3.4 Adsorption Isotherm and Scatchard Analysis
Figure 5 Adsorption isotherm of the cordycepin molecularly imprinted polymer and nonimprinted polymer
The binding isotherm curves of cordycepin on the molecularly imprinted and nonimprinted polymers are shown in Figure 5.The adsorption capacity of the polymers increased with the concentration of cordycepin from 2.5μg/mL to 100.0μg/m L.The adsorption capacity was reached at higher concentrations.The adsorption capacity of molecularly imprinted polymer was higher than that of nonimprinted polymer.A Scatchard plot of the binding of the molecularly imprinted polymer to cordycepin was prepared to evaluate selective binding characteristics(Figure 6).Two linear parts with different slopes were observed，which implied that there were two kinds of adsorption sites with specific adsorption on the polymer(Komiyama 2004).In the recognition process，the molecularly imprinted polymer combined with the cordycepin at higher affinity adsorption sites，and interacted with cordycepin through synergism at lower affinity adsorption sites.Linear fitting is applied to both regions.(https://www.daowen.com)
Figure 6 Scatchard plot of the cordycepin molecularly imprinted polymer to cordycepin
The linear regression equations were Q/Cb=491.05—111.5Q(r=0.9864)and Q/Cb=245.73—28.714Q(r=0.9957)，respectively.The K d and Q max for the lower affinity adsorption sites were 0.035μmol/mL and 6.047μmol/g，whereas for the higher affinity adsorption sites，the values were 0.0089μmol/mL and 4.78μmol/g.