Search Results (257)

Semiconducting clathrates are a distinct class of inclusion compounds with considerable interest for thermoelectric applications. We report here the synthesis, crystal structure and thermoelectric properties of Sn₃₈Sb₈I₈. The compound was synthesized via planetary ball milling of the corresponding elements for 6 h and then sintering of amorphous mixture at 620 K for 3 days. The crystal structure of the polycrystalline product was determined via X-ray powder diffraction and Rietveld refinement as a type-I clathrate (a = 12.0390(2), space group Pm-3n, No. 223) with mixed-occupied Sn/Sb framework sites and fully occupied I guest sites. Further analysis on the chemical composition, nanomorphology and vibrational modes of the material was carried out via Induced-Coupled-Plasma–Mass Spectrometry, SEM/EDX microscopy and Raman spectroscopy, respectively. Thermoelectric measurements were performed on hot-pressed samples with ca. 98% of the crystallographic density. The clathrate compound behaves as an n-type semiconductor with a band gap of 0.737 eV and exhibits a maximum ZT of 0.0016 at 473 K. Theoretical calculations on the formation enthalpy, electron density of states and transport properties provide insights into the experimentally observed physical behavior. Full article

In this study, we review the use of cyclodextrin-based formulations to develop oral tablets of cladribine by enhancing its bioavailability and to improve the solubility and stability of retrometabolic chemical delivery systems (CDSs) in general and estredox, a brain-targeting estradiol-CDS, in particular. Cyclodextrins (CDs), cyclic oligosaccharides that can form host–guest inclusion complexes with a variety of molecules, are widely utilized in pharmaceuticals to increase drug solubility, stability, bioavailability, etc. The stability of the complex depends on how well the guest fits within the cavity of the CD host; a model connecting this to the size of the guest molecules is briefly discussed. Modified CDs, and particularly 2-hydroxypropyl-β-cyclodextrin (HPβCD), provided dramatically increased water solubility and oxidative stability for estredox (estradiol-CDS, E₂-CDS), making its clinical development possible and highlighting the potential of our brain-targeted CDS approach for CNS-targeted delivery with minimal peripheral exposure. A unique HPβCD-based formulation also provided an innovative solution for the development of orally administrable cladribine. The corresponding complex dual CD-complex formed by an amorphous admixture of inclusion- and non-inclusion cladribine–HPβCD complexes led to the development of tablets that provide adequate oral bioavailability for cladribine, as demonstrated in both preclinical and clinical studies. Cladribine–HPβCD tablets (Mavenclad) offer a convenient, effective, and well-tolerated oral therapy for multiple sclerosis, achieving worldwide approval and significant clinical success. Overall, the developments summarized here underscore the importance of tailored cyclodextrin-based approaches for overcoming barriers in drug formulation for compounds with challenging physicochemical properties, and demonstrate the versatility and clinical impact of CD inclusion complexes in modern pharmaceutical development. Full article

The cosmetic industry is constantly evolving to create new formulations that offer controlled and specific release of active ingredients, as well as greater penetration, duration and stability of the resulting products. To fulfil all these objectives, the use of cyclodextrins in different cosmetic formulations is being considered. CDs are cyclic oligosaccharides with a hydrophilic outer surface and an inner cavity able to encapsulate hydrophobic molecules. This property can be used to form complexes with hydrophobic molecules and solubilise them in aqueous matrices, such as creams or gels. This review analyses the main advantages that these agents provide in cosmetic products, such as protection, administration and controlled release of bioactive ingredients, improved water solubility, reduced fragrance volatility, masking off unpleasant odours, modification of the physicochemical properties of formulations or prevention of ingredient side effects, among others. Formulations of lotions, sunscreens, deodorants, gels or perfumes containing CDs are already on the market, and new ones are being developed. Moreover, the regulations concerning their use, the types of cyclodextrins allowed and the mechanism required to produce CD-guest inclusion complexes are reviewed. Likewise, the use of CDs alone or encapsulating other compounds makes them an extremely versatile nanomaterial for dermofacial and cosmetic formulations. Full article

Apixaban (APX) is a direct oral anticoagulant with low aqueous solubility and limited bioavailability. This study aimed to improve APX solubility by forming spray-dried inclusion complexes (ICs) with β-cyclodextrin (β-CD) derivatives. ICs were prepared using hydroxypropyl-β-CD (HP-β-CD), sulfobutylether-β-CD (SBE-β-CD), randomly methylated-β-CD (RM-β-CD), and heptakis(2,6-di-O-methyl)-β-CD (DM-β-CD). Complex formation (1:1 stoichiometry) was confirmed by phase solubility studies and Job’s plots. The ICs were characterized by SEM, PXRD, DSC, and FTIR, and their saturated solubility was evaluated. Molecular docking assessed host–guest interactions. Among the tested carriers, DM-β-CD exhibited the highest stability constant (K_C = 371.92 M⁻¹) and produced amorphous ICs. DM-ICs achieved the greatest solubility enhancement at all pH conditions, with a maximum solubility of 1968.7 μg/mL at pH 1.2 and ~78.7-fold increase in water compared with pure APX. Docking results supported stable inclusion with the lowest binding free energy (−8.01 kcal/mol). These findings indicate that DM-β-CD-based ICs effectively enhance APX dissolution and show potential as solubilizing carriers for oral dosage forms. Full article

A novel inclusion complex of a fluorinated pyrazolopiperidine derivative (5-benzyl-7-(2-fluorobenzylidene)-2,3-bis(2-fluorophenyl)-3,3a,4,5,6,7-hexahydro-2H-pyrazolo [4,3-c]pyridine hydrochloride, PP·HCl) with β-cyclodextrin (PPβCD) was designed, synthesized, and characterized as a potential therapeutic agent for chemotherapy-induced myelosuppression and lymphopenia. Encapsulation of PP within β-cyclodextrin increased aqueous solubility by approximately 3.4-fold and improved dissolution rate by 2.8-fold compared with the free compound. Structural analysis using IR, ^1H/^13C NMR, and TLC confirmed the formation of a stable 1:1 host–guest complex, and the disappearance of free PP signals further supported complete encapsulation. In vivo evaluation in a cyclophosphamide-induced myelosuppression model demonstrated that PPβCD accelerated hematopoietic recovery, restoring leukocyte and erythrocyte counts 35–40% faster than methyluracil, without any signs of systemic toxicity. These findings indicate that β-cyclodextrin complexation significantly enhances solubility, dissolution, and biological efficacy of the pyrazolopiperidine scaffold, supporting further preclinical development of PPβCD as a supportive therapy for chemotherapy-related hematological complications. Full article

Carmustine (BCNU) is a powerful alkylating agent primarily used in the chemotherapeutic treatment of malignant brain tumors. However, its clinical application faces significant constraints due to its lipophilicity, low thermal stability, and rapid degradation in physiological environments. To tackle these challenges, our research aimed at the development and detailed characterization of α-cyclodextrin (α-CD) inclusion complexes (ICs) with BCNU employing three different synthesis techniques: co-grinding, cryomilling, and co-precipitation. The selected synthetic methods displayed variations dependent on the technique used, affecting the efficiency, inclusion ratios, and drug-loading capacities, with co-precipitation achieving the most favorable complexation parameters. Structural elucidation through ¹H NMR chemical shifts analysis indicated that only partial inclusion of BCNU occurred within α-CD in ICs produced via co-grinding, while cryomilling and co-precipitation allowed for complete inclusion. Multimodal spectroscopic analyses (FT-IR, UV-Vis, ¹³C CP MAS NMR, and ESI-MS) further substantiated the effective encapsulation of BCNU within α-CD, and systematic solubility assessments via Job’s continuous variation and the Benesi-Hildebrand method revealed a 1:1 host-guest stoichiometry. The ICs obtained were evaluated for BCNU release in vitro at pH levels of 4, 5, 6.5, and 7.4. The mechanism of BCNU drug release was determined to be Fickian diffusion, with the highest cumulative release noted in the acidic microenvironment. These findings collectively validate the effectiveness of α-CD as a functional excipient for the modulation of BCNU’s physicochemical properties through non-covalent complexation. This strategy shows potential for increasing the stability and solubility of BCNU, which may enhance its therapeutic effectiveness in the treatment of brain tumors. Full article

Cyclodextrins in metal oxide nanoparticles (NPs) serve as stabilizing, dispersing, and functionalizing agents that enhance antimicrobial performance through better nanoparticle stability, synergistic action, and potential controlled release mechanisms, making them ideal for advanced biomedical and environmental antimicrobial applications. In this study, NPs of vanadium pentoxide (V₂O₅) were obtained by the precipitation method, and, following a supramolecular assembly, were synthesized using the impregnation method via addition of β-cyclodextrin (BCD) and its derivatives, such as hydroxypropyl-β-cyclodextrin (HCD) and methyl-β-cyclodextrin (MCD). The formation of the V₂O₅:CDs was driven by non-covalent host–guest interactions, leading to a stable supramolecular structure with enhanced physicochemical properties. Morphological analysis using scanning electron microscopy (SEM) revealed uniformly distributed V₂O₅ NPs within the CD matrix. Structural characterization was further supported by proton nuclear magnetic resonance (NMR) spectroscopy, which confirmed the inclusion interactions between V₂O₅ and CDs. The synthesized NPs demonstrated significant antimicrobial activity against Gram-positive and fungal strains, indicating a synergistic enhancement in bioactivity due to the supramolecular architecture. This work highlights the potential of CD-assisted V₂O₅ NPs as promising antimicrobial agents for biomedical and environmental applications. Full article

Nerolidol (REL), a sesquiterpene with cis and trans isomers, exhibits diverse bioactive and sensory properties. In this study, we integrate single-crystal X-ray diffraction (SC-XRD), molecular docking, molecular dynamics (MD) simulations, and MM/GBSA binding free energy calculations to investigate its inclusion behavior in β-cyclodextrin (β-CD). Crystallization from a cis/trans mixture yielded a complex containing exclusively the trans isomer, forming a 2:1 host–guest assembly where a head-to-head β-CD dimer encapsulates one trans-REL molecule in an extended conformation. Computational models of cis-REL (bent c1 and extended c8 conformers) also stabilized within the β-CD cavity, with the extended conformer showing the most favorable dynamics. The computed binding affinities for all complexes differed by less than the estimated MM/GBSA uncertainty, indicating no statistically significant preference. Since cis/trans separation of nerolidol and related long-chain terpenoids is of considerable interest, our findings suggest that crystallization selectivity in β-CD inclusion complexes cannot be rationalized solely by binding affinity; instead, it likely arises from crystal packing forces and conformational preferences that govern the solid-state assembly. Full article

Methicillin-resistant S. aureus is a problematic pathogen due to its high-risk infections and resistance mechanisms. To fight against this bacterium, novel antimicrobial sources and new delivery systems must be developed. Antimicrobial polyurethanes for developing biomaterials can function as preventive strategies. In this study, we explore the synthesis of partially renewable polyurethanes as biomaterial carriers of novel antimicrobials. An antibacterial extract from a Streptomyces sp. strain and its inclusion complexes with β-cyclodextrin, used as an additional protective approach, were incorporated into castor oil-based polyurethane films through bulk or surface loading. The inclusion complexes were characterized to confirm host–guest interactions. The films were characterized by FTIR, XRD spectra, surface SEM images, hydrophilicity, thermal stability, and mechanical performance. FTIR suggested successful polyurethane synthesis. The polymers were semicrystalline and thermally stable until 260 °C, and Tg ranged between −16.9 and −9 °C. Bulk modification decreased the mechanical performance of the films. Surface modification promoted good antibacterial performance but cytotoxic potential against HDFa cells. However, PU active films showed favorable properties and hemocompatibility, making them a promising alternative for applications such as short-term dressings, serving as an antimicrobial delivery system and a preventive strategy against methicillin-resistant S. aureus. Full article

This study investigates the self-assembly and host–guest complexation behaviour of novel resveratrol-based lipophenols (LipoResv)—resveratrol-4′-linoleate (Resv-4′-LA) and resveratrol-4′-docosahexaenoate (Resv-4′-DHA)—with hydroxypropyl-β-cyclodextrins (HP-β-CDs). These amphiphilic molecules display surfactant-like properties, forming micellar aggregates in aqueous media. Fluorescence spectroscopy was used to determine the critical micelle concentration (CMC), revealing that LipoResv exhibit significantly lower CMC values than their free fatty acids, indicating higher hydrophobicity. The formation of inclusion complexes with HP-β-CDs was evaluated based on changes in CMC values and further confirmed by dynamic light scattering (DLS) and molecular modelling analyses. Resv-4′-LA formed 1:1 complexes (Kc = 720 M⁻¹), while Resv-4′-DHA demonstrated a 1:2 stoichiometry with lower affinity constants (K₁ = 17 M⁻¹, K₂ = 0.18 M⁻¹). Environmental parameters (pH, temperature, and ionic strength) significantly modulated CMC and binding constants. Computational docking and molecular dynamics simulations supported the experimental findings by revealing the key structural determinants of the host–guest affinity and micelle stabilization. Ligand efficiency (LE) analysis further aligned with the experimental data, favouring the unmodified fatty acids. These results highlight the versatile encapsulation capacity of HP-β-CDs for bioactive amphiphile molecules and support their potential applications in drug delivery and functional food systems. Full article

Cyclodextrins (CDs) are cyclic oligosaccharides capable of forming inclusion complexes with various guest molecules, enhancing solubility, stability, and bioavailability. This review outlines the structural features of native CDs and their chemically modified derivatives, emphasizing the influence of functionalization on host–guest interactions. Synthetic approaches for CD derivatization are summarized, with attention to recent developments in stimuli-responsive systems and targeted drug delivery. Analytical techniques commonly employed for characterizing CD complexes, such as spectroscopy, thermal analysis, and molecular modeling, are briefly reviewed. Applications in pharmaceutical formulations are discussed, including inclusion complexes, CD-based conjugates, and nanocarriers designed for solubility enhancement, controlled release, and site-specific delivery. Special consideration is given to emerging multifunctional platforms with biomedical relevance. The regulatory status of CDs is addressed, with reference to FDA- and EMA-approved formulations. Safety profiles and toxicological considerations associated with chemically modified CDs, particularly for parenteral use, are highlighted. This review presents an integrative perspective on the design, characterization, and application of CD-based systems, with a focus on translational potential and current challenges in pharmaceutical development. Full article

Cyclodextrins (CDs) have been widely employed as natural host molecules to form inclusion complexes with bioactive molecules such as antioxidants. Their particular spatial configuration, in the form of truncated cones formed through α(1–4) ether linkages of glucopyranose units, makes them very appropriate for the formation of host–guest complexes, modifying their physicochemical properties and their location in multiphasic systems. Here, we investigated the effects of 2-hydroxypropyl-β-cyclodextrin (HPCD) on the efficiency of a series of gallic acid derivatives (propyl (PG), butyl (BG), octyl (OG), and lauryl (LG) gallates) in inhibiting the oxidation of soybean oil-in-water emulsions. For this purpose, we investigated the effects of HPCD on both the kinetics of lipid oxidation and the distribution of antioxidants in the same intact emulsions. The results show that in an aqueous solution, the antioxidants form 1:1 inclusion complexes with HPCD, with inclusion constants ranging from 383 M⁻¹ (PG) to 1946 M⁻¹ (OG). The results also show that the addition of HPCD to emulsions containing antioxidants does not lead to significant changes in their antioxidant effectiveness, with their efficiency being similar to that when no HPCD molecules are present. The results are interpreted in terms of the blocking effect exerted by the Tween 20 molecules, which act as effective guest competitors capable of removing the antioxidants from the HPCD cavity. The Tween 20 surfactant molecules need to be employed to stabilize the emulsions kinetically. This blocking effect, as a primary consequence, indicates that the interfacial concentration of the antioxidants, which is the region where the inhibition reaction takes place, remains constant; thus, their efficiency is not altered. Full article

This work represents the first use of a phosphonium salt-functionalized β-Cyclodextrin polymer (β-CDP) as a highly selective sensing membrane for monitoring the safety of drinking water against perchlorate ions (ClO₄⁻) using electrochemical impedance spectroscopy (EIS). Structural confirmation via ¹H NMR, ¹³C NMR, ³¹P NMR, and FT-IR spectroscopies combined with AFM and contact angle measurements demonstrate how the enhanced solubility of modified cyclodextrin improves thin film quality. The innovation lies in the synergistic combination of two detection mechanisms: the “Host-Guest” inclusion in the cyclodextrin cavity and anionic exchange between the bromide ions of the phosphonium groups and perchlorate anions. Under optimized functionalization conditions, EIS reveals high sensitivity and selectivity, achieving a record-low detection limit (LOD) of ~10⁻¹² M and a wide linear range of detection (10⁻¹¹ M–10⁻⁴ M). Sensing mechanisms at the functionalized transducer interfaces are examined through numerical fitting of Cole-Cole impedance spectra via a single relaxation equivalent circuit. Real water sample analysis confirms the sensor’s practical applicability, with recoveries between 96.9% and 109.8% and RSDs of 2.4–4.8%. Finally, a comparative study with reported membrane sensors shows that β-CDP offers superior performance, wider range, higher sensitivity, lower LOD, and simpler synthesis. Full article

Innovative functional materials integrating host–guest complexes in cryogels offer promising applications in topical drug delivery, enhancing drug solubility and stability. In this study, we designed and developed a cryogel-based patch for acne treatment by polymerizing an acrylate-functionalized γ-cyclodextrin (γ-CD) and trimethoprim (TMP) inclusion complex with [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETMA) at low temperatures. A multistep workflow was applied to synthesize the inclusion complex via mortar-assisted kneading, followed by cryogel formulation through radical cryopolymerization. The resulting hybrid system leverages the cationic nature of AETMA to promote adhesion and electrostatic interactions with the skin surface. At the same time, γ-CD serves as a drug reservoir, facilitating sustained release of the drug. The system was characterized by FT-IR, TGA, and SEM analyses. In vitro release studies demonstrated a sustained TMP release profile, best described by the Korsmeyer–Peppas diffusion model. Antibacterial assays confirmed the system’s effectiveness against Staphylococcus aureus, supporting its potential for localized and prolonged acne treatment. Moreover, cytocompatibility tests demonstrated that the formulation is biocompatible, further validating its suitability for topical application. Full article

This paper aims to compare the perceptions of hotel customers and hotel staff regarding the value of green hotel attributes. By examining both stakeholder groups, the study addresses a gap in sustainable hospitality research, which largely overlooks employee perspectives in favour of customer preferences. An exploratory, cross-sectional survey was conducted using structured questionnaires, administered to hotel guests (n = 307) and hotel staff (n = 89) in Porto, Portugal. Respondents rated 15 green hotel attributes using a five-point Likert scale. Demographic data were also collected to analyse perceptual differences across gender, age, income, and education. The results revealed that both customers and staff exhibited environmental awareness, though their prioritisation of specific green practices differed. Customers tended to value visible environmental measures, such as recycling bins, energy-saving light bulbs, and renewable energy signage, while staff placed greater emphasis on operational sustainability aspects, including low-flow plumbing fixtures, refillable soap dispensers, and durable goods used in service areas. These differences reflect the stakeholders’ distinct roles and experiences within the hotel ecosystem. This study enriches the discourse on sustainable hospitality by providing a dual-stakeholder analysis of green hotel attributes using a shared evaluative framework. The findings offer practical insights for hotel managers aligning sustainability strategies with the expectations of both guests and employees, supporting more effective and inclusive green implementation in the lodging sector. Full article