Yubin Ding

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.

Ruthenium Polypyridine Complexes Combined with Oligonucleotides for Bioanalysis: A Review

Ruthenium complexes are among the most interesting coordination complexes and they have attracted great attention over the past decades due to their appealing biological, catalytic, electronic and optical properties. Ruthenium complexes have found a unique niche in bioanalysis, as demonstrated by the substantial progress made in the field. In this review, the applications of ruthenium complexes coordinated with polypyridine ligands (and analogues) in bioanalysis are discussed. Three main detection methods based on electrochemistry, electrochemiluminescence, and photoluminscence are covered. The important targets, including DNA and other biologically important targets, are detected by specific biorecognition with the corresponding oligonucleotides as the biorecognition elements (i.e., DNA is probed by its complementary strand and other targets are detected by functional nucleic acids, respectively). Selected examples are provided and thoroughly discussed to highlight the substantial progress made so far. Finally, a brief summary with perspectives is included.

Protein-directed approaches to functional nanomaterials: a case study of lysozyme

Functional nanomaterials have found wide applications in diverse areas because of their intrinsically different properties compared to their bulk counterparts. To achieve the goal of preparing functional nanomaterials, various strategies have been successfully developed. Among them, the biomolecule-directed approach has been extensively explored to synthesize many functional nanomaterials owing to their programmability, self-assembly and recognition capabilities. This Feature Article highlights the use of lysozyme as a model protein to the direct synthesis of nanomaterials. Future advances in rational de novo design and synthesis of functional nanomaterials with proteins will depend on a deep understanding of the synthetic strategies and the formation mechanisms. This Feature Article discusses the synthesis of nanomaterials with lysozyme in both the solution phase and crystal form. The synthetic strategies, formation mechanisms and wide applications of several kinds of materials, such as metals, oxides, metal sulfides, and composites, are covered. The lessons from this case study will provide invaluable guidance in future materials design using proteins and other biomolecules. Rational design of personalized functional nanomaterials will be possible in the future (366 references).

Acid/Base Switching of the Tautomerism and Conformation of a Dioxoporphyrin for Integrated Binary Subtraction

Compared with most of the reported logic devices based on the supramolecular approach, systems based on individual molecules can avoid challenging construction requirements. Herein, a novel dioxoporphyrin DPH22 was synthesized and two of its tautomers were characterized by single-crystal X-ray diffraction studies. Compound DPH22 exhibits multichannel controllable stepwise tautomerization, protonation, and deprotonation processes through interactions with H(+) and F(-) ions. By using the addition of H(+) and F(-) ions as inputs and UV/Vis absorption values at λ=412, 510, 562, and 603 nm as outputs, the controlled tautomerism of DPH22 has been successfully used for the construction of an integrated molecular level half-subtractor and comparator. In addition, this acid/base-switched tautomerism is reversible, thus endowing the system with ease of reset and recycling; consequently, there is no need to modulate complicated intermolecular interactions and electron-/charge-transfer processes.

A supercharged fluorescent protein based FRET sensing platform for detection of heparin contamination

Development of biosensors for the detection of oversulfated chondroitin sulfate (OSCS), the key contaminant in heparin (Hep), is a greatly demanding but challenging task. In this work, a FRET system for the detection of OSCS was successfully constructed by using supercharged green fluorescent protein (ScGFP) as the energy donor and dye labelled Hep (Hep-RF1) as the energy acceptor. With heparinase treatment, Hep-RF1 was hydrolyzed into small fragments, resulting in quenching of the FRET signal. On the other hand, since OSCS is an inhibitor for heparinase, the presence of OSCS would enable the effective FRET from ScGFP to Hep-RF1 even after heparinase treatment. With this ScGFP based FRET sensing platform, as low as 0.001% (w/w) OSCS in Hep has been successfully detected.