Zetasizer nano z zen2600

¹H NMR spectra were recorded on a JNM-GSX-400 (JEOL, Tokyo, Japan, 400 MHz) nuclear magnetic resonance spectrometer using deuterated solvent. The chemical shifts were calibrated against tetramethylsilane (TMS) and/or solvent signal. The number average molecular weights (Mn) and polydispersity indices (M_W/Mn) of OLA were determined by size exclusion chromatography (SEC) (column: TSKgel Multipore HXLM × 2; detector: RI). The measurements were performed using dimethylformamide (DMF) as an eluent at a flow rate of 1.0 mL/min at 40 °C and a series of polystyrenes were used as standards. Hydrodynamic diameters of nanogels were measured by DLS (Zetasizer nano Z ZEN 2600, Malvern Instruments, Ltd., Malvern, UK). Fluorescence emission spectra of pyrene in the presence of nanogels were recorded by a fluorescence spectrophotometer (Shimadzu UV-2400PC, SIMADZU Co., Kyoto, Japan) using the excitation wavelength of 335 nm at room temperature (rt) in PB (phosphate buffer) solution (50 mM, pH 7.4). The critical aggregation concentration (CAC) of the nanogels in PB solution were determined using pyrene as a fluorescence probe. Fluorescence intensities of I₁ and I₃ were measured at the wavelengths of 373 and 383 nm, corresponding to the first and third vibronic bands. The CAC can be obtained from the flexion point in the I₁/I₃ ratio vs. concentration plots.

The hydrodynamic diameters for tri-L and gb-D aggregates in aqueous solution were measured using dynamic light scattering (DLS) (Zetasizer nano Z ZEN2600, Malvern Instruments Ltd., Malvern, UK) at 25 or 37 °C at a detection angle of 173° with a He–Ne laser as the incident beam. The tri-L and gb-D were dissolved in water (0.2 wt%) and were filtered using a Millex (Millipore, Burlington, MA, USA) 0.8 μm membrane before measurement.