A pressure-colorimetric multimode system with photothermal activated multiple rolling signal amplification for ovarian cancer biomarker detection.

Utilizing the photothermal effect to activate enzyme activity, realize signal conversion and amplification show promising prospects in biosensing. Herein, a pressure-colorimetric multi-mode bio-sensor was proposed through the multiple rolling signal amplification strategy of photothermal control. Under NIR light radiation, the Nb2C MXene labeled photothermal probe caused notable temperature elevation on a multi-functional signal conversion paper (MSCP), leading to decomposition of thermal responsive element and in-situ formation of Nb2C MXene/Ag-Sx hybrid. The generation of Nb2C MXene/Ag-Sx hybrid accompanied with valid color change from pale yellow to dark brown on MSCP. Moreover, the Ag-Sx as a signal amplification element enhanced the NIR light absorption to further improve the photothermal effect of Nb2C MXene/Ag-Sx thereby induce cyclic in situ production of Nb2C MXene/Ag-Sx hybrid with rolling enhanced photothermal effect. Subsequently, the continuously enhanced photothermal effect rolling activated catalase-like activity of Nb2C MXene/Ag-Sx, which accelerated the decomposition of H2O2 and promoted the pressure elevation. Therefore, the rolling-enhanced photothermal effect and rolling activated catalase-like activity of Nb2C MXene/Ag-Sx considerately amplified the pressure and color change. Making full use of multi-signal readout conversion and rolling signal amplification, accurate results can be obtained in a short time, whether in the laboratory or in the patient's homes.

Photoelectrochemical biosensor constructed using TiO2 mesocrystals based multipurpose matrix for trypsin detection.

Herein, a delicate photoelectrochemical biosensor for quantitative detection of trypsin was successfully established by virtue of polyethylenimine-sensitized TiO2 mesocrystal as the photoactive matrix integrated with Boron-doped carbon quantum dots labeled peptide as the signal amplification tags. Specifically, polyethylenimine with fine photo-stability was introduced here as the electron transporting layer to reduce the energy barrier of TiO2 mesocrystal, thereby facilitating the carriers transfer and improving the photocurrent response. Moreover, the Boron-doped carbon dots-peptide bioconjugates could noticeably decrease the photocurrent due to the competitively light harvesting by Boron-doped carbon dots and the steric hindrance of peptide chains, leading to less light energy arriving at the TiO2 mesocrystal and hindering the electrons transfer between the electrolyte and electrode. The anchored conjugates synergistically promoted the decline of photocurrent signal, evidently enhancing the sensitivity of this detection protocol. When trypsin was incubated, the photoelectric signal was obviously re-promoting because arginine-containing peptide chains could be specifically cleaved by trypsin and the Boron-doped carbon quantum dots was affranchised from the electrode, making the most of the previous suppression effects released. Therefore, the intensity of photocurrent signal was proportional to the trypsin concentration in a wide linger range from 1×10-7mg/mL to 1.0mg/mL. This practical and elegant "on-off-on" biosensor with high sensitivity offered a promising scheme to monitor various proteases and the inhibitors screening for early diagnoses of different diseases.

An electrochemical impedimetric sensor based on biomimetic electrospun nanofibers for formaldehyde.

Herein, simple molecular recognition sites for formaldehyde were designed on electrospun polymer nanofibers. In order to improve the conductivity of the electrospun polymer nanofibers, carbon nanotubes were introduced into the resulting nanofibers. By employing these functionalized nanocomposite fibers to fabricate a biomimetic sensor platform, an obvious change caused by recognition between recognition sites and formaldehyde molecules was monitored through electrochemical impedance spectroscopy (EIS). The experimental conditions were optimized and then a quantitative method for formaldehyde sensing in low concentration was established. The relative results demonstrated that the sensor based on biomimetic recognition nanofibers displays an excellent recognition capacity toward formaldehyde. The linear response range of the sensor was between 1 × 10(-6) mol L(-1) and 1 × 10(-2) mol L(-1), with the detection limit of 8 × 10(-7) mol L(-1). The presented research provided a fast, feasible and sensitive method for formaldehyde with good anti-interference capabilities and good stability, which could meet the practical requirement for formaldehyde assay.