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Creative Biostructure is a professional institution for all kinds of analysis for drug carriers. Our liposome platform is equipped with advanced facilities and specialized scientists for cyclodextrin analytical service to characterize cyclodextrins and cyclodextrin inclusion complex.
Why Cyclodextrin analytical service is important?
Cyclodextrin molecules are cyclic oligosaccharides. Cyclodextrins with six to eight α-D-glucopyranose units are denoted as α-, β- and γ-Cyclodextrins respectively. Besides, over 1500 different cyclodextrin derivatives have been described in the literature. Therefore, it becomes necessary to characterize and identify their chemical structure to make sure they will perform as needed. Both cyclodextrin and its derivatives have great potential to form complex with guest molecules, such as drugs, steroids, ionic liquids and dyes. It becomes crucial to characterize physicochemical properties of cyclodextrins and cyclodextrin inclusion complex because different cyclodextrins and their derivatives are characterized with different ability for guest molecule solubilization and stabilization.
Figure 1. Schematic illustration of the formation of an inclusion complex between a cyclodextrin (host) and a guest. (Molecules 2018, 23(5), 1204)
Cyclodextrin analytical service and methods
Cyclodextrin identification and purity analysis
Quality control of cyclodextrin involves identity test, degree of substitution determination and residual, solvent analyses and so on.
NMR: A few methods can be used to determine the average degree of substitution (DS) for a modified cyclodextrin. NMR is the most frequently used method and involves comparing the NMR signal for anomeric C-1 or its respective hydrogen to signal(s) distinct to the substituent.
TLC: The most widely used routine test for identiﬁcation of water soluble CDs is TLC under controlled conditions.
HPLC: HPLC is the best way to analyze the small difference of heterogeneous derivatives.
Scanning electron microscopy (SEM) is the most widely used method for particle morphology analysis. In Creative biostructure, we offer analytical service for cyclodextrin, guest, their physical mixture and the inclusion complex.
Determination of binding constant (Kf) values of cyclodextrin inclusion complex
UV-Visible spectroscopy is a direct titration method to determine Kf. CDs will be titrated in a fixed concentration of guest molecules, the absorbance of guest molecules will be monitored to calculated Kf.
Static Headspace-Gas Chromatography (SH-GC):
SH-GC analyses directly the signal of the guest without any interference of the CD signal. Therefore, it is particularly useful to determine Kf values of individual component when more than one guest molecule is present in a complex mixture where the concentration of each component is unknown.
Isothermal Titration Calorimetry (ITC):
ITC is the only technique which gives access to both Kf values and additional thermodynamic data (enthalpy, free enthalpy and entropy).
Phase Solubility Studies:
Determining the saturated concentration of guest in different CD aqueous solutions. Kf value could be calculated from the phase solubility diagram.
Identification of CD-guest complex
High-Performance Liquid Chromatography (HPLC):
Guest molecule is absorbed at the surface of stationary phase, while CD is not. Therefore CD-guest complex is not absorbed by stationary phase after encapsulation and eluted from the HPLC column. Generally mobile phase needs to be modified with CD in order to study the stability of inclusion complexes.
Nuclear magnetic resonance (NMR):
NMR is a powerful to characterize CD complex because it provides direct evidence on the inclusion of guest into CDs. When guest molecules are incorporated into the hydrophobic cavity of CD, it changes the spectrum of hydrogen located inside the cavity of CDs. Besides, NMR has an exclusive advantage to solve the conformation of CD inclusion complex at the same time.
Fourier-transform infrared spectroscopy (FTIR):
FTIR analysis allows the detection of inclusion of guest molecules into CD cavities by comparing the difference of diffraction and infrared (IR) spectra patterns of CD inclusion complex to those of individual diffraction and IR spectra patterns.
X-ray diffractometry diffractograms:
X-ray diffractograms pattern could be used to detect the inclusion of guest into CD cavities. CD-guest complex shares similar pattern with CDs.
Fluorescence spectroscopy is a useful tool to study the CD inclusion complex with fluorescent guest molecule. The fluorescence of guest molecule increases as CD concentration increases due to the variation of the polarity of environment of these fluorophore. Duo to its high sensitivity, fluorescence spectroscopy is method to be used to detect very low guest molecule concentration.
Creative Biostructure is a leading company for authoritative identification and analysis of cyclodextrins and their inclusion complex. We have comprehensive equipment as well as strong scientist team for cyclodextrin synthesis, its related products development and characterization. We are engaged in providing satisfactory service for worldwide researchers. Please contact us to share more details and get a formal quote.