Amplified solid-state electrochemiluminescence detection of cholesterol in near-infrared range based on CdTe quantum dots decorated multiwalled carbon nanotubes@reduced graphene oxide nanoribbons.

An amplified solid-state electrochemiluminescence (ECL) biosensor for detection of cholesterol in near-infrared (NIR) range was constructed based on CdTe quantum dots (QDs) decorated multiwalled carbon nanotubes@reduced graphene nanoribbons (CdTe-MWCNTs@rGONRs), which were prepared by electrostatic interactions. The CdTe QDs decorated on the MWCNTs@rGONRs resulted in the amplified ECL intensity by ~4.5 fold and decreased onset potential by ~100 mV. By immobilization of the cholesterol oxidase (ChOx) and NIR CdTe-MWCNTs@rGONRs on the electrode surface, a solid-state ECL biosensor for cholesterol detection was constructed. When cholesterol was added to the detection solution, the immobilized ChOx catalyzed the oxidation of cholesterol to generate H2O2, which could be used as the co-reactant in the ECL system of CdTe-MWCNTs@rGONRs. The as-prepared biosensor exhibited good performance for cholesterol detection including good reproducibility, selectivity, and acceptable linear range from 1 µM to 1mM with a relative low detection limit of 0.33 µM (S/N=3). The biosensor was successfully applied to the determination of cholesterol in biological fluid and food sample, which would open a new possibility for development of solid-state ECL biosensors with NIR emitters.

Label-free impedimetric aptasensor for detection of femtomole level acetamiprid using gold nanoparticles decorated multiwalled carbon nanotube-reduced graphene oxide nanoribbon composites.

Gold nanoparticles (Au NPs) decorated multiwalled carbon nanotube-reduced graphene oxide nanoribbon (Au/MWCNT-rGONR) composites were synthesized by a one-pot reaction. By employing the resulting Au/MWCNT-rGONR composites as the support for aptamer immobilization, we developed an ultrasensitive label-free electrochemical impedimetric aptasensor for acetamiprid detection, which was based on that the variation of electron transfer resistance was relevant to the formation of acetamiprid-aptamer complex at the modified electrode surface. Compared with pure Au NPs and MWCNT-rGONR, the Au/MWCNT-rGONR composites modified electrode was the most sensitive aptasensing platform for the determination of acetamiprid. The proposed aptasensor displayed a linear response for acetamiprid in the range from 5×10(-14) M to 1×10(-5) M with an extremely low detection limit of 1.7×10(-14) M (S/N=3). In addition, this impedimetric aptasensor possessed great advantages including the simple operation process, low-cost, selectivity and sensitivity, which provided a promising model for the aptamer-based detection with a direct impedimetric method.

"Signal on" electrochemiluminescence pentachlorophenol sensor based on luminol-MWCNTs@graphene oxide nanoribbons system.

A "signal on" electrochemiluminescence (ECL) sensor for pentachlorophenol (PCP) detection was constructed based on the amplified ECL of luminol at a multiwalled carbon nanotubes@graphene oxide nanoribbons (MWCNTs@GONRs) modified electrode. Due to the good electrocatalytic activity of MWCNTs@GONRs toward luminol system, the oxidation peak current of luminol at the MWCNTs@GONRs modified electrode was enhanced for ~6-fold than that of the bare electrode; and the ECL intensity of luminol was amplified for ~5.3-fold correspondingly. Furthermore, the amplified ECL signal of luminol was linear with the concentration of PCP in the range between 2 pg mL(-1) and 10 ng mL(-1) with a detection limit of 0.7 pg mL(-1) (S/N=3). With the merits of good reproducibility, acceptable stability, wide linear range, low detection limit and simplicity, the proposed luminol ECL sensor showed great potential in the field of analytical applications.