ± 7.6 mV (12% difference from the predicted value).

Lipid-Based Delivery Systems for Flavonoids and Flavonolignans: Liposomes, Nanoemulsions, and Solid Lipid Nanoparticles

Herbal chemicals with a long history in medicine have attracted a lot of attention. Flavonolignans and flavonoids are considered as two classes of the above-mentioned compounds with different functional groups which exhibit several therapeutic capabilities such as antimicrobial, anti-inflammatory, antioxidant, antidiabetic, and anticancer activities. Based on the studies, high hydrophobic properties of the aforementioned compounds limit their bioavailability inside the human body and restrict their wide application. Nanoscale formulations such as solid lipid nanoparticles, liposomes, and other types of lipid-based delivery systems have been introduced to overcome the above-mentioned challenges. This approach allows the aforementioned hydrophobic therapeutic compounds to be encapsulated between hydrophobic structures, resulting in improving their bioavailability. The above-mentioned enhanced delivery system improves delivery to the targeted sites and reduces the daily required dosage. Lowering the required daily dose improves the performance of the drug by diminishing its side effects on non-targeted tissues. The present study aims to highlight the recent improvements in implementing lipid-based nanocarriers to deliver flavonolignans and flavonoids.

Solid Lipid Nanoparticles vs. Nanostructured Lipid Carriers: A Comparative Review

Solid-lipid nanoparticles and nanostructured lipid carriers are delivery systems for the delivery of drugs and other bioactives used in diagnosis, therapy, and treatment procedures. These nanocarriers may enhance the solubility and permeability of drugs, increase their bioavailability, and extend the residence time in the body, combining low toxicity with a targeted delivery. Nanostructured lipid carriers are the second generation of lipid nanoparticles differing from solid lipid nanoparticles in their composition matrix. The use of a liquid lipid together with a solid lipid in nanostructured lipid carrier allows it to load a higher amount of drug, enhance drug release properties, and increase its stability. Therefore, a direct comparison between solid lipid nanoparticles and nanostructured lipid carriers is needed. This review aims to describe solid lipid nanoparticles and nanostructured lipid carriers as drug delivery systems, comparing both, while systematically elucidating their production methodologies, physicochemical characterization, and in vitro and in vivo performance. In addition, the toxicity concerns of these systems are focused on.

Recent Progress of Lipid Nanoparticles-Based Lipophilic Drug Delivery: Focus on Surface Modifications

Numerous drugs have emerged to treat various diseases, such as COVID-19, cancer, and protect human health. Approximately 40% of them are lipophilic and are used for treating diseases through various delivery routes, including skin absorption, oral administration, and injection. However, as lipophilic drugs have a low solubility in the human body, drug delivery systems (DDSs) are being actively developed to increase drug bioavailability. Liposomes, micro-sponges, and polymer-based nanoparticles have been proposed as DDS carriers for lipophilic drugs. However, their instability, cytotoxicity, and lack of targeting ability limit their commercialization. Lipid nanoparticles (LNPs) have fewer side effects, excellent biocompatibility, and high physical stability. LNPs are considered efficient vehicles of lipophilic drugs owing to their lipid-based internal structure. In addition, recent LNP studies suggest that the bioavailability of LNP can be increased through surface modifications, such as PEGylation, chitosan, and surfactant protein coating. Thus, their combinations have an abundant utilization potential in the fields of DDSs for carrying lipophilic drugs. In this review, the functions and efficiencies of various types of LNPs and surface modifications developed to optimize lipophilic drug delivery are discussed.

Bio-Inspired Smart Nanoparticles in Enhanced Cancer Theranostics and Targeted Drug Delivery

Globally, a significant portion of deaths are caused by cancer.Compared with traditional treatment, nanotechnology offers new therapeutic options for cancer due to its ability to selectively target and control drug release. Among the various routes of nanoparticle synthesis, plants have gained significant recognition. The tremendous potential of medicinal plants in anticancer treatments calls for a comprehensive review of existing studies on plant-based nanoparticles. The study examined various metallic nanoparticles obtained by green synthesis using medicinal plants. Plants contain biomolecules, secondary metabolites, and coenzymes that facilitate the reduction of metal ions into nanoparticles. These nanoparticles are believed to be potential antioxidants and cancer-fighting agents. This review aims at the futuristic intuitions of biosynthesis and applications of plant-based nanoparticles in cancer theranostics.

Optimization of the Conditions of Solid Lipid Nanoparticles (SLN) Synthesis

Solid lipid nanoparticles (SLNs) have been synthesized as potential drug delivery systems. They are classified as solid lipid nanocarriers that can successfully carry both hydrophilic and hydrophobic drugs. SLNs are based on a biocompatible lipid matrix that is enzymatically degraded into natural components found in the human body. Solid lipid nanoparticles are suitable for the incorporation of hydrophobic active ingredients such as curcumin. The study included the optimization of lipid nanoparticle composition, incorporation of the active compound (curcumin), a stability evaluation of the obtained nanocarriers and characterization of their lipid matrix. Through process optimization, a dispersion of solid lipid nanoparticles (solid lipid:surfactant—2:1.25 weight ratio) predisposed to the incorporation of curcumin was developed. The encapsulation efficiency of the active ingredient was determined to be 99.80%. In stability studies, it was found that the most suitable conditions for conducting high-pressure homogenization are 300 bar pressure, three cycles and a closed-loop system. This yields the required values of the physicochemical parameters (a particle size within a 200−450 nm range; a polydispersity index of <30%; and a zeta potential of about |±30 mV|). In this work, closed-loop high-pressure homogenization was used for the first time and compared to the currently preferred open-loop method.

Advances in Delivery of Chemotherapeutic Agents for Cancer Treatment

Presently, most of the treatment strategies for cancer are focused on the surgical removal of cancerous tumors, along with physical and chemical treatment such as radiotherapy and chemotherapy, respectively. The primary issue associated with these methods is the inhibition of normal cell growth and serious side effects associated with systemic toxicity. The traditional chemotherapeutics which were delivered systemically were inadequate and had serious dose limiting side effects. Recent advances in the development of chemotherapeutics have simultaneously paved the way for efficient targeted drug delivery. Despite the advances in the field of oncogenic drugs, several limitations remain, such as early blood clearance, acquired resistance against cytotoxic agents, toxicity associated with chemotherapeutics, and site-specific drug delivery. Hence, this review article focuses on the recent scientific advancements made in different types of drug delivery systems, including, organic nanocarriers (polymers, albumins, liposomes, and micelles), inorganic nanocarriers (mesoporous silica nanoparticles, gold nanoparticles, platinum nanoparticles, and carbon nanotubes), aptamers, antibody-drug conjugates, and peptides. These targeted drug delivery approaches offer numerous advantages such as site-specific drug delivery, minimal toxicity, better bioavailability, and an increased overall efficacy of the chemotherapeutics. Graphical abstract.

Nano-Structured Lipid Carrier-Based Oral Glutathione Formulation Mediates Renoprotection against Cyclophosphamide-Induced Nephrotoxicity, and Improves Oral Bioavailability of Glutathione Confirmed through RP-HPLC Micellar Liquid Chromatography

The study aimed to develop a new glutathione (GSH) oral formulation to enhance the delivery of GSH and counter the nephrotoxicity of the anticancer drug, cyclophosphamide (CP). A nanostructured lipid carrier glutathione formulation (GSH-NLCs) composed of glutathione (500 mg), stearic and oleic acid (300 mg, each), and Tween® 80 (2%, w/v) was prepared through the emulsification-solvent-evaporation technique, which exhibited a 452.4 ± 33.19 nm spheroidal-sized particulate material with narrow particle size distributions, -38.5 ± 1.4 mV zeta potential, and an entrapment efficiency of 79.8 ± 1.9%. The GSH formulation was orally delivered, and biologically tested to ameliorate the CP-induced renal toxicity in a rat model. Detailed renal morphology, before and after the GSH-NLCs administration, including the histopathological examinations, confirmed the ameliorating effects of the prepared glutathione formulation together with its safe oral delivery. CP-induced oxidative stress, superoxide dismutase depletion, elevation of malondialdehyde levels, depletion of Bcl-2 concentration levels, and upregulated NF-KB levels were observed and were controlled within the recommended and near normal/control levels. Additionally, the inflammatory mediator marker, IL-1β, serum levels were marginally normalized by delivery of the GHS-NLCs formulation. Oral administration of the pure glutathione did not exhibit any ameliorating effects on the renal tissues, which suggested that the pure glutathione is reactive and is chemically transformed during the oral delivery, which affected its pharmacological action at the renal site. The protective effects of the GSH-NLCs formulation through its antioxidant and anti-inflammatory effects suggested its prominent role in containing CP-induced renal toxicity and renal tissue damage, together with the possibility of administrating higher doses of the anticancer drug, cyclophosphamide, to achieve higher and effective anticancer action in combination with the GSH-NLCs formulation.

Solid lipid nanoparticles by Venturi tube: Preparation, Characterization and Optimization by Box-Behnken design

In this study, a Venturi tube is proposed as an efficient static mixer incorporated into a continuous recirculation system for obtaining solid lipid nanoparticles (SLN) of monoolein. The device's operating principle consists of producing a turbulent flux in the throat of a Venturi tube. Taking advantage of this effect SLN of monoolein were obtained by rapid diffusion of the organic phase into the aqueous phase (stabilizer), causing lipid aggregation on the nanometric particles. The main aim of the present study was to evaluate the critical factors for obtaining the SLN of monoolein in order to control the independent variables of this methodology. A Box-Behnken design was used to study such independent variables (factors) as injection rate (X1), recirculation rate (X2), and stabilizer (X3) on the dependent variables; namely, process yield (Y1), particle size (Y2), polydispersity index (Y3) and zeta potential (Y4). The optimum operating conditions for preparing SLN were: injection rate, 1.6 mL/min; recirculation rate, 4.2 L/min; and stabilizer concentration, 1.0 w/v, with a value of D = 0.84. The predicted responses of the particle size were 212.0 nm, with a polydispersity index of 0.21, a zeta potential of -19.9 mV, and a process yield of 96.0%. Under the same operating condition, SLN formed with different lipids and stabilizers were obtained with nanometric size and zeta potential of ∼ -30.0 mV. Results show that the Venturi tube method (VTM) is an innovative and versatile technique for preparing SLN of nanometric size with high process yields through a turbulent flow.

An Overview on Topical Administration of Carotenoids and Coenzyme Q10 Loaded in Lipid Nanoparticles

Carotenoids and coenzyme Q10 are naturally occurring antioxidant compounds that are also found in human skin. These bioactive compounds have been the focus of considerable research due to their antioxidant, anti-inflammatory, and photoprotective properties. In this review, the current state of the art in the encapsulation of carotenoids and coenzyme Q10 in lipid nanoparticles to improve their bioavailability, chemical stability, and skin absorption is discussed. Additionally, the main findings are highlighted on the cytotoxic and photoprotective effects of these systems in the skin.

Enhanced Antibacterial Activity of Echinacea angustifolia Extract against Multidrug-Resistant Klebsiella pneumoniae through Niosome Encapsulation

With the increased occurrence of antibiotic-resistant bacteria, alternatives to classical antibiotics are urgently needed for treatment of various infectious diseases. Medicinal plant extracts are among the promising candidates due to their bioactive components. The aim of this study was to prepare niosome-encapsulated Echinacea angustifolia extract and study its efficacy against multidrug-resistant Klebsiella pneumoniae strains. Encapsulation was first optimized by Design of Experiments, followed by the empirical study. The obtained niosomes were further characterized for the size and morphology using dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Spherical niosomes had a diameter of 142.3 ± 5.1 nm, as measured by DLS. The entrapment efficiency (EE%) of E. angustifolia extract reached up to 77.1% ± 0.3%. The prepared niosomes showed a controlled drug release within the tested 72 h and a storage stability of at least 2 months at both 4 and 25 °C. The encapsulated E. angustifolia displayed up to 16-fold higher antibacterial activity against multidrug-resistant K.pneumoniae strains, compared to the free extract. Additionally, the niosome exhibited negligible cytotoxicity against human foreskin fibroblasts. We anticipate that the results presented herein could contribute to the preparation of other plant extracts with improved stability and antibacterial activity, and will help reduce the overuse of antibiotics by controlled release of natural-derived drugs.

All-trans retinoic acid in anticancer therapy: how nanotechnology can enhance its efficacy and resolve its drawbacks

Introduction: All-trans retinoic acid (ATRA, tretinoin) is the main drug used in the treatment of acute promyelocytic leukemia (APL). Despite its impressive activity against APL, the same could not be clinically observed in other types of cancer. Nanotechnology can be a tool to enhance ATRA anticancer efficacy and resolve its drawbacks in APL as well as in other malignancies.Areas covered: This review covers ATRA use in APL and non-APL cancers, the problems that were found in ATRA therapy and how nanoencapsulation can aid to circumvent them. Pre-clinical results obtained with nanoencapsulated ATRA are shown as well as the two ATRA products based on nanotechnology that were clinically tested: ATRA-IV® and Apealea®.Expert opinion: ATRA presents interesting properties to be used in anticancer therapy with a notorious differentiation and antimetastatic activity. Bioavailability and resistance limitations impair the use of ATRA in non-APL cancers. Nanotechnology can circumvent these issues and provide tools to enhance its anticancer activities, such as co-loading of multiple drug and active targeting to tumor site.

Solid Lipid Nanoparticles Produced via a Coacervation Method as Promising Carriers for Controlled Release of Quercetin

Quercetin is a poorly water-soluble flavonoid with many benefits to human health. Besides the natural food resources that may provide Quercetin, the interest in delivery systems that could enhance its bioavailability in the human body has seen growth in recent years. Promising delivery system candidates are represented by Solid Lipid Nanoparticles (SLNs) which are composed of well-tolerated compounds and provide a relatively high encapsulation efficiency and suitable controlled release. In this study, Quercetin-loaded and negatively charged Solid Lipid Nanoparticles were synthesized based on a coacervation method, using stearic acid as a core lipid and Arabic Gum as a stabilizer. Samples were qualitatively characterized by Dynamic light scattering (DLS), Zeta Potential, Surface infrared spectroscopy (FTIR-ATR), and Time of flight secondary ion mass spectrometry (ToF-SIMS). Encapsulation efficiency, drug release, and antioxidant effect against ABTS•+ were evaluated in vitro by UV-VIS spectrophotometry.

Dermatokinetic assessment of luliconazole-loaded nanostructured lipid carriers (NLCs) for topical delivery: QbD-driven design, optimization, and in vitro and ex vivo evaluations

The present study is concerned with the QbD-based design and development of luliconazole-loaded nanostructured lipid carriers (NLCs) hydrogel for enhanced skin retention and permeation. The NLCs formulation was optimized employing a 3-factor, 3-level Box-Behnken design. The effect of formulation variable lipid content, surfactant concentration, and sonication time was studied on particle size and % EE. The optimized formulation exhibited particle size of 86.480 ± 0.799 nm; 0.213 ± 0.004 PDI, ≥ - 10 mV zeta potential and 85.770 ± 0.503% EE. The in vitro release studies revealed sustained release of NLCs up to 42 h. The designed formulation showed desirable occlusivity, spreadability (0.748 ± 0.160), extrudability (3.130 ± 1.570), and the assay was found to be 99.520 ± 0.890%. The dermatokinetics assessment revealed the C_{max Skin} to be ~ 2-fold higher and AUC_0-24 to be ~ 3-fold higher in the epidermis and dermis of NLCs loaded gel in contrast with the marketed cream. The T_max of both the formulations was found to be 6 h in the epidermis and dermis. The obtained results suggested that luliconazole NLCs can serve as a promising formulation to enhance luliconazole's antifungal activity and also in increasing patient compliance by reducing the frequency of application.

Capsaicin-loaded solid lipid nanoparticles: design, biodistribution, in silico modeling and in vitro cytotoxicity evaluation

Lower doses of capsaicin (8-methyl-N-vanillyl-6-nonenamide) have the potential to serve as an anticancer drug, however, due to its pungency, irritant effect, poor water solubility and high distribution volume often linked to various off-target effects, its therapeutic use is limited. This study aimed to determine the biodistribution and anticancer efficacy of capsaicin loaded solid lipid nanoparticles (SLNs) in human hepatocellular carcinoma in vitro. In this study, SLNs of stearic acid loaded with capsaicin was formulated by the solvent evaporation-emulsification technique and were instantly characterized for their encapsulation efficiency, morphology, loading capacity, stability, particle size, charge and in vitro drug release profile. Synthesized SLNs were predominantly spherical, 80 nm diameter particles that proved to be biocompatible with good stability in aqueous conditions. In vivo biodistribution studies of the formulated SLNs showed that 48 h after injection in the lateral tail vein, up to 15% of the cells in the liver, 1.04% of the cells in the spleen, 3.05% of the cells in the kidneys, 3.76% of the cells in the heart, 1.31% of the cells in the lungs and 0% of the cells in the brain of rats were determined. Molecular docking studies against the identified targets in HepG2 cells showed that the capsaicin is able to bind Abelson tyrosine-protein kinase, c-Src kinase, p38 MAP kinase and VEGF-receptor. Molecular dynamic simulation showed that capsaicin-VEGF receptor complex is highly stable at 50 nano seconds. The IC₅₀ of capsaicin loaded SLNs in HepG2 cells in vitro was 21.36 μg × ml^-1. These findings suggest that capsaicin loaded SLNs are stable in circulation for a period up to 3 d, providing a controlled release of loaded capsaicin and enhanced anticancer activity.

Preparation, Optimization and In-Vitro Evaluation of Curcumin-Loaded Niosome@calcium Alginate Nanocarrier as a New Approach for Breast Cancer Treatment

Cancer is one of the most common causes of mortality, and its various treatment methods can have many challenges for patients. As one of the most widely used cancer treatments, chemotherapy may result in diverse side effects. The lack of targeted drug delivery to tumor tissues can raise the possibility of damage to healthy tissues, with attendant dysfunction. In the present study, an optimum formulation of curcumin-loaded niosomes with a calcium alginate shell (AL-NioC) was developed and optimized by a three-level Box-Behnken design-in terms of dimension and drug loading efficiency. The niosomes were characterized by transmission electron microscopy, Fourier-transform infrared spectroscopy, and dynamic light scattering. The as-formulated niosomes showed excellent stability for up to 1 month at 4 °C. Additionally, the niosomal formulation demonstrated a pH-dependent release; a slow-release profile in physiological pH (7.4), and a more significant release rate at acidic conditions (pH = 3). Cytotoxicity studies showed high compatibility of AL-NioC toward normal MCF10A cells, while significant toxicity was observed in MDA-MB-231 and SKBR3 breast cancer cells. Gene expression studies of the cancer cells showed downregulation of Bcl2, cyclin D, and cyclin E genes, as well as upregulation of P53, Bax, caspase-3, and caspase-9 genes expression following the designed treatment. Flow cytometry studies confirmed a significant enhancement in the apoptosis rate in the presence of AL-NioC in both MDA-MB-231 and SKBR3 cells as compared to other samples. In general, the results of this study demonstrated that-thanks to its biocompatibility toward normal cells-the AL-NioC formulation can efficiently deliver hydrophobic drugs to target cancer cells while reducing side effects.

Use of Nanoparticles in Delivery of Nucleic Acids for Melanoma Treatment

Melanoma accounts for 4% of all skin cancer malignancies, with only 14% of diagnosed patients surviving for more than 5 years after diagnosis. Until now, there is no clear understanding of the detailed molecular contributors of melanoma pathogenesis. Accordingly, more research is needed to understand melanoma development and prognosis.All the treatment approaches that are currently applied have several significant limitations that prevent effective use in melanoma. One major limitation in the treatment of cancer is the acquisition of multidrug resistance (MDR). The MDR results in significant treatment failure and poor clinical outcomes in several cancers, including skin cancer. Treatment of melanoma is especially retarded by MDR. Despite the current advances in targeted and immune-mediated therapy, treatment arms of melanoma are severely limited and stand as a significant clinical challenge. Further, the poor pharmacokinetic profile of currently used chemotherapeutic agents is another reason for treatment failure. Therefore, more research is needed to develop novel drugs and carrier tools for more effective and targeted treatment.Nucleic acid therapy is based on nucleic acids or chemical compounds that are closely related, such as antisense oligonucleotides, aptamers, and small-interfering RNAs that are usually used in situations when a specific gene implicated in a disorder is deemed a therapeutically beneficial target for inhibition. However, the proper application for nucleic acid therapies is hampered by the development of an effective delivery system that can maintain their stability in the systemic circulation and enhance their uptake by the target cells. In this chapter, the prognosis of the different types of melanoma along with the currently used medications is highlighted, and the different types of nucleic acids along with the currently available nanoparticle systems for delivering these nucleic acids into melanoma cells are discussed. We also discuss recently conducted research on the use of different types of nanoparticles for nucleic acid delivery into melanoma cells and highlight the most significant outcomes.

Using pyrene to probe the effects of poloxamer stabilisers on internal lipid microenvironments in solid lipid nanoparticles

Solid lipid nanoparticles (SLNs) have proved to be effective nanocarriers with many advantages over other non-lipid-based systems. The development of new SLN formulations is often hindered through poor drug loading capacity and time-consuming optimisation of lipid/stabiliser combinations. One challenge in the development of new SLN formulations is understanding the complex interactions between amphiphilic stabilisers and hydrophobic lipids; the nature of these interactions can significantly impact SLN properties, including the internal polarity within the nanoparticle core. Herein, we report the use of pyrene to probe the internal lipid microenvironment inside SLNs. We investigate the effect of using different poloxamer stabilisers on the internal polarity of SLNs formed using the common solid lipid, Compritol 888 ATO. We show that the polarity of the internal lipid environment is modified by the length of the poly(propylene oxide) (PPO) block of the poloxamer stabiliser, with longer PPO blocks producing SLNs with less polar lipid cores. Blending of stabilisers could also be used to tune the polarity of the core lipid environment, which may allow for adjusting the polarity of the lipid to assist the loading of different therapeutics.

Tailoring functional nanostructured lipid carriers for glioblastoma treatment with enhanced permeability through in-vitro 3D BBB/BBTB models

The blood-brain barrier (BBB) and blood-brain tumour barrier (BBTB) pose a significant challenge to drug delivery to brain tumours, including aggressive glioblastoma (GB). The present study rationally designed functional nanostructured lipid carriers (NLC) to tailor their BBB penetrating properties with high encapsulation of CNS negative chemotherapeutic drug docetaxel (DTX). We investigated the effect of four liquid lipids, propylene glycol monolaurate (Lauroglycol® 90), Capryol® propylene glycol monocaprylate, caprylocaproylmacrogol-8-glycerides (Labrasol®) and polyoxyl-15-hydroxystearate (Kolliphor® HS15) individually and in combination to develop NLCs with effective permeation across in-vitro 3D BBB model without alteration in the integrity of the barrier. With desirable spherical shape as revealed by TEM and an average particle size of 123.3 ± 0.642 nm and zeta potential of -32 mV, DTX-NLCs demonstrated excellent stability for six months in its freeze-dried form. The confocal microscopy along with flow cytometry data revealed higher internalisation of DTX-NLCs in U87MG over SVG P12 cells. Micropinocytosis was observed to be one of the dominant pathways for internalisation in U87MG cells while clathrin-mediated pathway was more predominat in patient-derived glioblastoma cells. The NLCs readily penetrated the actively proliferating peripheral cells on the surface of the 3D tumour spheroids as compared to the necrotic core. The DTX-NLCs induced cell arrest through G2/M phase with a significant decrease in the mitochondrial reserve capacity of cells. The NLCs circumvented BBTB with high permeability followed by accumulation in glioblastoma cells with patient-derived cells displaying ~2.4-fold higher uptake in comparison to U87MG when studied in a 3D in-vitro model of BBTB/GB. We envisage this simple and industrially feasible technology as a potential candidate to be developed as GB nanomedicine.

In vitro synergic activity of diethyldithiocarbamate and 4-nitrochalcone loaded in beeswax nanoparticles against melanoma (B16F10) cells

The use of nanoparticles as drug delivery systems to simultaneously carry several therapeutic agents is an attractive idea to create new synergic treatments and to develop the next generation of cancer therapies. Therefore, the goal of this study was the simultaneous encapsulation of a hydrophilic drug, sodium diethyldithiocarbamate (DETC), and a hydrophobic drug, 4-nitrochalcone (4NC), in beeswax nanoparticles (BNs) to evaluate the in vitro synergic activity of this combination against melanoma (B16F10) cells. BNs were prepared by water/oil/water double emulsion in the absence of organic solvents. Transmission electron microscopy imaging and dynamic light scattering analyses indicated the formation of BNs with a semispherical shape, average diameter below 250 nm, relatively narrow distributions, and negative zeta potential. The double emulsion technique proved to be effective for the simultaneous encapsulation of DETC and 4NC with efficiencies of 86.2% and 98.7%, respectively, and this encapsulation did not affect the physicochemical properties of the BNs. DETC and 4NC loaded in BNs exhibited a higher cytotoxicity toward B16F10 cells than free 4NC and DETC. This simultaneous encapsulation led to a synergic effect of DETC and 4NC on B16F10 cells, decreasing the cell viability from 46% (DETC BNs) and 54% (4NC BNs) to 64% (DETC+4NC BNs). Therefore, the IC₅₀ of DETC+4NC was also lower than that of either when individually encapsulated, and that of free DETC or 4NC. Therefore, DETC and 4NC were efficiently simultaneously encapsulated in BNs and this drug combination was able to generate an in vitro synergic therapeutic effect on B16F10 cells.

Application of smart solid lipid nanoparticles to enhance the efficacy of 5-fluorouracil in the treatment of colorectal cancer

5-Fluorouracil (5-FU) is a standard treatment option for colorectal cancer (CRC) but its rapid metabolism and systemic instability (short half-life) has hindered its therapeutic efficacy. The objective of this study was to develop a novel drug delivery system, solid lipid nanoparticle (SLN), capable of delivering high payload of 5-FU to treat CRC. The rational was to improve 5FU-nanocarrier compatibility and therapeutic efficacy. The SLN-loaded 5-FU was developed by utilizing a Strategic and unique Method to Advance and Refine the Treatment (SMART) of CRC through hot and cold homogenization approach. The SLN was made of unique PEGylated lipids and combination of the surfactants. Cytotoxicity studies, clonogenic assay, flow cytometry and confocal imaging were conducted to evaluate the effectiveness and cellular uptake of 5FU-SLN4 in HCT-116 cancer cells. Pharmacokinetic (PK) parameters and receptor expressions were determined while tumor efficacy studies were conducted on mouse bearing subcutaneous HCT-116 cancer. Among the all the formulations, 5FU-SLN4 was the most effective with particle size of was 263 ± 3 nm, zeta potential was 0.1 ± 0.02 and entrapment efficiency of 81 ± 10%. The IC50 value of 5FU-SLN4 (7.4 ± 0.02 µM) was 2.3 fold low compared with 5-FU (17.7 ± 0.03 µM). For tumor efficacy studies, 5FU-SLN4 significantly inhibited tumor growth in comparison to 5-FU while area-under plasma concentration-time curve (AUC) of 5FU-SLN4 was 3.6 fold high compared with 5-FU. HER2 receptors expression were markedly reduced in 5-FU-SLN4 treated mice compared with 5FU and liver and kidney tissues showed no toxicity at dose of 20 mg/kg. 5FU-SLN4 was highly cytotoxic against HCT-116 cells and significantly inhibited subcutaneous tumor growth in mice compared with 5-FU. This emphasizes the significance of developing a smart nano-delivery system to optimize the delivery efficiency of anticancer drugs to tumors.

A brief review on solid lipid nanoparticles: part and parcel of contemporary drug delivery systems

Drug delivery technology has a wide spectrum, which is continuously being upgraded at a stupendous speed. Different fabricated nanoparticles and drugs possessing low solubility and poor pharmacokinetic profiles are the two major substances extensively delivered to target sites. Among the colloidal carriers, nanolipid dispersions (liposomes, deformable liposomes, virosomes, ethosomes, and solid lipid nanoparticles) are ideal delivery systems with the advantages of biodegradation and nontoxicity. Among them, nano-structured lipid carriers and solid lipid nanoparticles (SLNs) are dominant, which can be modified to exhibit various advantages, compared to liposomes and polymeric nanoparticles. Nano-structured lipid carriers and SLNs are non-biotoxic since they are biodegradable. Besides, they are highly stable. Their (nano-structured lipid carriers and SLNs) morphology, structural characteristics, ingredients used for preparation, techniques for their production, and characterization using various methods are discussed in this review. Also, although nano-structured lipid carriers and SLNs are based on lipids and surfactants, the effect of these two matrixes to build excipients is also discussed together with their pharmacological significance with novel theranostic approaches, stability and storage.

Lipid-Based Nanosystem As Intelligent Carriers for Versatile Drug Delivery Applications

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The contemporary drug discovery research shows that most of the drug candidates are highly potent, but showing poor aqueous solubility leads a variety of challenges for formulation scientists to develop a suitable formulation to improve the systemic bioavailability of such drugs. Lipid-based nanocarriers act as a major and most projecting approach overcoming the limitations which affect several physiochemical properties of drug such as the solubility, partition coefficient and bioavailability or absorption. This also fulfills a variety of product requirements and helps to overcome several limitations as decided by symptoms of the disease, various routes of administration of drug, price concern, increasing strength of product, noxious or harmful effect of drug, and dose efficacy. The lipidic nanosystem formulates aqueous drug in lipid base and is also a commercially feasible approach for the formulation of different dosage forms meant for topical or transdermal, oral, ocular, pulmonary, and parenteral delivery. This review provides a brief on lipid-based drug delivery nanocarrier and the mechanisms by which lipids and lipidic excipients improve the oral absorption of drugs with poor aqueous solubility and also provide a viewpoint on the promising applications of lipidic nanoparticulate systems.

Amazonia Products in Novel Lipid Nanoparticles for Fucoxanthin Encapsulation

Lipid nanoparticles (LNs) are traditional systems able to effectively increase skin hydration. However, due to its reduced viscosity, LNs suspensions are less attractive for skin administration. To overcome this disadvantage, the LN were incorporated in the semi-solid formulation is easy manipulation. This study demonstrated that it is possible to obtain novel LN-loaded fucoxanthin (LN-FUCO) for topical administration containing a combination of bacuri butter and tucumã oil prepared by high shear homogenization for improved stability. The particle size was found to be 243.0 nm and the entrapment efficiency up to 98% of FUCO was incorporated and achieved the suitability of formula. The LN-FUCO hydrogel characteristics of slight acidity, drug content near 100%, and nanometric mean size assure to this formulation high compatibility to dermal application. Photostability assay by UVA, LN-FUCO, and LN-FUCO hydrogel improved photostability and conferred greater protection against FUCO degradation. The results obtained from in vitro skin permeation studies presented a significant difference between LN-FUCO hydrogel and FUCO (p < 0.05), with no detection of the drug in the receptor medium. Therefore, high shear homogenization is demonstrated to be a simple, available, and effective method to prepare high-quality LN-FUCO hydrogel for topical application.

Lipid nanostructures for antioxidant delivery: a comparative preformulation study

This investigation is a study of new lipid nanoparticles for cutaneous antioxidant delivery. Several molecules, such as α-tocopherol and retinoic acid, have been shown to improve skin condition and even counteract the effects of exogenous stress factors such as smoking on skin aging. This work describes the design and development of lipid nanoparticles containing antioxidant agents (α-tocopherol or retinoic acid) to protect human skin against pollutants. Namely, solid lipid nanoparticles and nanostructured lipid carriers were prepared using different lipids (tristearin, compritol, precirol or suppocire) in the presence or absence of caprylic/capric triglycerides. The formulations were characterized by particle size analysis, cryogenic transmission electron microscopy, small-angle X-ray diffraction, encapsulation efficiency, preliminary stability, in vitro cytotoxicity and protection against cigarette smoke. Nanostructured lipid carriers were found to reduce agglomerate formation and provided better dimensional stability, as compared to solid lipid nanoparticles, suggesting their suitability for antioxidant loading. Based on the preformulation study, tristearin-based nanostructured lipid carriers loaded with α-tocopherol were selected for ex vivo studies since they displayed superior physico-chemical properties as compared to the other nanostructured lipid carriers compositions. Human skin explants were treated with α-tocopherol-loaded nanostructured lipid carriers and then exposed to cigarette smoke, and the protein levels of the stress-induced enzyme heme oxygenase were analyzed in skin homogenates. Interestingly, it was found that pretreatment with the nanoformulation resulted in significantly reduced heme oxygenase upregulation as compared to control samples, suggesting a protective effect provided by the nanoparticles.

Improved Dermal Delivery of Cyclosporine A Loaded in Solid Lipid Nanoparticles

Cyclosporine A (CsA) is an immunosuppressant frequently used in the therapy of autoimmune disorders, including skin-related diseases. Aiming towards topical delivery, CsA was successfully incorporated into lipid nanoparticles of Lipocire DM and Pluronic F-127 using the hot homogenization method. Two different nanocarriers were optimized: solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) where oleic acid was the liquid lipid. The developed nanoparticles showed mean sizes around 200 nm, a negative surface charge, and drug entrapment efficiencies around 85% and 70% for SLNs and NLCs, respectively. The spherical CsA-loaded lipid nanoparticles were stable for 9 weeks when stored at room temperature, and exhibited in vitro pH-dependent release under skin mimetic conditions, following the Peppas-Korsmeyer model. CsA, when loaded in SLNs, was safe to be used up to 140 μg mL-1 in fibroblasts and keratinocytes, while CsA-loaded NLCs and free drug exhibited IC50 values of 55 and 95 μg mL-1 (fibroblasts) and 28 and 30 μg mL-1 (keratinocytes), respectively. The developed SLNs were able to retain the drug in pork skin with a reduced permeation rate in relation to NLCs. These findings suggest that SLNs are a potential alternative to produce stable and safe CsA nanocarriers for topical administration.

Acoustic Cavitation-Assisted Formulation of Solid Lipid Nanoparticles using Different Stabilizers

Because of excellent bioavailability and high biocompatibility, solid lipid nanoparticles (SLNs) have gained attention in recent years, especially in drug delivery systems. SLNs are composed of a drug that is loaded in a lipid matrix and stabilized by surfactants. In this work, we have investigated the feasibility of the acoustic cavitation-assisted hot melt mixing method for the formulation of SLNs using different stabilizers. A lipid Compritol 888 ATO (CPT) and a poorly water-soluble drug ketoprofen (KP) were used as a model lipid and drug, respectively. Gelucire 50/13 (GEL), poloxamer 407 (POL), and Pluronic F-127 (PLU) were used as the stabilizers. The effect of the stabilizers on the physico-chemical properties of SLNs was thoroughly studied in this work. The particle size and stability in water at different temperatures were measured using a dynamic light scattering method. The spherical shape (below 250 nm) and core-shell morphology were confirmed by field-emission scanning electron microscopy and transmission electron microscopy. The chemical, crystal, and thermal properties of SLNs were studied by FTIR, XRD analysis, and DSC, respectively. SLNs prepared using different stabilizers showed an encapsulation efficiency of nearly 90% and a drug loading efficiency of 12%. SLNs showed more than 90% of drug released in 72 h and increased with pH was confirmed using in vitro drug release studies. SLNs were nontoxic to raw 264.7 cells. All stabilizers were found suitable for acoustic cavitation-assisted SLN formulation with high encapsulation efficiency and drug loading and good biocompatibility.

Carvacrol Loaded Solid Lipid Nanoparticles of Propylene Glycol Monopalmitate and Glyceryl Monostearate: Preparation, Characterization, and Synergistic Antimicrobial Activity

To develop solid lipid nanoparticles (SLNs) with stable lipid matrix structures for the delivery of bioactive compounds, a new class of SLNs was studied using propylene glycol monopalmitate (PGMP) and glyceryl monostearate (GMS) mixtures and carvacrol as a model lipophilic antimicrobial. Stable SLNs were fabricated at PGMP:GMS mass ratios of 2:1 and 1:1, and the carvacrol loading was up to 30% of lipids with >98% encapsulation efficiency and absence of visual instability. Fluorescence spectra and release profiles indicated the carvacrol was successfully encapsulated and homogeneously distributed within the SLNs. SLNs fabricated with equal masses of PGMP and GMS had better stability of carvacrol during storage and higher sphericity than those with a ratio of 2:1 and were much more effective than free carvacrol against Escherichia coli O157:H7 and Staphylococcus aureus. These findings demonstrated the potential applications of the studied SLNs in delivering lipophilic bioactive compounds in food and other products.