Efficient synthesis of pure monotosylated beta-cyclodextrin and its dimers

A novel cationic β-cyclodextrin decorated with a choline-like pendant exhibits Iodophor, Mucoadhesive and bactericidal properties

Iodine is a vital microelement and a powerful antiseptic with a rapid and broad spectrum of action. The development of iodophor compounds to improve the solubility and stability of iodine is still challenging. Here, we report the synthesis of a novel cationic β-cyclodextrin bearing a choline-like pendant (β-CD-Chol) designed to complex and deliver iodine to bacterial cells. The characterization of β-CD-Chol and the investigation of the inclusion complex with iodine were performed by NMR spectroscopy, mass spectrometry, UV-vis spectrophotometry, isothermal titration calorimetry, and dynamic light scattering. The functionalization with the positively charged unit conferred improved water-solubility, mucoadhesivity, and iodine complexation efficiency to the β-CD scaffold. The water-soluble β-CD-Chol/iodine complex efficiently formed both in solution and by solid-vapor reaction. The solid complex exhibited a significant stability for months. Iodine release from the inclusion complex was satisfactory and the bactericidal activity was proved against a Staphylococcus epidermidis strain. The absence of cytotoxicity tested on human keratinocytes and the improved mucoadhesivity make β-CD-Chol a promising drug delivery system and an appealing iodophor candidate for iodine-based antisepsis including mucosa disinfection.

Controlled delivery of sildenafil by β-Cyclodextrin-decorated sulfur-doped carbon nanodots: a synergistic activation of ROS signaling in tumors overexpressing PDE-5

Fluorescent sulfur- and nitrogen-doped carbon nanodots (CDs) are zero-dimensional nanoparticles that mediate ROS production in cancer cells, displaying inherent anticancer properties. Thus, they have been proposed as nanotheranostic tools useful in image-guided cancer therapy. Here, we try to show that cancerous cells (high PDE-5 expression) receiving sildenafil delivered by CDs-based nanostructures promote positive reinforcement of PDE-5-mediated cell death via the overexpression of genes involved in the production of ROS. We explored the regioselective Huisgen cycloaddition between azide-β-cyclodextrin and CDs-alkyne to synthetize homogeneous nanostructures, named CDs-PEG4-β-Cdx, consisting of CDs functionalized at the surface with β-cyclodextrins capable of including high amount drugs such as sildenafil (>20 % w/w), and releasing them in a controlled manner. We investigated how CDs-PEG4-β-Cdx bearing sildenafil enter cells, enhancing ROS production and cell death specifically in cancer cells overexpressing PDE-5. These nanoplatforms go beyond the bounds of EPR-based nanomedicines in which carriers are conceived as inert vehicles of toxic drugs. Our findings enable the development of clever anticancer nanoplatforms that synergistically combine nanomedicines that perturb the mitochondrial electron transport chain (ROS production) with PDE-5 inhibitors which trigger oxidative stress specifically in cancer cells regardless of their location.

Cyclodextrin Inclusion Complexes for Improved Drug Bioavailability and Activity: Synthetic and Analytical Aspects

Many active pharmaceutical ingredients show low oral bioavailability due to factors such as poor solubility and physical and chemical instability. The formation of inclusion complexes with cyclodextrins, as well as cyclodextrin-based polymers, nanosponges, and nanofibers, is a valuable tool to improve the oral bioavailability of many drugs. The microencapsulation process modifies key properties of the included drugs including volatility, dissolution rate, bioavailability, and bioactivity. In this context, we present relevant examples of the stabilization of labile drugs through the encapsulation in cyclodextrins. The formation of inclusion complexes with drugs belonging to class IV in the biopharmaceutical classification system as an effective solution to increase their bioavailability is also discussed. The stabilization and improvement in nutraceuticals used as food supplements, which often have low intestinal absorption due to their poor solubility, is also considered. Cyclodextrin-based nanofibers, which are polymer-free and can be generated using environmentally friendly technologies, lead to dramatic bioavailability enhancements. The synthesis of chemically modified cyclodextrins, polymers, and nanosponges based on cyclodextrins is discussed. Analytical techniques that allow the characterization and verification of the formation of true inclusion complexes are also considered, taking into account the differences in the procedures for the formation of inclusion complexes in solution and in the solid state.

Three generations of thiolated cyclodextrins: A direct comparison of their mucus permeating and mucoadhesive properties

AIM

This study aims to compare the mucus permeating and mucoadhesive properties of three generations of thiolated cyclodextrins (CDs).

METHODS

Free thiol groups of thiolated γ-CDs (CD-SH) were S-protected with 2-mercaptonicotinic acid (MNA), leading to a second generation of thiolated CDs (CD-SS-MNA) and with 2 kDa polyethylene glycol (PEG) bearing a terminal thiol group leading to a third generation of thiolated CDs (CD-SS-PEG). The structure of these thiolated CDs was confirmed and characterized by FT-IR, ¹H NMR and colorimetric assays. Thiolated CDs were evaluated regarding viscosity, mucus diffusion, and mucoadhesion.

RESULTS

The viscosity of the mixture of CD-SH, CD-SS-MNA, or CD-SS-PEG with mucus increased up to 11-, 16-, and 14.1-fold compared to unmodified CD within 3 hours, respectively. Mucus diffusion increased in the following rank order: unprotected CD-SH < CD-SS-MNA < CD-SS-PEG. The residence time of CD-SH, CD-SS-MNA, and CD-SS-PEG on porcine intestine was up to 9.6-, 12.55-, and 11.2-fold prolonged compared to native CD, respectively.

CONCLUSION

According to these results, S-protection of thiolated CDs can be a promising approach to improve their mucus permeating and mucoadhesive properties.

STATEMENT OF SIGNIFICANCE

Three generations of thiolated cyclodextrins (CDs) with different types of thiol ligands have been synthesized to improve mucus interaction. 1^st generation of thiolated CDs was synthesized by converting hydroxyl groups into thiols by reaction with Thiourea. For 2^nd generation, free thiol groups were S-protected by reaction with 2-mercaptonicotinic acid (MNA), resulting in high reactive disulfide bonds. For 3^rd generation, terminally thiolated short PEG chains (2 kDa) were used for S-protection of thiolated CDs. Mucus penetrating properties were found to be increased as follows: 1^st generation < 2^nd generation < 3^rd generation. Furthermore, mucoadhesive properties were improved in the following rank order: 1^st generation < 3^rd generation < 2^nd generation. This study suggests that the S-protection of thiolated CDs can enhance mucus penetrating and mucoadhesive properties.

Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin

The first continuous flow method was developed for the synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin starting from native β-cyclodextrin through three reaction steps, such as monotosylation, azidation and reduction. All reaction steps were studied separately and optimized under continuous flow conditions. After the optimization, the reaction steps were coupled in a semi-continuous flow system, since a solvent exchange had to be performed after the tosylation. However, the azidation and the reduction steps were compatible to be coupled in one flow system obtaining 6-monoamino-6-monodeoxy-β-cyclodextrin in a high yield. Our flow method developed is safer and faster than the batch approaches.

A supramolecular injectable hydrogel based on β-cyclodextrin-grafted alginate and pluronic-amine loaded with kartogenin for chondrogenic differentiation of mesenchymal stem cells

Owing to the similarity of hydrogels to cartilage ECM, they have been extensively utilized in the chondral lesions. Moreover, their tunable administration properties are desirable for reducing injuries in lesion sites. Generally, injectable hydrogels are mechanically weak, requiring some modifications for being used as a cell carrier in place of articular cartilage. In this study, a combination of β-cyclodextrin-grafted alginate (Alg-β-CD) and pluronic-amine (PA) with multiple physical crosslinking was used for the first time. Supramolecular interactions, including electrostatic forces, host-guest interaction, and hydrophobic interaction with increasing temperature maintain injectability of hydrogels while these interactions boost mechanical properties to the extent that shear modulus surpassed 40 kPa. Vacant β-CD cavities in conjunction with gel network was exploited for kartogenin (KGN) loading. All groups had gel time of less than one minute and gel temperature was 28 ℃. No toxic effect of hydrogels on encapsulated cells was observed. While the optimum combination of polymers provided a sustainable release for KGN, it also extended the in vitro degradation time of hydrogels from 6 days to 2 weeks. KGN facilitated encapsulated mesenchymal stem cells (MSCs) differentiation towards chondrocytes. Taken together, the synthesized hydrogel proved to be a promising candidate for being utilized in cartilage regeneration.

L-Arginine-Derived Polyamidoamine Oligomers Bearing at Both Ends β-Cyclodextrin Units as pH-Sensitive Curcumin Carriers

The aza-Michael polyaddition of L-arginine and N,N′-methylene-bis-acrylamide gives the biocompatible and easily cell-internalized polyamidoamine ARGO7. By controlled synthesis, two ARGO7 oligomers, namely a trimer and a pentamer, bearing acrylamide terminal units, were obtained as precursors of the β-cyclodextrin-end-terminated oligomers P3 and P5, which have been shown to encapsulate curcumin at both pH 7.4 and 4.5. After lyophilization, P3- and P5-curcumin complexes gave stable water solutions. The apparent solubility of encapsulated curcumin was in the range 20–51 μg mL⁻¹, that is, three orders of magnitude higher than the water solubility of free curcumin (0.011 μg mL⁻¹). The drug release profiles showed induction periods both at pH levels 4.5 and 7.4, suggesting a diffusive release mechanism, as confirmed by kinetic studies. The release rate of curcumin was higher at pH 7.4 than at pH 4.5 and, in both cases, it was higher for the P5 complex. Encapsulated curcumin was more photostable than the free drug. Molecular mechanics and molecular dynamics simulations explain at atomistic level the formation of aggregates due to favorable van der Waals interactions. The drug molecules interact with the external surface of carriers or form inclusion complexes with the β-cyclodextrin cavities. The aggregate stability is higher at pH 4.5.

Copper-doped functionalized β-cyclodextrin as an efficient green nanocatalyst for synthesis of 1,2,3-triazoles in water

The synthesis of 1,2,3-triazoles with immobilized Cu(I) in thiosemicarbazide-functionalized β-cyclodextrin (Cu@TSC-β‐CD) as a supramolecular catalyst was discussed. The catalyst was characterized by Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) measurements. The catalyst showed high activity (up to 95% yields of triazole products under optimized reaction conditions), providing a one-pot, atom-economic, and highly regioselective green method for 1,2,3-triazoles synthesis in an azide-alkyne cycloaddition (AAC) protocol in water. High stability and no appreciable leaching of Cu(I) were observed, owing to its strong binding via the coordination with thiosemicarbazide functionality.

Design, synthesis, and characterization of a series of novel β-cyclodextrin functional monomers

In order to increase its solubility in water and improve β-cyclodextrin combination with guest molecules, chemical modification of β-cyclodextrin is a feasible and effective method. A variety of β-cyclodextrin derivatives are designed and introduced for pharmaceutical complexation and analytical chemistry application. In this study, a series of β-cyclodextrin derivatives containing unsaturated bonds is designed and synthesized. The products are characterized by MS, FTIR, 1H NMR, and 13C NMR. Some of the functional monomers may be used in the preparation of molecularly imprinted polymers, and preliminary studies have shown excellent molecular recognition ability. The prepared β-cyclodextrin functional monomers have potential application value in molecular recognition materials based on polymers.

Novel self-assembled nanogels of PEG-grafted poly HPMA with bis(α-cyclodextrin) containing disulfide linkage: synthesis, bio-disintegration, and in vivo biocompatibility

Synthesis of self-assembled nanogels of PEG-grafted poly HPMA with bis(α-cyclodextrin) containing disulfide linkage.

A Self-locked β-Cyclodextrin-rhodamine B Spirolactam with Photoswitching Properties

Supramolecular organization and self-assembly are the pillars of functionality of many nanosystems. The covalent conjugate (6-spirolactam rhodamine B-6-monodeoxy)-β-cyclodextrin (Rho-βCD) is assembled as a self-included, rigid nanostructure, identical in the crystal and in aqueous solution, as revealed by detailed X-ray and NMR analyses. Rho-βCD self-assembly is the result of an interesting reaction pathway, which partially de-aggregates Rho and disturbs the zwitterion↔spirolactone equilibrium. Rho-βCD is stable at pH 4.6, but displays controllable photoswitching between the colored, fluorescent, zwitterionic and the colorless, non-fluorescent closed structures, during several iterative cycles. After an initial drop in absorbance, the on-off process continues without further changes under our irradiation conditions, a consequence of the specific self-locked arrangement of Rho in the cavity. Rho-βCD exemplifies a water soluble photoresponsive nanosystem with improved photostability suggesting promising applications in super resolution bioimaging.

Mono-6-Substituted Cyclodextrins-Synthesis and Applications

Cyclodextrins are well known supramolecular hosts used in a wide range of applications. Monosubstitution of native cyclodextrins in the position C-6 of a glucose unit represents the simplest method how to achieve covalent binding of a well-defined host unit into the more complicated systems. These derivatives are relatively easy to prepare; that is why the number of publications describing their preparations exceeds 1400, and the reported synthetic methods are often very similar. Nevertheless, it might be very demanding to decide which of the published methods is the best one for the intended purpose. In the review, we aim to present only the most useful and well-described methods for preparing different types of mono-6-substituted derivatives. We also discuss the common problems encountered during their syntheses and suggest their optimal solutions.

Self-healable and flexible supramolecular gelatin/MoS2 hydrogels with molecular recognition properties

Two-dimensional MoS₂ is emerging as a unique platform for a wide range of biomedical applications including extracellular matrix mimics, drug delivery systems and antimicrobial agents. However, low processability and nonspecific interactions at biointerfaces are serious challenges that hamper the biomedical applications of this nanomaterial. Herein, we show how specific interactions between MoS₂ and a gelatin matrix results in a biomimetic hydrogel with the self-healing and molecular recognition properties. β-Cyclodextrin was conjugated to the surface of freshly exfoliated MoS₂ through a one pot nucleophilic substitution reaction and the obtained cyclodextrin-functionalized MoS₂ was used to construct an injectable, self-healable and flexible supramolecular hydrogel upon host-guest interactions with adamantane-modified gelatin matrix. Incorporation of almost 1 wt% of CDMoS₂ into gelatin matrix with 1cm² cross-section resulted in a hydrogel that was able to tolerate one hundred grams. Also, storage modulus (G'), loss modulus (G″) of the obtained hydrogel was 10 and 25 times higher than that for the neat gelatin, respectively. Due to its self-healing, molecular recognition and mechanical properties as well as its flexibility, injectability, and processability, MoS₂gel is a promising candidate for a wide range of future biomedical applications including extracellular matrix mimics and tissue engineering.

First Class of Phosphorus Dendritic Compounds Containing β-Cyclodextrin Units in the Periphery Prepared by CuAAC

A new class of phosphorus dendritic compounds (PDCs) having a cyclotriphosphazene (P₃N₃) core and decorated with six β-cyclodextrin (βCD) units, named P₃N₃-[O-C₆H₄-O-(CH₂)_n-βCD]₆, where n = 3 or 4 was designed, and the synthesis was performed using copper (I) catalyzed alkyne-azide cycloaddition (CuAAC). To obtain the complete substitution of the P₃N₃, two linkers consisting of an aromatic ring and an aliphatic chain of two different lengths were assessed. We found that, with both linkers, the total modification of the periphery was achieved. The two new obtained dendritic compounds presented a considerably high water solubility (>1 g/mL). The compounds comprised in this new class of PDCs are potential drug carrier candidates, since the conjugation of the βCD units to the P₃N₃ core through the primary face will not only serve as surface cover but, also, provide them the faculty to encapsulate various drugs inside the βCDs cavities.

Efficient modification of PAMAM G1 dendrimer surface with β-cyclodextrin units by CuAAC: impact on the water solubility and cytotoxicity

The toxicity of the poly(amidoamine) dendrimers (PAMAM) caused by the peripheral amino groups has been a limitation for their use as drug carriers in clinical applications. In this work, we completely modified the periphery of PAMAM dendrimer generation 1 (PAMAM G1) with β-cyclodextrin (β-CD) units through the Cu(i)-catalyzed azide–alkyne cycloaddition (CuAAC) to obtain the PAMAM G1-β-CD dendrimer with high yield. The PAMAM G1-β-CD was characterized by ¹H- and ¹³C-NMR and mass spectrometry studies. Moreover, the PAMAM G1-β-CD dendrimer showed remarkably higher water solubility than native β-CD. Finally, we studied the toxicity of PAMAM G1-β-CD dendrimer in four different cell lines, human breast cancer cells (MCF-7 and MDA-MB-231), human cervical adenocarcinoma cancer cells (HeLa) and pig kidney epithelial cells (LLC-PK1). The PAMAM G1-β-CD dendrimer did not present any cytotoxicity in cell lines tested which shows the potentiality of this new class of dendrimers.

The toxicity of the poly(amidoamine) dendrimers (PAMAM) caused by the peripheral amino groups has been a limitation for their use as drug carriers in clinical applications.

Preparation and evaluation of an ethylenediamine dicarboxyethyl diamido-bridged bis(β-cyclodextrin)-bonded chiral stationary phase for high performance liquid chromatography

An ethylenediamine dicarboxyethyl diacetamido-bridged bis(β-cyclodextrin) was firstly synthesized through the reaction of 6-deoxy-6-amino-β-cyclodextrin (NH₂-CD) with ethylenediaminetetraacetic dianhydride. Then it was bonded onto the surface of silica gel SBA-15 to obtain an ethylenediamine dicarboxyethyl diacetamido-bridged bis(β-CD)-bonded chiral stationary phase (EBCDP). The structures of the bridged bis(β-CD) and EBCDP were characterized by infrared spectroscopy, mass spectrometry, elemental analysis and thermogravimetric analysis, accordingly. The chiral chromatographic performances of EBCDP were systematically evaluated by separating 28 racemic analytes in the reversed-phase or polar organic mode, including eight flavanones, eight bolckers, five dansyl-amino acids, three DL-amino acids and four other common drugs. As a result, the relatively high enantioselectivity of EBCDP was observed in comparison with a native β-CD-CSP (CDSP). All selected analytes were separated on EBCDP, of which 20 analytes had resolutions up to baseline, 2'-hydroxyflavanone and arotinolol had resolutions up to 4.35 and 2.05 in about 30 min, respectively, whereas CDSP only separated 11 analytes with low resolutions (0.55~1.69). Moreover, EBCDP was able to utilize the complexation of the bridging linker (ethylenediamine dicarboxyethyl diamide group, EDTA-based) to realize direct separations of DL-amino acids with a mobile phase containing copper ion (Cu²⁺), which was similar to the chiral ligand exchange chromatography. Unlike the native cyclodextrin with small cavity (~242 ų), the bridged bis(β-CD) combined two β-CD units with a bridging linker, having a well-organized "pseudo-cavity" as an organic whole to encapsulate more analytes, which made EBCDP have broad-spectrum applications in chiral separations.

Diaminated Starch: A Competitor of Chitosan with Highly Mucoadhesive Properties due to Increased Local Cationic Charge Density

The purpose of this study was to synthesize diaminated starch as a novel mucoadhesive polymer. Starch was tosylated and then reacted with ethylenediamine. The degree of amination was determined by 2,4,6-trinitrobenzene sulfonic acid assay. Properties of diaminated starch including solubility, cytotoxicity, swelling behavior, and mucoadhesion were compared to chitosan. Diaminated starch displayed 2083 ± 121.6 μmol of diamine substructures/g of polymer. At pH 6, diaminated starch exhibited a ζ potential of 6 mV, whereas it was close to zero in the case of unmodified starch. In addition, diaminated starch displayed water solubility over the entire pH range and minor cytotoxicity. The novel polymer showed pronounced swelling behavior in water increasing its initial weight 18- and 6-fold at pH 5 and 6, respectively. Moreover, diaminated starch exhibited 92-fold higher-mucoadhesivity properties than those of chitosan. According to these results, diaminated starch might be a promising novel excipient for the design of mucoadhesive formulations.

Fabrication of new generation of co-delivery systems based on graphene-g-cyclodextrin/chitosan nanofiber

Although many techniques have been devoted to promote therapeutic purposes of drug carrier systems, however, there are still many challenges in this area. Here, we designed co-loaded delivery systems, composed of curcumin loaded cyclodextrin-graphene oxide core (Cur@CD-GO) and gallic acid loaded chitosan shell nanofibers (Cur-Ga NF), which can promote the therapeutic efficiency of drugs. The synthesized nanofibres were fabricated by electrospinning technique with the coaxial system. Results showed that co-loaded delivery systems (Cur-Ga NF) provide better performance over single drug-loaded NFs (Cur@CD-GO). It was demonstrated that the nanofibers were successfully prepared, and the drugs in the core and sell of nanofibers were released in a controlled and sustained manner. The produced Cur-Ga NF, providing improved anti-cancer activity, antimicrobial activity, antioxidant activity and anti-inflammatory outcome as compared to single drug-loaded NFs. Our investigations showed that such co-delivery fiber systems could be employed as a promising nanocarrier for therapeutic applications.

Fabricating β-cyclodextrin based pH-responsive nanotheranostics as a programmable polymeric nanocapsule for simultaneous diagnosis and therapy

Background

Fabrication of a smart drug delivery system that could dramatically increase the efficiency of chemotherapeutic drugs and reduce the side effects is still a challenge for pharmaceutical researchers. By the emergence of nanotechnology, a huge window was opened towards this goal, and a wide type of nanocarriers were introduced for delivering the chemotherapeutic to the cancer cells, among them are cyclodextrins with the ability to host different types of hydrophobic bioactive molecules through inclusion complexation process.

Aim

The aim of this study is to design and fabricate a pH-responsive theranostic nanocapsule based on cyclodextrin supramolecular nano-structure.

Materials and methods

This nanostructure contains iron oxide nanoparticles in the core surrounded with three polymeric layers including polymeric β-cyclodextrin, polyacrylic acid conjugated to sulfadiazine, and polyethylenimine functionalized with β-cyclodextrin. Sulfadiazine is a pH-responsive hydrophobic component capable of making inclusion complex with β-cyclodextrin available in the first and third layers. Doxorubicin, as an anti-cancer drug model, was chosen and the drug loading and release pattern were determined at normal and acidic pH. Moreover, the biocompatibility of the nanocapsule (with/without drug component) was examined using different techniques such as MTT assay, complement activation, coagulation assay, and hemolysis.

Results

The results revealed the successful preparation of a spherical nanocapsule with mean size 43±1.5 nm and negatively charge of −43 mV that show 160% loading efficacy. Moreover, the nanocapsule has an on/off switching release pattern in response to pH that leads to drug released in low acidic pH. The results of the biocompatibility tests indicated that this nano drug delivery system had no effect on blood and immune components while it could affect cancer cells even at very low concentrations (0.3 μg mL⁻¹).

Conclusion

The obtained results suggest that this is a “switchable” theranostic nanocapsule with potential application as an ideal delivery system for simultaneous cancer diagnosis and therapy.

Gas-Phase Fragmentation of Cyclic Oligosaccharides in Tandem Mass Spectrometry

Modern mass spectrometry, including electrospray and MALDI, is applied for analysis and structure elucidation of carbohydrates. Cyclic oligosaccharides isolated from different sources (bacteria and plants) have been known for decades and some of them (cyclodextrins and their derivatives) are widely used in drug design, as food additives, in the construction of nanomaterials, etc. The peculiarities of the first- and second-order mass spectra of cyclic oligosaccharides (natural, synthetic and their derivatives and modifications: cyclodextrins, cycloglucans, cyclofructans, cyclooligoglucosamines, etc.) are discussed in this minireview.

Inclusion complexes of cysteinyl β-cyclodextrin with baicalein restore collagen synthesis in fibroblast cells following ultraviolet exposure

Baicalein, a bioactive flavonoid, has poor water solubility, thereby limiting its use in a wide range of biological applications. In the present study, we used inclusion complexes of cysteinyl β-cyclodextrin (β-CD) with baicalein to enhance the stability and solubility of baicalein in aqueous solution. We examined the effects of inclusion complexes of cysteinyl β-CD on collagen synthesis following ultraviolet (UV) irradiation, as well as the mechanisms underlying its effects. Our findings demonstrated that baicalein significantly restored collagen synthesis in the UV-exposed human fibroblast Hs68 cells. In addition, synthetic cysteine functionalized β-CDs were found to promote baicalein-induced collagen synthesis. Inclusion complexes of cysteinyl β-CDs with baicalein significantly upregulated the protein expression of type I collagen and activated the transcription of type I, II, and III collagen. Inclusion complexes of cysteinyl β-CDs with baicalein also downregulated matrix metalloproteinase -1 and -3, and α-smooth muscle actin expression. In addition, inclusion complexes of cysteinyl β-CDs with baicalein attenuated the expression of caveolin-1, but this treatment enhanced the UV-induced phosphorylation of Smad in the transforming growth factor-β pathway. These results suggested that the newly synthesized derivative of CD can be used as a complexing agent to enhance the bioavailability of flavonoids such as baicalein, especially in restoring collagen synthesis.

Monosubstituted hydrazone β-cyclodextrin derivatives for pH-sensitive complex formation with aromatic drugs

A new and convenient synthetic pathway was developed to produce monosubstituted cyclodextrins with high yields. Each of the β-cyclodextrin derivatives described in this work has an aromatic substituent connected with cyclodextrin core by a pH-sensitive hydrazone linker and a carbon chain. Carbon chains differ in lengths having one or three carbon atoms. The correlation between water solubility and linker length was determined using UV–Vis spectroscopy, while the dependence of hydrazone bond hydrolysis on the electrolyte pH was confirmed by cyclic voltammetry. The pH-dependent complex-formation ability between the hydrazone derivative of cyclodextrin and anthracycline drug was examined by square wave voltammetry. The significantly big solubility and the appropriate pH, at which the hydrolysis of the hydrazone bond occurs, make the newly synthesized derivatives attractive for pharmaceutical and medical applications.

β-Cyclodextrin-Functionalized Chitosan/Alginate Compact Polyelectrolyte Complexes (CoPECs) as Functional Biomaterials with Anti-Inflammatory Properties

Nowadays, the need for therapeutic biomaterials displaying anti-inflammatory properties to fight against inflammation-related diseases is continuously increasing. Compact polyelectrolyte complexes (CoPECs) represent a new class of materials obtained by ultracentrifugation of a polyanion/polycation complex suspension in the presence of salt. Here, a noncytotoxic β-cyclodextrin-functionalized chitosan/alginate CoPEC was formulated, characterized, and described as a promising drug carrier displaying an intrinsic anti-inflammatory property. This new material was successfully formed, and due to the presence of cyclodextrins, it was able to trap and release hydrophobic drugs such as piroxicam used as a model drug. The intrinsic anti-inflammatory activity of this CoPEC was analyzed in vitro using murine macrophages in the presence of lipopolysaccharide (LPS) endotoxin. In this model, it was shown that CoPEC inhibited LPS-induced TNF-α and NO release and moderated the differentiation of LPS-activated macrophages. Over time, this kind of bioactive biomaterial could constitute a new family of delivery systems and expand the list of therapeutic tools available to target inflammatory chronic diseases such as arthritis or Crohn's disease.

AMF-responsive doxorubicin loaded β-cyclodextrin-decorated superparamagnetic nanoparticles

An alternating magnetic field (AMF)-responsive controlled release system has been developed by the binding of mono-6-deoxy-6-(p-tolylsulfonyl)-β-cyclodextrin (βCD-Ts) onto amine-modified superparamagnetic iron oxide nanoparticles (MNP-NH₂), resulting in a MNP-βCD nanocarrier.

Transfection-capable polycationic nanovectors which include PEGylated-cyclodextrin structural units: a new synthesis pathway

Polycationic nanoentities with low variability are able to act as cooperating carriers for dsDNA complexation and transport.

Characterization and Enhanced Antioxidant Activity of the Cysteinyl β-Cyclodextrin-Baicalein Inclusion Complex

Baicalein is a type of flavonoid isolated from the roots of a medicinal plant, Scutellaria baicalensis. Although it has attracted considerable attention due to its antiviral, anti-tumor, and anti-inflammatory activities, its limited aqueous solubility inhibits the clinical application of this flavonoid. The present study aimed to prepare and characterize a host-guest complex in an effort to improve the solubility and antioxidant activity of baicalein. The host molecule is a macrocyclic β-cyclodextrin (β-CD) functionalized with cysteine for a synergetic effect. The structure of the synthesized cysteinyl β-CD was analyzed using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. The inclusion complex with baicalein was studied by UV-vis, NMR spectroscopy, scanning electron microscopy, and X-ray powder diffractometry. The formed cysteinyl β-CD/baicalein inclusion complex efficiently improved the solubility and antioxidant ability of baicalein. Therefore, we suggest that the present cysteinyl β-CD is a potential host molecule for inclusion complexation and for bioavailability augmentation.

Near-infrared light-triggered drug release nanogels for combined photothermal-chemotherapy of cancer

Near-infrared (NIR) light-triggered drug release polymeric nanogels were fabricated based on host–guest interaction and were explored to encapsulate indocyanine green (ICG) and doxorubicin (DOX) for combined photothermal-chemotherapy of cancer.

A complete series of 6-deoxy-monosubstituted tetraalkylammonium derivatives of α-, β-, and γ-cyclodextrin with 1, 2, and 3 permanent positive charges

An efficient synthetic route toward the preparation of a complete series of monosubstituted tetraalkylammonium cyclodextrin (CD) derivatives is presented. Monotosylation of native CDs (α-, β-, γ-) at position 6 gave the starting material. Reaction of monotosylate (mono-Ts-CD) with 45% aqueous trimethylamine gave CDs substituted with one cationic functional group in a single step. Derivatives equipped with a substituent containing two cationic sites separated by an ethylene or a propylene linker were prepared by reacting mono-Ts-CD with neat N,N,N’-trimethylethane-1,2-diamine or N,N,N’-trimethylpropane-1,3-diamine and subsequent methylation by CH₃I in good yields. Finally, analogues bearing a moiety with three tetraalkylammonium sites were synthesized by reacting mono-Ts-CD with bis(3-aminopropyl)amine and subsequent methylation. The majority of the presented reactions are very straightforward with a simple work-up, which avoids the need of chromatographic separation. Thus, these reactions are suitable for the multigram-scale production of monosubstituted cationic CDs.

Biotinylation of the rhizobial cyclic β-glucans and succinoglycans crucial for symbiosis with legumes

The cyclic β-glucans and succinoglycans produced by rhizobia are required for nodulation during symbiosis with legume hosts. However, only gene deletion analyses have been used to investigate their biological importance. For future studies on the physiological activity of those during symbiosis, biochemical methods need to be developed with separate carbohydrate compounds. Here, we isolated and purified rhizobial cellular carbohydrates using various chromatographic methods. Purified cyclic β-glucans, cyclosophoraoses, were monofunctionalized with biotin using the following three steps: tosylation, azidation, and amination. The mono-6-amino-cyclosophoraoses were linked with biotinamidohexanoic acid N-hydroxysuccinimide ester. Succinoglycans and monomers were tagged with biotinamidocaproyl hydrazide at the reducing sugar via reductive amination. The resulting biotinylated rhizobial carbohydrates were characterized by Fourier transform infrared and nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy, and electrospray ionization mass spectrometry. The resulting neoglycoconjugates can be used as solid probes to study putative plant receptors and for non-invasive imaging for in vivo tracing.