The development of materials toward ppb-level nitric oxide (NO) sensing at room temperature remains in high demand for the monitoring of respiratory inflammatory diseases. In order to find an iron-containing molecule without steric hindrance to combine with graphene for room temperature NO gas sensing, here a supramolecular assembly of ferrocene (Fc) and reduced graphene oxide (rGO) was designed and prepared for NO sensing. The assembly of Fc/rGO was characterized using FT-IR, TEM, and XPS measurements. The Fc/rGO-based sensors exhibited superior NO sensing properties at room temperature including high response (R_a/R_g = 1.73, 1 ppm), high selectivity against other exhaled gases, reliable repeatability and stability (less than 4 % decrease after 40 days). A practical limit of detection (LOD) of 200 ppb was achieved. The theoretical simulation demonstrates that ferrocene is assembled via π-π interaction with rGO in edge-to-face configuration which provides relatively lower energy than face-to-face configuration does for the whole assembly. It was first verified that the enhanced adsorption capacity and the charge transfer between NO and Fc/rGO would result in improvement of the assembly's sensitivity toward NO after ferrocene was assembled with graphene. This work provides a fresh approach of anchoring iron on graphene for gas sensing via supramolecular methods.

Achieving high-performance, low-power gas detection at room temperature is critical to safety and energy efficiency, and the key is to deeply explore the interaction mechanisms between sensitive materials and gases. In this work, a magnetic field-assisted strategy is developed to achieve high-performance, low-power NO₂ sensing with the Fe₃GaTe₂ at room temperature. Fe₃GaTe₂ nanoflakes are obtained from green solvents using ultrasound-assisted liquid phase exfoliation. The experimental results confirming that the Fe₃GaTe₂ nanoflakes sensor demonstrates an excellent response (S = 16 for 10 ppm NO₂, 1.4 times higher than that without magnetic field), a lower actual detection limit (50 ppb) and a low-power consumption (0.25 nW) under 21 mT magnetic field at room temperature. Combining theoretical calculations and quasi in situ XPS, it is indicated that Fe is the main electron donor and serves as the main response site for NO₂. Magnetic field-enhancing effect for gas sensing is revealed via comparing the in situ field-dependent magnetization curves of Fe₃GaTe₂ in air and NO₂. It is found for the first time that the enhancement of gas sensing is mainly attributed to the gas adsorption magnetic variation effect (GAMVE) which generates in NO₂. This study provides a strategy of GAMVE-driven sensing for next-generation gas sensors.

To develop multifunctional small-molecule prodrugs is highly desirable for cancer treatment but remains challenging in intrinsic traceability. As an acid-cleavable linkage, a Schiff bases benefiting from its distinctive fluorescence quenching ability was selected to prepare a small-molecule prodrug with cancer-targeted and self-indicating. In this study, we designed and developed a multifunctional self-assembled nanobomb of amphiphilic TPE-Lenalidomide prodrug, which comprises a hydrophobic aggregation-induced emission (AIE) probe 4-(1,2,2-triphenylvinyl)benzaldehyde (TPE-CHO) and a hydrophilic anticancer drug Lenalidomide via a Schiff base linkage. We investigated the synergistic effect of d-PET and C═N isomerization which would keep the fluorescence of TPE-Lenalidomide in the “always off” state by density functional theory (DFT) calculation. Once reaching the pathological site, such a vesicular nanobomb of TPE-Lenalidomide will be acidolyzed to release the AIE probe and Lenalidomide molecules simultaneously, consequently realizing high-efficiency effects of tumor imaging and cancer therapy (cell viability: normal cell L929, ∼79.49%; cancer cell 4T1, ∼27.08%; p = 0.000118). This work may pave an avenue to prepare small-molecule prodrugs for tumor-targeted diagnosis and cancer therapy.

It is a great challenge to develop efficient room-temperature sensing materials and sensors for nitric oxide (NO) gas, which is a biomarker molecule used in the monitoring of inflammatory respiratory diseases. Herein, Hemin (Fe (III)-protoporphyrin IX) is introduced into the nitrogen-doped reduced graphene oxide (N-rGO) to obtain a novel sensing material HNG-ethanol. Detailed XPS spectra and DFT calculations confirm the formation of carbon–iron bonds in HNG-ethanol during synthesis process, which act as electron transport channels from graphene to Hemin. Owing to this unique chemical structure, HNG-ethanol exhibits superior gas sensing properties toward NO gas (R_a/R_g = 3.05, 20 ppm) with a practical limit of detection (LOD) of 500 ppb and reliable repeatability (over 5 cycles). The HNG-ethanol sensor also possesses high selectivity against other exhaled gases, high humidity resistance, and stability (less than 3% decrease over 30 days). In addition, a deep understanding of the gas sensing mechanisms is proposed for the first time in this work, which is instructive to the community for fabricating sensing materials based on graphene-iron derivatives in the future.

Graphene foams are promising three-dimensional (3D) architectures with the combination of the intrinsic nature of graphene and unique cellular structures for various realms. Herein, a facile technique is developed by combining supramolecular assembly with lyophilization to functionalize graphene with donor−π-acceptor (D−π-A) molecules and then massively transform the two-dimensional (2D) plane nanosheets into 3D foams. The as-prepared gas sensors work at room temperature (RT) and reveal comprehensive gas sensing performance with an ultrahigh response (R _a/R _g = 3.2, 10 ppm), excellent selectivity, and reliable repeatability toward NO ₂. Notably, a gas sensing enhancement mechanism with density functional theory (DFT) calculations is proposed to unravel the synergetic effect of the “Greater Electron Transferring Area” and the specific 3D foam structure for the enhancement of charge transfer and NO ₂ adsorption. The combination of supramolecular assembly and the lyophilization technique provides a strategy to prepare 3D architectural graphene-based materials for high-performance gas sensors and chemical trace detectors.