Sijia Sun,Chaozheng Liu,Shuai Zhang,Qinglin Wu,Dan Tian,Changtong Mei,Mingzhu Pan
Regulating structural phase transitions of metal insulator transition (MIT) correlated materials is an ideal approach to modulate their properties. However, due to phase transition hysteresis, ultrasensitive electron transition is difficult to achieve. Here, we develop a convenient method via Fe ions surface doping-induced oxygen vacancies (OVs) at the Ti 3 O 5 surface to enable ultrasensitive electronic transitions. The Fe doping promotes the formation of free electrons , which is attributed to the reduced bandwidth, making it relatively easy for valence band electrons to leap to the conduction band . The formation of OVs increase the electron concentration and enhance the electronic conductivity (2.49×10 −4 S/cm) at low temperatures, resulting in an ultrasensitive sensing over a wide temperature range before metal insulator transition. This unique property facilitates its application in fire warning with ultrasensitive sensing (response time 0.63 s, and response temperature 150 °C) and good durability. Moreover, the as-obtained MIT correlated material with rich-OVs structure exhibits excellent oxygen sensing and photothermal conversion properties. These results offer a novel design for MIT correlated materials and provide an innovative insight for modulating their multifunctional properties.
An ultrasensitive and enzyme-free sensing platform was designed for sensitive detection of anterior gradient homolog 2 (AGR2) based on the fluorescence quenching of gold nanoparticles (AuNPs) coupled with hybridization chain reaction (HCR) amplification. To construct the sensor, two fluorophore labeled hairpin probes (HP 1 and HP 2 ) that contained the sticky tails were designed, and AGR2 aptamer was used as an initiator for the happen of HCR between HP 1 and HP 2 to form a long nicked dsDNA duplex. Such DNA duplex could not adsorb onto the surface of AuNPs, and a strong fluorescence signal appeared due to the label of HP 1 and HP 2 with fluorophore. In the presence of AGR2, AGR2 aptamer would specifically recognize with it and accordingly could not trigger the happen of HCR. As a result, the sticky tails of HP 1 and HP 2 would adsorb onto the surface of AuNPs to bring the fluorophore into the close proximity of the AuNPs, and lead to the quenching of the fluorescence signal. By using such method, AGR2 could be sensitively detected in the range of 5.0 pM–1.0 nM based on monitoring the decrease of the fluorescence signal. Importantly, the assay could realize the detection of AGR2 effectively in diluted human serum samples.
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