Asymmetrically coordinated single-atom iron nanozymes with Fe-N_(1)C_(2)structure:A peroxidase mimetic for melatonin detection

Owing to the unique coordination environment and high atom utilization efficiency,single atom catalysts have been considered as an ideal artificial enzyme to mimic natural enzymes.Herein,single-atom Fe nanozyme anchored on N-doped Ti_(3)C_(2)Tx(Fe SA/N-Ti_(3)C_(2)Tx)with asymmetrically coordinated Fe-N_(1)C_(2)configuration is synthesized by vacancy capture and heteroatom doping strategy,which exhibits excellent peroxidase-like activity.Based on the results of peroxidase catalytic kinetics and X-ray adsorption fine spectroscopy,the Fe-N_(1)C_(2)active sites in Fe SA/N-Ti_(3)C_(2)Tx are responsible for the excellent performance.Furthermore,the developed Fe SA/N-Ti_(3)C_(2)Tx can be employed to quantitative detection of melatonin(MT),which shows a wide linear detection range(0.01-100μM)and an excellent detection limit(7.3 nM)in buffer,0.01-100μM and 7.8 nM in serum samples.Our work proves that MXene-based single atoms can be promising nanozyme in the field of bioassays.

CH_(3)I sensing using yttrium single atom-doped perovskite nanocrystals

Nanocrystals(NCs)of cesium lead halide perovskites are optically unstable,which prevents their use in optical sensors.The combination of perovskite NCs and metal single atoms(SAs)may be a good solution to this issue.Unfortunately,depositing metal SAs on perovskite NCs remains a challenge due to relative weak metal-halide bonds.Herein,we present that,via a photo assisted method using cesium lead halide perovskite NCs as host material to anchor Y single atoms,we successfully synthesize Y SA anchored CsPbBr_(3)NCs(Y-SA/CsPbBr_(3)NCs)with outstanding fluorescence stability through the formation of two Y-O bonds and two Y-Br bonds.In comparison to bare CsPbBr_(3)NCs,Y-SA/CsPbBr_(3)NCs possess more stable optical characteristics.The as-synthesized Y-SA/CsPbBr_(3)NCs can be employed as a colorimetric platform to perform rapid CH_(3)I sensing.Detection limit of 0.044 ppm is exhibited in this approach with excellent anti-interference performance.The YSA/CsPbBr_(3)NCs-based system has been applied to the detection of CH_(3)I in sweet potato samples with satisfying results.

Pafuranones A and B, two dimeric polyketides from a rare marine algae-derived fungus Paraconiothyrium sp.

Pafuranones A(1)and B(2),a pair of new epimeric polyketide dimers,were isolated from the fungus Paraconiothyrium sp.OUCMDZ-3316 associated with the marine algae Enteromorpha prolifera.Their structures,including absolute configurations,were fully elucidated based on spectroscopic analysis,calculated ECD,and chemical methods.Pafuranones A(1)and B(2)possess a rare dimeric furanone skeleton,which might be formed through a conjugate addition of the monomeric units followed by an intramolecular cyclization.