Laquatwin ph meter

Denatured
BSA solutions were prepared by mixing 10 vol % of a solution
of BSA (10 mg/mL) in PBS and 90 vol % of a solution of urea (6.67
M) and NaCl (0.57 M) in PBS. The final composition thus was BSA (1
mg/mL), urea (6 M), and NaCl (0.6 M) at pH 7.4. BSA-SCNPs were formed
by the addition of cross-linker in DMSO (with concentrations of 5–8
wt %) and stirred for at least 12 h. SANS samples were prepared with
partially hydrogenated BSA, hydrogenated cross-linkers in deuterated
DMSO, deuterated urea, d-PBS, and D₂O.
The structural characterization with SANS and SAXS (see the SI) was performed directly in the reacting medium.
Samples for ¹H-NMR were dialyzed against decreasing concentrations
of urea until the proteins were in water and subsequently dialyzed
against water. Then, the protein SCNPs were lyophilized and redissolved
in D₂O.
¹H nuclear magnetic resonance
(¹H NMR) spectra were recorded at room temperature on a
Bruker spectrometer operating at 400 MHz using D₂O as solvent.
The solution density was measured with a DMA 4500 M apparatus from
Anton Paar. The pH was measured with a Laquatwin pH meter from Horiba.