Humid Heat Autoclaving of Hybrid Nanoparticles Achieved by Decreased Nanoparticle Concentration and Improved Nanoparticle Stability Using Medium Chain Triglycerides as a Modifier

Structural Changes in Liposomal Vesicles in Association with Sodium Taurodeoxycholate

Liposomes composed of soy lecithin (SL) have been studied widely for drug delivery applications. The stability and elasticity of liposomal vesicles are improved by incorporating additives, including edge activators. In this study, we report the effect of sodium taurodeoxycholate (STDC, a bile salt) upon the microstructural characteristics of SL vesicles. Liposomes, prepared by the thin film hydration method, were characterized by dynamic light scattering (DLS), small-angle neutron scattering (SANS), electron microscopy, and rheological techniques. We noticed a reduction in the size of vesicles with the incremental addition of STDC. Initial changes in the size of spherical vesicles were ascribed to the edge-activating action of STDC (0.05 to 0.17 µM). At higher concentrations (0.23 to 0.27 µM), these vesicles transformed into cylindrical structures. Morphological transitions at higher STDC concentrations would have occurred due to its hydrophobic interaction with SL molecules in the bilayer. This was ascertained from nuclear magnetic resonance observations. Whereas shape transitions underscored the deformability of vesicles in the presence of STDC, the consistency of bilayer thickness ruled out any dissociative effect. It was interesting to notice that SL-STDC mixed structures could survive high thermal stress, electrolyte addition, and dilution.

AuNCs-LHRHa nano-system for FL/CT dual-mode imaging and photothermal therapy of targeted prostate cancer

As the most common cancer in men worldwide, prostate cancer has a serious impact on people's health. Until now, the development of a platform for integrating tumor targeting, imaging and an effective treatment for prostate cancer has remained challenging. Herein, a nano-system is designed to improve both diagnosis and treatment for prostate cancer. We successfully synthesized an AuNCs-LHRHa nano-system by combining PEI-modified gold nanoclusters (AuNCs) with LHRH analogues (LHRHa). Due to the good tunable optical properties and photothermal properties of AuNCs, the nano-system can not only achieve efficient fluorescence/computed tomography dual-mode imaging, but can also be used for photothermal therapy (PTT). After modifying the LHRHa antibody of a prostate tumor, AuNCs-LHRHa can be more effectively recognized by the gonadotropin-releasing hormone receptors (GnRH-R) on the membrane of RM-1 cells, enhancing the tumor cell uptake of the nano-system, improving the targeting accuracy and PTT therapy efficacy for prostate cancer. It is hoped that the nano-system, which combines dual-mode imaging and targeted therapy, will provide a promising strategy for the integration of FL/CT diagnosis and PTT therapy for GnRH-R positive prostate cancer.

Optimization, and in vitro and in vivo evaluation of etomidate intravenous lipid emulsion

The aim of this investigation was to develop an etomidate intravenous lipid emulsion (ETM-ILE) and evaluate its properties in vitro and in vivo. Etomidate (ETM) is a hydrophobic drug, and organic solvents must be added to an etomidate injectable solution (ETM-SOL) to aid dissolution, that causes various adverse reactions on injection. Lipid emulsions are a novel drug formulation that can improve drug loading and reduce adverse reactions. ETM-ILE was prepared using high-pressure homogenization. Univariate experiments were performed to select key conditions and variables. The proportion of oil, egg lecithin, and poloxamer 188 (F68) served as variables for the optimization of the ETM-ILE formulation by central composite design response surface methodology. The optimized formulation had the following characteristics: particle size, 168.0 ± 0.3 nm; polydispersity index, 0.108 ± 0.028; zeta potential, −36.4 ± 0.2 mV; drug loading, 2.00 ± 0.01 mg/mL; encapsulation efficiency, 97.65% ± 0.16%; osmotic pressure, 292 ± 2 mOsmol/kg and pH value, 7.63 ± 0.07. Transmission electron microscopy images showed that the particles were spherical or spheroidal, with a diameter of approximately 200 nm. The stability study suggested that ETM-ILE could store at 4 ± 2 °C or 25 ± 2 °C for 12 months. Safety tests showed that ETM-ILE did not cause hemolysis or serious vascular irritation. The results of the pharmacokinetic study found that ETM-ILE was bioequivalent to ETM-SOL. However, a higher concentration of ETM was attained in the liver, spleen, and lungs after administration of ETM-ILE than after administration of ETM-SOL. This study found that ETM-ILE had great potential for clinical applications.

Insights into Terminal Sterilization Processes of Nanoparticles for Biomedical Applications

Nanoparticles possess a huge potential to be employed in numerous biomedical purposes; their applications may include drug delivery systems, gene therapy, and tissue engineering. However, the in vivo use in biomedical applications requires that nanoparticles exhibit sterility. Thus, diverse sterilization techniques have been developed to remove or destroy microbial contamination. The main sterilization methods include sterile filtration, autoclaving, ionizing radiation, and nonionizing radiation. Nonetheless, the sterilization processes can alter the stability, zeta potential, average particle size, and polydispersity index of diverse types of nanoparticles, depending on their composition. Thus, these methods may produce unwanted effects on the nanoparticles' characteristics, affecting their safety and efficacy. Moreover, each sterilization method possesses advantages and drawbacks; thus, the suitable method's choice depends on diverse factors such as the formulation's characteristics, batch volume, available methods, and desired application. In this article, we describe the current sterilization methods of nanoparticles. Moreover, we discuss the advantages and drawbacks of these methods, pointing out the changes in nanoparticles' biological and physicochemical characteristics after sterilization. Our main objective was to offer a comprehensive overview of terminal sterilization processes of nanoparticles for biomedical applications.

The modulation of drug-loading stability within lipid membranes via medium chain triglycerides incorporation

The current research aimed to explore medium chain triglycerides (MCT) incorporation in liposomes to overcome stability challenges when drugs with high molecular weight and payload are loaded within lipid membranes. A model drug clarithromycin was loaded in lipid dispersions with various MCT/phospholipids ratios (R_M/P = 0, 0.5, 1.75 and 7.5 w/w). TEM images demonstrated a liposome-to-emulsion structural transformation by MCT incorporation to cause increased particle size (104.3-167.7 nm) but decreased zeta potential (-63.6 to -44.4 mV) of lipid particles. MCT incorporation produced biphasic release in PBS and accelerated released in plasma. The tolerance of liposomes for thermal sterilization, high temperature test and freeze-thaw cycles were significantly improved by MCT incorporation. However, MCT incorporation produced adverse effects on colloidal stability in plasma and pharmacokinetics behavior in vivo to some extent. MCT stabilizing mechanism attributes to the modulation of drug loading area and stability improvement of lipid carriers. MCT incorporated liposomes achieved 2-3 fold cellular uptake level than traditional liposomes without significant cytotoxicity. These results indicated that MCT incorporation could be a promising strategy to apply in liposome production to achieve stable drug loading.

Polyester-Solid Lipid Mixed Nanoparticles with Improved Stability in Gastro-Intestinal Tract Facilitated Oral Delivery of Larotaxel

The objective of this study was to investigate the role of core stability of nanoparticles on their performances in oral drug delivery. Solid lipids (Geleol Mono and Diglycerides Nf) were incorporated into nanoparticles composed of mPEG-b-PCL by the dialysis method. The prepared solid lipid loaded nanoparticles were found to be spherical nanoparticles with a core state and size distribution dependent on the amount of solid lipid incorporated. The critical aggregation concentrations of lipid-loaded nanoparticles were determined using pyrene fluorescence. Then, the stability of block copolymer in nanoparticles with different solid lipid contents was studied in simulated gastric fluid and simulated intestinal fluid. Solid lipids were found to stabilize nanoparticle cores by improving not only the thermodynamic stability (lowered CAC) of the nanoparticle but also the chemical stability of the block copolymer in the gastrointestinal environment. The stability of the loaded drug (larotaxel, LTX) in nanoparticles with different solid lipid contents was challenged by intestinal homogenate and rat liver microsome, and solid lipid loaded nanoparticles showed superior drug-protecting capability. Solid lipid incorporation exhibited limited influence on the cytotoxicity and cellular uptake but improved the transcytosis of nanoparticles in Caco-2 monolayers. The results of pharmacokinetic study indicated that core stabilization was helpful in promoting oral larotaxel absorption as the absolute bioavailability of LTX delivered by solid lipid loaded nanoparticles was found to be 13.17%, compared with that by the lipid-free nanoparticles (6.264%) and LTX solution (2.435%). Additionally, the results of biodistribution study indicated relatively higher particle integrity of solid lipid loaded nanoparticles, shown by slower liver and spleen accumulation rate, compared with its lipid-free counterpart. Overall, incorporation of solid lipids made the nanoparticles more suitable for oral drug delivery.