Shichao Lin

Monitoring of Heparin Activity in Live Rats Using Metal–Organic Framework Nanosheets as Peroxidase Mimics

Metal-organic framework (MOF) nanosheets are a class of two-dimensional (2D) porous and crystalline materials that hold promise for catalysis and biodetection. Although 2D MOF nanosheets have been utilized for in vitro assays, ways of engineering them into diagnostic tools for live animals are much less explored. In this work, a series of MOF nanosheets are successfully engineered into a highly sensitive and selective diagnostic platform for in vivo monitoring of heparin (Hep) activity. The iron-porphyrin derivative is selected as a ligand to synthesize a series of archetypical MOF nanosheets with intrinsic heme-like catalytic sites, mimicking peroxidase. Hep-specific AG73 peptides as recognition motifs are physically adsorbed onto MOF nanosheets, blocking active sites from nonspecific substrate-catalyst interaction. Because of the highly specific interaction between Hep and AG73, the activity of AG73-MOF nanosheets is restored upon the binding of Hep, but not Hep analogues and other endogenous biomolecules. Furthermore, by taking advantages of biocompatibility and diagnostic property enabled by AG73-MOF nanosheets, the elimination process of Hep in live rats is quantitatively monitored by coupling with microdialysis technology. This work expands the biomedical applications of 2D MOF nanomaterials and provides access to a promising in vivo diagnostic platform.

Deciphering the quenching mechanism of 2D MnO2 nanosheets towards Au nanocluster fluorescence to design effective glutathione biosensors

Two-dimensional (2D) nanomaterials (such as 2D MnO2 nanosheets) have received increasing attention due to their unique photophysical properties, rich redox chemistry, excellent colloidal stability, good biocompatibility, etc. Recently, numerous sensing platforms have been reported by exploring the 2D MnO2 nanosheet mediated fluorescence quenching towards fluorophores and/or redox reactions between MnO2 and reductive targets. Though various fluorophores have been used in 2D MnO2 nanosheet based turn-on sensing systems, ultrasmall metal nanoclusters have not been exploited yet. Furthermore, the quenching mechanisms of MnO2 nanosheets towards various fluorophores have remained elusive. To address these issues, we studied the quenching of Au nanocluster fluorescence by 2D MnO2 nanosheets. First, we demonstrated that 2D MnO2 nanosheets were effective quenchers towards the fluorescence of metal nanoclusters (e.g., AuNC@BSA, the bovine serum albumin stabilized Au nanocluster). We further revealed that both dynamic and static quenching effects played critical roles in the quenching process while fluorescence resonance energy transfer (FRET) and inner filter effect (IFE) only played very minor roles in the quenching process. Finally, we developed a turn-on sensing strategy for detection of glutathione (GSH), an important antioxidant with good sensitivity and selectivity. This work provides useful insights in understanding the mechanisms of nanomaterial-induced fluorescence quenching. It also paves a way to design turn-on fluorescent sensors for important reductive targets.

Investigation of Thermal Diffusivity of Nano‐Structured TiO2 Films

We investigate the thermal diffusivity of nano‐structured TiO2 and TiO2 with 3% ZnFe2O4 ceramic films (nm films) sputtered on a 〈111〉 cut Si substrates by using the Mirage effect method. Two series of films are prepared by the magneto‐rf‐spurt method. The investigation results show that: The thermal diffusivity of nano‐structured film depends on the thickness of film and the annealing temperature. The thicker the film, the lower thermal diffusivity of the sample is. The value of thermal diffusivity increases with the increasing of the annealing temperature. It means that the thermal diffusivity depends on the phase structure of the film. The detail results, analyses and discussions will be presented in this paper.

Study on the influence of fraction of SiC particles on the thermal diffusivity of composite

We investigate the influence of the volume fraction of silicon carbide particles (SiCp) on the thermal diffusivity of Al matrix reinforced by SiCp composite by using mirage effect. A series of silicon carbide particles reinforced LY12 aluminum alloy (SiCp/LY12-Al) composites with six volume fractions of SiCp are used as samples. The results show that the value of the thermal diffusivity decreases with the increasing of the volume fraction of SiCp. The relative thermal diffusivity changes can be reached to 33%. We also calculation the thermal diffusivities for those composites based on several theoretical models. The detailed results and discussions are presented in this paper.

Thermal wave determination of the thermal diffusivity of composite ZrO2/Al-Si alloy

We improve our mirage detection system including the hardware and software respectively. We investigate the thermal diffusivity of Al matrix reinforced by ZrO2 particles composite by using this system. A series of ZrO2 particles reinforced A356 aluminum alloy (ZrO2/A356Al) composites are used as samples. The results show that the value of the thermal diffusivity decreases with the increasing of the fraction of ZrO2 particles. The relative thermal diffusivity changes can be reached to 28.6%. We also calculation the thermal diffusivities for those composites based on several theoretical models. The detailed results and discussions are presented in this paper.