Microanalysis of beta-cyclodextrin and glucosyl-beta-cyclodextrin in human plasma by high-performance liquid chromatography with pulsed amperometric detection

Active-electrode biosensor of SnO2 nanowire for cyclodextrin detection from microbial enzyme

Cyclodextrin (CD) is a conical compound used in food and pharmaceutical industry to complexation of hydrophobic substances. It is a product of microbial enzymes which converts starch into CD during their activity. We aim to detect CD using active-electrode biosensor of SnO₂. They were grown on active electrode by the VLS method. The CD consists of several glucose units which have hydroxyl groups which tend to bind to interface states present in nanowires changing their conductivity. Experimental results of electrical conductivity at different CD concentrations are presented. A model that describes the influence of adsorbed glucose on nanowires and its electrical properties is also presented. Some general observations are performed on the applicability of the CD adsorption method by the nanowire-based biosensor.

A monoclonal antibody to cyclomaltoheptaose (beta-cyclodextrin): Characterization and use for immunoassay of beta-cyclodextrin and its derivatives

Cyclomaltoheptaose (beta-cyclodextrin, beta-CD) is a promising compound for application in various industrial fields because of its ability to entrap various compounds into its hydrophobic cavity. A monoclonal antibody (A7) to beta-CD was generated by using a conjugate of glucosaminylmaltosyl-beta-CD and bovine serum albumin as an antigen. The A7 monoclonal antibody was IgM/kappa and reacted with beta-CD with high specificity. The epitope recognized by the A7 monoclonal antibody seemed to be located on the secondary hydroxyl groups of the rim side of the beta-CD molecule. The dissociation constant of the complex of beta-CD and the immobilized A7 monoclonal antibody was determined to be 1.2 x 10(-4) M. A competitive ELISA using the A7 monoclonal antibody enabled determination of beta-CD and its derivatives with a detection limit of 0.05 muM. This immunoassay was useful to determine beta-CD in biological fluids such as human plasma and urine after appropriate pretreatment of the samples.

Simultaneous quantification of different cyclodextrins and Gantrez by HPLC with evaporative light scattering detection

A rapid and simple HPLC method with evaporative scattering detection (ELSD) has been developed for the separation and quantitation of beta-cyclodextrin (beta-CD), 2-hydroxypropyl-beta-cyclodextrin (2-HP-beta-CD) and poly(methyl vinyl ether-co-maleic anhydride) (Gantrez). Separation was carried out on a Zorbax Eclipse XDB-Phenyl narrow bore column, with water-acetonitrile in gradient elution as mobile phase at a flow-rate of 0.25 ml/min. Polyethylenglycol 6000 was used as internal standard. The limit of quantification was of about 0.2 mg/ml for cyclodextrins and 0.05 mg/ml for Gantrez. The precision did not exceed 7%. This method was successfully applied to the rapid analysis of CD-Gantrez nanoparticle conjugates without interference from other components of the formulation.

High-performance liquid chromatographic determination of 2-hydroxypropyl-gamma-cyclodextrin in different biological fluids based on cyclodextrin enhanced fluorescence

A high-performance size exclusion chromatographic method with analyte enhanced fluorescence detection is described for the analysis of 2-hydroxypropyl-gamma-cyclodextrin (HPGCD) in different biological fluids. The principle of detection was the in situ complexation of 8-anilinonaphthalene-1-sulfonic acid (ANS) by HPGCD. When HPGCD eluted from the column the increased fluorescence was measured at excitation and emission wavelengths of 270 and 512 nm, respectively. Solid-phase extraction cleanup and concentration of samples resulted in higher than 78% recovery of HPGCD for each of the studied biological fluids. Some important details of the method development as well as the validation of the method for rabbit plasma, rabbit aqueous humour, monkey plasma and monkey urine are given. The limits of quantification varied between 1 and 10 nmol/ml (correspond to 1.5-15 microg/ml) depending on the biological matrix used. The method was successfully adapted in another laboratory proving that HPGCD had not absorbed into aqueous humour and plasma after topical application of HPGCD containing eye drop in rabbits.

Fluorescence determination of sulphobutylether-beta-cyclodextrin in human plasma by size exclusion chromatography with inclusion complex formation

A selective method for the determination of sulphobutylether-beta-cyclodextrin (SBECD) in human plasma has been developed and validated over the range 4-200 microg ml(-1). SBECD is extracted from plasma using end-capped cyclohexyl solid phase extraction cartridges. This is followed by high performance size exclusion chromatography with a mobile phase consisting of 1-naphthol (0.1 mM) in methanol-potassium nitrate (0.2 M) (1:9 v/v), 1 ml min(-1). The high aqueous content of the mobile phase quenches the fluorescence of 1-naphthol. However, the naphthol forms an inclusion complex with SBECD. The non-polar 'bucket' environment of the inclusion region restores the fluorescence, which is measured at excitation and emission wavelengths of 290 and 360 nm, respectively, when SBECD elutes from the column.

Pharmacokinetic analysis of 6-monoamino-beta-cyclodextrin after intravenous or oral administration to rats using a specific enzyme immunoassay

We have developed a highly sensitive enzyme immunoassay for 6-monoamino-beta-CD (mono(6-amino-6-deoxy)cyclomaltoheptaose) and its parent compound (beta-CD) with a detection limit in the 100 pg/mL range. The polyclonal antibodies obtained are highly specific for the beta-cyclodextrin core and do not recognize other cyclic cyclodextrins (i.e., alpha- and gamma-CD) or linear analogues. This enzyme immunoassay can be used to quantify 6-monoamino-beta-CD in rat urine and plasma. Using this immunoassay, we have evaluated the main pharmacokinetic parameters of 6-monoamino-beta-CD after iv administration to the rat of a 25 mg/kg dose. Since this method is strictly specific to the native beta-CD form, we have demonstrated that the molecule rapidly disappeared from plasma but is probably distributed in the tissues. The urinary route appears as the predominant way of elimination since almost all the administered drug is recovered in urine. Finally, analysis of the same molecule after oral administration to the rat (25 mg/kg) demonstrates low plasma levels and that about 1% of the administered dose is excreted in urine. These experiments demonstrate the high stability of the beta-CD core irrespective of the method of administration. This immunological method could provide relevant information on the fate of beta-CD and some derivatives for drug delivery using different modes of administration (oral, parenteral, transmucosal, or dermal).

Improvements to in-line desalting of oligosaccharides separated by high-pH anion exchange chromatography with pulsed amperometric detection

High-pH anion exchange chromatography with pulsed amperometric detection (HPAEC/PAD) (1) is routinely used to separate neutral and charged oligosaccharides differing by branch, linkage, and positional isomerism. Oligosaccharides are eluted in 0.1 M NaOH with gradients of sodium acetate (up to 0.25 M). Analyses of HPAEC/PAD-purified oligosaccharides generally require neutralization and removal of eluent salts. To facilitate the process, we designed and produced a cation-exchange system to remove sodium ions (Na+) from the eluent after oligosaccharide detection [the Carbohydrate Membrane Desalter (CMD), with a volatile regenerant]. Exchange of >99.5% of eluent Na+ for hydronium ions (H3O+) within the CMD generates dilute acetic acid (removable by vacuum evaporation). The exchange process desalts up to 0.35 M Na+ at 1.0 ml/min. Oligosaccharides collected after on-line desalting, evaporated and resuspended in their original volume of deionized water contained < or = 350 muM residual Na+ when the eluting sodium concentration was 300 mM. This represents a desalting efficiency of >99.8%. Recovery of neutral and sialylated oligosaccharides under these conditions ranged from 75 to 100%. With the CMD system and postcollection evaporation, HPAEC/PAD can purify oligosaccharides ready for further characterization. As a proof test, oligosaccharides from a human monoclonal antibody were separated by HPAEC/PAD, desalted with the CMD system, dried, and analyzed by matrix-assisted laser desorption-ionization, time-of-flight mass spectrometry.

Liquid chromatographic determination of beta-cyclodextrin derivatives based on fluorescence enhancement after inclusion complexation

A liquid chromatographic method using fluorescence detection for the determination of beta-cyclodextrin (beta CD) and its derivatives is presented. The chromatographic system is based on size-exclusion chromatography with the addition of the fluorophoric compound 1-naphthol to the mobile phase. Detection is based on fluorescence enhancement caused by the formation of inclusion complexes. By incorporating 10(-4) M 1-naphthol in the mobile phase, detection limits of 90, 27, 370 and 37 pmol were obtained for beta CD, hydroxypropyl-beta CD, trimethyl-beta CD and dimethyl-beta CD, respectively. The method was applied to the determination of dimethyl-beta CD in urine: the minimum detectable concentration was 0.2 microgram/ml after preconcentration of 10 ml of urine.