Ta q2000

All chemicals were commercially available and used without further purification. FT-IR spectra of KBr pellets were recorded on a Perkin-Elmer Spectrum One FT-IR spectrometer from 4000 to 400 cm⁻¹. PXRD patterns (Cu-Kα) were collected on a Bruker Advance D8 θ–2θ diffractometer. Thermogravimetric analyses (TGA) were carried out on a TA Q50 system at a heating rate of 10 K min⁻¹ in a N₂ flow. Differential scanning calorimeter (DSC) measurements were performed on a TA Q2000 instrument, at a heating/cooling rate of 10 K min⁻¹. Variable-temperature SHG experiments with a programmable temperature control system were executed by Kurtz-Perry powder SHG test using an Nd:YAG laser (1064 nm). The values of the NLO coefficients for SHG were determined by the comparison with commercialized KDP (KH₂PO₄).

The DSC studies were carried out using a TA Instruments temperature modulated DSC (TA Q2000, TA Instruments, New Castle, DE, USA). The instrument was previously calibrated with indium for the accurate determination of heat flow and temperature. The sample mass was kept constant at around 5 mg for all crystallization kinetics tests, while a nitrogen gas flow of 50 mL/min was purged into the DSC cell. The sample and reference pans were of identical mass, with an error ±0.01 mg.
Initially the samples were cooled to 0 °C and then heated at a rate of 20 °C/min to a temperature 40 °C higher than the melting temperature. The samples were held at this temperature for 5 min in order to erase any thermal history and were then cooled back to the isothermal crystallization temperature (T_c) with the highest achievable rate. At that temperature, the sample was held for a time t_c, which was selected based on the recommendations from Muller and co-workers, that crystallization time should be 5 times the time to reach the minimum of the exothermic signal generated as a function of time at T_c [36 (link)]. After the samples were isothermally crystallized at different temperatures, they were re-heated at a rate of 20 °C/min up to 230 °C, in order to study their melting behaviour after isothermal crystallization.

Changes in thermal stability of proteins were measured using a differential scanning calorimeter (TA Q2000, TA Instruments, New Castle, DE, USA) as previously described by Liu et al. [17 (link)] with slight modifications. Thawed samples (10 mg) were accurately weighed and placed in a tightly sealed aluminum pan, while a sealed empty aluminum pan was used as a control group. Samples were equilibrated at 20 °C for 2 min and then heated from 20 to 100 °C at a heating rate of 5 °C/min.

The shape-memory property was characterized by a dynamic mechanical analyzer (DMA, type: TA Q800). The maximal force was 18 N and the resolution was 0.1 mN. Using stretching mode, the strain and stress could be auto detected. In addition, the temperature could be controlled by a temperature sensor. In order to avoid sliding, the sample was clamped tightly. Differential scanning calorimetry (DSC) measurements were conducted using a TA Q2000 machine under N₂ at a temperature ramping rate of 5 °C/min. Mechanical tests were performed using a Zwick/Roell tensile machine at a stretching speed of 10 mm/min and the sample geometry was 25 mm × 5 mm × 0.3 mm. The applied force sensor was 1.5 kN, and it utilized physical clamps.

Individual samples of the PEG shell, unmedicated SNA 15 base, AS, AMT, AS HTS and AMT HTS were thermally analysed using a differential scanning calorimeter (TA Q2000, TA instruments, New Castle, DE, USA) equipped with TA-Q Universal Analysis 2000 software. Approximately 5–7 mg sample was precisely weighed and heated from 0–250 °C at a rate of 5 °C/min, with nitrogen gas flowing at 20 mL/min. Interference in the melting behaviour of the HTS shell and the drug loaded core was evaluated for each sample.