betadex and cadmium-sulfide

Nowadays, acquired immunodeficiency syndrome has become a formidable danger to human health, and its early diagnosis is urgent need with the increasing quantity of patients around the world. Herein, we first synthesized beta-cyclodextrin-functionalized CdS nanorods (β-CD@CdS NRs) with high stability and desirable photo-electricity activity, and served as easy-to-assemble building modules to design a novel photoelectrochemical biosensor for human immune deficiency virus (HIV) DNA detection by coupling with catalytic hairpin assembly (CHA)-mediated biocatalytic precipitation and the host-guest interaction between adamantine (ADA) and β-CD. In the presence of HIV DNA, CHA process was triggered with the aid of hairpin DNA1 and ADA-labelled hairpin DNA2, and then generated large amounts of G-quadruplex, which could be formed hemin/G-quadruplex DNAzyme to catalyze 4-chloro-1-naphthol to generate insoluble precipitation on photoelectrode surface, followed by the decreased photocurrent response due to the corresponding stereo-hindrance effect. Under optimized conditions, this biosensor exhibited wide linear dynamic range (10 fM - 1 nM) and low detection limit of 1.16 fM, as well as high sensitivity, excellent stability, and satisfactory feasibility in human-serum samples. Moreover, the prepared β-CD@CdS NRs could be applied to the construction of other advanced sensing platform, showing great prospect in clinical diagnostics.

Topics: beta-Cyclodextrins; Biosensing Techniques; Cadmium Compounds; DNA, Catalytic; DNA, Viral; Electrochemical Techniques; G-Quadruplexes; HIV; HIV Infections; Humans; Limit of Detection; Nanotubes; Sulfides

A sensitive electrochemical aptasensor for thrombin detection is presented based on the host-guest recognition technique. In this sensing protocol, a 15 based thrombin aptamer (ab. TBA) was dually labeled with a thiol at its 3' end and a 4-((4-(dimethylamino)phenyl)azo) benzoic acid (dabcyl) at its 5' end, respectively, which was previously immobilized on one Au electrode surface by AuS bond and used as the thrombin probe during the protein sensing procedure. One special electrochemical marker was prepared by modifying CdS nanoparticle with β-cyclodextrins (ab. CdS-CDs), which employed as electrochemical signal provider and would conjunct with the thrombin probe modified electrode through the host-guest recognition of CDs to dabcyl. In the absence of thrombin, the probe adopted linear structure to conjunct with CdS-CDs. In present of thrombin, the TBA bond with thrombin and transformed into its special G-quarter structure, which forced CdS-CDs into the solution. Therefore, the target-TBA binding event can be sensitively transduced via detecting the electrochemical oxidation current signal of Cd of CdS nanoparticles in the solution. Using this method, as low as 4.6 pM thrombin had been detected.

Topics: Aptamers, Nucleotide; beta-Cyclodextrins; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Metal Nanoparticles; Microscopy, Electron, Transmission; Nuclear Magnetic Resonance, Biomolecular; Sulfides; Thrombin

A fundamental and systematic study on the fabrication of a supramolecularly assembled nanostructure of an organic ligand-capped CdS nanocrystal (NC) and multiple heptamine β-cyclodextrin ((NH(2))(7)βCD) molecules in aqueous solution has been here reported. The functionalization process of presynthesized hydrophobic CdS NCs by means of (NH(2))(7)βCD has been extensively investigated by using different spectroscopic and structural techniques, as a function of different experimental parameters, such as the composition and the concentration of CD, the concentration of CdS NCs, the nature of the NC surface capping ligand (oleic acid and octylamine), and the organic solvent. The formation of a complex based on the direct coordination of the (NH(2))(7)βCD amine groups at the NC surface has been demonstrated and found responsible for the CdS NC phase transfer process. The amine functional group in (NH(2))(7)βCD and the appropriate combination of pristine capping agent coordinating the NC surface and a suitable solvent have been found decisive for the success of the CdS NC phase transfer process. Furthermore, a layer-by-layer assembly experiment has indicated that the obtained (NH(2))(7)βCD functionalized CdS NCs are still able to perform the host-guest chemistry. Thus, they offer a model of a nanoparticle-based material with molecular receptors, useful for bio applications.

Topics: Amines; beta-Cyclodextrins; Cadmium Compounds; Hydrophobic and Hydrophilic Interactions; Microscopy, Electron, Transmission; Nanoparticles; Nanotechnology; Oleic Acid; Phase Transition; Solutions; Solvents; Spectroscopy, Fourier Transform Infrared; Sulfides; Water

The fluorescence of beta-cyclodextrin-modified CdS quantum dots can be reversibly tuned by introducing different substrates in aqueous media.

Topics: beta-Cyclodextrins; Cadmium Compounds; Fluorescence; Quantum Dots; Solubility; Sulfides; Water