system,HSA,can also beconveniently estimated by this method
and the resolved distribution diagram is shown in Fig.4D. Based on
the calculation of the absolute concentration of all species in an
equilibrium state,the apparent binding constant at 298.15 K can be
estimated to be 8.4108 M1, which correlates well with earlier
reports [49]. As can beclearly seen in Fig.4 C, there is almost no
difference between the true spectra and resolved spectra in the case
of AuNPs with the similarity coefficient of 0.9999,further giving
evidence for the absence of rotational ambiguity in ther esolution
process.Inaddition,the SPR band of the AuNPs–HSA conjugate,
relative to that of AuNPs,broadens,intensifies and red-shifts from
519nm to 523nm and this conjugate has a molar extinction
coefficient of 2.6108 M1 cm1 at peakwavelength, 1.1-fold
larger than that of AuNPs(Fig.4C). Fig.4D displays that the absolute
concentrations of HSA are very low before the binding process
reaches a steady state,and then they increase almost linearly with
the increasing concentrations of HSA