Use of cyclodextrin and its derivatives for increased transformation efficiency of competent bacterial cells

Effect of Cyclodextrins on the Biofilm Formation Capacity of Pseudomonas aeruginosa PAO1

Quorum sensing (QS) is a population-density-dependent communication process of microorganisms to coordinate their activities by producing and detecting low-molecular-weight signal molecules. In pathogenic bacteria, the property controlled by QS is often related to infectivity, e.g., biofilm formation. Molecular encapsulation of the QS signals is an innovative method to prevent the signals binding to the receptors and to attenuate QS. Cyclodextrins (CDs) may form an inclusion complex with the signals, thus reducing the communication (quorum quenching, QQ). A systematic study was performed with α-, β-cyclodextrin, and their random methylated, quaternary amino and polymer derivatives to evaluate and compare their effects on the biofilm formation of Pseudomonas aeruginosa. To examine the concentration-, temperature- and time-dependency of the QQ effect, the CDs were applied at a 0.1–12.5 mM concentration range, and biofilm formation was studied after 6, 24, 48 and 72 h at 22 and 30 °C. According to the results, the QS mechanism was significantly inhibited; the size of the cavity, the structure of the substituents, as well as the monomeric or polymeric character together with the concentration of the CDs have been identified as key influencing factors of biofilm formation. Statistically determined effective concentration values demonstrated outstanding efficiency (higher than 80% inhibition) of α-CD and its random methylated and polymer derivatives both on the short and long term. In summary, the potential value of CDs as inhibitors of QS should be considered since the inhibition of biofilm formation could significantly impact human health and the environment.

Cyclodextrin-Based Nanosponges as Perse Antimicrobial Agents Increase the Activity of Natural Antimicrobial Peptide Nisin

At present, antibiotic resistance is considered a real problem. Therefore, for decades scientists have been looking for novel strategies to treat bacterial infections. Nisin Z, an antimicrobial peptide (AMP), can be considered an option, but its usage is mainly limited by the poor stability and short duration of its antimicrobial activity. In this context, cyclodextrin (CD)-based nanosponges (NSs), synthesized using carbonyldiimidazole (CDI) and pyromellitic dianhydride (PMDA), were chosen for nisin Z loading. To determine the minimum inhibitory of nisin Z loaded on CD-NS formulations, agar well diffusion plates were used. Then, the bactericide concentrations of nisin Z loaded on CD-NS formulations were determined against Gram-positive (Staphylococcus aureus) and -negative (Escherichia coli) bacteria, using microdilution brain heart infusion (BHI) and tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). The minimum and bactericide inhibitory values of the nisin complex with NSs were potentially decreased against both bacteria, compared with the nisin-free sample, while the nisin complex with β-CD showed lower antibacterial activity. The antimicrobial effect was also demonstrated by free NSs. Furthermore, the total viable counts (TVCs) antibacterial experiment indicated that the combination of nisin Z in both PMDA and CDI β-CD-based NSs, especially CDI, can provide a better conservative effect on cooked chicken meat. Generally, the present study outcomes suggest that the cross-linked β-CD-based NSs can present their own antimicrobial potency or serve as promising carriers to deliver and enhance the antibacterial action of nisin Z.

Binding abilities of polyaminocyclodextrins: polarimetric investigations and biological assays

Three polyaminocyclodextrin materials, obtained by direct reaction between heptakis(6-deoxy-6-iodo)-β-cyclodextrin and the proper linear polyamines, were investigated for their binding properties, in order to assess their potential applications in biological systems, such as vectors for simultaneous drug and gene cellular uptake or alternatively for the protection of macromolecules. In particular, we exploited polarimetry to test their interaction with some model p-nitroaniline derivatives, chosen as probe guests. The data obtained indicate that binding inside the host cavity is mainly affected by interplay between Coulomb interactions and conformational restraints. Moreover, simultaneous interaction of the cationic polyamine pendant bush at the primary rim was positively assessed. Insights on quantitative aspects of the interaction between our materials and polyanions were investigated by studying the binding with sodium alginate. Finally, the complexation abilities of the same materials towards polynucleotides were assessed by studying their interaction with the model plasmid pUC19. Our results positively highlight the ability of our materials to exploit both the cavity and the polycationic branches, thus functioning as bimodal ligands.

Improvement of a P450-Based Recombinant Escherichia coli Whole-Cell System for the Production of Oxygenated Sesquiterpene Derivatives

Sesquiterpenes are common constituents of essential oil in plants. Their oxygenated derivatives often possess desirable flavor, fragrance, and pharmaceutical properties. Recently, the CYP264B1-based recombinant Escherichia coli whole-cell system has been constructed for the oxidation of sesquiterpenes. However, limiting factors of this system related to the high volatility of substrates and the suitability of the P450 redox partner need to be addressed. In this work, the improvement of the system was implemented with (+)-α-longipinene as a model substrate. By using 2-hydroxypropyl-β-cyclodextrin and an alternative ferredoxin reductase, the conversion of (+)-α-longipinene was improved 77.1%. Applying the optimized conditions, the yields of the main products were 54.2, 34.2, and 47.2 mg L^-1, corresponding to efficiencies of 82.1, 51.8, and 71.5% for the conversion of (+)-α-longipinene, (-)-isolongifolene, and α-humulene, respectively, at a 200 mL scale. These products were characterized as 12-hydroxy-α-longipinene, isolongifolene-9-one, and 5-hydroxy-α-humulene, respectively, by nuclear magnetic resonance spectroscopy.

Targeted gene delivery by new folate-polycationic amphiphilic cyclodextrin-DNA nanocomplexes in vitro and in vivo

AIM

Development and evaluation of a new targeted gene delivery system by first preforming self-assembled nanocomplexes from a polycationic amphiphilic cyclodextrin (paCD) and pDNA and then decorating the surface of the nanoparticles with folic acid (FA).

EXPERIMENTAL SECTION

The cyclodextrin derivative (T2) is a tetradecacationic structure incorporating 14 primary amino groups and 7 thioureido groups at the primary face of a cyclomaltoheptaose (β-CD) core and 14 hexanoyl chains at the secondary face.

RESULTS AND CONCLUSIONS

T2 complexed and protected pDNA (luciferase-encoding plasmid DNA, pCMVLuc) and efficiently mediated transfection in vitro and in vivo with no associated toxicity. The combination of folic acid with CDplexes afforded ternary nanocomplexes (Fol-CDplexes) that enhanced significantly the transfection activity of pCMVLuc in human cervix adenocarcinoma HeLa cells, especially when formulated with 1 μg FA/μg DNA. The observed transfection enhancement was associated to specific folate receptor (FR)-mediated internalization of Fol-CDplexes, as corroborated by employing a receptor-deficient cell line (HepG2) and an excess of free folic acid. The in vivo studies, including luciferase reporter gene expression and biodistribution, indicated that 24h after intravenous administration of the T2-pDNA nanocomplexes, transfection takes part mainly in the liver and partially in the lung. Interestingly, the corresponding Fol-CDplexes lead to an increase in the transfection activity in the lung and the liver compared to non-targeted CDplexes. Folate-CDplexes developed in this study have improved transfection efficiency and although various methods have been used for the preparation of ligand-DNA-complexes, covalent binding is usually needed and insoluble aggregates are formed unless the concentration of the components is minimized. However, the complexes developed by first time in this work were prepared by simple mixing. The synthetic nature of this formulation provides the potential of flexibility in terms of composition and the capability of inexpensive and large-scale production of the complexes. These nanovectors may be an adequate alternative to viral vectors for gene therapy in the future.

Cyclodextrin-based gene delivery systems

Cyclodextrin (CD) history has been largely dominated by their unique ability to form inclusion complexes with guests fitting in their hydrophobic cavity. Chemical funcionalization was soon recognized as a powerful mean for improving CD applications in a wide range of fields, including drug delivery, sensing or enzyme mimicking. However, 100 years after their discovery, CDs are still perceived as novel nanoobjects of undeveloped potential. This critical review provides an overview of different strategies to promote interactions between CD conjugates and genetic material by fully exploiting the inside-outside/upper-lower face anisotropy of the CD nanometric platform. Covalent modification, self-assembling and supramolecular ligation can be put forward with the ultimate goal to build artificial viruses for programmed and efficient gene therapy (222 references).

Recent Findings Concerning PAMAM Dendrimer Conjugates with Cyclodextrins as Carriers of DNA and RNA

We have evaluated the potential use of various polyamidoamine (PAMAM) dendrimer [dendrimer, generation (G) 2-4] conjugates with cyclodextrins (CyDs) as novel DNA and RNA carriers. Among the various dendrimer conjugates with CyDs, the dendrimer (G3) conjugate with α-CyD having an average degree of substitution (DS) of 2.4 [α-CDE (G3, DS2)] displayed remarkable properties as DNA, shRNA and siRNA delivery carriers through the sensor function of α-CDEs toward nucleic acid drugs, cell surface and endosomal membranes. In an attempt to develop cell-specific gene transfer carriers, we prepared sugar-appended α-CDEs. Of the various sugar-appended α-CDEs prepared, galactose- or mannose-appended α-CDEs provided superior gene transfer activity to α-CDE in various cells, but not cell-specific gene delivery ability. However, lactose-appended α-CDE [Lac-α-CDE (G2)] was found to possess asialoglycoprotein receptor (AgpR)-mediated hepatocyte-selective gene transfer activity, both in vitro and in vivo. Most recently, we prepared folate-poly(ethylene glycol)-appended α-CDE [Fol-PαC (G3)] and revealed that Fol-PαC (G3) imparted folate receptor (FR)-mediated cancer cell-selective gene transfer activity. Consequently, α-CDEs bearing integrated, multifunctional molecules may possess the potential to be novel carriers for DNA, shRNA and siRNA.