Cyclodextrin Research Articles

Polyurethane-Type Poly[3]rotaxanes Synthesized from Cyclodextrin-Based [3]Rotaxane Diol and Diisocyanates.

Synthesis of polyurethane-type poly[3]rotaxanes is achieved by polyaddition between a cyclodextrin (CD)-based [3]rotaxane diol and various diisocyanate species, which provide a more defined structure compared to conventional polyrotaxane syntheses. In this study, hydroxyl groups on CDs of [3]rotaxane diol are initially acetylated, and deprotected after the polyaddition to introduce polyurethane backbone structure into polyrotaxane framework. Despite a relatively complicated chemical structure, [3]rotaxane diol monomer is successfully synthesized in a high yield (overall 67%) without any taxing purification process, which is beneficial for practical applications. The polymerization itself proceeds well under a standard polyaddition reaction condition to afford corresponding polyurethanes around 80% yield with Mn > 30kDa. The poly[3]rotaxanes show different aggregation behavior or optical properties, whether or not acetyl groups are present, and are analyzed by XRD, SEM, and fluorescence measurements.

Variation of Cyclodextrin (CD) Complexation with Biogenic Amine Tyramine: Pseudopolymorphs of β-CD Inclusion vs. α-CD Exclusion, Deep Atomistic Insights.

Tyramine (TRM) is a biogenic catecholamine neurotransmitter, which can trigger migraines and hypertension. TRM accumulated in foods is reduced and detected using additive cyclodextrins (CDs) while their association characteristics remain unclear. Here, single-crystal X-ray diffraction and density functional theory (DFT) calculation have been performed, demonstrating the elusive pseudopolymorphs in β-CD inclusion complexes with TRM base/HCl, β-CD·0.5TRM·7.6H2O (1) and β-CD·TRM HCl·4H2O (2) and the rare α-CD·0.5(TRM HCl)·10H2O (3) exclusion complex. Both 1 and 2 share the common inclusion mode with similar TRM structures in the round and elliptical β-CD cavities, belong to the monoclinic space group P21, and have similar herringbone packing structures. Furthermore, 3 differs from 2, as the smaller twofold symmetry-related, round α-CD prefers an exclusion complex with the twofold disordered TRM-H+ sites. In the orthorhombic P21212 lattice, α-CDs are packed in a channel-type structure, where the column-like cavity is occupied by disordered water sites. DFT results indicate that β-CD remains elliptical to suitably accommodate TRM, yielding an energetically favorable inclusion complex, which is significantly contributed by the β-CD deformation, and the inclusion complex of α-CD with the TRM aminoethyl side chain is also energetically favorable compared to the exclusion mode. This study suggests the CD implications for food safety and drug/bioactive formulation and delivery.

A non-toxic inclusion complexation of loxoprofen with hydroxypropyl-β-cyclodextrin for complete solubility and anti-inflammatory efficacy

In recent days, there has been a significant demand for drugs that are easily soluble, non-toxic, safe, and biocompatible for human use. Recently, active pharmaceutical ingredient (API) complexes with cyclodextrins (CDs) and their derivatives have gained considerable attention. In line with this trend, we have developed an inclusion complex material for loxoprofen using hydroxypropyl derivatives of beta-cyclodextrin (Hyd-β-CD). The formation of the complex between loxoprofen (LXP) and Hyd-β-CD has been confirmed through changes in absorbance and fluorescence intensity, indicating a 1:1 stoichiometric ratio. The addition of Hyd-β-CD significantly enhanced the solubility of LXP, reflecting successful complexation. Proton NMR and ROESY analyses show that the phenyl group of LXP resides within the cavity of the Hyd-β-CD. Further validation is provided by DFT orientations and their associated energy parameters. Cell viability studies indicate that the increased solubility of the inclusion complex (IC) improves the bioavailability of the drug, while toxicity tests show that our IC material does not induce toxicity in normal cells. Moreover, the anti-inflammatory efficacy of LXP is markedly enhanced in its IC form. These findings underscore the potential of IC in extending the application of LXP, especially in pharmaceuticals, where the enhanced stability and efficacy of natural active ingredients and anti-inflammatory agents are crucial.

Supramolecular chemistry in cyclodextrin inclusion complexes: The formation rules of terpenes/β-cyclodextrin inclusion complexes

Supramolecular chemistry of cyclodextrins (CDs) inclusion complexes is a hot research topic at present, but current studies often focus on the host-guest interaction between CDs and hydrophobic substances, while ignoring the self-assembly behavior of the host and guest during the inclusion process. Based on the spatial structures, six representative terpenes were selected in this study, and the stoichiometric ratio between terpenes and β-cyclodextrin (β-CD) was investigated by isothermal titration calorimetry (ITC) method. Meanwhile, the constructed inclusion complexes (ICs) were characterized by nuclear magnetic resonance, X-ray diffraction, scanning electron microscope, etc. On this basis, the assembly process of β-CD and terpenes was investigated firstly by molecular simulation method, and the inclusion process between β-CD and terpenes was further studied in terms of the formation of individual ICs and ICs aggregates. Results showed that hydrophobic interaction and van der Waals force were the main driving forces of the reaction between terpenes and β-CD, and the formation of ICs, β-CD molecule aggregation, terpene aggregation, and ICs aggregation occurred simultaneously during the inclusion process of terpenes and β-CD. To sum up, this study may provide certain thinking and reference for the subsequent supramolecular chemical research on CDs.

Cyclodextrin nano-organogels as a delivery vehicle for peppermint essential oil to enhance its physico-chemical properties and skin photoprotective performance

Acute sun exposure could lead to erythema and inflammation. This Investigation aims to determine the efficacy of the complexation of peppermint oil (PO) with cyclodextrin in enhancing its physicochemical properties. Nano-organogels were prepared by direct hot melting method. Cyclodextrin (CD) PO was prepared by co-lyophilized method and included in F6. The particle size values were all below 150 nm. F6 polymeric showed high antioxidant activity, in vitro SPF, and stability. CD nano-organogel showed the least release and the highest skin deposition values. This high skin deposition is assured by confocal microscopy. Histology revealed its anti-inflammatory effect against acute UV irradiation. PO CD nano-organogel demonstrates a promising modality for anti-inflammatory therapy against UV irradiation.

Following the Trace of Cyclodextrins on the Selenium and Tellurium Odyssey.

There is an urgent need to develop safer and more effective modalities for the treatment of numerous pathologies due to the increasing rates of drug resistance, undesired side effects, poor clinical outcomes, etc. Over the past decades, cyclodextrins (CDs) have gathered great attention as potential drug carriers due to their ability to enhance their bioactivities and properties. Likewise, selenium (Se) and tellurium (Te) have been extensively studied during the last decades due to their possible therapeutical applications. Although there is limited research on the relationship between Se and Te and CDs, herein, we highlight different representative examples of the advances related to this topic as well as give our view on the future directions of this emerging area of research. This review encompasses three different aspects of this relationship: (1) modification of the structure of the different CDs; (2) formation of host-guest interaction complexes of naïve CDs with Se and Te derivatives in order to overcome specific limitations of the latter; and (3) the use of CDs as catalysts to achieve novel Se and Te compounds.

Investigation of the structural and thermodynamic properties of the inclusion complex of apixaban with natural cyclodextrins

Apixaban (APX) is an anticoagulant drug with poor aqueous solubility, limiting its bioavailability. This study investigates whether solubility can be enhanced by inclusion of APX within the native (α-, β-, and γ-) cyclodextrins (CDs). Phase solubility studies revealed an enhancement in solubility in the presence of β-CD. The complex formation constant for β-CD was found to be one order of magnitude higher than that of α-CD and γ-CD (K11 = 35, 268 and 41 M−1 for α-, β- and γ-CDs, respectively). 1H NMR spectra in DMSO confirmed the formation of the APX/β-CD complex in solution. Infrared (IR) spectroscopy and differential scanning calorimetry (DSC) confirmed the formation of an APX/β-CD inclusion complex in the solid state. Molecular dynamics (MD) simulations were employed to study the dynamics and host-guest interactions of APX with the CDs. MM-PBSA estimates of the binding free energies revealed a higher stability of the complex with β-CD compared to the other two, in agreement with the experimental results, with favorable van der Waals and electrostatic interactions, and with the former contributing much more significantly.

Dexamethasone-loaded ROS stimuli-responsive nanogels for topical ocular therapy of corneal neovascularization

Dexamethasone (DEX) has been demonstrated to inhibit the inflammatory corneal neovascularization (CNV). However, the therapeutic efficacy of DEX is limited by the poor bioavailability of conventional eye drops and the increased risk of hormonal glaucoma and cataract associated with prolonged and frequent usage. To address these limitations, we have developed a novel DEX-loaded, reactive oxygen species (ROS)-responsive, controlled-release nanogel, termed DEX@INHANGs. This advanced nanogel system is constructed by the formation of supramolecular host-guest complexes by cyclodextrin (CD) and adamantane (ADA) as a cross-linking force. The introduction of the ROS-responsive material, thioketal (TK), ensures the controlled release of DEX in response to oxidative stress, a characteristic of CNV. Furthermore, the nanogel's prolonged retention on the corneal surface for over 8 h is achieved through covalent binding of the integrin β1 fusion protein, which enhances its bioavailability. Cytotoxicity assays demonstrated that DEX@INHANGs was not notably toxic to human corneal epithelial cells (HCECs). Furthermore, DEX@INHANGs has been demonstrated to effectively inhibit angiogenesis in vitro. In a rabbit model with chemically burned eyes, the once-daily topical application of DEX@INHANGs was observed to effectively suppress CNV. These results collectively indicate that the nanomedicine formulation of DEX@INHANGs may offer a promising treatment option for CNV, offering significant advantages such as reduced dosing frequency and enhanced patient compliance.

Cyclodextrins as a Strategy for Enhancing Solubility of Therapeutic Agents for Neglected Tropical Diseases: A Systematic Review.

Neglected Tropical Diseases (NTD) are chronic infectious conditions that primarily affect marginalized populations. The chemotherapeutic arsenal available for treating NTD is limited and outdated, which poses a challenge in controlling and eradicating these diseases. This is exacerbated by the pharmaceutical industry's lack of interest in funding the development of new therapeutic alternatives. In addition, a considerable number of drugs used in NTD therapy have low aqueous solubility. To address this issue, solubility enhancement strategies, such as the use of inclusion complexes with cyclodextrins (CD) can be employed. Therefore, this systematic review aims to present the application of CD in complexing with drugs and chemotherapeutic compounds used in the therapy of some of the most prevalent NTD worldwide and how these complexes can enhance the treatment of these diseases. Two bibliographic databases, Science Direct and PubMed, were used to conduct the search. The selection of studies and the writing of this systematic review followed the criteria outlined by the PRISMA guidelines. From a total of 978 articles, 23 were selected after applying the exclusion criteria. All the studies selected were consistent with the use of CD as a strategy to increase the solubility of therapeutic agents used in NTD. The results indicate that CD can enhance the solubility of chemotherapeutic agents for the treatment of Neglected Tropical Diseases (NTD). This review presents data that clearly highlights the potential use of CD in the development of new treatments for neglected tropical diseases. It can assist in the formulation of future treatments that are more effective and safer.

Faceted crystal growth of cyclodextrin-oil inclusion complexes

The spontaneous formation of cyclodextrin (CD)-oil inclusion complexes (ICs) and their further growth into patterned crystals present a bottom-up route to the fabrication of periodic macroscopic structure. Although the inclusion processes are well established for the molecules, understanding intermediate structures during the crystal growth and emerging of persistent crystalline order has been lacking. Here we build a hierarchy of oriented micro/nanostructures of CD-oil ICs in solution by choosing different oil guests including several straight-chain alkanes of C12, C14 and C16, oleic acid (OA), glycerol trioleate (TG) and soybean oil (SO), in an attempt to reveal the roles of oil guests in the formation of their crystallites. Remarkably, the ICs tend to grow into clusters and terminate at a certain finite size as long columns or lamella plates with well-defined facets, dependent on the type of oil used. For the first time, we report a non-equilibrium growth of crystallites with surface faceting directed by the guests by means of Arching and Bundling.

Long-Chain Alkylthio Cyclodextrin Derivatives for Modulation of Quorum-Sensing-Based Bioluminescence in Aliivibrio fischeri Model System.

Quorum sensing (QS) allows bacteria to coordinate their activities by producing and detecting low-molecular-weight signal molecules based on population density, thereby controlling the infectivity of bacteria through various virulence factors. Quorum-sensing inhibition is a promising approach to tackle bacterial communication. Cyclodextrins (CDs) are a class of cyclic oligosaccharides that reversibly encapsulate the acyl chain of the signal molecules, thereby preventing their binding to receptors and interrupting bacterial communication. This results in the inhibition of the expression of various properties, including different virulence factors. To examine the potential quorum-quenching (QQ) ability of newly prepared cyclodextrin derivatives, we conducted short-term tests using Aliivibrio fischeri, a heterotrophic marine bacterium capable of bioluminescence controlled by quorum sensing. α- and β-cyclodextrins monosubstituted with alkylthio moieties and further derivatized with quaternary ammonium groups were used as the test agents. The effect of these cyclodextrins on the quorum-sensing system of A. fischeri was investigated by adding them to an exponential growth phase of the culture and then measuring bioluminescence intensity, population growth, and cell viability. Our results demonstrate that the tested cyclodextrins have an inhibitory effect on the quorum-sensing system of A. fischeri. The inhibitory effect varies based on the length of the alkyl chain, with alkylthio substitution enhancing it and the presence of quaternary ammonium groups decreasing it. Our findings suggest that cyclodextrins can be a promising therapeutic agent for the treatment of bacterial infections.

Potential of Native Cyclodextrins and L-Lysine for Enhancing Ellagic Acid Aqueous Solubility

This study aimed to examine the influence of β cyclodextrin (βCD) and γ cyclodextrin (γCD) alone and in combination with L-lysine on ellagic acid (EA) solubility. Indeed, complexation with cyclodextrins can be used to improving the solubility of drugs poorly soluble in water such as EA. EA is a Biopharamceutical Classification System (BCS) IV bioactive polyphenol with numerous therapeutic activities, including antimalarial activities. However, its unfavorable physicochemical properties limit its therapeutic use. Therefore, after a phase solubility study, we successfully prepared EA-βCD and γ CD binary solid complexes using the freeze-drying technique. Methods including proton nuclear magnetic resonance (1H-NMR) analysis and fourier-transform infrared (FTIR) spectroscopy were used to characterize the inclusion behaviors of the complexes of EA with cyclodextrins both in solution and solid forms. The results of the phase solubility study indicated Ap-type diagrams of EA with the two cyclodextrins (CDs). The solubility of EA was multiplied by 9.92 and 2.98 in the presence of γCD and βCD respectively. Moreover, the complexes characterization by FTIR spectroscopy revealed the involvement of the C=O and EA OH groups in the interaction with the CDs. The results of NMR spectroscopic characterization revealed that the formation of EA inclusion complexes with βCD was partial. However, these results did not indicate the appearance of EA inclusion complexes with γCD. These relatively modest results in terms of increased EA solubility, obtained with cyclodextrins, prompted us to use a third compound, l-lysine, to enhance CDs complexation. Thus, the formation of ternary complexes led to a very significant increase EA solubility. Indeed, the incorporation of EA into EA-L-lysine-βCD and γ CD complexes increased its water solubility at pH 7.4 by a factor of 555 and 663, respectively.

A ROS-responsive multifunctional targeted prodrug micelle for atherosclerosis treatment

Atherosclerosis is a chronic multifactorial cardiovascular disease. To combat atherosclerosis effectively, it is necessary to develop precision and targeted therapy in the early stages of plaque formation. In this study, a simvastatin (SV)-containing prodrug micelle SPCPV was developed by incorporating a peroxalate ester bond (PO). SPCPV could specifically target VCAM-1 overexpressed at atherosclerotic lesions. SPCPV contains a carrier (CP) composed of cyclodextrin (CD) and polyethylene glycol (PEG). At the lesions, CP and SV exerted multifaceted anti-atherosclerotic effects. In vitro studies demonstrated that intracellular reactive oxygen species (ROS) could induce the release of SV from SPCPV. The uptake of SPCPV was higher in inflammatory cells than in normal cells. Furthermore, in vitro experiments showed that SPCPV effectively reduced ROS levels, possessed anti-inflammatory properties, inhibited foam cell formation, and promoted cholesterol efflux. In vivo studies using atherosclerotic rats showed that SPCPV reduced the thickness of the vascular wall and low-density lipoprotein (LDL). This study developed a drug delivery strategy that could target atherosclerotic plaques and treat atherosclerosis by integrating the carrier with SV. The findings demonstrated that SPCPV possessed high stability and safety and had great therapeutic potential for treating early-stage atherosclerosis.

QbD Assisted Systematic Review for Optimizing the Selection of PVP as a Ternary Substance in Enhancing the Complexation Efficiency of Cyclodextrins: a Pilot Study.

Inclusion complexes require higher concentration of Beta cyclodextrins (βCD) resulting in increased formulation bulk, toxicity, and production costs. This systematic review offers a comprehensive analysis using Quality by design (QbD) as a tool to predict potential applications of Polyvinylpyrrolidone (PVP) as a ternary substance to address issues of inclusion complexes. We reviewed 623 documents from 2013 to 2023 and Eighteen (18) research papers were selected for statistical and meta-analysis using the QbD concept to identify the most critical factors for selecting drugs and effect of PVP on inclusion complexes. The QbD analysis revealed that Molecular weight (MW), Partition coefficient (Log P), and the auxiliary substance ratio directly affected complexation efficiency (CE), thermodynamic stability in terms of Gibbs free energy (ΔG), and percent drug release. However, Stability constant (Ks) remained unaffected by any of these parameters. The results showed that low MW (250), median Log P (6), and a βCD: PVP ratio of 2:3 would result in higher CE, lower G, and improved drug release. PVP improves drug solubility, enhances delivery and therapeutic outcomes, and counteracts increased drug ionization due to decreased pH. In certain cases, its bulky nature and hydrogen bonding with CD molecules can form non-inclusion complexes. The findings of the study shows that there is potential molecular interaction between PVP and β-cyclodextrins, which possibly enhances the stability of inclusion complexes for drug with low MW and log P values less than 9. The systematic review shows a comprehensive methodology based on QbD offers a replicable template for future investigations into drug formulation research.

Rational design of disulfide bonds to improve the thermostability and γ-cyclodextrin production capacity of γ-cyclodextrin glycosyltransferase

The ability of γ-cyclodextrin(γ-CD)to form inclusion complexes with various guest compounds, together with its relatively high solubility, gives γ-CD advantages over both α-cyclodextrin(α-CD) and β-cyclodextrin(β-CD). The thermostability of γ-cyclodextrin glycosyltransferases (γ-CGTase) which can produce γ-CD discovered so far is poor, which is one of the problems limiting its industrial application. To enhance the thermostability of γ-CGTase from Bacillus clarkii 7364, potential disulfide bond mutants were predicted by Disulfide by Design. Five pairs of mutants were constructed by analyzing the predicted results. The t1/2 of S172C-R183C was 2.25 h, which was 3.17 times of WT. Molecular dynamics simulations confirmed that the increase of thermostability of S172C-R183C may be due to the formation of disulfide bond, which leads to the increase of structure rigidity of protein. Then the ability of S172C-R183C mutant to produce cyclodextrins(CDs) was tested. Compared with WT, the maximum CD yield, γ-CD yield and γ-CD specificity of S172C-R183C in the non-complexant catalysed reaction were increased by 6.9 %, 8.8 %, and 2.4 % respectively. In the complexant catalyzed reaction, the CDs yield of S172C-R183C increased by 17.0 %, in which the γ-CD yield increased by 21.7 %, and the γ-CD specificity increased by 3.9 %. Molecular docking results showed that S172C-R183C formed more hydrogen bonds with γ-CD, especially Y186, which was the key central site affecting product specificity. This work involving rational protein engineering provided a new method for adjusting γ-CGTase thermostability.

Coumarin/β-Cyclodextrin Inclusion Complexes Promote Acceleration and Improvement of Wound Healing.

Coumarins have great pharmacotherapeutic potential, presenting several biological and pharmaceutical applications, like antibiotic, fungicidal, anti-inflammatory, anticancer, anti-HIV, and healing activities, among others. These molecules are practically insoluble in water, and for biological applications, it became necessary to complex them with cyclodextrins (CDs), which influence their bioavailability in the target organism. In this work, we studied two coumarins, and it was possible to conclude that there were structural differences between 4,7-dimethyl-2H-chromen-2-one (DMC) and 7-methoxy-4-methyl-2H-chromen-2-one (MMC)/β-CD that were solubilized in ethanol, frozen, and lyophilized (FL) and the mechanical mixtures (MM). In addition, the inclusion complex formation improved the solubility of DMC and MMC in an aqueous medium. According to the data, the inclusion complexes were formed and are more stable at a molar ratio of 2:1 coumarin/β-CD, and hydrogen bonds along with π-π stacking interactions are responsible for the better stability, especially for (MMC)2@β-CD. In vivo wound healing studies in mice showed faster re-epithelialization and the best deposition of collagen with the (DMC)2@β-CD (FL) and (MMC)2@β-CD (FL) inclusion complexes, demonstrating clearly that they have potential in wound repair. Therefore, (DMC)2@β-CD (FL) deserves great attention because it presented excellent results, reducing the granulation tissue and mast cell density and improving collagen remodeling. Finally, the protein binding studies suggested that the anti-inflammatory activities might exert their biological function through the inhibition of MEK, providing the possibility of development of new MEK inhibitors.

Evaluation of the performance of Hydroxypropyl-β-cyclodextrin for the consolidation of vegetable-tanned leather artifacts

The fragility and weakness of historical, archaeological, and heritage leather artifacts in museums, and libraries due to unsuitable environmental conditions are significant challenges. This study aims to assess the effectiveness of Hydroxypropyl Beta Cyclodextrin, a novel material, in consolidating leather artifacts by examining their physical, chemical, and mechanical properties. Vegetable-tanned leather samples were treated with different concentrations of Hydroxypropyl Beta Cyclodextrin and subjected to artificial heat aging. Evaluation methods included digital and scanning electron microscopy, contact angle measurements, mechanical testing, color analysis, pH measurement, and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy. Results showed that Hydroxypropyl Beta Cyclodextrin at 1% and 2% concentrations improved chemical stability, surface morphology, color retention, and mechanical properties of the leather samples. The third concentration yielded less favorable outcomes. This study recommends using Hydroxypropyl Beta Cyclodextrin at 1% and 2% concentrations for consolidating historical leathers.

Characterization of behavior of the inclusion complex between Sulfobutylether-β-cyclodextrin loaded alginate/chitosan nanoparticles and indomethacin as a potential approach for drug delivery

Indomethacin (IND) is a nonsteroidal anti-inflammatory drug with low aqueous solubility and irritating gastrointestinal side effects. By complexing this drug inside the cavity of cyclodextrin (CD) and loading it into polymer nanoparticles such as Chitosan (CS) and Alginate (Alg), in addition to increasing its solubility, a targeted drug delivery platform can be created to release this drug. In this study, initially, the complex of IND with Sulfobutylether-β-cyclodextrin (SBE-β-CD) was created using the freeze-drying method. Then, by ionic gelation method, the complex was loaded into CS nanoparticles, and finally, these nanoparticles were coated with Alg to enable drug release in the intestinal environment. Complexes and nanoparticles formation were investigated by phase solubility, FTIR, HNMR, XRD, and SEM methods. Moreover, the Zeta potential method was used to measure the stability of nanoparticles coated with Alg. According to phase solubility studies, drug solubility increased linearly with increasing CD concentration, indicating an AL-type system. In addition, according to the phase solubility diagram, the stability constant and complexation efficiency were obtained 177 M−1 and 0.388, respectively. In the following, the formation of chitosan nanoparticles was confirmed through spectral shifts observed in FTIR analysis as well as morphological changes revealed in SEM analysis. Also, the zeta potential of Alg coated nanoparticles was 110.067 mV, which indicates the good stability of these nanoparticles. At the end, in vitro release studies were conducted to investigate the pH-sensitive capability of these nanoparticles at pH = 1.5 and pH = 7. The formed nanosystem successfully released 78.51 % of the drug at pH = 7 and prevented its release in acidic pH.

Isolation of β-Cyclodextrin Gycosyl Transferase (β-CGTase) Producing Bacteria from Potato Plantation Soil

Cyclodextrin glycosyltransferase (CGTase) is an extracellular enzyme produced by several microorganisms, particularly bacteria, that converts starch into cyclodextrin (CD). CD has various applications in fields such as food, textiles, pharmaceuticals, chemistry, and biotechnology. The objective of this study was to isolate β-CGTase-producing bacteria from soil in a potato plantation located in Kerinci, and to conduct their characterization. Screening was conducted using Horikoshi agar media with phenolphthalein and methyl orange color indicators. The results indicated that one isolate, coded CK-2, produced the optimum β-CGTase enzyme when incubated for 30 hours at 37 ºC and pH 10. The CGTase enzyme converted starch to CD when incubated for 60 minutes at 37 ºC and pH 7. The CK-2 isolate was identified as monobacilli Gram-positive bacteria, having spores, positive in the catalase test, and motile. The study concluded that the bacteria producing β-CGTase enzyme are found in the soil of potato plantations in Kerinci, which is believed to originate from the genus Bacillus sp.

Modification of Nano-Zero-Valent Iron and its Simultaneous Removal of Mixed Heavy Metal-Organic Contaminants in the Water Environment

With the rapid development of economy and society, heavy metal and organic contaminants, as a typical combination of mixed contaminants, enter into the environment through multiple pathways and pose a serious threat to human beings. Therefore, there is an urgent need to find an efficient, rapid and non-secondary pollution method to remove them from the water environment. However, it is difficult for traditional water treatment technologies to completely degrade them in a short time. With the continuous progress of nanotechnology, nano-zero-valent iron (nZVI) has become one of the very promising materials for the removal of mixed contaminants from aqueous environments due to its high reducibility, fast reaction rate and environmental friendliness. However, nZVI is prone to agglomeration and oxidation, which limits its practical application. Therefore, this paper reviews the modification methods of nZVI and the problems they face. In addition, the degradation mechanisms of modified nZVI for heavy metals and organic contaminants is also reviewed. The removal of heavy metal-organic mixed contaminants by sodium alginate (SA), cyclodextrin (CD) and chitosan (CS)-modified nZVI was also analyzed in details. Finally, challenges and future perspectives are discussed, as well as providing a more comprehensive perspective on nanomaterial modification.