Dual-channel MIRECL portable devices with impedance effect coupled smartphone and machine learning system for tyramine identification and quantification.

We designed a novel, portable, and visual dual-potential molecularly imprinted ratiometric electrochemiluminescence (MIRECL) sensor for tyramine (TYM) detection based on smartphone and deep learning-assisted optical devices. Molecularly imprinted polymer-Ce2Sn2O7 (MIP-Ce2Sn2O7) layers were fabricated by in-situ electropolymerization method as the capture and signal amplification probe. Oxygen vacancies in Ce2Sn2O7 not only enhance the electrochemical redox capability but also accelerate the energy transfer, thereby enhancing the luminescence of cathode ECL. Under optimal conditions, the ECL signals of MIP-Ce2Sn2O7 at the cathode and the anode response of Ru(bpy)32+ was reduced, thus a wide linear range from 0.01 µM to 1000 µM with the detection limit as low as 0.005 µM. Interestingly, combined with an artificial intelligence image recognition algorithm and the principle of optical signal reading by smartphone, the developed MIRECL sensor has been applied to the portable and visual determination of TYM in aquatic samples, and its practicability has been satisfactorily verified.

Bimetallic MOF synergy molecularly imprinted ratiometric electrochemical sensor based on MXene decorated with polythionine for ultra-sensitive sensing of catechol.

Dual-signal ratiometric molecularly imprinted polymer (MIP) electrochemical sensors with bimetallic active sites and high-efficiency catalytic activity were fabricated for the sensing of catechol (CC) with high selectivity and sensitivity. The amino-functionalization bimetallic organic framework materials (Fe@Ti-MOF-NH2), coupled with two-dimensional layered titanium carbide (MXene) co-modified glassy carbon electrode provides an expanded surface while amplifying the output signal through the electropolymerization immobilization of polythionine (pTHi) and MIP. The oxidation of CC and pTHi were presented as the response signal and the internal reference signal. The oxidation peak current at +0.42 V rose with increased concentration of CC, while the peak currents of pTHi at -0.20 V remained constant. Compared to the common single-signal sensing system, this one (MIP/pTHi/MXene/Fe@Ti-MOF-NH2/GCE), a novel ratiometric MIP electrochemical sensor exhibited two segments wide dynamic range of 1.0-300 µM (R2 = 0.9924) and 300-4000 µM (R2 = 0.9912), as well as an ultralow detection limit of 0.54 µM (S/N = 3). Due to the specific recognition function of MIPs and the advantages of built-in correction of pTHi, the prepared surface imprinting sensor presented an excellent performance in selectivity and reproducibility. Besides, this sensor possessed superior anti-interference ability with ions and biomolecules, excellent reproducibility, repeatability, and acceptable stability. Furthermore, the proposed sensing system exhibits high specific recognition in the determination of environmental matrices and biological fluids in real samples with satisfactory results. Therefore, this signal-enhanced ratiometric MIP electrochemical sensing strategy can accurately and selectively analyze and detect other substances.

A handheld multifunctional smartphone platform integrated with 3D printing portable device: On-site evaluation for glutathione and azodicarbonamide with machine learning.

Azodicarbonamide (ADA) in flour can be easily decomposed to semi-carbazide and biuret, exhibiting strong genotoxicity in vitro and carcinogenicity. Glutathione (GSH) can be conjugated with some ketone-containing compounds and unsaturated aldehydes to form toxic metabolites. Here, a novel ratio fluorescence probe based on blue emitting biomass-derived carbon dots (BCDs) and yellow emitting 2,3-diaminophenazine (OxOPD) was prepared for the bifunctional determination of glutathione (GSH) and ADA. This strategy includes three processes: (1) Ag+ oxidizes o-phenylenediamine (OPD) to produce OxOPD. The peak at 562 nm was enhanced, and the peak at 442 nm was reduced due to fluorescence resonance energy transfer (FRET), (2) glutathione binds Ag+ and inhibits the production of OxOPD, (3) ADA oxidizes GSH to form GSSG, resulting in the release of Ag+ by GSH. Therefore, the newly designed ratio fluorescence probe can be based on the intensity ratio (I442/I562) changes and significant fluorescent color changes to detect GSH and ADA. Moreover, a smartphone WeChat applet and a yolov3-assisted deep learning classification model have been developed to quickly detect GSH and ADA on-site based on an image processing algorithm. These results indicate that smartphone ratiometric fluorescence sensing combined with machine learning has broad prospects for biomedical analysis.

Preparation of porous uranium oxide hollow nanospheres with peroxidase mimicking activity: application to the colorimetric determination of tin(II).

Porous uranium oxide hollow sphere nanoparticles were synthesized in ionic liquids under hydrothermal conditions. Various precipitating agents and ionic liquids were investigated to determine their respective impact on the resultant uranium oxide morphologies. Using hydrazine hydrate as precipitating agent and N-butyl pyridinium bromide as templating agent, a porous-hollow structure was created with a surface area of 1958 m2.g-1 and an average pore diameter of 30 nm. The nanoparticles revealed high peroxidase-mimicking activity. This was evaluated by using the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) that is catalytically oxidized by H2O2 to give oxidized TMB (oxTMB) which is blue (with an absorption peak at 652 nm). The material was used as a nanozyme for colorimetric detection of Sn2+. Meanwhile, it is found that BSA strongly improves the catalytic activity of the nanozyme, while Sn(II) inhibits its activity. Thus, a colorimetric method for Sn2+ detection was designed. The method works in the 0.5-100 µM Sn(II) concentration range and has a lower detection limit of 0.36 µM (at S/N = 3). Graphical abstract The catalytic activity of porous-hollow nano-UO2 toward the oxidation of 3,3',5,5'-tetramethylbenzidine by H2O2 is remarkably improved in the presence of bovine serum albumin, while tin(II) inhibits its activity. This finding has been applied to design a method for colorimetric quantification of tin(II) in water samples.

QSAR study for cytotoxicity of diterpenoid tanshinones.

A quantitative structure-activity relationship (QSAR) of a series of tanshinone compounds with cytotoxicity against murine leukemia cell lines P-388 has been studied using density functional theory (DFT) method combined with statistical analysis. Four main independent factors contributing to the cytotoxicity including the maximum molecular electrostatic potential at the SAS surface (SAS (max)), the average nucleophilic superdelocalizability (ANS), the dihedral between ring A and B (u) and the net atomic charge of C (12) (Q(C (12))) were selected by stepwise multiple regression method, then the QSAR equation was established via multiple linear regression (MLR) analysis. These descriptors accounted for 74.2% of the variation in the in vitro biological activity among the tanshinone analogues. The QSAR equation was used to estimate the cytotoxicity for new compounds of this series by calculating the four descriptors. Based on this model, six new compounds with higher cytotoxicity were theoretically designed.

The community structure of human cellular signaling network.

Living cell is highly responsive to specific chemicals in its environment, such as hormones and molecules in food or aromas. The reason is ascribed to the existence of widespread and diverse signal transduction pathways, between which crosstalks usually exist, thus constitute a complex signaling network. Evidently, knowledge of topology characteristic of this network could contribute a lot to the understanding of diverse cellular behaviors and life phenomena thus come into being. In this presentation, signal transduction data is extracted from KEGG to construct a cellular signaling network of Homo sapiens, which has 931 nodes and 6798 links in total. Computing the degree distribution, we find it is not a random network, but a scale-free network following a power-law of P(K) approximately K(-gamma), with gamma approximately equal to 2.2. Among three graph partition algorithms, the Guimera's simulated annealing method is chosen to study the details of topology structure and other properties of this cellular signaling network, as it shows the best performance. To reveal the underlying biological implications, further investigation is conducted on ad hoc community and sketch map of individual community is drawn accordingly. The involved experiment data can be found in the supplementary material.