Theory of Analyte Recognition Sensing

This is a critical factor in using probes which l d specific analytes. The binAng constant of Ae probe must be comparable to analyte concentration. The useful range of analyte concentrations is typically restricted to 0.1 [A] 1011 1). Concentrations lower Aan O.lJiTD and higher Aan lOKp will produce little change in Ae 

The relative concentrations of the free and bound forms of Ae probe are ven by 

Figur e19 45. RdatioosbMweea nalytBcoiiomnaiioa([Al),Ai ocift-tioo constant (AT ) of the uulyte-probeconytot. and reUti we cooccgfri-tioas of tfie ee (Pp) ind bound (Pg) fonns of the probe. Pma Ref. 12. 

Intensity-Based Sensing. There are a number of probes which display changes in inlensicy but do not display spectral shifts. Such probes include the calcium probes Calcium Green . Fluo-3, and Rhod-2. In these cases, the analyte concentration can be obtained finsn 

In order to determine the analyte concentration using Eq. [19.10), all intensities must be deteimined with the same instrumental configuration, the same optical path length, and the same probe concentration. These requiremenlx are often hard to satisfy, especially in microscopy when observing cells. Measurement of and requites 

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