Synthesis of near-Infrared Quantum Dots in Cultured Cancer Cells

Intracellular synthesis of near-infrared fluorescent silver sulfide quantum dots in HepG2 cancer cells is demonstrated. By delivering quantum dot precursors into cultured hepatoma carcinoma cells (HepG2 cells), silver sulfide quantum dots with emission efficiency qualified for in vivo imaging were successfully synthesized with the aid of endogenous glutathione in the cells

Ag₂S Quantum Dots Conjugated Chitosan Nanospheres toward Light-Triggered Nitric Oxide Release and Near-Infrared Fluorescence Imaging

Nanoscaled light-triggered nitric oxide (NO) delivery vehicles with the ability of near-infrared (NIR) fluorescence imaging was presented, which consisted of chitosan (CS)-based <i>S</i>-nitrosothiols (SNO) and encapsulated silver sulfide quantum dots (Ag₂S QDs). CS-SNO compounds that bore NO-storing functional groups were prepared via amino modification of chitosan. Water-soluble Ag₂S QDs were synthesized and conjugated with the CS-SNO compounds with the aid of ethylenediaminetetraacetic acid (EDTA). The biocompatible Ag₂S-CS-SNO nanospheres, with dimension of ∼117 nm, exhibited bright NIR fluorescence and satisfactory photostability under NIR irradiation. The Ag₂S-CS-SNO nanospheres could release NO under irradiation of UV or visible light at physiological pH and temperature yet would hardly release NO if NIR irradiation was applied. Cell imaging was successfully performed, demonstrating that the Ag₂S-CS-SNO nanospheres could emit readily observable NIR fluorescence and release NO in living cells. The NIR fluorescence imaging of the Ag₂S-CS-SNO nanospheres did not interfere with the light-triggered NO release from them, which would provide new perspectives for the application of multifunctional nanostructured materials in diagnostics and imaging

Biotransformation of HSP into 2,5-DHP by HSP hydroxylase from <i>A. tumefaciens</i> S33.

<p>Effects of temperature (a) and pH (b) on the enzymatic formation of 2,5-DHP (<i>squares</i>) from HSP (<i>circles</i>). (a) The reactions were carried out in 50 mM sodium phosphate (pH 8.0) at the temperature indicated. (b) The reactions were performed at 35°C in sodium phosphate buffer at pH indicated. (c) The reaction was performed in 50 mM sodium phosphate (pH 8.0) at 35°C. The values are means of three replicates, and the error bars indicate the standard deviations.</p

LC-MS profiles of the reaction catalyzed by purified HSP hydroxylase from <i>A. tumefaciens</i> S33.

<p>(a) HPLC profile monitored with PDA detector; (b–d) mass spectra of products 2,5-DHP (<i>m/z</i> 110.18) and succinic acid (<i>m/z</i> 117.15) and substrate HSP (<i>m/z</i> 194.04), respectively. Negatively charged ions were detected.</p

Purification of HSP hydroxylase from <i>A. tumefaciens</i> S33.

<p>Purification of HSP hydroxylase from <i>A. tumefaciens</i> S33.</p

Proposed pathway for nicotine degradation by <i>A. tumefaciens</i> S33.

<p>The steps from nicotine to 6-hydroxy-pseudooxynicotine are same to part of the pyridine pathway, and the step catalyzed by 6-hydroxy-3-succinoylpyridine hydroxylase, which is indicated in the box, is same to the pyrrolidine pathway.</p

Effects of temperature and pH on the activity of HSP hydroxylase from A. <i>tumefaciens</i> S33.

<p>(a) The reactions were carried out in 50 mM Tris-HCl (pH 8.0) at the temperature indicated. (b) The reactions were performed at 30°C in different buffers: citric acid-sodium hydrogen phosphate (pH 5.0 and pH 6.0), sodium phosphate (pH 6.0, pH 7.0 and pH 8.0), Tris-HCl (pH 8.0, pH 9.0 and pH 10.0) and sodium bicarbonate-sodium hydroxide (pH 10.0 and pH 11.0). The values are means of three replicates, and the error bars indicate the standard deviations.</p

RT-PCR analysis of HSP hydroxylase gene transcription in <i>A. tumefaciens</i> S33.

<p>The cells were grown in the medium with nicotine as the sole source of carbon and nitrogen (lane nic) and in the glucose and ammonium medium (lane glu), respectively. The gene is 1,176 bp long. Lane RNA, negative control, the total RNA isolated from the culture grown in the medium with nicotine as the sole source of carbon and nitrogen as the template; lane gDNA, positive control, the genomic DNA isolated from the culture grown in the glucose and ammonium medium as the template.</p

Ratiometric and Time-Resolved Fluorimetry from Quantum Dots Featuring Drug Carriers for Real-Time Monitoring of Drug Release in Situ

An effective ratiometric and time-resolved fluorimetry was described. On the basis of Förster resonance energy transfer (FRET) between semiconductor quantum dots (QDs) and fluorescent drugs, poly­(ethylene glycol)-modified QDs were successfully prepared and further developed as QDs featuring carriers for real-time monitoring of drug release in situ

Aqueous Synthesis of Multidentate-Polymer-Capping Ag₂Se Quantum Dots with Bright Photoluminescence Tunable in a Second Near-Infrared Biological Window

A new strategy for fabricating water-dispersible Ag₂Se quantum dots (QDs) is presented. A multidentate polymer (MDP) was synthesized and used as a capping agent for Ag₂Se QDs. The MDP-capping Ag₂Se QDs were synthesized in aqueous solution at room temperature, which are highly photoluminescent in a second near-infrared (NIR-II) biological window and possess good photostability. These readily prepared NIR-II fluorescent nanoprobes have great potential for biomedical applications, especially useful for in vivo imaging