Mechanisms by which cyclodextrins modify drug release from polymeric drug delivery systems

Exploring oral drug delivery: In vitro release and mathematical modeling of hydrophobic drug (Na-L-thyroxine) and its cyclodextrin inclusion complex in chitosan microparticles

Na-l-Thyroxine (Na-l-Thy) is a frequently prescribed synthetic hormone for hypothyroidism treatment. Despite its efficacy, its hydrophobic nature poses a challenge for achieving optimal bioavailability. To address this, researchers explored various delivery methods, including micro-formulations and nano-formulations, for precise and prolonged release of hydrophobic and hydrophilic drugs. In this study, we developed micro-formulations with cyclodextrin and chitosan. Docking studies identified γ-cyclodextrin as the preferred option for forming a stable complex with Na-l-Thyroxine compared to α, and β-cyclodextrins. Two micro-formulations were prepared compared: Na-l-Thyroxine loaded on chitosan (CS + Na-l-Thy) and Na-l-Thyroxine and γ-cyclodextrin inclusion complex (IC) loaded on chitosan (CS + IC). CS + IC exhibited superior encapsulation efficiency (91.25 %) and loading capacity (18.62 %) compared to CS + Na-l-Thy (encapsulation efficiency: 70.24 %, loading capacity: 21.18 %). Characterization using FTIR, SEM, and TGA validated successful encapsulation of Na-l-Thy in spherical microparticles with high thermal stability. In-vitro release studies at pH 1.2 and 7.4 showed that the CS + IC microparticles displayed gradual, consistent drug release compared to CS + Na-l-Thy -Thy. Both formulations showed faster release at pH 1.2 than at pH 7.4. Reaction kinetics analysis of release studies of CS + Na-l-Thy and CS + IC were best described by Higuchi kinetic model and Korsemeyer-Peppas kinetic model respectively. This study suggests that the CS + IC microparticles are an effective and stable delivery system for sustained release of hydrophobic Na-l-Thy.

Supramolecular chitin-based hydrogels with self-adapting and fast-degradation properties for enhancing wound healing

Due to the features of high porosity, high water content, and tunable viscoelasticity, hydrogels have attracted numerous attentions in the promotion of wound closure. However, the lack of abilities to adapt the wounds of complex shapes and prevent postoperative adhesion limits their therapeutic outcomes in wound healing. To address the above challenges, the supramolecular chitin-based (SMCT) hydrogels are created via the host-guest pre-assembly strategy of β-cyclodextrin (βCD) and adamantane (Ad). The reversible host-guest crosslinks endow the SMCT hydrogels with highly dynamic networks, which can better accommodate irregularly shaped wounds compared with the covalent chitin-based hydrogels with similar mechanical properties. In addition, the SMCT hydrogels show rapid in vivo degradability (degradation time ≈ 2 days) due to the enzyme-triggered degradability of chitin, which do not need to be removed from the wounds after service and thus avoid the secondary damage to skin during dressing change. Owing to the hydrophobic cavity of βCD, the SMCT hydrogels can facilitate the load and release of curcumin with anti-inflammatory, antibacterial, and antioxidative activities, thereby significantly improving the wound healing efficiency. This work provides valuable guidance to the design of self-adaptive and fast-degradable hydrogels that hold great potential for enhancing the wound healing in skin and other tissues.

Preparation and In Vitro and In Vivo Evaluation of Rectal In Situ Gel of Meloxicam Hydroxypropyl-β-cyclodextrin Inclusion Complex

Meloxicam (MLX) is one of the most effective NSAIDs, but its poor water solubility and low bioavailability limit its clinical application. In this study, we designed a thermosensitive in situ gel of the hydroxypropyl-β-cyclodextrin inclusion complex (MLX/HP-β-CD-ISG) for rectal delivery to improve bioavailability. The best method for preparing MLX/HP-β-CD was the saturated aqueous solution method. The optimal inclusion prescription was optimized using an orthogonal test, and the inclusion complex was evaluated via PXRD, SEM, FTIR and DSC. Then, MLX/HP-β-CD-ISG was characterized regarding the gel properties, release in vitro, and pharmacokinetics in vivo. The inclusion rate of the inclusion complex obtained via the optimal preparation process was 90.32 ± 3.81%. The above four detection methods show that MLX is completely embedded in the HP-β-CD cavity. The developed MLX/HP-β-CD-ISG formulation has a suitable gelation temperature of 33.40 ± 0.17 °C, a gelation time of 57.33 ± 5.13 s, pH of 7.12 ± 0.05, good gelling ability and meets the requirements of rectal preparations. More importantly, MLX/HP-β-CD-ISG significantly improved the absorption and bioavailability of MLX in rats, prolonging the rectal residence time without causing rectal irritation. This study suggests that the MLX/HP-β-CD-ISG can have a wide application prospect with superior therapeutic benefits.

Injectable Hydrogels Based on Cyclodextrin/Cholesterol Inclusion Complexation and Loaded with 5-Fluorouracil/Methotrexate for Breast Cancer Treatment

Breast cancer is the second most common cancer in women worldwide. Long-term treatment with conventional chemotherapy may result in severe systemic side effects. Therefore, the localized delivery of chemotherapy helps to overcome such a problem. In this article, self-assembling hydrogels were constructed via inclusion complexation between host β-cyclodextrin polymers (8armPEG20k-CD and pβ-CD) and the guest polymers 8-armed poly(ethylene glycol) capped either with cholesterol (8armPEG20k-chol) or adamantane (8armPEG20k-Ad) and were loaded with 5-fluorouracil (5-FU) and methotrexate (MTX). The prepared hydrogels were characterized by SEM and rheological behaviors. The in vitro release of 5-FU and MTX was studied. The cytotoxicity of our modified systems was investigated against breast tumor cells (MCF-7) using an MTT assay. Additionally, the histopathological changes in breast tissues were monitored before and after their intratumor injection. The results of rheological characterization indicated the viscoelastic behavior in all cases except for 8armPEG-Ad. In vitro release results showed a variable range of release profiles from 6 to 21 days, depending on the hydrogel composition. MTT findings indicated the inhibition ability of our systems against the viability of cancer cells depending on the kind and concentration of the hydrogel and the incubation period. Moreover, the results of histopathology showed the improvement of cancer manifestation (swelling and inflammation) after intratumor injection of loaded hydrogel systems. In conclusion, the obtained results indicated the applicability of the modified hydrogels as injectable vehicles for both loading and controlled release of anticancer therapies.

Direct cyclodextrin based powder extrusion 3D printing of budesonide loaded mini-tablets for the treatment of eosinophilic colitis in paediatric patients

The purpose of this study was to combine direct powder extrusion (DPE) 3D printing and fluid bed coating techniques to create a budesonide (BD) loaded solid oral formulations for the treatment of eosinophilic colitis (EC) in paediatric patients. The preferred medication for EC treatment is BD, which has drawbacks due to its poor water solubility and low absorption. Additionally, since commercially available medications for EC treatment are created and approved for adult patients, administering them to children sometimes requires an off-label use and an impromptu handling, which can result in therapeutic ineffectiveness. The DPE 3D approach was investigated to create Mini-Tablets (MTs) to suit the swallowing, palatability, and dose flexibility control requirements needed by paediatric patients. Additionally, DPE 3D and the inclusion of hydroxypropyl-β-cyclodextrin in the initial powder mixture allowed for an improvement in the solubility and rate of BD dissolution in aqueous medium. Then, to accomplish a site-specific drug release at the intestinal level, MTs were coated with a layer of Eudragit FS 30D, an enteric polymer responsive at pH > 7.0 values. In vitro release experiments showed that film-coated MTs were suitable in terms of size and dose, enabling potential therapeutic customization and targeted delivery of BD to the colon.

Conductometric Studies of Formation the Inclusion Complexes of Phenolic Acids with β-Cyclodextrin and 2-HP-β-Cyclodextrin in Aqueous Solutions

An attempt was made to evaluate the possibility of creating and assessing the stability of inclusion complexes of selected phenolic acids [trans-4-hydroxycinnamic acid (trans-p-coumaric acid), trans-3,4-dihydroxycinnamic acid (trans-caffeic acid), trans-4-hydroxy-3-methoxycinnamic acid, (trans-ferulic acid) and trans-3-phenylacrylic acid (trans-cinnamic acid)] with β-cyclodextrin and 2-HP-β-cyclodextrin in aqueous solutions in a wide temperature range 283.15 K-313.15 K. On the basis of the values of the limiting molar conductivity (Λ_CDNaDod), calculated from the experimental data, the values of the formation constants and the thermodynamic functions of formation (standard enthalpy, entropy, and Gibs standard enthalpy) of the studied complexes were determined. It has been found that the stability of the studied complexes increases with lowering of the molar mass of cyclodextrin and lowering of the temperature.

Development and Characterization of Cyclodextrin-Based Nanogels as a New Ibuprofen Cutaneous Delivery System

Nanogels combine the properties of hydrogels and nanocarrier systems, resulting in very effective drug delivery systems, including for cutaneous applications. Cyclodextrins (CDs) have been utilised to enhance the nanogels' loading ability towards poorly soluble drugs and promote/sustain drug release. However, formation of CD-based nanogels requires the use of specially modified CDs, or of crosslinking agents. The aim of this work was to develop a CD-based nanogel to improve the cutaneous delivery of ibuprofen by using the soluble β-cyclodextrin/epichlorohydrin polymer (EPIβCD) without adding any potentially toxic crosslinker. The use of EPIβCD enabled increasing ibuprofen loading due to its complexing/solubilizing power towards the poorly soluble drug and prolonging drug release over time due to the nanogel formation. DLS analysis proved that EPIβCD allowed the formation of nanostructures ranging from 60 up to 400 nm, depending on the gelling agent type and the gel preparation method. EPIβCD replacement with monomeric HPβCD did not lead in any case to nanogel formation. Permeation experiments using skin-simulating artificial membranes proved that the EPIβCD-based nanogel enhanced ibuprofen solubility and release, increasing its permeation rate up to 3.5 times, compared to a reference formulation without CD and to some commercial gel formulations, and also assured a sustained release. Moreover, EPIβCD replacement with HPβCD led to a marked increase in drug solubility and initial release rate, but did not provide a prolonged release due to the lack of a nano-matrix structure controlling drug diffusion.

Patches as Polymeric Systems for Improved Delivery of Topical Corticosteroids: Advances and Future Perspectives

Mucoadhesive polymer patches are a promising alternative for prolonged and controlled delivery of topical corticosteroids (CS) to improve their biopharmaceutical properties (mainly increasing local bioavailability and reducing systemic toxicity). The main biopharmaceutical advantages of patches compared to traditional oral dosage forms are their excellent bioadhesive properties and their increased drug residence time, modified and unidirectional drug release, improved local bioavailability and safety profile, additional pain receptor protection, and patient friendliness. This review describes the main approaches that can be used for the pharmaceutical R&D of oromucosal patches with improved physicochemical, mechanical, and pharmacological properties. The review mainly focuses on ways to increase the bioadhesion of oromucosal patches and to modify drug release, as well as ways to improve local bioavailability and safety by developing unidirectional -release poly-layer patches. Various techniques for obtaining patches and their influence on the structure and properties of the resulting dosage forms are also presented.

Pharmacological effects of a complex α-bisabolol/β-cyclodextrin in a mice arthritis model with involvement of IL-1β, IL-6 and MAPK

Inflammatory arthritis is the most prevalent chronic inflammatory disease worldwide. The pathology of the disease is characterized by increased inflammation and oxidative stress, which leads to chronic pain and functional loss in the joints. Conventional anti-arthritic drugs used to relieve pain and other arthritic symptoms often cause severe side effects. α-bisabolol (BIS) is a sesquiterpene that exhibits high anti-inflammatory potential and a significant antinociceptive effect. This study evaluates the anti-arthritic, anti-inflammatory and antihyperalgesic effects of BIS alone and in a β-cyclodextrin (βCD/BIS) inclusion complex in a CFA-induced arthritis model. Following the intra-articular administration of CFA, male mice were treated with vehicle, BIS and βCD/BIS (50 mg/kg, p.o.) or a positive control and pain-related behaviors, knee edema and inflammatory and oxidative parameters were evaluated on days 4, 11, 18 and/or 25. Ours findings shows that the oral administration of BIS and βCD/BIS significantly attenuated spontaneous pain-like behaviors, mechanical hyperalgesia, grip strength deficit and knee edema induced by repeated injections of CFA, reducing the joint pain and functional disability associated with arthritis. BIS and βCD/BIS also inhibited the generation of inflammatory and oxidative markers in the knee and blocked MAPK in the spinal cord. In addition, ours results also showed that the incorporation of BIS in cyclodextrin as a drug delivery system improved the pharmacological profile of this substance. Therefore, these results contribute to the pharmacological knowledge of BIS and demonstrated that this terpene appears to be able to mitigate deleterious symptoms of arthritis.

Polymerized β-Cyclodextrin-Based Injectable Hydrogel for Sustained Release of 5-Fluorouracil/Methotrexate Mixture in Breast Cancer Management: In Vitro and In Vivo Analytical Validations

An inclusion complexation, between polymerized β-cyclodextrin and cholesterol end-capping branched polyethylene glycol, was utilized for constructing a self-assembled hydrogel. The physicochemical properties, the in vitro release profiles of 5-Fluorouracil/methotrexate (anticancer drugs), and the surface morphology of the resulting hydrogel were studied. Moreover, in vivo studies were carried out on female rats bearing breast cancer. The results revealed that the prepared systems were white in color, rubbery, and homogenous. The in vitro release studies showed an efficient ability of the modified system for drug loading and release in a sustained release manner for 14 days. The surface morphology was spongy porous. Moreover, the tumors’ healing was indicated from the analysis of tumor volume, plasma tumor markers, and histopathological analysis, compared to the controlled rats. The pharmacokinetic parameters appeared significant differences (p < 0.05) in the Cmax and Tmax of the medicated hydrogel samples, as compared with sole or combined saline-injected samples. The whole AUC of each drug in the medicated hydrogel samples was five-fold more than the mixture administrated in PBS. In conclusion, the proposed work delivered a hydrogel system that has a convenient ability for localized sustained release of breast cancer management.

Smart Injectable Chitosan Hydrogels Loaded with 5-Fluorouracil for the Treatment of Breast Cancer

The treatment of breast cancer requires long chemotherapy management, which is accompanied by severe side effects. Localized delivery of anticancer drugs helps to increase the drug concentration at the site of action and overcome such a problem. In the present study, chitosan hydrogel was prepared for local delivery of 5-Fluorouracil. The in vitro release behavior was investigated and the anticancer activity was evaluated against MCF-7 cells using MTT assay. The in vivo studies were investigated via intra-tumoral injection of a 5-FU loaded hydrogel into breast cancer of female rats. The results indicated that the modified hydrogel has excellent physicochemical properties with a sustained in vitro release profile matching a zero-order kinetic for one month. In addition, the hydrogel showed superior inhibition of cell viability compared with the untreated control group. Moreover, the in vivo studies resulted in antitumor activity with minor side effects. The tumor volume and level of tumor markers in blood were inhibited significantly by applying the hydrogel compared with the untreated control group. In conclusion, the designed injectable hydrogels are potential drug delivery systems for the treatment of breast cancer with a controlled drug release profile, which could be suitable for decreasing the side effects of chemotherapy agents.

Recent advances in cyclodextrin-based films for food packaging

Cyclodextrins are garnering increasing attention because they offer several benefits. For instance, cyclodextrins can form several complexes and supramolecular structures not only for food packaging but also for applications in other fields of science. In this review, we discussed the physical and chemical properties of cyclodextrins and the mechanism of their inclusion complex formation. The use of cyclodextrins in various types of food packaging is elaborated upon. We also explain the effects of cyclodextrins on the packaging of fruits, vegetables, meat, fish, and processed foods. Furthermore, some feasible suggestions for future applications are provided. In addition to the positive attributes of cyclodextrins, there are some limitations and drawbacks, which are discussed briefly in this review. In summary, this review can serve as a guide for researchers exploring cyclodextrins for the development of various packaging films.

Ultrasound Triggered Drug Release from Affinity-Based β-Cyclodextrin Polymers for Infection Control

This work demonstrates a slow, sustained drug delivery system that provides on-demand delivery bursts through the application of pulsed therapeutic ultrasound (TUS). Insoluble β-cyclodextrin-polymer (pCD) disks were loaded with a saturated antibiotic solution of rifampicin (RIF) and used for drug delivery studies. To obtain on-demand release from the implants, TUS was applied at an intensity of 1.8 W/cm². The therapeutic efficacy of the combination treatment was assessed in bacterial culture via an in vitro Staphylococcus aureus bioluminescence assay. The results demonstrated that the application of pulsed TUS at 3 MHz and 1.8 W/cm² to pCD implants leads to a significantly higher short-term burst in the drug release rate compared to samples not treated with TUS. The addition of TUS increased the drug release by 100% within 4 days. The pCD disk + RIF stimulated with TUS showed a comparatively higher bacterial eradication with CFU/mL of 4.277E+09, and 8.00E+08 at 1 and 24 h compared with control treated bacteria at 1.48E+10. Overall, these results suggest that the addition of pulsed TUS could be an effective technology to noninvasively expedite antibiotic release on demand at desired intervals.

Effect of the Cross-Linking Density on the Swelling and Rheological Behavior of Ester-Bridged β-Cyclodextrin Nanosponges

The cross-linking density influences the physicochemical properties of cyclodextrin-based nanosponges (CD-NSs). Although the effect of the cross-linker type and content on the NSs performance has been investigated, a detailed study of the cross-linking density has never been performed. In this contribution, nine ester-bridged NSs based on β-cyclodextrin (β-CD) and different quantities of pyromellitic dianhydride (PMDA), used as a cross-linking agent in stoichiometric proportions of 2, 3, 4, 5, 6, 7, 8, 9, and 10 moles of PMDA for each mole of CD, were synthesized and characterized in terms of swelling and rheological properties. The results, from the swelling experiments, exploiting Flory-Rehner theory, and rheology, strongly showed a cross-linker content-dependent behavior. The study of cross-linking density allowed to shed light on the efficiency of the synthesis reaction methods. Overall, our study demonstrates that by varying the amount of cross-linking agent, the cross-linked structure of the NSs matrix can be controlled effectively. As PMDA βCD-NSs have emerged over the years as a highly versatile class of materials with potential applications in various fields, this study represents the first step towards a full understanding of the correlation between their structure and properties, which is a key requirement to effectively tune their synthesis reaction in view of any specific future application or industrial scale-up.

Mucoadhesive Poloxamer-Based Hydrogels for the Release of HP-β-CD-Complexed Dexamethasone in the Treatment of Buccal Diseases

Oral lichen planus (OLP) is an ongoing and chronic inflammatory disease affecting the mucous membrane of the oral cavity. Currently, the treatment of choice consists in the direct application into the buccal cavity of semisolid formulations containing a corticosteroid molecule to decrease inflammatory signs and symptoms. However, this administration route has shown various disadvantages limiting its clinical use and efficacy. Indeed, the frequency of application and the incorrect use of the preparation may lead to a poor efficacy and limit the treatment compliance. Furthermore, the saliva clearance and the mechanical stress present in the buccal cavity also involve a decrease in the mucosal exposure to the drug. In this context, the design of a new pharmaceutical formulation, containing a steroidal anti-inflammatory, mucoadhesive, sprayable and exhibiting a sustained and controlled release seems to be suitable to overcome the main limitations of the existing pharmaceutical dosage forms. The present work reports the formulation, optimization and evaluation of the mucoadhesive and release properties of a poloxamer 407 thermosensitive hydrogel containing a poorly water-soluble corticosteroid, dexamethasone acetate (DMA), threaded into hydroxypropyl-beta-cyclodextrin (HP-β-CD) molecules. Firstly, physicochemical properties were assessed to ensure suitable complexation of DMA into HP-β-CD cavities. Then, rheological properties, in the presence and absence of various mucoadhesive agents, were determined and optimized. The hydration ratio (0.218-0.191), the poloxamer 407 (15-17 wt%) percentage and liquid-cyclodextrin state were optimized as a function of the gelation transition temperature, viscoelastic behavior and dynamic flow viscosity. Deformation and resistance properties were evaluated in the presence of various mucoadhesive compounds, being the sodium alginate and xanthan gum the most suitable to improve adhesion and mucoadhesion properties. Xanthan gum was shown as the best agent prolonging the hydrogel retention time up to 45 min. Furthermore, xanthan gum has been found as a relevant polymer matrix controlling drug release by diffusion and swelling processes in order to achieve therapeutic concentration for prolonged periods of time.

Development of Arabinoxylan-Reinforced Apple Pectin/Graphene Oxide/Nano-Hydroxyapatite Based Nanocomposite Scaffolds with Controlled Release of Drug for Bone Tissue Engineering: In-Vitro Evaluation of Biocompatibility and Cytotoxicity against MC3T3-E1

Fabrication of reinforced scaffolds to repair and regenerate defected bone is still a major challenge. Bone tissue engineering is an advanced medical strategy to restore or regenerate damaged bone. The excellent biocompatibility and osteogenesis behavior of porous scaffolds play a critical role in bone regeneration. In current studies, we synthesized polymeric nanocomposite material through free-radical polymerization to fabricate porous nanocomposite scaffolds by freeze drying. Functional group, surface morphology, porosity, pore size, and mechanical strength were examined through Fourier Transform Infrared Spectroscopy (FTIR), Single-Electron Microscopy (SEM), Brunauer-Emmet-Teller (BET), and Universal Testing Machine (UTM), respectively. These nanocomposites exhibit enhanced compressive strength (from 4.1 to 16.90 MPa), Young’s modulus (from 13.27 to 29.65 MPa) with well appropriate porosity and pore size (from 63.72 ± 1.9 to 45.75 ± 6.7 µm), and a foam-like morphology. The increasing amount of graphene oxide (GO) regulates the porosity and mechanical behavior of the nanocomposite scaffolds. The loading and sustained release of silver-sulfadiazine was observed to be 90.6% after 260 min. The in-vitro analysis was performed using mouse pre-osteoblast (MC3T3-E1) cell lines. The developed nanocomposite scaffolds exhibited excellent biocompatibility. Based on the results, we propose these novel nanocomposites can serve as potential future biomaterials to repair defected bone with the load-bearing application, and in bone tissue engineering.

Mechanism and optimization of supramolecular complexation-enhanced fluorescence spectroscopy for the determination of SN-38 in plasma and cells

Quantitative detection of two different forms of SN-38 in biological samples is, currently, cumbersome and difficult. A revisit to the mechanism of supramolecular complexation-enhanced fluorescence spectroscopy helps to optimize the determination of SN-38 in plasma and the cellular pharmacokinetics in A549 cells based on the supramolecular complexation. Firstly, the inclusion mechanism dominated by thermodynamic constants was determined by measuring kinetic/thermodynamic parameters (k_on , k_off , ΔG, ΔH, ΔS). On this basis, the best effect of fluorescence sensitization was optimized through screening the interaction conditions (cyclodextrin species and concentrations, drug levels, temperature, pH of the buffer, and reaction time). Furthermore, the proportional relationship between the concentration of the inclusion complex and the fluorescence intensity was confirmed. Finally, a highly sensitive, selective spectrofluorimetric method was established and validated for quantitative analysis of the lactone and carboxylate molecular states of SN-38 plasma levels in rats and cell membrane transfer kinetics in A549 cell lines. The limits of detection for the lactone and carboxylate forms in plasma were found to be 0.44 ng·ml^-1 and 0.28 ng·ml^-1 , respectively. Precision and accuracy met the requirements of biological samples analysis. The proposed detection method provided a reference for elucidating the biodistribution of SN-38.

A blend hydrogel based on polyoxometalate for long-term and repeatedly localized antibacterial application study

Herein, a polyoxometalate (POM)-based blend hydrogel system was in situ constructed by incorporating cetyltrimethylammoniumbromide (CTAB)-encapsulated POM cationic micelles to bare hydrogel matrixes followed by copolymerization of multivalent crosslinking groups. It was demonstrated that the fabricated blend hydrogel possessed tunable physicochemical properties, good swelling behavior (maximum swelling rate of 229% in buffer solution of pH 8.0), excellent local action and sustained release of POM component (release ratio achieved nearly 100% at the time of 120 min). Antibacterial activity study revealed that the introduction of POM greatly improved the bioavailability of itself, namely, leading to a more effective enhancement of therapeutic effects (survival ratio of both strains less than 5%). Besides, bactericidal rates (ca. 51%) were achieved even after six runs repeated, thereby verifying the biological application potential of this material. Finally, the practical application potentials were investigated and future prospects in relevant research areas were forecasted.

Preparation and characterization of an injectable dexamethasone-cyclodextrin complexes-loaded gellan gum hydrogel for cartilage tissue engineering

In this study, 6-(6-aminohexyl) amino-6-deoxy-β-cyclodextrin-gellan gum complex hydrogel (HCD-GG) was developed to enhance the affinity of anti-inflammatory drug dexamethasone (Dx), improve chondrogenesis, and decrease the inflammatory response. The modified chemical structure was confirmed by NMR and FTIR. Mechanical and physicochemical properties were characterized by performing viscosity study, compression test, injection force test, swelling kinetic, weight loss, and morphological study. The release profile of the drug-loaded hydrogels was analyzed to confirm the affinity of the hydrophobic drugs and the matrix and characterize cumulative release. In vitro test was carried out with MTT assay, live/dead staining, glycosaminoglycan (GAGs) content, double-stranded DNA (dsDNA) content, morphological analysis, histology, and gene expression. In vivo experiment was conducted by implanting the samples under a subcutaneous area of SPD rat and cartilage defected rabbit model. The results displayed successfully synthesized HCD-GG. The gelation temperature of the modified hydrogels was decreased while the mechanical property was improved when the drug was loaded in the modified hydrogel. Swelling and degradation kinetics resulted in a higher level compared to the pristine GG but was a sufficient level to support drugs and cells. The affinity and release rate of the drug was higher in the HCD-GG group which shows an improved drug delivery system of the GG-based material. The microenvironment provided a suitable environment for cells to grow. Also, chondrogenesis was affected by the existence of Dx and microenvironment, resulting in higher expression levels of cartilage-related genes while the expression of the inflammation mediators decreased when the Dx was loaded. In vivo study showed an improved anti-inflammatory response in the drug-loaded hydrogel. Furthermore, the cartilage defected rabbit model showed an enhanced regenerative effect when the Dx@HCD-GG was implanted. These results suggest that HCD-GG and Dx@HCD-GG have the potential for cartilage regeneration along with multiple applications in tissue engineering and regenerative medicine.

Cyclodextrin as a magic switch in covalent and non-covalent anticancer drug release systems

Cancer has been a threat to human health, so its treatment is a huge challenge to the present medical field. One of commonly used methods is the controlled release of anticancer drug to reduce the dose for patients, increase the stability of drug treatment and minimize side effects. Cyclodextrin is a kind of cyclic oligosaccharide produced by amylase hydrolysis. Because cyclodextrin contains a cavity structure and active hydroxyl groups, it has a positive effect on the study of the controlled release of anticancer drugs. This article reviews the controlled release of current anticancer drugs based on cyclodextrins as a "flexible switch", and discusses the classification of different types of release systems, highlighting their role in cancer treatment. Moreover, the opportunities and challenges of cyclodextrin as a magic switch in the controlled release of anticancer drugs are discussed.

In Vitro Release of 5-Fluorouracil and Methotrexate from Different Thermosensitive Chitosan Hydrogel Systems

5-Fluorouracil is a member of cytotoxic drugs with poor selectivity to cancer cells. Currently, systemic administration of this anti-cancer drug (oral or injection) exposes normal tissues to the drug-induced toxicity. Nowadays, attention has been greatly directed towards in situ gel-forming systems that can be injected into the affected tissues in its sol form with a minimally invasive technique. More specifically, chitosan hydrogel systems were in focus due to their antibacterial effect as well as their biodegradable, biocompatible, and mucoadhesive properties. In the present work, 5-fluorouracil was loaded on various thermosensitive chitosan hydrogel systems cross linked with different linking agents like β-glycerophosphate, pluronic F127, and hydroxyapatite. Also, methotrexate was added to 5-fluorouracil in order to gain its previously reported synergistic effects. Firstly, a compatibility study was performed using UV-spectrophotometric, infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) techniques to exclude the possibility of any physical or chemical interactions between the selected drugs and excipients. The prepared hydrogel systems were characterized for their physicochemical properties including organoleptic, pH, syringeability and injectability, viscosity, and gelation temperature (Tgel) by various analysis techniques. Moreover, the in vitro release behavior of 5-fluorouracil and methotrexate was determined with a modified analytical method. The results indicated that chitosan hydrogel system cross-linked with a combination of β- glycerophosphate, and 10 % pluronicF127 (F4) showed the most suitable physicochemical properties and release profile. Accordingly, this formula can be considered as a missionary system for localized sustained delivery of cytotoxic drugs.

Characterisation of 2-HP-β-cyclodextrin-PLGA nanoparticle complexes for potential use as ocular drug delivery vehicles

Aim: 2-HP-β-cyclodextrin-PLGA nanoparticle complexes were prepared to enhance the aqueous humour delivery of Triamcinolone acetonide.Materials & methods: Drug-loaded 2-HP-β-CD/PLGA nanoparticle complexes prepared by adapting a quasi-emulsion solvent evaporation technique. In vitro drug release, in vitro transcorneal permeation study, histopathological study and in vivo transcorneal penetration of PLGA nanoparticles and 2-HP-β-CD/PLGA nanoparticle complexes were evaluated. Results: Particle size distributions of 2-HP-β-CD/PLGA nanoparticle complexes were 149.4 ± 3.7 nm and presented stable system. Corneal penetration studies revealed steady sustained drug release (First-order); 2-HP-β-CD/PLGA nanoparticle complexes increased ocular bioavailability by increasing dispersion in the tear film and improving drug release. Conclusion: 2-HP-β-CD/PLGA nanoparticle complex formulation is a promising alternative to conventional eye drops.

Facile synthesis of Ca2+-crosslinked sodium alginate/graphene oxide hybrids as electro- and pH-responsive drug carrier

The design of stimuli-responsive drug carrier for controlled drug release is of significant importance in pharmaceutics, medicine and biology. Here, sodium alginate (SA) was integrated with graphene oxide (GO) by using Ca²⁺ as the crosslinker. The resultant SA-Ca²⁺-GO composites were freeze-dried to produce SA-Ca²⁺-GO hybrids, which were then examined by Fourier transform infrared (FT-IR) spectrometry, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The SA-Ca²⁺-GO hybrids were used as the drug carrier of methotrexate (MTX), and electro- and pH-responsive release of MTX was successfully achieved due to the excellent conductive ability of GO and the pH-sensitive property of SA. Finally, Higuchi model was employed to investigate the release kinetics of MTX from the SA-Ca²⁺-GO hybrids, and the results indicate that the release of MTX is controlled by Fickian diffusion.

Enhanced antitumour effect for hepatocellular carcinoma in the advanced stage using a cyclodextrin-sorafenib-chaperoned inclusion complex

Hepatocellular carcinoma (HCC) is a hypervascular tumour characterized by tumour-driven neovascularization. The degrees of blood oxygen saturation (DBOS), microvessel density (MVD) and tumour size (TS) are indicators in identifying the development stage of HCC. Herein, we proposed an HCC staging model using HepG2 tumour-bearing mice based on DBOS, MVD and TS. According to the patterns of these three criteria, HCC was classified into four stages: early, intermediate, advanced and end stages. The advanced stage was characterized by MVD of 50-90 (number per mm²), DBOS of 12-16% and TS of 250-600 mm³, which poses a critical challenge in HCC therapy. In order to efficiently control and treat HCC in the advanced stage, we developed a cyclodextrin (CD)-based chaperoned inclusion complex using Sorafenib (Sor), β-CD and γ-CD (SCD) via the co-crystallization method. The structural study manifested that CDs could encapsulate Sor with the hydrophobic cavities at a 1 : 1 stoichiometry ratio. The crystallographic analysis indicated that Sor-β-CD presented a diagonal stacking pattern, while Sor-γ-CD possessed a channel-type structure. The resultant chaperoned inclusion complexes significantly improved the solubility, dissolution rate and drug release of Sor, leading to superior pharmacokinetics, biodistribution and biosafety through oral administration. The antitumour effect was then evaluated on a mouse model with advanced HCC through oral administration and intratumour injection. The treatment involving the oral administration of SCDs showed a promising therapeutic effect on advanced HCC, which efficiently blocked angiogenesis and inhibited tumour progression. For the treatments using intratumour injections, only Sor-γ-CD exhibited a satisfactory anti-tumour effect with reduction in TS, MVD and DBOS. The enhanced therapeutic performance of Sor-γ-CD was attributed to its channel-type structure, which had an impact on the dissociation and release of the drug. Thus, Sor-γ-CD can be used as a potential pro-drug for clinical medicine and basic research to treat HCC.

Controlled delivery of ibuprofen from poly(vinyl alcohol)-poly(ethylene glycol) interpenetrating polymeric network hydrogels

Hydrogels composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) were synthesized using glutaraldehyde as crosslinker and investigated for controlled delivery of the common anti-inflammatory drug, ibuprofen (IBF). To regulate the drug delivery, solid inclusion complexes (ICs) of IBF in β-cyclodextrin (β-CD) were prepared and added to the hydrogels. The ICs were prepared by the microwave irradiation method, which is more environmentally benign. The formation of IC was confirmed by various analytical techniques and the synthesized hydrogels were also characterized. Controlled release of drug was achieved from the hydrogels containing the ICs in comparison to the rapid release from hydrogels containing free IBF. The preliminary kinetic analysis emphasized the crucial role of β-CD in the drug release process that influences the polymer relaxation, thereby leading to prolonged release. The cytotoxicity assay validated the hydrogels as non-toxic in nature and hence can be utilized for controlled delivery of IBF.

Mechano-responsive microcapsules with uniform thin shells

Capsules often prolong the shelf-life of active ingredients, such as many types of drugs, food additives, or cosmetic substances, because they delay oxidation of these substances or prevent their reactions with molecules contained in the surrounding. If capsules are appropriately designed, they can offer an additional benefit: they allow close control over the timing and location of the release of active ingredients. To take advantage of these features, capsules must possess shells whose thickness and composition are well-defined. However, the shell thickness of capsules often varies considerably even within a single capsule, thereby hampering good control over the release kinetics of encapsulants. These variations can be reduced, and hence the degree of control over the release kinetics increased, if shells are made thin. Unfortunately, the controlled fabrication of mechanically stable microcapsules with well-defined sub-μm thick shells is difficult. Here, we introduce a method to fabricate capsules with uniform semi-permeable shells with a thickness as low as 400 nm. This is achieved using water-oil-water double emulsions with 800 nm thick shells as templates to fabricate capsules with uniform 400 nm thin shells. These shells occupy less than 2% of the capsule volume, thereby minimizing their footprint. Despite their thin shells, these capsules are mechanically robust: they withstand pressures up to 1.3 MPa without deformation and remain intact if exposed to pressures up to 2.75 MPa. Moreover, while they are permeable towards water, they retain low molecular weight encapsulants even if dried and re-dispersed. The thin shells of the capsules open up new possibilities of their use to functionalize materials with at least one dimension that is small, such as coatings, where thick shells introduce defects, or as building blocks of new types of functional materials.

Active Food Packaging Coatings Based on Hybrid Electrospun Gliadin Nanofibers Containing Ferulic Acid/Hydroxypropyl-Beta-Cyclodextrin Inclusion Complexes

In this work, hybrid gliadin electrospun fibers containing inclusion complexes of ferulic acid (FA) with hydroxypropyl-beta-cyclodextrins (FA/HP-β-CD-IC) were prepared as a strategy to increase the stability and solubility of the antioxidant FA. Inclusion complex formation between FA and HP-β-CD was confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), and X-ray diffraction (XRD). After adjusting the electrospinning conditions, beaded-free fibers of gliadin incorporating FA/HP-β-CD-IC with average fiber diameters ranging from 269.91 ± 73.53 to 271.68 ± 72.76 nm were obtained. Control gliadin fibers containing free FA were also produced for comparison purposes. The incorporation of FA within the cyclodextrin molecules resulted in increased thermal stability of the antioxidant compound. Moreover, formation of the inclusion complexes also enhanced the FA photostability, as after exposing the electrospun fibers to UV light during 60 min, photodegradation of the compound was reduced in more than 30%. Moreover, a slower degradation rate was also observed when compared to the fibers containing the free FA. Results from the release into two food simulants (ethanol 10% and acetic acid 3%) and PBS also demonstrated that the formation of the inclusion complexes successfully resulted in improved solubility, as reflected from the faster and greater release of the compounds in the three assayed media. Moreover, in both types of hybrid fibers, the antioxidant capacity of FA was kept, thus confirming the suitability of electrospinning for the encapsulation of sensitive compounds, giving raise to nanostructures with potential as active packaging structures or delivery systems of use in pharmaceutical or biomedical applications.

An Additive to PMMA Bone Cement Enables Postimplantation Drug Refilling, Broadens Range of Compatible Antibiotics, and Prolongs Antimicrobial Therapy

Poly(methyl methacrylate) (PMMA) bone cement is used in several biomedical applications including as antibiotic-filled beads, temporary skeletal spacers, and cement for orthopedic implant fixation. To mitigate infection following surgery, antibiotics are often mixed into bone cement to achieve local delivery. However, since implanted cement is often structural, incorporated antibiotics must not compromise mechanical properties; this limits the selection of compatible antibiotics. Furthermore, antibiotics cannot be added to resolve future infections once cement is implanted. Finally, delivery from cement is suboptimal as incorporated antibiotics exhibit early burst release with most of  the drug remaining permanently trapped. This prolonged subtherapeutic dosage drives pathogen antibiotic resistance. To overcome these limitations of antibiotic-laden bone cement, insoluble cyclodextrin (CD) microparticles are incorporated into PMMA to provide more sustained delivery of a broader range of drugs, without impacting mechanics. PMMA formulations with and without CD microparticles are synthesized and filled with one of three antibiotics and evaluated using zone of inhibition, drug release, and compression studies. Additionally, the ability of PMMA with microparticles to serve as a refillable antibiotic delivery depot is explored. Findings suggest that addition of CD microparticles to cement promotes postimplantation antibiotic refilling and enables incorporation of previously incompatible antibiotics while preserving favorable mechanical properties.

Stimuli responsive biopolymer (chitosan) based blend hydrogels for wound healing application

Stimuli responsive chitosan (CS) and poly (N-vinyl-2-pyrrolidone) (PVP) have attained hydrogel properties in the presence of 74% neutralized poly acrylic acid (PAA) which can be exploited for wound healing applications. The FTIR spectra confirmed the presence of all specific functional groups and the developed interactions in the hydrogels. The thermal analysis explained that the hydrogel samples are thermally more stable than individual chitosan and PVP. The antimicrobial analysis revealed that all the samples show antibacterial activity against E. coli and the biodegradation analysis is performed to confirm the hydrogels degradation. The hydrogels showed enhanced responsive swelling behavior against different media depending upon the amount of PVP. The %age swelling in water is decreased with the increase in the amount of PVP. The most considerable swelling behavior is observed against pH, as they manifested low swelling at acidic pH and high swelling at neutral pH while at pH 8, the prominent values are obtained. This distinctive behavior of hydrogels and their biocompatibility made them pertinent to drug delivery and their release profile is examined spectrophotometrically using silver sulfadiazine (antibiotic for burnt wounds) showed 91.2% of drug release for a period of 1 h in phosphate buffer saline (PBS) in a consistent and controlled manner.

Effect on Nail Structure and Transungual Permeability of the Ethanol and Poloxamer Ratio from Cyclodextrin-Soluble Polypseudorotaxanes Based Nail Lacquer

Aqueous-based nail lacquers have shown potential in promoting the diffusion of drugs into the nail. In our laboratory, we have recently developed a transungual delivery system based on an aqueous dispersion of cyclodextrin-poloxamer soluble polypseudorotaxanes, supramolecular host−guest assemblies that improves the drug permeation into the nail. However, the high-water content and the rheological and adhesive properties of this lacquer negatively affect properties that play a fundamental role in the patients’ acceptance such as stickiness, nail film formation or drying rate, properties. In this work, we have optimized the composition of these lacquers to improve these properties whilst maintaining good drug permeation profiles. Incorporating ethanol into the vehicle and reducing the proportion of Poloxamer 407 (PL), provided a good strategy. The use of hydro-ethanolic mixtures (>50% ethanol) and the reduction of the poloxamer concentration significantly improved the lacquer drying speed by reducing the stickiness and promoting film formation on the nail surface. Additionally, in a surprising way, the use of hydro-ethanolic vehicles further enhanced the permeation of ciclopirox olamine and clobetasol propionate, used for the treatment of onychomycosis and nail psoriasis respectively, into the nail and hooves.

Incorporating β-cyclodextrin into collagen scaffolds to sequester growth factors and modulate mesenchymal stem cell activity

The development of biomaterials for a range of tissue engineering applications increasingly requires control over the bioavailability of biomolecular cues such as growth factors in order to promote desired cell responses. While efforts have predominantly concentrated on covalently-bound or freely-diffusible incorporation of biomolecules in porous, three-dimensional biomaterials, opportunities exist to exploit transient interactions to concentrate growth factor activity over desired time frames. Here, we report the incorporation of β-cyclodextrin into a model collagen-GAG scaffold as a means to exploit the passive sequestration and release of growth factors via guest-host interactions to control mesenchymal stem cell differentiation. Collagen-GAG scaffolds that incorporate β-cyclodextrin show improved sequestration as well as extended retention and release of TGF-β1. We further show extended retention and release of TGF-β1 and BMP-2 from β-cyclodextrin modified scaffolds was sufficient to influence the metabolic activity and proliferation of mesenchymal stem cells as well as differential activation of Smad 2/3 and Smad 1/5/8 pathways associated with differential osteo-chondral differentiation. Further, gene expression analysis showed TGF-β1 release from β-cyclodextrin CG scaffolds promoted early chondrogenic-specific differentiation. Ultimately, this work establishes a novel method for the incorporation and display of growth factors within CG scaffolds via supramolecular interactions. Such a design framework offers opportunities to selectively alter the bioavailability of multiple biomolecules within a three-dimensional collagen-GAG scaffold to enhance cell activity for a range of musculoskeletal regenerative medicine applications.

STATEMENT OF SIGNIFICANCE

We describe the incorporation of β-cyclodextrin into a model CG-scaffold under development for musculoskeletal tissue engineering applications. We show β-cyclodextrin modified scaffolds promote the sequestration of soluble TGF-β1 and BMP-2 via guest-host interactions, leading to extended retention and release. Further, β-cyclodextrin modified CG scaffolds promote TGF-β1 or BMP-2 specific Smad signaling pathway activation associated with divergent osseous versus chondrogenic differentiation pathways in mesenchymal stem cells.