In the present study, thiol b-cyclodextrin (SH-CD) and ethylenediamine b-cyclodextrin (NH 2 -b-CD) were simultaneously grafted on the same interface of an Au NP deposited carboxyl SiC (Au@CSiC)nanocomposite. An electrochemical sensor for the simultaneous determination of nitrophenol isomers (onitrophenol, o-NP; p-nitrophenol, p-NP) using SH-CD and NH 2 -b-CD functionalized Au@SiC (Au@CSiC-SH/NH 2 -CD) nanocomposite was successfully constructed. Differential pulse voltammetry was used to quantify o-NP and p-NP within the concentration range of 0.01-150 mM under the optimal conditions. The detection limit (S/N ¼ 3) of the sensor was 0.019 and 0.023 mM for o-NP and p-NP, respectively, indicating a low detection limit. Interference study results demonstrated that the sensor was not affected in the presence of similar aromatic compounds during the determination of NP isomers, showing high selectivity. The proposed electrochemical sensing platform was successfully used to determine NP isomers in tap water. The low detection limit and high selectivity of the proposed electrochemical sensor were caused by the high surface area, the excellent conductivity, and the more recognized (enriched) NP isomer molecules by SH-b-CD and NH 2 -b-CD of the Au@CSiC-SH/NH 2 -CD nanocomposite.
A turn-on fluorescent sensing platform for labetalol has been developed based on competitive host–guest interaction between p-sulfonated calix[6]arene (SCX6) and target molecule by using SCX6 functionalized MnO2@reduced graphene oxide as a receptor.
Alternative cleavage and polyadenylation (APA) is involved in several important biological processes in animals, e.g. cell growth and development, and cancer progression. The increasing data show that cancer cells are inclined to produce mRNA isoforms with a shortened 3'UTR undergoing APA. For example, the Dicer1 isoform with a shorter 3'untranslated region (3'UTR) was found to be overexpressed in some cancer cells, which may be used as a potential novel prognostic biomarker for cancer. In the present work, a novel electrochemical biosensor for ultrasensitive determination of Dicer1 was designed by using gold nanoparticles and p-sulfonated calix[6]arene functionalized reduced graphene oxide (Au@SCX6-rGO) as nanocarriers. The results showed that the expressions of the shorter 3'UTR (Dicer1-S) both in BT474 and SKBR3 were obviously higher than those of the longer Dicer1 (Dicer1-L) by the constructed biosensor, which agreed well with the result analyzed by the RT-qPCR method. The detection ranges of Dicer1-S and Dicer1-L were 10-10 M and 10-10 M. The LODs were 3.5 and 0.53 fM. The specificity of the proposed biosensor was also very high. For the first time, the expressional analysis of different 3'UTRs caused by APA was studied by an electrochemical method. Moreover, the use of a macrocyclic host for constructing an electrochemical/biosensing platform has rarely been reported. The proposed electrochemical sensing strategy is thus expected to provide a new method for determination of novel biomarkers and a novel method for fast and cheap analysis of APA.
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