Novel quantum dots–carboxymethyl chitosan nanocomposite nitric oxide donors capable of detecting release of nitric oxide in situ

Nitric oxide (NO) donor compounds are primarily monofunctional in that they release NO under the requisite conditions. To detect the amount and duration of NO released, subsequent analysis methods are required. It would be advantageous if a NO donor compound could both release and detect NO at the same time. This would eliminate potential errors in the analysis. In this paper, novel cadmium telluride quantum dots (CdTe QD)–carboxymethyl chitosan (CMCS) nanocomposite NO donors, including both diazeniumdiolates and fluorescence probes, were fabricated by first synthesizing CdTe QD in CMCS aqueous solution and then reacting NO as well as ethyl bromide with the resultant CdTe QD–CMCS nanocomposites. Transmission electron microscopy, scanning electron microscopy and particle size analysis were used to examine the morphology and size distribution of the CdTe QD–CMCS nanocomposite NO donors. The donors are nanospheres with CdTe QD encapsulated and have dimensions of ∼300 nm. Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and contact angle tests were employed to characterize the chemical structure of the donors, and the results also show that CdTe QD are well incorporated into CMCS, and many of them are close to the surface of the donors. The precursors of the donors exhibit a fluorescent effect, and the fluorescence can be quenched by NO. The donors can release NO spontaneously in a phosphate-buffered saline solution similar to a physiological environment, and can quantitatively detect the release of NO in situ based on fluorescence quenching of the donors by the NO.

Graphical abstractWhen CdTe QDs-CMCS nanocomposite NO donors are in a PBS solution, NO molecules are released, some of which diffuse into the donors and form NO-Cd complex with CdTe QDs. Consequently the fluorescence of the donors under excitation is reduced, signifying the release of NO.Figure optionsDownload full-size imageDownload high-quality image (97 K)Download as PowerPoint slide