Evaluation of β-cyclodextrin-modified gemini surfactant-based delivery systems in melanoma models

Gemini and Bicephalous Surfactants: A Review on Their Synthesis, Micelle Formation, and Uses

The use of surfactants in polymerization reactions is particularly important, mainly in emulsion polymerizations. Further, micelles from biocompatible surfactants find use in pharmaceutical dosage forms. This paper reviews recent developments in the synthesis of novel gemini and bicephalous surfactants, micelle formation, and their applications in polymer and nanoparticle synthesis, oil recovery, catalysis, corrosion, protein binding, and biomedical area, particularly in drug delivery.

Uptake of Upconverting Nanoparticles by Breast Cancer Cells: Surface Coating versus the Protein Corona

Fluorophores with multifunctional properties known as rare-earth-doped nanoparticles (RENPs) are promising candidates for bioimaging, therapy, and drug delivery. When applied in vivo, these nanoparticles (NPs) have to retain long blood-circulation time, bypass elimination by phagocytic cells, and successfully arrive at the target area. Usually, NPs in a biological medium are exposed to proteins, which form the so-called "protein corona" (PC) around the NPs and influence their targeted delivery and accumulation in cells and tissues. Different surface coatings change the PC size and composition, subsequently deciding the fate of the NPs. Thus, detailed studies on the PC are of utmost importance to determine the most suitable NP surface modification for biomedical use. When it comes to RENPs, these studies are particularly scarce. Here, we investigate the PC composition and its impact on the cellular uptake of citrate-, SiO₂-, and phospholipid micelle-coated RENPs (LiYF₄:Yb³⁺,Tm³⁺). We observed that the PC of citrate- and phospholipid-coated RENPs is relatively stable and similar in the adsorbed protein composition, while the PC of SiO₂-coated RENPs is larger and highly dynamic. Moreover, biocompatibility, accumulation, and cytotoxicity of various RENPs in cancer cells have been evaluated. On the basis of the cellular imaging, supported by the inhibition studies, it was revealed that RENPs are internalized by endocytosis and that specific endocytic routes are PC composition dependent. Overall, these results are essential to fill the gaps in the fundamental understanding of the nano-biointeractions of RENPs, pertinent for their envisioned application in biomedicine.

Inclusion Complexes of Melphalan with Gemini-Conjugated β-Cyclodextrin: Physicochemical Properties and Chemotherapeutic Efficacy in In-Vitro Tumor Models

β-cyclodextrin (βCD) has been widely explored as an excipient for pharmaceuticals and nutraceuticals as it forms stable host–guest inclusion complexes and enhances the solubility of poorly soluble active agents. To enhance intracellular drug delivery, βCD was chemically conjugated to an 18-carbon chain cationic gemini surfactant which undergoes self-assembly to form nanoscale complexes. The novel gemini surfactant-modified βCD carrier host (hereafter referred to as 18:1βCDg) was designed to combine the solubilization and encapsulation capacity of the βCD macrocycle and the cell-penetrating ability of the gemini surfactant conjugate. Melphalan (Mel), a chemotherapeutic agent for melanoma, was selected as a model for a poorly soluble drug. Characterization of the 18:1βCDg-Mel host–guest complex was carried out using 1D/2D ¹H NMR spectroscopy and dynamic light scattering (DLS). The 1D/2D NMR spectral results indicated the formation of stable and well-defined 18:1βCDg-Mel inclusion complexes at the 2:1 host–guest mole ratio; whereas, host–drug interaction was attenuated at greater 18:1βCDg mole ratio due to hydrophobic aggregation that accounts for the reduced Mel solubility. The in vitro evaluations were performed using monolayer, 3D spheroid, and Mel-resistant melanoma cell lines. The 18:1βCDg-Mel complex showed significant enhancement in the chemotherapeutic efficacy of Mel with 2–3-fold decrease in Mel half maximal inhibitory concentration (IC₅₀) values. The findings demonstrate the potential applicability of the 18:1βCDg delivery system as a safe and efficient carrier for a poorly soluble chemotherapeutic in melanoma therapy.

Application of 3D cultured multicellular spheroid tumor models in tumor-targeted drug delivery system research

Tumor-targeted drug delivery systems are promising for their advantages in enhanced tumor accumulation and reduced toxicity towards normal organs. However, few nanomedicines have been successfully translated into clinical application. One reason is the gap between current pre-clinical and clinical studies. The prevalent in vitro models utilized in pre-clinical phase are mainly based on the two-dimensional (2D) cell culture and are limited by the difficulty of simulating three-dimensional physiological conditions in human body, such as three-dimensional (3D) architecture, cell heterogeneity, nutrient gradients and the interaction between cells and the extracellular matrix (ECM). In addition, traditional animal models have drawbacks such as high-cost, long periods and physiological differences between animal and human. On the other hand, the employment of 3D tumor cell culture models, especially multicellular tumor spheroids (MCTS), has increased significantly in recent decades. These models have been shown to simulate 3D structures of tumors in vitro with relatively low cost and simple protocols. Currently, MCTS have also been widely exploited in drug delivery system research for comprehensive study of drug efficacy, drug penetration, receptor targeting, and cell recruitment abilities. This review summarizes the delivery barriers for nano-carriers presented in tumor microenvironment, the characteristics and formation methods for applicable multicellular tumor spheroid culture models and recent studies related to their applications in tumor-targeted drug delivery system research.

Rapid and simple flow injection analysis tandem mass spectrometric method for the quantification of melphalan in a lipid-based drug delivery system

RATIONALE

The use of the anticancer drug melphalan is limited due to its poor water solubility. To address this limitation, it is incorporated within a novel delivery system using β-cyclodextrin-gemini surfactants (18:1βCDg).

METHODS

Herein, two fast and simple flow injection analysis/tandem mass spectrometric (FIA-MS/MS) methods are developed for the quantification of melphalan (Mel) within the drug delivery system so that the solubilization efficiency of the system can be assessed. FIA-MS/MS methods are developed using a triple quadrupole linear ion trap mass spectrometer, equipped with electrospray ionization (ESI) in the positive ion mode. A deuterated form of melphalan (melphalan-d8) was used as an internal standard (IS). The methods were validated according to the FDA guidance.

RESULTS

A linearity in the range of 2-100 ng/mL and accuracy and precision below 15% were observed for all standard points and quality control samples. The intra- and inter-day variations and freeze-thaw stability were within the acceptable range according to the criteria set by regulatory guidelines. On the other hand, other stability measures, such as room temperature stability and long-term stability, did not meet the required guidelines in some cases, indicating the need for quick sample analysis upon preparation. Such a fact could have been overlooked if full method validation had not been performed.

CONCLUSIONS

The developed methods were applied to determine the encapsulation/solubilization of the [18:1βCDg/Mel] delivery system. 18:1βCDg enhances the aqueous solubility of melphalan without the need for co-solvent. The highest melphalan solubility was observed at a melphalan18:1βCDg/Mel complex molar ratio of 2:1. This study demonstrated that a fast analysis for the purpose of quantifying a chemically unstable drug, such as melphalan, is feasible and important for the development of commercial dosage forms.

Influence of the microwave technology on solid dispersions of mefenamic acid and flufenamic acid

The present studies were undertaken to develop solvent-free solid dispersions (SDs) for poorly soluble anti-inflammatory drugs mefenamic acid (MA) and flufenamic acid (FFA) in order to enhance their in vitro dissolution rate and in vivo anti-inflammatory effects. The SDs of MA and FFA were prepared using microwaves irradiation (MW) technique. Different carriers such as Pluronic F127^® (PL), Eudragit EPO^® (EPO), polyethylene glycol 4000 (PEG 4000) and Gelucire 50/13 (GLU) were used for the preparation of SDs. Prepared MW irradiated SDs were characterized physicochemically using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infra-red (FT-IR) spectroscopy, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The physicochemical characteristics and drug release profile of SDs were compared with pure drugs. The results of DSC, TGA, FT-IR, PXRD and SEM showed that SDs were successfully prepared. In vitro dissolution rate of MA and FFA was remarkably enhanced by SDs in comparison with pure MA and FFA. The SDs of MA and FFA prepared using PEG 400 showed higher drug release profile in comparison with those prepared using PL, EPO or GLU. The dissolution efficiency for MA-PEG SD and FFA-PEG SD was obtained as 61.40 and 59.18%, respectively. Optimized SDs were also evaluated for in vivo anti-inflammatory effects in male Wistar rats. The results showed significant % inhibition by MA-PEG (87.74% after 4 h) and FFA-PEG SDs (81.76% after 4 h) in comparison with pure MA (68.09% after 4 h) and pure FFA (55.27% after 4 h) (P<0.05). These results suggested that MW irradiated SDs of MA and FFA could be successfully used for the enhancement of in vitro dissolution rate and in vivo therapeutic efficacy of both drugs.