Cyclodextrins in drug delivery systems

β-Cyclodextrin and Hyaluronic Acid-Modified Targeted Nanodelivery System for Atherosclerosis Prevention

Natural products have been widely recognized in clinical treatment because of their low toxicity and high activity. It is worth paying attention to modifying the biopolymer into nanostructures to give natural active ingredients additional targeting effects. In this study, based on the multifunctional modification of β-cyclodextrin (β-CD), a nanoplatform encapsulating the unstable drug (-)-epicatechin gallate (ECG) was designed to deliver to atherosclerotic plaques. Acetalization cyclodextrin (PH-CD), which responds to low-pH environments, and hyaluronic acid cyclodextrin, which targets the CD44 receptor on macrophage membranes, were synthesized from β-CD and hyaluronic acid using acetalization and transesterification, respectively. The resulting dual-carrier nanoparticles (Double-NPs) loaded with ECG were prepared using a solvent evaporation method. The Double-NPs effectively scavenged reactive oxygen species, promoted macrophage migration, inhibited macrophage apoptosis, and suppressed abnormal proliferation and migration of vascular smooth muscle cells. Furthermore, the Double-NPs actively accumulated in atherosclerotic plaques in ApoE-/- mice fed with a high-fat diet, leading to a reduced plaque area, inflammatory infiltration, and plaque instability. Our findings demonstrate that the newly developed ECG nanopreparation represents an effective and safe nanotherapy for diseases such as atherosclerosis.

Enhancing Systemic Translocation of Insecticides via Nanoformulations Incorporating β-Cyclodextrin Octadecarboxylate as a Carrier

The conversion of contact-killing pesticides into systemic pesticides can significantly enhance the bioavailability of pesticides, thereby reducing pesticide usage and environmental harm. A series of β-cyclodextrin fatty acid esters with varying branch chains were synthesized and employed as carriers in nanoformulation of insecticide. The investigation revealed that nanoformulations prepared using β-cyclodextrin octadecarboxylate (β-CDs) exhibited superior stability and remarkable systemic translocation within plants. Six contact-killing insecticide nanoformulations were developed utilizing β-CDs as carriers, and tests indicated that β-CDs significantly enhanced the systemic translocation of insecticides in plants compared to carrier-free nanoformulations. It was found that β-CDs increased the level of systemic translocation of insecticides by 5-12 times. Additionally, characterization results from λ-cyhalothrin-β-CDs nanoformulation demonstrated their superior ability to improve photolysis resistance, prolong release time, and extend insecticidal duration. Consequently, β-CDs can be utilized as a green additive in pesticide production to enhance the systemic translocation of pesticides in plants and increase their bioavailability.

Cholesterol depletion inhibits rabies virus infection by restricting viral adsorption and fusion

Rabies is an ancient zoonotic disease caused by the rabies virus (RABV), and a sharp increase in rabies cases and deaths were observed following the COVID-19 pandemic, indicating that it still poses a severe public health threat in most countries in the world. Cholesterol is one of the major lipid components in cells, and the exact role of cholesterol in RABV infection remains unclear. In this study, we initially observed that cellular cholesterol levels were significantly elevated in RABV infected cells, while cholesterol depletion by using methyl-β-cyclodextrin (MβCD) could restrict RABV entry. We further found that decreasing the cholesterol level of the viral envelope could change the bullet-shaped morphology of RABV and dislodge the glycoproteins on its surface to affect RABV entry. Moreover, the depletion of cholesterol could decrease lysosomal cholesterol accumulation to inhibit RABV fusion. Finally, it was found that the depletion of cholesterol by MβCD was due to the increase of oxygen sterol production in RABV-infected cells and the enhancement of cholesterol efflux by activating liver X receptor alpha (LXRα). Together, our study reveals a novel role of cholesterol in RABV infection, providing new insight into explore of effective therapeutics for rabies.

Cyclodextrin: A prospective nanocarrier for the delivery of antibacterial agents against bacteria that are resistant to antibiotics

Supramolecular chemistry introduces us to the macrocyclic host cyclodextrin, which has a hydrophobic cavity. The hydrophobic cavity has a higher affinity for hydrophobic guest molecules and forms host-guest complexation with non-covalent interaction. Three significant cyclodextrin kinds are α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. The most often utilized is β-cyclodextrin (β-CD). An effective weapon against bacteria that are resistant to antibiotics is cyclodextrin. Several different kinds of cyclodextrin nanocarriers (β-CD, HP-β-CD, Meth-β-CD, cationic CD, sugar-grafted CD) are utilized to enhance the solubility, stability, dissolution, absorption, bioavailability, and permeability of the antibiotics. Cyclodextrin also improves the effectiveness of antibiotics, antimicrobial peptides, metallic nanoparticles, and photodynamic therapy (PDT). Again, cyclodextrin nanocarriers offer slow-release properties for sustained-release formulations where steady-state plasma antibiotic concentration is needed for an extended time. A novel strategy to combat bacterial resistance is a stimulus (pH, ROS)-responsive antibiotics released from cyclodextrin carrier. Once again, cyclodextrin traps autoinducer (AI), a crucial part of bacterial quorum sensing, and reduces virulence factors, including biofilm formation. Cyclodextrin helps to minimize MIC in particular bacterial strains, keep antibiotic concentrations above MIC in the infection site and minimize the possibility of antibiotic and biofilm resistance. Sessile bacteria trapped in biofilms are more resistant to antibiotic therapy than bacteria in a planktonic form. Cyclodextrin also involves delivering antibiotics to biofilm and resistant bacteria to combat bacterial resistance.

Host Dynamics under General-Purpose Force Fields

Macrocyclic hosts as prototypical receptors to gaseous and drug-like guests are crucial components in pharmaceutical research. The external guests are often coordinated at the center of these macromolecular containers. The formation of host-guest coordination is accompanied by the broken of host-water and host-ion interactions and sometimes also involves some conformational rearrangements of the host. A balanced description of various components of interacting terms is indispensable. However, up to now, the modeling community still lacks a general yet detailed understanding of commonly employed general-purpose force fields and the host dynamics produced by these popular selections. To fill this critical gap, in this paper, we profile the energetics and dynamics of four types of popular macrocycles, including cucurbiturils, pillararenes, cyclodextrins, and octa acids. The presented investigations of force field definitions, refitting, and evaluations are unprecedently detailed. Based on the valuable observations and insightful explanations, we finally summarize some general guidelines on force field parametrization and selection in host-guest modeling.

Robust Inclusion Complex of Topotecan Comprised within a Rhodamine-Labeled β-Cyclodextrin: Competing Proton and Energy Transfer Processes

Monitoring the biological fate of medicaments within the environments of cancer cells is an important challenge which is nowadays the object of intensive studies. In this regard, rhodamine-based supramolecular systems are one of the most suitable probes used in drug delivery thanks to their high emission quantum yield and sensitivity to the environment which helps to track the medicament in real time. In this work, we used steady-state and time-resolved spectroscopy techniques to investigate the dynamics of the anticancer drug, topotecan (TPT), in water (pH ~6.2) in the presence of a rhodamine-labeled methylated β-cyclodextrin (RB-RM-βCD). A stable complex of 1:1 stoichiometry is formed with a K_eq value of ~4 × 10⁴ M^-1 at room temperature. The fluorescence signal of the caged TPT is reduced due to: (1) the CD confinement effect; and (2) a Förster resonance energy transfer (FRET) process from the trapped drug to the RB-RM-βCD occurring in ~43 ps with 40% efficiency. These findings provide additional knowledge about the spectroscopic and photodynamic interactions between drugs and fluorescent functionalized CDs, and may lead to the design of new fluorescent CD-based host-guest nanosystems with efficient FRET to be used in bioimaging for drug delivery monitoring.

The Role of Cyclodextrin in the Construction of Nanoplatforms: From Structure, Function and Application Perspectives

Cyclodextrins (CyDs) in nano drug delivery systems have received much attention in pursuit of good compatibility, negligible toxicity, and improved pharmacokinetics of drugs. Their unique internal cavity has widened the application of CyDs in drug delivery based on its advantages. Besides this, the polyhydroxy structure has further extended the functions of CyDs by inter- and intramolecular interactions and chemical modification. Furthermore, the versatile functions of the complex contribute to alteration of the physicochemical characteristics of the drugs, significant therapeutic promise, a stimulus-responsive switch, a self-assembly capability, and fiber formation. This review attempts to list recent interesting strategies regarding CyDs and discusses their roles in nanoplatforms, and may act as a guideline for developing novel nanoplatforms. Future perspectives on the construction of CyD-based nanoplatforms are also discussed at the end of this review, which may provide possible direction for the construction of more rational and cost-effective delivery vehicles.

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.

Host-guest drug delivery by β-cyclodextrin assisted polysaccharide vehicles: A review

Among different form of cyclodextrin (CD), β-CD has been taken a special attraction in pharmaceutical science due to lowest aqueous solubility and adequate cavity size. When β-CD forms inclusion complex with drugs then biopolymers such as polysaccharides in combination plays a vital role as a vehicle for safe release of drugs. It is noticed that, β-CD assisted polysaccharide-based composite achieves better drug release rate through host-guest mechanism. Present review is a critical analysis of this host-guest mechanism for release of drugs from polysaccharide supported β-CD inclusion complex. Various important polysaccharides such as cellulose, alginate, chitosan, dextran, etc. in relevant to drug delivery are logically compared in present review by their association with β-CD. Efficacy of mechanism of drug delivery by different polysaccharides with β-CD is analytically examined in schematic form. Drug release capacity at different pH conditions, mode of drug release, along with characterization techniques adopted by individual polysaccharide-based CD complexes are comparatively established in tabular form. This review may explore better visibility for researchers those are working in the area of controlled release of drugs by vehicle consist of β-CD associated polysaccharide composite through host-guest mechanism.

A Comparison between the Molecularly Imprinted and Non-Molecularly Imprinted Cyclodextrin-Based Nanosponges for the Transdermal Delivery of Melatonin

Melatonin is a neurohormone that ameliorates many health conditions when it is administered as a drug, but its drawbacks are its oral and intravenous fast release. To overcome the limitations associated with melatonin release, cyclodextrin-based nanosponges (CD-based NSs) can be used. Under their attractive properties, CD-based NSs are well-known to provide the sustained release of the drug. Green cyclodextrin (CD)-based molecularly imprinted nanosponges (MIP-NSs) are successfully synthesized by reacting β-Cyclodextrin (β-CD) or Methyl-β Cyclodextrin (M-βCD) with citric acid as a cross-linking agent at a 1:8 molar ratio, and melatonin is introduced as a template molecule. In addition, CD-based non-molecularly imprinted nanosponges (NIP-NSs) are synthesized following the same procedure as MIP-NSs without the presence of melatonin. The resulting polymers are characterized by CHNS-O Elemental, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric (TGA), Differential Scanning Calorimetry (DSC), Zeta Potential, and High-Performance Liquid Chromatography (HPLC-UV) analyses, etc. The encapsulation efficiencies are 60-90% for MIP-NSs and 20-40% for NIP-NSs, whereas melatonin loading capacities are 1-1.5% for MIP-NSs and 4-7% for NIP-NSs. A better-controlled drug release performance (pH = 7.4) for 24 h is displayed by the in vitro release study of MIP-NSs (30-50% released melatonin) than NIP-NSs (50-70% released melatonin) due to the different associations within the polymeric structure. Furthermore, a computational study, through the static simulations in the gas phase at a Geometry Frequency Non-covalent interactions (GFN2 level), is performed to support the inclusion complex between βCD and melatonin with the automatic energy exploration performed by Conformer-Rotamer Ensemble Sampling Tool (CREST). A total of 58% of the CD/melatonin interactions are dominated by weak forces. CD-based MIP-NSs and CD-based NIP-NSs are mixed with cream formulations for enhancing and sustaining the melatonin delivery into the skin. The efficiency of cream formulations is determined by stability, spreadability, viscosity, and pH. This development of a new skin formulation, based on an imprinting approach, will be of the utmost importance in future research at improving skin permeation through transdermal delivery, associated with narrow therapeutic windows or low bioavailability of drugs with various health benefits.

A novel gedunin-2-hydroxypropyl-β-cyclodextrin inclusion complex improves anti-nociceptive and anti-inflammatory activities of gedunin in rodents

Gedunin is a bioactive compound, obtained from Entandrophragma angolense (EA), which has limited therapeutic usefulness due to poor aqueous solubility and first-pass effects. Cyclodextrins are cyclic oligosaccharides that form complexes with poorly soluble compounds, thus enhancing their pharmacological activity. In this article, we evaluated the pharmacological activities of gedunin-2-hydroxypropyl-β-cyclodextrin complex (GCD) in rodents. The antinociceptive activity of GCD (50, 100, 200 mg/kg) and Gedunin (50mg/kg) was tested in acetic acid-induced writhing and formalin-induced paw licking in mice. The anti-inflammatory activity was investigated in carrageenan-induced paw oedema and air pouch inflammation models in rats. Leucocytes counts, Tumour Necrosis Factor-alpha (TNF-α) level, nitric oxide, malondialdehyde, reduced glutathione, and myeloperoxidase enzyme activities were assessed in the air pouch exudate. The GCD (200mg/kg) significantly decreased writhing response, reduced licking duration and decreased oedema compared with gedunin and control. Exudate volume and leucocyte count were significantly reduced by GCD (200 mg/kg), it decreased myeloperoxidase activity and inhibited TNF-α release. The carrageenan-induced GSH depletion, increased malondialdehyde and nitrite levels were significantly reversed by GCD (200 mg/kg) relative to gedunin and control.  The GCD complex demonstrated significant antinociceptive and anti-inflammatory activities relative to gedunin alone via mechanisms associated with inhibition of oxidative stress and inflammation in rodents.

The Effect of Traditional and Cyclodextrin-Assisted Extraction Methods on Trifolium pratense L. (Red Clover) Extracts Antioxidant Potential

Red clover is the subject of numerous studies because of its antioxidant properties, the positive influence of isoflavones on the health, and its potential use in the prevention and treatment of chronic diseases. The right excipients, such as cyclodextrins, can increase the profile of valuable phenolic compounds in extraction media to obtain rich in antioxidants, extracts that can be used in nutraceuticals production. The aim of this study was to investigate and compare the total phenolic content, flavonoid content, and antioxidant activity of red clover aerial parts, aqueous and ethanolic extracts prepared using traditional and cyclodextrins-assisted methods. The antioxidant activity of the extracts was established using ABTS, DPPH, FRAP, and ABTS-post column methods. It was determined that cyclodextrins significantly increased total phenolic content (compared with control)—using β-cyclodextrin 20.29% (in aqueous samples); γ-cyclodextrin 22.26% (in ethanolic samples). All the samples prepared with excipients demonstrated a strong relationship between total phenolic content and DPPH assay. Study showed that for extraction with water, the highest amounts of phenolic compounds, flavonoids and antioxidant activity will be achieved with β-cyclodextrin, but extractions with ethanol will give the best results with γ-cyclodextrin. Therefore, cyclodextrins are a great and safe tool for obtaining rich, red clover flower extracts that are high in antioxidant activity, which can be used in the pharmaceutical industry for nutraceuticals production.

Cyclodextrins: Structural, Chemical, and Physical Properties, and Applications

Due to their unique structural, physical and chemical properties, cyclodextrins and their derivatives have been of great interest to scientists and researchers in both academia and industry for over a century. Many of the industrial applications of cyclodextrins have arisen from their ability to encapsulate, either partially or fully, other molecules, especially organic compounds. Cyclodextrins are non-toxic oligopolymers of glucose that help to increase the solubility of organic compounds with poor aqueous solubility, can mask odors from foul-smelling compounds, and have been widely studied in the area of drug delivery. In this review, we explore the structural and chemical properties of cyclodextrins that give rise to this encapsulation (i.e., the formation of inclusion complexes) ability. This review is unique from others written on this subject because it provides powerful insights into factors that affect cyclodextrin encapsulation. It also examines these insights in great detail. Later, we provide an overview of some industrial applications of cyclodextrins, while emphasizing the role of encapsulation in these applications. We strongly believe that cyclodextrins will continue to garner interest from scientists for many years to come, and that novel applications of cyclodextrins have yet to be discovered.

Cyclodextrin-Containing Hydrogels: A Review of Preparation Method, Drug Delivery, and Degradation Behavior

Hydrogels possess porous structures, which are widely applied in the field of materials and biomedicine. As a natural oligosaccharide, cyclodextrin (CD) has shown remarkable application prospects in the synthesis and utilization of hydrogels. CD can be incorporated into hydrogels to form chemically or physically cross-linked networks. Furthermore, the unique cavity structure of CD makes it an ideal vehicle for the delivery of active ingredients into target tissues. This review describes useful methods to prepare CD-containing hydrogels. In addition, the potential biomedical applications of CD-containing hydrogels are reviewed. The release and degradation process of CD-containing hydrogels under different conditions are discussed. Finally, the current challenges and future research directions on CD-containing hydrogels are presented.

Cyclodextrin-Modified Nanomaterials for Drug Delivery: Classification and Advances in Controlled Release and Bioavailability

In drug delivery, one widely used way of overcoming the biopharmaceutical problems present in several active pharmaceutical ingredients, such as poor aqueous solubility, early instability, and low bioavailability, is the formation of inclusion compounds with cyclodextrins (CD). In recent years, the use of CD derivatives in combination with nanomaterials has shown to be a promising strategy for formulating new, optimized systems. The goals of this review are to give in-depth knowledge and critical appraisal of the main CD-modified or CD-based nanomaterials for drug delivery, such as lipid-based nanocarriers, natural and synthetic polymeric nanocarriers, nanosponges, graphene derivatives, mesoporous silica nanoparticles, plasmonic and magnetic nanoparticles, quantum dots and other miscellaneous systems such as nanovalves, metal-organic frameworks, Janus nanoparticles, and nanofibers. Special attention is given to nanosystems that achieve controlled drug release and increase their bioavailability during in vivo studies.

Cyclodextrins as Anti-inflammatory Agents: Basis, Drugs and Perspectives

Inflammation is a biological response of the immune system to harmful stimuli. Importantly, inflammation is also a hallmark of several human diseases such as cancer or diabetes. Novel drugs to treat this response are constantly researched, but the formulation is usually forgotten. Cyclodextrins (CDs) are a well-known excipient for complexing and drug delivery. Anti-inflammatory drugs and bioactive compounds with similar activities have been favored from these CD processes. CDs also illustrate anti-inflammatory activity per se. This review tried to describe the capacities of CDs in this field, and is divided into two parts: Firstly, a short description of the inflammation disease (causes, symptoms, treatment) is explained; secondly, the effects of different CDs alone or forming inclusion complexes with drugs or bioactive compounds are discussed.

Preparation and Characterization of Liposomes Double-loaded with Amphotericin B and Amphotericin B/hydroxypropyl-beta-cyclodextrin Inclusion Complex

BACKGROUND

Amphotericin B (AMB) is water-insoluble polyene, which has a broad spectrum of antifungal activity. The hydrophobic drug only exits in the phospholipid bilayer, leading to a low-drug liposomal loading capacity.

OBJECTIVES

This study is designed to prepare water-soluble inclusion complex (IC) between AMB and cyclodextrin (CD) to formulate liposomal vesicles, double-loaded with drug molecules in the phospholipid bilayer and AMB/CD IC in the aqueous core.

METHODS

Water-soluble AMB/CD IC was prepared by pH adjustment of the aqueous media and consequently characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Liposomes double-loaded with AMB were formulated by the thin-film hydration method and accordingly evaluated for vesicle size, polydispersity index, entrapment efficiency, zeta potential, and in vitro drug leakage.

RESULTS

Hydroxypropyl β cyclodextrin (HP-β-CD) better solubilized AMB than both α-CD and β- CD e.g., the concentration of water-soluble AMB/HP-β-CD IC could reach 465 μg/mL. Both DSC and SEM data illustrated that the drug no longer existed in its crystalline form, in AMB/HP-β-CD IC. Liposomes double-loaded with hydrophilic AMB/HP-β-CD IC and hydrophobic AMB had a diameter of 270 nm, polydispersity index less than 0.27, and zeta potential ca.-42.8 mV. Moreover, liposomes double-loaded with AMB enhanced drug-liposomal loading capacity by 25%, less leaked drug in phosphate buffer pH 7.4 at 37°C in comparison to liposomes loaded with only hydrophobic AMB.

CONCLUSION

Liposomes double-loaded with AMB and AMB/HP-β-CD IC increased drug-encapsulation ability and in vitro stability, suggesting potential drug delivery systems.

Click Chemistry Enabling Covalent and Non-Covalent Modifications of Graphene with (Poly)saccharides

Graphene is a material with outstanding properties and numerous potential applications in a wide range of research and technology areas, spanning from electronics, energy materials, sensors, and actuators to life-science and many more. However, the insolubility and poor dispersibility of graphene are two major problems hampering its use in certain applications. Tethering mono-, di-, or even poly-saccharides on graphene through click-chemistry is gaining more and more attention as a key modification approach leading to new graphene-based materials (GBM) with improved hydrophilicity and substantial dispersibility in polar solvents, e.g., water. The attachment of (poly)saccharides on graphene further renders the final GBMs biocompatible and could open new routes to novel biomedical and environmental applications. In this review, recent modifications of graphene and other carbon rich materials (CRMs) through click chemistry are reviewed.

Impact of the Chain Length and Topology of the Acetylated Oligosaccharide on the Crystallization Tendency of Naproxen from Amorphous Binary Mixtures

The impact of the chain length or dispersity of polymers in controlling the crystallization of amorphous active pharmaceutical ingredients (APIs) has been discussed for a long time. However, because of the weak control of these parameters in the majority of macromolecules used in pharmaceutical formulations, the abovementioned topic is poorly understood. Herein, four acetylated oligosaccharides, maltose (acMAL), raffinose (acRAF), stachyose (acSTA), and α-cyclodextrin (ac-α-CD) of growing chain lengths and different topologies (linear vs cyclic), mimicking the growing backbone of the polymer, were selected to probe the influence of these structural factors on the crystallization of naproxen (NAP)—an API that does not vitrify regardless of the cooling rate applied in our experiment. It was found that in equimolar systems composed of NAP and linear acetylated oligosaccharides, the progress and activation barrier for crystallization are dependent on the molecular weight of the excipient despite the fact that results of Fourier transform infrared studies indicated that there is no difference in the interaction pattern between measured samples. On the other hand, complementary dielectric, calorimetric, and X-ray diffraction data clearly demonstrated that NAP mixed with ac-α-CD (cyclic saccharide) does not tend to crystallize even in the system with a much higher content of APIs. To explain this interesting finding, we have carried out further density functional theory computations, which revealed that incorporation of NAP into the cavity of ac-α-CD is hardly possible because this state is of much higher energy (up to 80 kJ/mol) with respect to the one where the API is located outside of the saccharide torus. Hence, although at the moment, it is very difficult to explain the much stronger impact of the cyclic saccharide on the suppression of crystallization and enhanced stability of NAP with respect to the linear carbohydrates, our studies clearly showed that the chain length and the topology of the excipient play a significant role in controlling the crystallization of this API.

Production and Mechanical Characterisation of TEMPO-Oxidised Cellulose Nanofibrils/β-Cyclodextrin Films and Cryogels

Wood-based TEMPO-oxidised cellulose nanofibrils (toCNF) are promising materials for biomedical applications. Cyclodextrins have ability to form inclusion complexes with hydrophobic molecules and are considered as a method to bring new functionalities to these materials. Water sorption and mechanical properties are also key properties for biomedical applications such as drug delivery and tissue engineering. In this work, we report the modification with β-cyclodextrin (βCD) of toCNF samples with different carboxyl contents viz. 756 ± 4 µmol/g and 1048 ± 32 µmol/g. The modification was carried out at neutral and acidic pH (2.5) to study the effect of dissociation of the carboxylic acid group. Films processed by casting/evaporation at 40 °C and cryogels processed by freeze-drying were prepared from βCD modified toCNF suspensions and compared with reference samples of unmodified toCNF. The impact of modification on water sorption and mechanical properties was assessed. It was shown that the water sorption behaviour for films is driven by adsorption, with a clear impact of the chemical makeup of the fibres (charge content, pH, and adsorption of cyclodextrin). Modified toCNF cryogels (acidic pH and addition of cyclodextrins) displayed lower mechanical properties linked to the modification of the cell wall porosity structure. Esterification between βCD and toCNF under acidic conditions was performed by freeze-drying, and such cryogels exhibited a lower decrease in mechanical properties in the swollen state. These results are promising for the development of scaffold and films with controlled mechanical properties and added value due to the ability of cyclodextrin to form an inclusion complex with active principle ingredient (API) or growth factor (GF) for biomedical applications.

The Opposed Effects of Polyvinylpyrrolidone K30 on Dissolution and Precipitation for Indomethacin Supersaturating Drug Delivery Systems

Amorphous solid dispersions (ASD) are one of the most important supersaturating drug delivery systems (SDDS) for poorly water-soluble drugs to improve their bioavailability. As a result of thermodynamic instability, drug molecules tend to precipitate during storage and dissolution in gastrointestinal tract. Various precipitation inhibitors (PI) have been widely used to improve the stability in the past decade. However, most studies have investigated the inhibiting capability of PI on drug precipitation, rarely considering their potential hindering effect on the drug dissolution. The present study designed an ASD of Indomethacin (IND) and Eudragit® EPO by hot melt extrusion to investigate the influence of the added PI (PVP-K30) into ASD both on dissolution and precipitation. The precipitation study by solvent shift method indicated PVP-K30 could inhibit the precipitation of IND significantly. The dissolution study in different concentrations of PVP-K30 showed when the concentration increased above 50 μg/mL, PVP-K30 displayed an acceptable precipitation inhibition without drug concentration decline but an unexpected dissolution impediment with the reduction of maximum concentration platform. The dissolution tests of physical mixtures (PMs) of ASD and PVP-K30 also showed the precipitation inhibition and dissolution impediment when more than 2% PVP-K30 in PMs. This opposed effect of PVP-K30 was strengthen in ternary systems prepared by hot melt extruding the mixtures of IND, Eudragit® EPO and PVP-K30. All of these results proved the PI may be a double-edged sword for the opposed effects of precipitation inhibition and dissolution impediment, which should be carefully considered in the design and development of SDDS.

Advantages of the combined use of cyclodextrins and nanocarriers in drug delivery: A review

Complexation with cyclodextrins (CDs) has been widely and successfully used in pharmaceutical field, mainly for enhancing solubility, stability and bioavailability of a variety of drugs. However, some important drawbacks, including rapid removal from the bloodstream after in vivo administration, or possible replacement, in biological media, of the entrapped drug moieties by other molecules with higher affinity for the CD cavity, can limit the CDs effectiveness as drug carriers. This review is focused on combined strategies simultaneously exploiting CD complexation, and loading of the complexed drug into various colloidal carriers (liposomes, niosomes, polymeric nanoparticles, lipid nanoparticles, nanoemulsions, micelles) which have been investigated as a possible means for circumventing the problems associated with both such carriers, when used separately, and join their relative benefits in a unique delivery system. Several examples of applications have been reported, to illustrate the possible advantages achievable by such a dual strategy, depending on the CD-nanocarrier combination, and mainly resulting in enhanced performance of the delivery system and improved biopharmaceutical properties and therapeutic efficacy of drugs. The major problems and/or drawbacks found in the development of such systems, as well as the (rare) case of failures in achieving the expected improvements have also been highlighted.

Selective Laser Sintering 3D Printing of Orally Disintegrating Printlets Containing Ondansetron

The aim of this work was to explore the feasibility of using selective laser sintering (SLS) 3D printing (3DP) to fabricate orodispersable printlets (ODPs) containing ondansetron. Ondansetron was first incorporated into drug-cyclodextrin complexes and then combined with the filler mannitol. Two 3D printed formulations with different levels of mannitol were prepared and tested, and a commercial ondansetron orally disintegrating tablet (ODT) product (Vonau^® Flash) was also investigated for comparison. Both 3D printed formulations disintegrated at ~15 s and released more than 90% of the drug within 5 min independent of the mannitol content; these results were comparable to those obtained with the commercial product. This work demonstrates the potential of SLS 3DP to fabricate orodispersible printlets with characteristics similar to a commercial ODT, but with the added benefit of using a manufacturing technology able to prepare medicines individualized to the patient.

Polydopamine-Inspired Surface Modification of Polypropylene Hernia Mesh Devices via Cold Oxygen Plasma: Antibacterial and Drug Release Properties

Mesh infection is a major complication of hernia surgery after polypropylene (PP) mesh implantation. Modifying the PP mesh with antibacterial drugs is an effective way to reduce the chance of infection, but the hydrophobic characteristic of PP fibers has obstructed the drug adhesion. Therefore, to prepare antimicrobial PP mesh with a stable drug coating layer and to slow the drug release property during the hernia repair process has a great practical meaning. In this work, PP meshes were coated by bio-inspired polydopamine (PDA), which can load and release levofloxacin. PP meshes were activated with cold oxygen plasma and then plasma activated PP fibers were coated with PDA. The PDA coated meshes were further soaked in levofloxacin. The levofloxacin loaded PP meshes demonstrate excellent antimicrobial properties for 6 days and the drug release has lasted for at least 24 h. Moreover, a control PP mesh sample without plasma treatment was also prepared, after coating with PDA and loading levofloxacin. The antimicrobial property was sustained only for two days. The maximum inhibition zone of PDA coated meshes with and without plasma treatment was 12.5 and 9 mm, respectively. On all accounts, the modification strategy can facilely lead to long-term property of infection prevention.

Electrospinning of Cyclodextrin Functional Nanofibers for Drug Delivery Applications

Electrospun nanofibers have sparked tremendous attention in drug delivery since they can offer high specific surface area, tailored release of drugs, controlled surface chemistry for preferred protein adsorption, and tunable porosity. Several functional motifs were incorporated into electrospun nanofibers to greatly expand their drug loading capacity or to provide the sustained release of the embedded drug molecules. In this regard, cyclodextrins (CyD) are considered as ideal drug carrier molecules as they are natural, edible, and biocompatible compounds with a truncated cone-shape with a relatively hydrophobic cavity interior for complexation with hydrophobic drugs and a hydrophilic exterior to increase the water-solubility of drugs. Further, the formation of CyD-drug inclusion complexes can protect drug molecules from physiological degradation, or elimination and thus increases the stability and bioavailability of drugs, of which the release takes place with time, accompanied by fiber degradation. In this review, we summarize studies related to CyD-functional electrospun nanofibers for drug delivery applications. The review begins with an introductory description of electrospinning; the structure, properties, and toxicology of CyD; and CyD-drug complexation. Thereafter, the release of various drug molecules from CyD-functional electrospun nanofibers is provided in subsequent sections. The review concludes with a summary and outlook on material strategies.

Electrospinning in water and in situ crosslinking of hyaluronic acid / cyclodextrin nanofibers: Towards wound dressing with controlled drug release

Hyaluronic acid (HA) is widely investigated due to its high potential for wound dressing applications. The fabrication of biomimetic HA-based scaffolds by electrospinning is thus extensively studied. However, HA is often dissolved in toxic organic solvents to allow the efficient production of electrospun nanofibers. Indeed, although HA is soluble in water, its ionic nature leading to long-range electrostatic interactions and the presence of counter ions induce a dramatic increase of the viscosity of aqueous HA solutions without insuring enough chain entanglements necessary for a stable and efficient electrospinning. In this study, biocompatible insoluble HA-based nanofibers were fabricated by electrospinning in pure water. To this end, poly(vinyl alcohol) (PVA) was added as a carrier polymer and it was found that the addition of hydroxypropyl-βcyclodextrin (HPβCD) stabilized the process of electrospinning and led to the efficient formation of uniform nanofibrous scaffolds. An in situ crosslinking process of the scaffolds is also proposed, insuring a whole fabrication process without any toxicity. Furthermore, the beneficial presence of HPβCD in the HA-based scaffolds paves the way for wound dressing applications with controlled drug encapsulation-release properties. As a proof of concept, naproxen (NAP), a non-steroidal anti-inflammatory drug was chosen as a model drug. NAP was impregnated into the scaffolds either in aqueous solution or under supercritical CO₂. The resulting functional scaffolds showed a regular drug release profile along several days without losing the fibrous structure. This study proposes a simple approach to form stable HA-based nanofibrous scaffolds embedding HPβCD using water as the only solvent, enabling the development of safe functional wound dressings.

Cyclodextrin-Based Magnetic Nanoparticles for Cancer Therapy

Polydopamine (PDA)-coated magnetic nanoparticles functionalized with mono-6-thio-β-cyclodextrin (SH-βCD) were obtained and characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Nuclear and Magnetic Resonance Imaging (NMR and MRI), and doxorubicin (DOXO)-loading experiments. The liver cancer cellular internalization of DOXO-loaded nanoparticles was investigated by confocal imaging microscopy. Synthesized nanomaterials bearing a chemotherapeutic drug and a layer of polydopamine capable of absorbing near-infrared light show high performance in the combined chemo- and photothermal therapy (CT-PTT) of liver cancer due to the synergistic effect of both modalities as demonstrated in vitro. Moreover, our material exhibits improved T₂ contrast properties, which have been verified using Carr-Purcell-Meiboom-Gill pulse sequence and MRI Spin-Echo imaging of the nanoparticles dispersed in the agarose gel phantoms. Therefore, the presented results cast new light on the preparation of polydopamine-based magnetic theranostic nanomaterials, as well as on the proper methodology for investigation of magnetic nanoparticles in high field MRI experiments. The prepared material is a robust theranostic nanoasystem with great potential in nanomedicine.

Selective binding of methotrexate to monomeric, dimeric and polymeric cyclodextrins

Selective binding of methotrexate to monomeric, dimeric and polymeric cyclodextrins characterized by formation of more stable complexes with dimeric β-cyclodextrin.

Shipment of a photodynamic therapy agent into model membrane and its controlled release: A photophysical approach

Harmine, an efficient cancer cell photosensitizer (PS), emits intense violet color when it is incorporated in well established self assembly based drug carrier formed by cationic surfactants of identical positive charge of head group but varying chain length, namely, dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB). Micelle entrapped drug emits in the UV region when it interacts with non-toxic β-cyclodextrin (β-CD). Inspired by these unique fluorescence/structural switching properties of the anticancer drug, in the present work we have monitored the interplay of the drug between micelles and non-toxic β-CDs. We have observed that the model membranes formed by micelles differing in their hydrophobic chain length interact with the drug differently. Variation in the surfactant chain length plays an important role for structural switching i.e. in choosing a particular structural form of the drug that will be finally presented to their targets. The present study shows that in case of necessity, the bound drug molecule can be removed from its binding site in a controlled manner by the use of non-toxic β-CD and it is exploited to serve a significant purpose for the removal of excess/unused adsorbed drugs from the model cell membranes. We believe this kind of β-CD driven translocation of drugs monitored by fluorescence switching may find possible applications in controlled release of the drug inside cells.

Mesoporous self-assembled nanoparticles of biotransesterified cyclodextrins and nonlamellar lipids as carriers of water-insoluble substances

Soft mesoporous hierarchically structured particles were created by the self-assembly of an amphiphilic deep cavitand cyclodextrin βCD-nC₁₀ (degree of substitution n = 7.3), with a nanocavity grafted by multiple alkyl (C₁₀) chains on the secondary face of the βCD macrocycle through enzymatic biotransesterification, and the nonlamellar lipid monoolein (MO). The effect of the non-ionic dispersing agent polysorbate 80 (P80) on the liquid crystalline organization of the nanocarriers and their stability was studied in the context of vesicle-to-cubosome transition. The coexistence of small vesicular and nanosponge membrane objects with bigger nanoparticles with inner multicompartment cubic lattice structures was established as a typical feature of the employed dispersion process. The cryogenic transmission electron microscopy (cryo-TEM) images and small-angle X-ray scattering (SAXS) structural analyses revealed the dependence of the internal organization of the self-assembled nanoparticles on the presence of embedded βCD-nC₁₀ deep cavitands in the lipid bilayers. The obtained results indicated that the incorporated amphiphilic βCD-nC₁₀ building blocks stabilize the cubic lattice packing in the lipid membrane particles, which displayed structural features beyond the traditional CD nanosponges. UV-Vis spectroscopy was employed to characterize the nanoencapsulation of a model hydrophobic dimethylphenylazo-naphthol guest compound (Oil red) in the created nanocarriers. In perspective, these dual porosity carriers should be suitable for co-encapsulation and sustained delivery of peptide, protein or siRNA biopharmaceuticals together with small molecular weight drug compounds or imaging agents.

A Comprehensive Review on Cyclodextrin-Based Carriers for Delivery of Chemotherapeutic Cytotoxic Anticancer Drugs

Most of the cytotoxic chemotherapeutic agents have poor aqueous solubility. These molecules are associated with poor physicochemical and biopharmaceutical properties, which makes the formulation difficult. An important approach in this regard is the use of combination of cyclodextrin and nanotechnology in delivery system. This paper provides an overview of limitations associated with anticancer drugs, their complexation with cyclodextrins, loading/encapsulating the complexed drugs into carriers, and various approaches used for the delivery. The present review article aims to assess the utility of cyclodextrin-based carriers like liposomes, niosomes, nanoparticles, micelles, millirods, and siRNA for delivery of antineoplastic agents. These systems based on cyclodextrin complexation and nanotechnology will camouflage the undesirable properties of drug and lead to synergistic or additive effect. Cyclodextrin-based nanotechnology seems to provide better therapeutic effect and sustain long life of healthy and recovered cells. Still, considerable study on delivery system and administration routes of cyclodextrin-based carriers is necessary with respect to their pharmacokinetics and toxicology to substantiate their safety and efficiency. In future, it would be possible to resolve the conventional and current issues associated with the development and commercialization of antineoplastic agents.

Selective Secondary Face Modification of Cyclodextrins by Mechanosynthesis

α-, β-, and γ-cyclodextrins (CDs) were modified on their secondary face by mechanosynthesis at room temperature using a laboratory-scale ball-mill. Mono-2-tosylated α-, β-, and γ-CDs were obtained in good yield from mixtures of native α-, β-, and γ-CDs, respectively, N-tosylimidazole, and an inorganic base, with each of them being in the solid state. The yields appeared to be dependent upon the nature of the base and the reaction time. A kinetic monitoring by (1)H NMR spectroscopy demonstrated that the highest yields in mono-2-tosyl-CDs were measured using KOH as a base in very short reaction times (up to 65% in 80 s). Mono-(2,3-manno-epoxide) α-, β-, and γ-CDs were subsequently synthesized by ball-milling a mixture of monotosylated α-, β-, and γ-CDs, respectively, and KOH. The characterization of the modified CDs was carried out by X-ray diffraction, mass spectrometry, solid-state NMR, and diffuse reflectance UV-vis (DR UV-vis) spectroscopies. Clues to the supramolecular arrangement of the molecules in the solid state provide information on the reaction mechanism.

Cyclodextrin-polysaccharide-based, in situ-gelled system for ocular antifungal delivery

Fluconazole was studied with two different hydrophilic cyclodextrins (hydroxypropyl-β-cyclodextrin (HPBCD) and sulfobutyl ether-β-cyclodextrin (SBECD)) for the formation of inclusion complexes. HPBCD and SBECD showed low cell cytotoxicity in human keratocytes as assessed by the label-free xCELLigence system for real-time monitoring. The fluconazole–HPBCD complex was incorporated into an ion-sensitive ophthalmic gel composed of the natural polysaccharides gellan gum and κ-carrageenan. This system showed good bioadhesive properties and effective control of fluconazole release.

A novel synthetic luteinizing hormone-releasing hormone (LHRH) analogue coupled with modified β-cyclodextrin: insight into its intramolecular interactions

BACKGROUND

Cyclodextrins (CDs) in combination with therapeutic proteins and other bioactive compounds have been proposed as candidates that show enhanced chemical and enzymatic stability, better absorption, slower plasma clearance and improved dose-response curves or immunogenicity. As a result, an important number of therapeutic complexes between cyclodextrins and bioactive compounds capable to control several diseases have been developed.

RESULTS

In this article, the synthesis and the structural study of a conjugate between a luteinizing hormone-releasing hormone (LHRH) analogue, related to the treatment of hormone dependent cancer and fertility, and modified β-cyclodextrin residue are presented. The results show that both the phenyl group of tyrosine (Tyr) as well as the indole group of tryptophan (Trp) can be encapsulated inside the cyclodextrin cavity. Solution NMR experiments provide evidence that these interactions take place intramolecularly and not intermolecularly.

CONCLUSIONS

The study of a LHRH analogue conjugated with modified β-cyclodextrin via high field NMR and MD experiments revealed the existence of intramolecular interactions that could lead to an improved drug delivery.

GENERAL SIGNIFICANCE

NMR in combination with MD simulation is of great value for a successful rational design of peptide-cyclodextrin conjugates showing stability against enzymatic proteolysis and a better pharmacological profile.