Studies on the interaction of the aromatic amino acids tryptophan, tyrosine and phenylalanine as well as tryptophan-containing dipeptides with cyclodextrins

Mass Spectrometric Evaluation of β-Cyclodextrins as Potential Hosts for Titanocene Dichloride

“…In the case of bent metallocenes, the cavity size of β-cyclodextrin (6.0-6.5 Å) is suitable for accommodating the Cp-ligands of titanocene dichloride with a diameter of 5.8 Å [1,22,24]. The driving forces of the interaction between the host and guest structures include hydrophobic interactions, electrostatic, van der Waals, as well as hydrogen bonding [1,2,25,30,31]. A key criterion that defines host-guest complexes is that no covalent bonds are broken nor newly formed [22,23,25,26].…”

“…Common techniques used to investigate the stability of cyclodextrin-substrate complexes are calorimetric analysis, nuclear magnetic resonance spectroscopy (NMR), X-ray diffraction, fluorescence spectroscopy, and FTIR. Phase solubility studies and conductometry titration are alternative methods suitable for the investigation of the efficiency of cyclodextrin complexation [2,13,26,31,32]. Furthermore, theoretical approaches and computational modeling have been applied to predict the structure of complexes [4,33].…”

“…Using these methods, the encapsulation of organic molecules including amino acids [2,31,34] and platinum compounds [4,35] has been described, and evidence for the inclusion of bent metallocenes with confirmed antitumor activity (M = Ti, Mo, Nb, V) in cyclodextrins was provided by various authors [12,13,15,29,33,[36][37][38][39]. Depending on the metallocene, its orientation and hydrolysis state for encapsulation was found to be different.…”

Coassembly of Macrocyclic Amphiphiles for Anti-β-Amyloid Therapy of Alzheimer’s Disease

“…34 The GCA-CD coassembly has been employed as a novel heteromultivalent recognition platform, where GCA tends to bind negatively charged amino acids, glutamic acid (E) and aspartic acid (D); CD favors encapsulation of aromatic amino acids, such as tyrosine (Y) and phenylalanine (F). 35 These four amino acids are significant components of Aβ peptides. Guanidinium groups modified at the upper rim of calixarene are known to contribute to cellular uptake, [36][37][38][39][40][41] and therefore, the complexation of Aβ with GCA-CD is expected to promote Aβ uptake by microglia for clearance.…”

Carbon-paste nanocomposites as unconventional gate electrodes for electrolyte-gated organic field-effect transistors: electrical modulation and bio-sensing

“…21 As a first demonstration of sensing applicability, a functionalized CNT-based NC-CPE with gold nanoparticles (Au-NPs) carrying a thiolated b-cyclodextrin (b-CD) has been developed taking into account the well-known supramolecular complex formation between tryptophan (TRP) and b-CD (see Scheme 1). 22,23 Novelly, this approach achieves a renewable sensing gate surface by a simple polishing step owing to the fact that the bio-recognition unit is included directly in the carbon-paste before the electrode mounting. 24 This approach led to an EGOFET bio-sensor exhibiting an excellent linear response (10 À12 to 10 À9 M) with a picomolar (1.0 AE 0.1 pM) detection limit.…”