U 2910 uv vis spectrophotometer

A Thermo Scientific Heraeus B12 incubator (Thermo Fisher Scientific, Waltham, MA, USA), Sanyo orbital incubator (Sanyo, Japan), Sanyo autoclave (Sanyo, Japan), Hitachi U-2910 UV/Vis spectrophotometer (Hitachi, Japan), WTW pH meter (inoLab, Germany), Multiskan EX plate reader (Thermo Fisher Scientific Inc., Vantaa, Finland), benchtop centrifuge (Hettich, Buford, GA, USA), Ultramicrotome Reichert Jung Ultracut E (LabX, Midland, ON, Canada), JEOL-1200EX Transmission electron microscope (TEM), and Attune NxT flow cytometer (Thermo Fisher Scientific Inc., Massachusetts, USA) were used throughout the experiments.
A Thermo Scientific Heraeus B12 incubator (Thermo Fisher Scientific, Waltham, MA, USA), Sanyo orbital incubator (Sanyo, Japan), Sanyo autoclave (Sanyo, Japan), Hitachi U-2910 UV/Vis spectrophotometer (Hitachi, Japan), WTW pH meter (inoLab, Germany), Multiskan EX plate reader (Thermo Fisher Scientific Inc., Vantaa, Finland), benchtop centrifuge (Hettich, USA), Ultramicrotome Reichert Jung Ultracut E (LabX, Canada), JEOL-1200EX Transmission electron microscope (TEM), and Attune NxT flow cytometer (Thermo Fisher Scientific Inc., Massachusetts, USA) were used throughout the experiments.

The degree of grafting of all gelatin solutions was determined by measuring the free amino acid (FAA) contents of all gelatin samples using the O-phthalaldehyde (OPA) method [14 (link)]. Glycosylated gelatin solutions (0.2 mL) were mixed with 4 mL of freshly prepared OPA reagent, and then the mixture was kept at 35 °C for 2 min. The absorbance of the mixture was measured with a U-2910 UV-Vis spectrophotometer (Hitachi, Ltd., Tokyo, Japan) at 340 nm. Ultrapure water was used as the control group. The FAA content was calculated using a Lys standard curve. The DG was calculated using the following equation: $$DG=\frac{A_0-A_t}{A}\times 100\%$$
where A₀ refers to the FAA contents of the FG-GLU mixture; A_t refers to the FAA contents of the FG- GLU conjugates; A refers to the FAA contents of the FG.

Transmission electron microscopy (TEM) images were obtained using a Tecnai F20 system (FEI, USA). UV-vis spectra were obtained using a U2910 UV-vis spectrophotometer (Hitachi, Japan) with two kinds of beams. Image analysis was conducted using Fiji ImageJ.