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. Author manuscript; available in PMC: 2008 Oct 27.
Published in final edited form as: Langmuir. 2008 Feb 5;24(6):2908–2915. doi: 10.1021/la703053h

Figure 3.

Figure 3

Optical sensor response following RGDR peptide synthesis steps on the PSi scaffold/sensor including two synthesis controls: (1) No APTMS treatment and (2) synthesis excluding the DIC reagent. The results illustrate on the normal APTMS-treated sample a cyclical trend of sensor optical red shift following each amino acid coupling step and sensor optical blue shift after each Fmoc deprotection in piperidine. After the RGDR coupling and Fmoc deprotection steps are completed, there is a cumulative red shift of >33 nm beyond the APTMS baseline indicating peptide synthesis. A cumulative optical sensor red shift does not result on either of the negative control samples. When DIC is eliminated from the synthesis, some nonspecific binding is observed after the coupling step, but exposure to piperidine returns the sensor to the baseline value. The data shows that peptide synthesis occurs only when DIC and free amines are present.