Amx 500 nmr spectrometer

AMX-500 NMR spectrometer (Bruker, Germany) was used to detect the DMSO solution's ¹H NMR spectrum of P(MMD-co-LA). Evaluated the surface morphology of fiber films by scanning electron microscope (SEM, JSM-IT200, JEOL, Japan), and used ImageJ software (v1.8.0, NIH, USA) to determine the fiber diameter. The mechanical properties of the fiber films were tested by an electronic universal material testing machine (Instron 5967, Instron Corporation, USA). Three sets of parallel samples were set for each characterization.
Prepared DFO solutions of various mass concentrations (1.0, 2.0, 4.0, 8.2, 16.5, 31.6,60.4, 121.7, 250.1, 500.0 ​μg/mL) and chelated them with excess FeCl₃ in a volume ratio of 9:1 respectively. Absorbance at 485 ​nm, measured by a microplate reader, drew the standard curve of DFO. Soak 100 ​mg of P(MMD-co-LA)/DFO membrane in 10 ​mL of PBS solution and place it in a shaker at 37 ​°C. Take out 0.9 ​mL of release medium at specific time points (1 ​h, 2 ​h, 4 ​h, 8 ​h, 16 ​h, 24 ​h, 36 ​h, 48 ​h, 60 ​h, 72 ​h, 7th day, 14th day, 21st day, and 28th day) and respectively add them to 0.1 ​mL FeCl₃ solution. After mixing well, measure the absorbance at 485 ​nm with a microplate reader to determine the release rate of DFO. Utilized equal volume of PBS to maintain system balance.

ASPA80-1 (40 mg) was dissolved in 0.5 mL of D₂O. After that, NMR (¹H NMR and ¹³C NMR) were recorded by Bruker AMX-500 NMR spectrometer. The parameters of ¹H NMR experiment are presented as follows: pulse program zg30, a spectral width of 8.22 kHz, an acquisition time of 4 s, a relaxation delay of 1 s, for 64 scans. For 100 MHz proton decoupled ¹³C NMR experiment, the parameters are presented as follows: pulse program zgpg30, a spectral width of 24.0 kHz, an acquisition time of 1.36 s, a relaxation delay of 1 s, for 73,728 scans.