Solvent-Free Loading of Vitamin A Palmitate into β-Cyclodextrin Metal-Organic Frameworks for Stability Enhancement

Preparation and Characterization of Muscone Oil-Based Cyclodextrin Metal-Organic Frameworks: Molecular Dynamics Simulations and Stability Evaluation

Objective: Muscone (MUS), a primary active component of musk, is known for its significant pharmacological properties. However, its clinical application is limited due to poor water solubility and moderate stability. This study aims to address these limitations by encapsulating MUS within biodegradable γ-cyclodextrin metal-organic frameworks (γ-CD-MOFs) using a solvent-free method to enable oral MUS delivery by improving solubility and stability, pending in vivo validation. Methods: MUS was encapsulated into γ-CD-MOFs using a solvent-free method, achieving an optimal loading rate of 10.6 ± 0.7%. Comprehensive characterization was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Biocompatibility was assessed using RAW264.7 cells, and molecular dynamics simulations were conducted to study the interactions between MUS and γ-CD-MOFs. Results: Characterization techniques confirmed the successful encapsulation of MUS into γ-CD-MOFs. Biocompatibility studies revealed no cytotoxicity, indicating that the system is safe for drug delivery. Molecular dynamics simulations showed that MUS preferentially occupies the large spherical cages of γ-CD-MOFs, driven by non-covalent interactions. Solubility tests and in vitro release studies demonstrated that the solubility of MUS was improved after encapsulation within γ-CD-MOFs. Stability assessments indicated that γ-CD-MOFs significantly enhanced the thermal and photostability of MUS, with high residual amounts remaining under various storage conditions. Conclusions: This study demonstrates the potential of γ-CD-MOFs to solidify MUS, enhance its solubility, and improve its storage stability, providing a foundation for its future use in pharmaceutical applications.

Enhancing the stability of spray-dried vitamin A acetate: the role of synergistic wall materials in microencapsulation

BACKGROUND

Vitamin A is a fat-soluble vitamin that is susceptible to environmental factors, which can result in reduced activity. The stability of vitamins directly affects the shelf life and market competitiveness of products in the nutrient-fortified foods/drugs sector. Encapsulation via emulsion spray drying is a commonly utilized method to enhance the stability of active substances. It boasts a wide range of applications and capability for automated and continuous production. The wall material of microcapsules represents one of the pivotal factors influencing their properties, potentially mitigating the degradation of active substances during storage.

RESULTS

This study aimed to investigate the characteristics of vitamin A acetate (VAA) high-loading-capacity emulsions and microcapsules formulated with different encapsulating agents (gum arabic (GA), gelatin (GEL), white sugar (WS) and octenyl succinic acid-modified starch) prepared by spray drying. According to the accelerated storage experiment formula, the shelf life of microcapsules stored at 60 °C for 35 days is about 1 year, and the retention rate of GA + GEL/WS microcapsules with a loading capacity of 100 g kg-1 reaches over 90%. The performance of microcapsules with different wall materials was investigated and the reasons for the enhanced stability through the interaction between wall materials were analyzed.

CONCLUSION

The results showed that spray drying of microcapsules improved the water solubility and storage stability of VAA. At high loading levels, the synergistic effect between wall materials can improve the density of microcapsules, thereby enhancing the storage stability of VAA microcapsules. Such higher storage stability is beneficial for extending the shelf life of fortified foods and pharmaceuticals, thereby expanding the application of VAA in the food sector. © 2025 Society of Chemical Industry.

Supramolecular cyclodextrin-based reservoir as nasal delivery vehicle for rivastigmine to brain

The purpose of this study involved the synthesis of supramolecular reservoir (i.e. cyclodextrin metal-organic framework, MOF) using cyclodextrins as building blocks, followed by cross-linking to obtain crosslinked CD framework (CDF) using CD-MOF as template and functionalized with borneol (BO) to enhance rivastigmine (RIV) permeation and facilitate brain targeting via intranasal administration. Utilizing BO modified CDF (BO-CDF) with cubic shape as a carrier for the encapsulation of RIV, a nasal RIV delivery system (RIV@BO-CDF) was fabricated. The particle size of RIV@BO-CDF was approximately 250 nm, and the drug loading capacity reached 15 ± 2 %. BO-CDF improved the mucoadhesion and enhanced RIV permeability with the plasma concentration-time curve (AUC), the brain AUC and the peak drug concentration within brain in rats 1.7, 2.3 and 8 times than that of oral RIV solution, respectively. The relative drug targeting efficiency percentage (DTE, 139.4 %) and direct drug transfer percentage (DTP, 28.3 %) of RIV@BO-COF indicated good targeting efficiency and direct nose-to-brain drug delivery. Overall, this study provides a potential application of supramolecular cyclodextrin-based reservoir to enhance the brain targeting and efficacy of the RIV via nasal delivery.

Controlled release of vitamin A palmitate from crosslinked cyclodextrin organic framework for dry eye disease therapy

Controlled release drug delivery systems of eye drops are a promising ophthalmic therapy with advantages of good patient compliance and low irritation. However, the lack of a suitable drug carrier for ophthalmic use limits the development of the aforementioned system. Herein, the crosslinked cyclodextrin organic framework (COF) with a cubic porous structure and a uniform particle size was synthesized and applied to solidify vitamin A palmitate (VAP) by using the solvent-free method. The VAP@COF suspension eye drops were formulated by screening co-solvents, suspending agents, and stabilizing agents to achieve a homogeneous state and improve stability. According to the in vitro release study, the VAP@COF suspension exhibited a controlled release of VAP within 12 h. Both the ex vivo corneal contact angle and in vivo fluorescence tracking indicated that the VAP@COF suspension prolonged the VAP residence time on the ocular surface. This suspension accelerated the recovery of the dry eye disease (DED) model in New Zealand rabbits. Furthermore, the suspension was non-cytotoxic to human corneal epithelial cells and non-irritation to rabbit eyes. In summary, the particulate COF is an eye-acceptable novel carrier that sustains release and prolongs the VAP residence time on the ocular surface for DED treatment.

Lutein Loaded in β-Cyclodextrin Metal-Organic Frameworks for Stability and Solubility Enhancements

Lutein (Lut) is a recognized nutritional supplement known for its antioxidative and anti-inflammatory properties, crucial in mitigating ocular disease. However, enhancements to Lut stability and solubility remain challenges to be addressed in the healthcare industry. Herein, we fabricated and evaluated a food-grade highly porous β-cyclodextrin metal-organic framework (β-CD-MOF) for its ability to encapsulate Lut. Lut stability considerably improved when loaded into β-CD-MOF to form a Lut@β-CD-MOF complex, which exhibited better stability than Lut loaded into the γ-cyclodextrin metal-organic framework (Lut@γ-CD-MOF), Lut@β-CD, and commercial product (Blackmores™) at 40°C, 60°C, and 70°C, respectively. The solubility of Lut@β-CD-MOF in water increased by 26.8-fold compared to raw Lut at 37°C. Lut@β-CD-MOF exhibited greater hydrophilicity, as determined by measuring the water contact angle. Molecular docking and other characterizations of Fourier transform infrared spectroscopy and powder X-ray diffraction confirmed that Lut was successfully encapsulated in the chamber formed by the three cyclodextrins in β-CD-MOF. Thermogravimetric analysis and Raman spectroscopy demonstrated that Lut distributed in the β-CD-MOF cavity deeply improved Lut stability and solubility. In conclusion, our findings underscored the function of β-CD-MOF in enhancing Lut stability and solubility for formulation applications.

Enhanced Stability and Solidification of Volatile Eugenol by Cyclodextrin-Metal Organic Framework for Nasal Powder Delivery

Eugenol (Eug) holds potential as a treatment for bacterial rhinosinusitis by nasal powder drug delivery. To stabilization and solidification of volatile Eug, herein, nasal inhalable γ-cyclodextrin metal-organic framework (γ-CD-MOF) was investigated as a carrier by gas-solid adsorption method. The results showed that the particle size of Eug loaded by γ-CD-MOF (Eug@γ-CD-MOF) distributed in the range of 10-150 μm well. In comparison to γ-CD and β-CD-MOF, γ-CD-MOF has higher thermal stability to Eug. And the intermolecular interactions between Eug and the carriers were verified by characterizations and molecular docking. Based on the bionic human nasal cavity model, Eug@γ-CD-MOF had a high deposition distribution (90.07 ± 1.58%). Compared with free Eug, the retention time Eug@γ-CD-MOF in the nasal cavity was prolonged from 5 min to 60 min. In addition, the cell viability showed that Eug@γ-CD-MOF (Eug content range 3.125-200 µg/mL) was non-cytotoxic. And the encapsulation of γ-CD-MOF could not reduce the bacteriostatic effect of Eug. Therefore, the biocompatible γ-CD-MOF could be a potential and valuable carrier for nasal drug delivery to realize solidification and nasal therapeutic effects of volatile oils.

Supramolecular Structure of the β-Cyclodextrin Metal-Organic Framework Optimizes Iodine Stability and Its Co-delivery with l-Menthol for Antibacterial Applications

The spread of upper respiratory tract (URT) infections harms people's health and causes social burdens. Developing targeted treatment strategies for URT infections that exhibit good biocompatibility, stability, and strong antimicrobial effects remains challenging. The dual antimicrobial and antiviral effects of iodine (I2) in combination with the cooling sensation of l-menthol in the respiratory tract can simultaneously alleviate URT inflammation symptoms. However, as both I2 and l-menthol are volatile, addressing stability issues is crucial. In this study, a potassium iodide β-cyclodextrin metal-organic framework [β-CD-POF(I)] with appropriate particle size was used to coload and deliver I2 and l-menthol. Primarily, β-CD-POF(I) was employed as the most efficient carrier to significantly enhance the stability of I2, surpassing any other known protection strategies in the pharmaceutical field (CD complexations, PVP conjugations, and cadexomer iodine). The mechanism underlying the improvement in stability of I2 by β-CD-POF(I) was investigated through scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and molecular docking. The results revealed that the key processes involved in improving stability were the inclusion of I2 by β-CD cavities in β-CD-POF(I) and the formation of polyiodide anion between iodine ions and I2. Furthermore, the potential of β-CD-POF(I) to load and deliver drugs was validated, and coloading of l-menthol and I2 demonstrated reliable stability. β-CD-POF(I) achieved a rate of URT deposition ≥95% in vitro, and the combined antibacterial effects of coloaded I2 and l-menthol was better than I2 or PVP-I alone, with no irritation noted following URT administration in rabbits. Therefore, the stable coloading of drugs by β-CD-POF(I), leading to enhanced antimicrobial effects, provides a new strategy for treating URT infections.

Synergistic applications of cyclodextrin-based systems and metal-organic frameworks in transdermal drug delivery for skin cancer therapy

This review article explores the innovative field of eco-friendly cyclodextrin-based coordination polymers and metal-organic frameworks (MOFs) for transdermal drug delivery in the case of skin cancer therapy. We critically examine the significant advancements in developing these nanocarriers, with a focus on their unique properties such as biocompatibility, targeted drug release, and enhanced skin permeability. These attributes are instrumental in addressing the limitations inherent in traditional skin cancer treatments and represent a paradigm shift towards more effective and patient-friendly therapeutic approaches. Furthermore, we discuss the challenges faced in optimizing the synthesis process for large-scale production while ensuring environmental sustainability. The review also emphasizes the immense potential for clinical applications of these nanocarriers in skin cancer therapy, highlighting their role in facilitating targeted, controlled drug release which minimizes systemic side effects. Future clinical applications could see these nanocarriers being customized to individual patient profiles, potentially revolutionizing personalized medicine in oncology. With further research and clinical trials, these nanocarriers hold the promise of transforming the landscape of skin cancer treatment. With this study, we aim to provide a comprehensive overview of the current state of research in this field and outline future directions for advancing the development and clinical application of these innovative nanocarriers.