1H-NMR Study of Silica-Poly(epsilon-carbobenzyloxy-L-lysine) Composite Particles as Function of Temperature

Nearly monodisperse silica-poly(epsilon-carbobenzyloxy-L-lysine) composite particles were synthesized. The hydrodynamic radius of the composite particles and silica core was 200 and 100 nm respectively. Separately, poly(epsilon-carbobenzyloxy-L-lysine) was synthesized having a molecular mass of 200 kDa and a polydispersity of about 1.08. 1H-NMR spectra of the untethered polypeptide dissolved in deuterated m-cresol was collected at different temperatures ranging from 15 to 40 $^{o}$C. The sharp change in the chemical shift of several protons at around 27 $^{o}$C suggests a coil-helix conformation transition. Similarly, 1H-NMR spectra of the composite particles exhibits a more subtle change in chemical shifts in the explored temperature range suggesting a conformation transition of the tethered polypeptide.