Yao Jiang

Silver Nanoclusters with Specific Ion Recognition Modulated by Ligand Passivation toward Fluorimetric and Colorimetric Copper Analysis and Biological Imaging

Silver nanoclusters were synthesized and passivated by glutathione (GSH) ligand, with high aqueous stability and powerful red fluorescence and UV-vis yellow colour. Importantly, the specific recognition of the AgNCs was modulated from Hg2+ ions to Cu2+ ions upon the GSH passivation, of which the unique GSH-Cu2+ chelating reaction could conduct the fluorescence quenching of AgNCs. Strong UV-vis absorbance of GSH-passivated AgNCs could also be realized depending on the Cu2+ levels. Moreover, the Cu2+-induced loss of fluorescence and UV-vis absorbance of GSH-passivated AgNCs could be well restored by using stronger Cu2+ chelating agent. A simultaneous and reversible fluorimetric and colorimetric sensing method was thereby developed for probing Cu2+ ions in blood with high sensitivity and selectivity. Subsequently, the fluorescence-trackable imaging for live tissues and cells was demonstrated towards the analysis Cu2+ ions using GSH-passivated AgNCs as the fluorescent probes. This study indicates that the use of functional ligands like GSH could not only modulate the specific ion recognition of AgNCs, but also endow them the high aqueous stability and powerful red fluorescence towards the wide applications for ion sensing and biological imaging in the complicated media like blood.

Fluorimetric Mercury Test Strips with Suppressed “Coffee Stains” by a Bio-inspired Fabrication Strategy

A fluorimetric Hg2+ test strip has been developed using a lotus-inspired fabrication method for suppressing the “coffee stains” toward the uniform distribution of probe materials through creating a hydrophobic drying pattern for fast solvent evaporation. The test strips were first loaded with the model probes of fluorescent gold-silver nanoclusters and then dried in vacuum on the hydrophobic pattern. On the one hand, here, the hydrophobic constraining forces from the lotus surface-like pattern could control the exterior transport of dispersed nanoclusters on strips leading to the minimized “coffee stains”. On the other hand, the vacuum-aided fast solvent evaporation could boost the interior Marangoni flow of probe materials on strips to expect the further improved probe distribution on strips. High aqueous stability and enhanced fluorescence of probes on test strips were realized by the hydrophilic treatment with amine-derivatized silicane. A test strips-based fluorimetry has thereby been developed for probing Hg2+ ions in wastewater, showing the detection performances comparable to the classic instrumental analysis ones. Such a facile and efficient fabrication route for the bio-inspired suppression of “coffee stains” on test strips may expand the scope of applications of test strips-based “point-of-care” analysis methods or detection devices in the biomedical and environmental fields.

Crosslinking catalysis-active center of hemin on the protein scaffold toward peroxidase mimic with powerful catalysis

An enzyme mimic synthesis protocol has been proposed by simply cross-linking the redox active center of peroxidase onto a protein scaffold. Colorimetric assays and kinetic studies indicate that the developed peroxidase mimic can present much stronger catalysis and better aqueous stability than native hemin.

Mesoporous Silver–Melamine Nanowires Formed by Controlled Supermolecular Self-Assembly: A Selective Solid-State Electroanalysis for Probing Multiple Sulfides in Hyperhaline Media through the Specific Sulfide–Chloride Replacement Reactions

Mesoporous silver-melamine (Ag-MA) nanocomposites were synthesized simply by the controlled supermolecular self-assembly process to be modified onto the electrodes for the electroanalysis of multiple sulfides in blood or wastewater. It was discovered that Ag-MA nanocomposites could be prepared with various morphological structures depending on the Ag-to-MA ratios. Furthermore, the electrodes modified with mesoporous Ag-MA nanowires could display stable and sharp electrochemical peaks of solid-state AgCl at a considerably low potential approaching zero, thus circumventing any interference from possibly coexisting electroactive substances in the background. More importantly, the yielded AgCl signals would decrease selectively induced by sulfides through the specific sulfide-chloride replacement reactions toward the transferring of AgCl into non-electroactive Ag2S. The developed electroanalysis strategy could facilitate the selective detection of multiple sulfides (i.e., S2- or H2S, Sx2-, cysteine, and S2O32-) in the complicated media with high-level salts such as blood and wastewater, showing a linear concentration range from 0.50 to 512 μM as exemplified for S2- ions in blood. Such an electroanalysis device equipped with the portable electrochemical transducer can be tailored for the field-deployable monitoring of a variety of sulfides in clinical and environmental analysis fields.

Encapsulating chromogenic reaction substrates with porous hydrogel scaffolds onto arrayed capillary tubes toward a visual and high-throughput colorimetric strategy for rapid occult blood tests

A porous hydrogel scaffold was fabricated for the first time to encapsulate chromogenic reaction substrates onto arrayed capillary tubes, resulting in a visual and high-throughput colorimetric method for rapid occult blood tests (OBTs) based on the hemoglobin (Hgb)-catalyzed chromogenic reactions. Gelatin (Gel), a biodegradable and biocompatible polymer, was introduced to couple with p-hydroxyphenyl-propionic acid (HPA) yielding the Gel-HPA hydrogel scaffold. Chromogenic reaction substrates of 3,3,5,5-tetramethylbenzidine and H2O2 were then encapsulated into the Gel-HPA matrix and further attached onto the amine-derivatized capillary tubes by forming porous chromogenic composites through the HPA-mediated bridging of Gel by the oxidization of H2O2. The developed Hgb catalysis-based OBT platform can facilitate the detection of Hgb with the level down to 0.125 μg mL-1 in human excreta (i.e., saliva, urine, and feces) through capillarity-enabled automatic sampling. This simple, sensitive, selective, and high-throughput colorimetric method may be promising for the bedside OBT for point-of-care monitoring and rapid diagnostics of clinical bleeding diseases.

Fluorimetric and colorimetric analysis of total iron ions in blood or tap water using nitrogen-doped carbon dots with tunable fluorescence

Fluorimetric and colorimetric analysis strategies have been developed for simultaneously probing Fe3+ and Fe2+ ions in blood or tap water using nitrogen-doped carbon dots (N-Cdots). Herein, the N-Cdots were prepared using melamine by a neutralization heat reaction one-step synthesis route showing high aqueous solubility and environmental stability. Importantly, unlike common carbon dots (Cdots) that generally display one emission of blue fluorescence, they can display excitation-dependent tunable emissions. Moreover, the bright blue-green fluorescence of N-Cdots could be specifically quenched by Fe3+ or Fe2+ ions simultaneously, showing a color change. Herein, the fluorescent quenching of N-Cdots is thought to result from the aggregation of N-Cdots triggered by the unique coordination interactions between Fe3+ or Fe2+ ions and amine and amide groups of N-Cdots. The developed analysis strategies were employed for the evaluation of the total iron levels in blood or tap water, with a detection limit down to about 5.0 nM, exemplified for Fe3+ ions. These strategies could be promising for use in practical applications for the clinical diagnosis of iron-relative diseases (i.e., anemia and cancers) and environmental monitoring of iron pollution. In addition, this one-step neutralization heat reaction route as a facile green synthesis candidate may be tailored for the fabrication of a variety of Cdots, especially those with doped heteroatoms (i.e., nitrogen) for extensive applications in biomedical and environmental fields.