betadex and 11-mercaptoundecanoic-acid

Controllable release of dopamine (DA) is worth studying for its significant in physiological metabolic process. β-cyclodextrin/11-mercaptoundecanoic acid self-assembled monolayer (β-CD/MUA SAM) based on hydrogen bonds network was constructed as simulated enzyme-containing biomembrane. DA interacted with β-CD based on intermolecular hydrogen bond and formed inclusion complexes in SAM, namely DA@β-CD/MUA SAM. The desorption process of DA from DA@β-CD/MUA SAM revealed the release behavior of DA from enzyme-containing biomembrane at molecular level. Positive biased potential as external stimulus was applied at DA@β-CD/MUA SAM, reducing the negative charge density of SAM. The decrease of negative charge density of SAM resulted in the weakening of hydrogen bond between DA and β-CD, which in turn caused DA to be released. Using scanning electrochemical microscopy, positive biased potential not only had specificity induction for the release of DA, but also was able to monitor the release quantitatively in real time. These results showed that positive biased potential as external stimulus was favorable for the controllable release of DA, suggesting the possible application of biased potential in controllable regulation field.

Topics: beta-Cyclodextrins; Dopamine; Electrochemistry; Fatty Acids; Hydrogen Bonding; Membranes, Artificial; Sulfhydryl Compounds

A novel luminescence probe based on mono-6-amino-β-cyclodextrin (NH2-β-CD) functionalised gold nanoclusters (β-CD-AuNC) was designed for dopamine (DA) detection. The NH2-β-CD molecules were conjugated onto the surface of 11-mercaptoundecanoic acid capped AuNCs (11-MUA-AuNC) via a carbodiimide coupling reaction. The integrity of the β-CD cavities was preserved on the surface of AuNCs and they retained their capability for molecular DA host-guest recognition. DA could be captured by the β-CD cavities to form an inclusion complex in which the oxidised DA could quench the fluorescence of the β-CD-AuNC probe by electron transfer. The probe could be used to quantify DA in the range of 5-1000 nM with a detection limit of 2 nM. This sensitivity was 1-2 orders of magnitude higher than that in previously reported methods. Interference by both ascorbic acid (AA) and uric acid (UA) was not observed. Therefore, the β-CD-AuNC probe could be directly used to determine the DA content in biological samples without further separation. This strategy was successfully applied to a DA assay in spiked human serum samples and it exhibited remarkable accuracy, sensitivity and selectivity.

Topics: beta-Cyclodextrins; Dopamine; Dopamine Agents; Fatty Acids; Gold; Humans; Limit of Detection; Luminescence; Luminescent Agents; Luminescent Measurements; Metal Nanoparticles; Sulfhydryl Compounds