In this paper, single-crystalline α-Si3N4 nanospheres with uniform size of ∼50 nm are successfully synthesized by using a radio frequency (RF) thermal plasma system in a one-step and continuous way. All Si3N4 nanoparticles present nearly perfect spherical shape with a narrow size distribution, and the diameter is well-controlled by changing the feeding rate. Compact Si3N4/PR (PR = phenolic resin) composites with high thermal conductivity, excellent temperature stability, low dielectric loss tangent, and enhanced breakdown strength are obtained by incorporating the as-synthesized Si3N4 nanospheres. These enhanced properties are the results of good compatibility and strong interfacial adhesion between compact Si3N4 nanospheres and polymer matrix, as large amount of Si3N4 nanospheres can uniformly disperse in the polymer matrix and form thermal conductive networks for diffusion of heat flow.
In this contribution, an electrochemical aptameric sensing scheme for the sensitive detection of small molecules is proposed using adenosine as a target model. A ferrocene (Fc)-functionalized thiolated aptamer probe is adapted and immobilized onto an electrode surface. Introducing a recognition site for EcoRI into the aptamer sequence not only suppresses the peak current corresponding to blank sample but also provides a signal-on response mechanism. In the absence of adenosine, the aptamer can fold into a hairpin structure and form a cleavable double-stranded region. Fc is capable of being removed from electrode surface by treatment with endonuclease, and almost no peak current is observed. The adenosine/aptamer binding induces the conformational transition of designed aptamer, dissociating the cleavable double-stranded segment. Therefore, the integrated aptamer sequence is maintained when exposing to endonuclease, generating a peak current of Fc. Utilizing the present sensing scheme, adenosine even at a low concentration can give a detectable current signal. Thus, a detection limit of 10−10 M and a linear response range from 3.74 × 10−9 to 3.74 × 10−5 M are achieved. The proposed proof-of-principle of a novel electrochemical sensing is expected to extend to establish various aptameric platforms for the analysis of a broad range of target molecules of interest.
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