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与FRET相关的双发射-高手进
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想知道，CdSe−CdS（给体）/花青素染料（受体）组成的FRET体系，用这个体系能测量温度，测量的信号时双发射信号？原理是什么？既然花青素和CdSe−CdS的荧光对热都敏感，为什么非要组成个FRET？这里的双发射有什么特点及优点？（J. Am. Chem. Soc. 2012, 134, 9565−9568） We show here that hybrid nanomaterials based on polymerwrapped CdSe−CdS quantum dot−quantum rod (QD−QRs) functionalized with temperature-responsive cyanine dyes address these issues in a single construct and exhibit enhanced thermometric response and sensitivity when translocated to the cytosol. By modeling optical changes in the nanocrystals components as a function of temperature, we find that response of this construct is also well explained by the change in quantum yield of the CdSe−CdS QD−QRs versus the cyanine dye and the red shift in QD−QR emission with increasing temperature. The molecular design of dual-emitting ratiometric nanothermometers (NanoTs) features a red-emitting CdSe−CdS QD−QR semiconductor nanocrystal heterostructure passivated with an amphiphilic polymer shell, to which is appended far-red emitting cyanine dyes (Scheme 1). QD−QRs have giant extinction coefficients9 owing to their CdS shells, and bright temperature-responsive luminescence due to well-behaved shifts in their bandgap (Figure S2). Cyanine dyes10 (e.g., Alexa Fluor 647), on the other hand, show temperaturedependent fluorescence quantum yields but no wavelength shifts (Figure S3). Together, they constitute FRET pairs with thermoresponsive character ideal for ratiometric imaging: their internally calibrated, strong optical read-out should translate to more reliable and precise temperature measurements in cells than is possible otherwise using conventional FRET donors like quantum dots, which are at least an order of magnitude less bright than QD−QRs. |
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2楼2013-03-18 21:37:15
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3楼2013-03-19 08:55:54