Inclusion complex of nateglinide with sulfobutyl ether β-cyclodextrin: Preparation, characterization and water solubility

Advancements in cyclodextrin-based controlled drug delivery: Insights into pharmacokinetic and pharmacodynamic profiles

This article discusses and summarizes some fascinating outcomes and applications of cyclodextrins (CDs) and their derivatives in drug delivery. These applications include the administration of protein, peptide medications, and gene delivery. Several innovative drug delivery systems, including NPs, microspheres, microcapsules, and liposomes, are designed with the help of CD, which is highlighted in this article. The use of these compounds as excipients in medicine formulation is reviewed, in addition to their well-known effects on drug solubility and dissolution, as well as their bioavailability, safety, and stability. Furthermore, the article focuses on many factors that influence the development of inclusion complexes, as having this information is necessary to manage these diverse materials effectively. An overview of the commercial availability, regulatory status, and patent status of CDs for pharmaceutical formulation is also presented. Due to the fact that CDs can discover new uses in drug delivery consistently, it is predicted that they will solve a wide range of issues related to the distribution of a variety of unique medications through various delivery channels.

Enhanced oral delivery of hesperidin-loaded sulfobutylether-β-cyclodextrin/chitosan nanoparticles for augmenting its hypoglycemic activity: in vitro-in vivo assessment study

Hesperidin (Hsd), a bioactive phytomedicine, experienced an antidiabetic activity versus both Type 1 and Type 2 Diabetes mellitus. However, its intrinsic poor solubility and bioavailability is a key challenging obstacle reflecting its oral delivery. From such perspective, the purpose of the current study was to prepare and evaluate Hsd-loaded sulfobutylether-β-cyclodextrin/chitosan nanoparticles (Hsd/CD/CS NPs) for improving the hypoglycemic activity of the orally administered Hsd. Hsd was first complexed with sulfobutylether-β-cyclodextrin (SBE-β-CD) and the complex (CX) was found to be formed with percent complexation efficiency and percent process efficiency of 50.53 ± 1.46 and 84.52 ± 3.16%, respectively. Also, solid state characterization of the complex ensured the inclusion of Hsd inside the cavity of SBE-β-CD. Then, Hsd/CD/CS NPs were prepared using the ionic gelation technique. The prepared NPs were fully characterized to select the most promising one (F1) with a homogenous particle size of 455.7 ± 9.04 nm, a positive zeta potential of + 32.28 ± 1.12 mV, and an entrapment efficiency of 77.46 ± 0.39%. The optimal formula (F1) was subjected to further investigation of in vitro release, ex vivo intestinal permeation, stability, cytotoxicity, and in vivo hypoglycemic activity. The results of the release and permeation studies of F1 manifested a modulated pattern between Hsd and CX. The preferential stability of F1 was observed at 4 ± 1 °C. Also, the biocompatibility of F1 with oral epithelial cell line (OEC) was retained up to a concentration of 100 µg/mL. After oral administration of F1, a noteworthy synergistic hypoglycemic effect was recorded with decreased blood glucose level until the end of the experiment. In conclusion, Hsd/CD/CS NPs could be regarded as a hopeful oral delivery system of Hsd with enhanced antidiabetic activity.

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.

Cyclodextrin Derivative Enhances the Ophthalmic Delivery of Poorly Soluble Azithromycin

Azithromycin (AZM), a macrolide antibiotic used for the treatment of chlamydial conjunctivitis, is less effective for the treatment of this disease due to its poor bioavailability (38%). Various alternatives have been developed for improving the physicochemical properties (i.e., solubility) of the AZM without much success. To overcome the problems associated with AZM, an inclusion complex employing a modified cyclodextrin, i.e., sulfobutylether-β-cyclodextrin (SBE-β-CD), was prepared and characterized by phase solubility studies and PXRD techniques. The results portrayed the formation of an inclusion complex of AZM with SBE-β-CD in 1:2 molar stoichiometric ratios. This inclusion complex was later incorporated into a polymer matrix to prepare an in situ gel. Various combinations of Carbopol 934P and hydroxypropyl methylcellulose (HPMC K4M) polymers were used and evaluated by rheological and in vitro drug release studies. The optimized formulation (F4) containing Carbopol 934P (0.2% w/v) and HPMC K4M (0.2% w/v) was evaluated for clarity, pH, gelling capacity, drug content, rheological properties, in vitro drug release pattern, ocular irritation test, and antimicrobial efficacy. Finally, owing to the improved antimicrobial efficacy and increased residence time, the AZM:SBE-β-CD in situ gel was found to be a promising formulation for the efficient treatment of bacterial ocular disease.

A multiple functional supramolecular system for synergetic treatments of hepatocellular carcinoma

In the current times, achieving specific targeted and controllable drug delivery remains one of the major challenges in the treatment of hepatocellular carcinoma (HCC). The present study reported the development of a multiple functional indocyanine green (ICG)-cyclodextrin (CD) system, wherein loaded etoposide (EPS) was used as the model chemotherapeutic drug. In the developed system, ICG segment served as a photosensitizer for photothermal therapy (PTT) and the targeting moiety, which was primarily attributed to the specific retention properties in HCC tissues. The Ex vivo evaluation showed that ICG-CD@EPS exhibited a laser-triggered release profile with the photothermal efficiency and cytotoxicity towards HepG2 cells. In vivo evaluation suggested that ICG could navigate the systems to HCC tissues and retained at the site for 48 h, producing a drug accumulation in HCC. Further, laser irradiation boosted EPS release and local hyperthermia effects in HCC. Thus, the present study explored a novel and specific HCC targeting mechanism, and provided a feasible and controllable strategy for synergistic PTT and chemotherapy treatments for HCC.

Enhanced Oral Bioavailability of Epalrestat SBE7-β-CD Complex Loaded Chitosan Nanoparticles: Preparation, Characterization and in-vivo Pharmacokinetic Evaluation

Background

Epalrestat (EPL) is a carboxylic acid derivative with poor aqueous solubility and its pharmacokinetic features are not fully defined.

Purpose

Current research aimed to fabricate inclusion complexation of EPL with SBE₇ β-CD (IC) and EPL/SBE₇ β-CD CS NPs (NP).

Methods

EPL was complexed with SBE₇ β-CD using the co-precipitation method, and the prepared complex was fabricated into nanoparticles using the ionic gelation method. The prepared formulations were characterized for particle size analysis, surface morphology, and in vitro dissolution study. The % inhibition of EPL against α-glucosidase enzyme was also conducted to check the drug’s antidiabetic activity. Finally, an in vivo pharmacokinetic investigation was carried out to determine the concentration of EPL in rabbit plasma of the prepared formulation. In vivo pharmacokinetic studies were conducted by giving a single dose of pure EPL, IC, and NP.

Results

The size of NP was found to be 241.5 nm with PDI 0.363 and zeta potential of +31.8 mV. The surface of the prepared NP was non-porous, smooth and spherical when compared with pure EPL, SBE₇ β-CD and IC. The cumulative drug release (%) from IC and NP was 73% and 88%, respectively, as compared to pure drug (25%). The % inhibition results for in vitro α-glucosidase was reported to be 74.1% and the predicted binding energy for in silico molecular docking was calculated to be −6.6 kcal/mol. The calculated C_max values for EPL, IC and NP were 4.75±3.64, 66.91±7.58 and 84.27±6.91 μg/mL, respectively. The elimination half-life of EPL was 4 h and reduced to 2 h for IC and NP. The AUC_0-α for EPL, IC and NP were 191.5±164.63, 1054.23±161.77 and 1072.5±159.54 μg/mL*h, respectively.

Conclusion

Taking these parameters into consideration it can be concluded that IC and NP have prospective applications for greatly improved delivery and regulatedt release of poorly water soluble drugs, potentially leading to increase therapeutic efficacy and fewer side effects.

Preparation of astaxanthin micelles self-assembled by a mechanochemical method from hydroxypropyl β-cyclodextrin and glyceryl monostearate with enhanced antioxidant activity

This research aimed to overcome the current challenges in the application of natural carotenoid antioxidants, such as their complex preparation processes, low bioavailability and poor drug stability. Herein, a mechanochemical method was used to prepare an inclusion complex (IC) that self-assembles into micelles in aqueous solution and achieves solid-phase loading of astaxanthin (AST). The NMR analysis, thermodynamics study, particle size analysis and electron microscopy image results showed that AST, hydroxypropyl β-cyclodextrin (HPβ-CD) and glyceryl monostearate (GMS) formed self-assembled micelles and maintained good stability in aqueous solution. The antioxidant performance experiments showed that the formation of IC increases free radical scavenging activity. The pharmacokinetic studies showed that the bioavailability of the astaxanthin inclusion complex increased 4-fold. The tissue distribution experiments showed that the astaxanthin inclusion complex targets the liver to exert its antioxidant effects. The proposed method uses an innovative preparation technology to produce an efficient drug delivery system without solvents, and it exerts powerful antioxidant activity against astaxanthin.

Preparation, characterization and biological evaluation of β-cyclodextrin-biotin conjugate based podophyllotoxin complex

Podophyllotoxin is a natural occurring aryltetralin lignin with pronounced cytotoxic activity. However, its clinical application for cancer treatment has been blocked due to its poor water solubility and selectivity. In this work, biotin as a tumor specific ligand was coupled with β-cyclodextrin and the resulting biotin modified β-cyclodextrin was used to complex with podophyllotoxin to improve its aqueous solubility and tumor selectivity. The solubility of β-cyclodextrin was greatly enhanced(>16 times) by conjugating with biotin. podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin inclusion complex was prepared by freeze-drying method and the complex behavior between mono-6-biotin-amino-6-deoxy-β-cyclodextrin and podophyllotoxin was studied by water solubility, phase solubility, Job's plot, UV spectroscopy, Proton Nuclear Magnetic Resonance, Rotating-frame Overhauser Effect Spectroscopy, Powder X-ray diffraction and Scanning electron microscopy. The solubility of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was greatly improved(9 times) compared with Podophyllotoxin. The stability constant of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex (K_s= 415.29 M^-1) was 3.2 times that of podophyllotoxin/β-cyclodextrin complex. The possible inclusion mode of podophyllotoxin/mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was inferred from the Proton Nuclear Magnetic Resonance and Rotating-frame Overhauser Effect Spectroscopy. The cellular uptake study showed that the introduction of biotin increased the cellular uptake of rhodamine-B/mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex. Moreover, cell cytotoxicity study showed that the antitumor activity of podophyllotoxin/ mono-6-biotin-amino-6-deoxy-β-cyclodextrin complex was more potent than podophyllotoxin/β-cyclodextrin complex and free podophyllotoxin. The superior water solubility and enhanced cytotoxicity suggested that the mono-6-biotin-amino-6-deoxy-β-cyclodextrin associated inclusion complex might be a potential and promising delivery system for hydrophobic chemotherapeutics such as podophyllotoxin.

Physical formulation approaches for improving aqueous solubility and bioavailability of ellagic acid: A review

Ellagic acid (EA) is a polyphenolic active compound with antimalarial and other promising therapeutic activities. However, its solubility and its permeability are both low (BCS IV). These properties greatly compromise its oral bioavailability and clinical utilizations. To overcome these limitations of the physicochemical parameters, several formulation approaches, including particle size reduction, amorphization and lipid-based formulations, have been used. Although these strategies have not yet led to a clinical application, some of them have resulted in significant improvements in the solubility and bioavailability of EA. This critical review reports and analyses the different formulation approaches used by scientists to improve both the biopharmaceutical properties and the clinical use of EA.

The investigation of binary and ternary sulfobutylether-β-cyclodextrin inclusion complexes with asiaticoside in solution and in solid state

Asiaticoside (AS) is poorly water-soluble compound that can lead to low the bioavailability. The aims of this study were to determine the cyclodextrin (CD) solubilization of AS and characterize binary AS/CD and ternary AS/CD/polymer complexes in solution- and solid-state. Thermal stability of AS through heating process was determined and found that It could withstand by heating through sonication method. Phase-solubility profiles showed that β-cyclodextrin (βCD) exhibited the greatest solubilizing effect but sulfobutylether-βCD (SBEβCD) was selected for further investigations due to its relatively high complexation efficiency (CE) value. The effect of polymers that were poloxamer 407 (P407) and chitosan (CS) on CD solubilization were investigated. It was found that the increment of CE was resulted from the formation of ternary complexes or complex aggregates with confirmed by dynamic light scattering and transmission electron microscopy. Proton nuclear magnetic resonance (¹H NMR) data indicated that the cyclohexane moiety of AS was totally inserted into the hydrophobic inner cavity of SBEβCD in the presence or absence of polymer. The molecular modeling study displayed the binding orientation of such complex which correlated to ¹H NMR result. The solid state characterized by Fourier transform infra-red, differential scanning calorimetry and powder X-ray diffraction demonstrated the formation of binary AS/SBEβCD and ternary AS/SBEβCD/polymer inclusion complexes. The enhancement of AS dissolution was achieved in both binary and ternary complexes. The permeation study showed that ternary AS/SBEβCD/CS nanoparticles exhibited a promising controlled drug release nanocarrier.

Tomato Oil Encapsulation by α-, β-, and γ-Cyclodextrins: A Comparative Study on the Formation of Supramolecular Structures, Antioxidant Activity, and Carotenoid Stability

Cyclodextrins (CDs) are oligosaccharides, comprising 6 (α), 7 (β), or 8 (γ) glucose residues, used to prepare oil-in-water emulsions and improve oil stability towards degradation. In this research, the aptitude of α-, β-, and γ-CDs to form complexes with a supercritical CO₂ extracted lycopene-rich tomato oil (TO) was comparatively assessed. TO/CD emulsions and the resulting freeze-dried powders were characterized by microscopy, Fourier transform infrared-attenuated total reflection (FTIR-ATR), and differential scanning calorimetry (DSC), as well as for their antioxidant activity. Furthermore, carotenoid stability was monitored for 90 days at 25 and 4 °C. Confocal and SEM microscopy revealed morphological differences among samples. α- and β-CDs spontaneously associated into microcrystals assembling in thin spherical shells (cyclodextrinosomes, Ø ≈ 27 µm) at the oil/water interface. Much smaller (Ø ≈ 9 µm) aggregates were occasionally observed with γ-CDs, but most TO droplets appeared "naked". FTIR and DSC spectra indicated that most CDs did not participate in TO complex formation, nevertheless structurally different interfacial complexes were formed. The trolox equivalent antioxidant capacity (TEAC) activity of emulsions and powders highlighted better performances of α- and β-CDs as hydrophobic antioxidants-dispersing agents across aqueous media. Regardless of CDs type, low temperature slowed down carotenoid degradation in all samples, except all-[E]-lycopene, which does not appear efficiently protected by any CD type in the long storage period.

Cell-Membrane-Targeted Drug Delivery System Based on Choline-Phosphate-Functionalized β-Cyclodextrin

In this study, a novel cyclodextrin derivative, i.e., zwitterionic choline phosphate (CP)-functionalized β-cyclodextrin (CP-β-CD) is successfully synthesized by click chemistry reaction. CP-β-CD has excellent cell-membrane-targeted ability because of the CP group can bind to phosphate choline (PC) in the cell membrane and promote the cellular uptake. Due to the introduction of CP group on β-CD, it disrupts the hydrogen network between natural β-CD molecules. Meanwhile, the water solubility of CP-β-CD is improved dramatically to 816 mg mL^-1 , which is 440 times as that of unmodified β-CD. Apatinib, a small molecular inhibitor, is used as a model of hydrophobic drug and loaded into CP-β-CD to study the solubilization effect and the anti-angiogenisis activity. In addition, the cytotoxicity of CP-β-CD is also studied, and it is demonstrated that CP-β-CD is nontoxic. These results indicate that the apatinib can be transported into cell interior and play an excellent anti-angiogenisis activity after being loaded into CP-β-CD drug delivery system. This work suggests that the water soluble CP-β-CD with excellent cell internalization efficiency has a potential application prospect in the field of drug delivery.

Preparation and Characterisation of Polyphenol-HP-β-Cyclodextrin Inclusion Complex that Protects Lamb Tripe Protein against Oxidation

Grape seed extract (GSE) displays strong antioxidant activity, but its instability creates barriers to its applications. Herein, three HP-β-CD/GSE inclusion complexes with host-guest ratios of 1:0.5, 1:1, and 1:2 were successfully prepared by co-precipitation method to improve stability. Successful embedding of GSE in the HP-β-CD cavity was confirmed by fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) analyses. The Autodock Tools 1.5.6 was used to simulate the three-dimensional supramolecular structure of the inclusion complex of 2-hydroxypropyl-β-cyclodextrin and grape seed extract (HP-β-CD/GSE) by molecular docking. The MALDI-TOF-MS technology and chemical database Pubchem, and structural database PDB were combined to reconstitute the three-dimensional structure of target protein. The binding mode of the HP-β-CD/GSE inclusion complex to target protein was studied at the molecular level, and the antioxidant ability of the resulting HP-β-CD/GSE inclusion complexes was investigated by measuring 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging. The effects of HP-β-CD/GSE on myofibrillar protein from lamb tripe were also investigated under oxidative conditions. The positions and interactions of the binding sites of HP-β-CD/GSE inclusion complexes and target protein receptors were simulated by molecular docking. The results showed that HP-β-CD/GSE inclusion complexes were successfully prepared, optimally at a molar ratio of 1:2. At low (5 μmol/g) to medium (105 μmol/g) concentrations, HP-β-CD/GSE inclusion complexes decreased the carbonyl content, hydrophobicity, and protein aggregation of myofibrillar protein from lamb tripe, and increased the sulphydryl content. Furthermore, high concentration (155 μmol/g) of HP-β-CD/GSE inclusion complexes promoted protein oxidation.

Preparation and Characterization of a Modified-β-Cyclodextrin/β-Carotene Inclusion Complex and Its Application in Pickering Emulsions

β-Cyclodextrin (β-CD) was modified using octenyl succinic anhydride (OSA) to introduce amphiphilic groups (hydrophilic carboxyl and lipophilic octenyl chains) by esterification under alkaline conditions. The FT-IR results indicated that the OSA-modified β-CD (OCD) showed new absorption peaks of an ester bond and a carboxylate (RCOO^-) at 1724 and 1570 cm^-1, respectively, confirming the successful preparation of OCD. Then the embedding effects of β-CD and OCD on β-carotene and the emulsifying and antioxidant properties of their inclusion complexes were evaluated. The results of XRD showed that the β-CD (or OCD)/β-carotene inclusion complexes were converted from a cage-type structure to a channel-type structure. AFM and SEM showed that the crystal characteristics and surface morphologies of the inclusion complexes were different from those of the physical mixture. The emulsion stabilized by OCD exhibited smaller droplet sizes and larger zeta-potentials than that stabilized by β-CD. In addition, the inclusion complexes-prepared emulsion exhibited lower POV values and TBARS contents than did the physical mixture. OCD/β-carotene inclusion complexes can improve the physical and oxidative stability of the emulsion, which is of great significance to the food industry.

Nanotherapeutic silibinin: An insight of phytomedicine in healthcare reformation

Most of the herbal origin drugs possess water insoluble active constituents which lower the bioavailability and increase systemic clearance after administration of repeated or higher dose of drug. Silymarin is extracted from the seeds and fruits of milk thistle plant Silybum marianum which consists of main biologically active component as silibinin. However, the clinical applications of silibinin show some limitations due to low aqueous solubility, poor penetration into the epithelial cells of intestine, high metabolism and rapid systemic elimination. But nanotechnology-based drug delivery system explores great potential for phytochemicals to enhance the aqueous solubility and bioavailability of BCS class II and IV drugs, improve stability and modify the pharmacological activity. This review focuses on the therapeutic properties of silibinin and discusses the benefits, challenges and applications of silibinin nanoformulations. Such nanotherapeutic system as a regular medicine will be an attractive approach to reduce the adverse events and toxicities of current therapies.

Inclusion Complexes of Lycopene and β-Cyclodextrin: Preparation, Characterization, Stability and Antioxidant Activity

In this study, the inclusion complexes of lycopene with β-cyclodextrin (β-CD) were prepared by the precipitation method. Then the inclusion complexes were characterized by the scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV), microscopic observation, liquid chromatography, differential scanning calorimetry (DSC) and phase-solubility study. Moreover, the stability and antioxidant activity were tested. The results showed that lycopene was embedded into the cavity of β-CD with a 1:1 stoichiometry. Moreover, the thermal and irradiant stabilities of lycopene were all significantly increased by the formation of lycopene/β-CD inclusion complexes. Antioxidant properties of lycopene and its inclusion complexes were evaluated on the basis of measuring the scavenging activity for 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and superoxide anion radicals. The results showed that the scavenging activity of DPPH radicals was obviously increased by the formation of the inclusion complex with β-cyclodextrin at concentrations of 5–30 μg/mL, however, some significant positive effects on the scavenging activity of hydroxyl and superoxide anion radicals were not observed and the reasons are worth further study.

Development of daidzein nanosuspensions: Preparation, characterization, in vitro evaluation, and pharmacokinetic analysis

The purpose of this investigation was to improve the solubility and oral bioavailability of daidzein via preparing nanosuspensions (NS) with steric stabilizers, electrostatic stabilizers, or a combination of both. Based on particle size and zeta potential, daidzein NS stabilized by HP-β-CD, soy lecithin, HP-β-CD + soy lecithin, TPGS, TPGS + SBE-β-CD, SDS, or HPMC E5 + SDS were generated and characterized by scanning electron microscopy, powder X-ray diffraction, and Fourier transform-infrared spectroscopy. In addition, the stability, cytotoxicity, solubility, dissolution, and pharmacokinetics of NS were evaluated. The resulting daidzein NS were physically stable and biocompatible and presented as regular shapes with homogenous particle sizes of 360-600 nm and decreased crystallinity. Due to the increased solubility and dissolution rate, the oral bioavailability of daidzein NS in rats was 1.63-2.19 times greater than that of crude daidzein. In particular, among the investigated seven daidzein NS formulations, daidzein NS prepared with the costabilizers HPMC E5 + SDS is an optimal formulation for increased daidzein bioavailability. The present study proposes that the combined usage of steric and electrostatic stabilizers is a promising strategy for improving the bioavailability of water-insoluble flavonoid compounds by an NS approach.

Complexation induced aggregation and deaggregation of acridine orange with sulfobutylether-β-cyclodextrin

The present study illustrates intriguing switching of multi-mode binding interactions of acridine orange dye with a sulfobutylether-β-cyclodextrin host.