Rheology experiments were carried out on an Anton Paar Rheometer MCR 102 (Anton Paar, Graz, Austria) using a parallel plate configuration (25 mm diameter). Experiments were performed at constant temperature of 23 °C controlled by the integrated Peltier system and a Julabo AWC100 cooling system. Oscillatory amplitude sweep experiments (γ: 0.01–100%) were carried out to determine the linear viscoelastic (LVE) range at a fixed frequency of 1 rad s−1. Once the LVE of each hydrogel was established, frequency sweep tests were performed (ω: 0.1–100 rad s−1) at a constant strain within the LVE region of each sample (γ = 0.04%). Step strain experiments were performed on hydrogels to analyze the thixotropic behavior of the material. The sample was subjected to consecutive deformation and recovery steps. The recovery step was performed by keeping the sample at a constant strain γ = 0.04%, i.e., within the LVE region, for a period of 400 s. The deformation step was performed by applying to the gel a constant strain γ = 100%, i.e., above the LVE region of the sample for a period of 300 s. The cycles were performed 3 times at a fixed frequency ω = 10 rad s−1.
Awc 100
Manufactured by Julabo
Sourced in Germany
The AWC 100 is a compact and powerful water circulator designed for laboratory applications. It features a temperature range of -20°C to +100°C and a pump capacity of up to 22 liters per minute. The AWC 100 is equipped with a digital display and intuitive controls for easy operation.
Automatically generated - may contain errors
Lab products found in correlation
Mcr 102 rheometer, by Anton Paar (1 mentions)
Mcr 102, by Anton Paar (1 mentions)
Rheoplus software, by Anton Paar (1 mentions)
Ar1500ex rheometer, by TA Instruments (1 mentions)
J 810 spectropolarimeter, by Jasco (1 mentions)
Quartz cuvette, by Hellma (1 mentions)
10 mm quartz cuvette, by Hellma (1 mentions)
J 810, by Jasco (1 mentions)
Pfd 425s, by Jasco (1 mentions)
7 protocols using awc 100
1
Rheological Characterization of Hydrogels
2
Rheological Characterization of Hydrated Samples
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The rheological measurements were performed using a rotational rheometer (Anton Paar MCR 102, Graz, Austria) operating in a plate-plate configuration. Experiments were performed keeping the temperature constant at 25 °C through the integrated Peltier system and a Julabo AWC100 cooling system, Seelbach, Germany. The sample was kept hydrated during the measurements through the use of a solvent trap (H-PTD200). Time-sweep oscillatory tests were carried out at a fixed strain amplitude of 0.3% and an angular frequency of 1 rad s−1
3
UV-Vis Spectroscopy of Compounds 1a-9a
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Stock
solutions were prepared
by dissolving compounds1a –9a in
DMSO (10 mM). 1980 μL of PBS buffer (pH 7.4), 12 μL of
DMSO, and 8 μL of stock solution were mixed to obtain a final
concentration of 40 μM. Immediately, UV–vis spectra were
recorded hourly over 48 h with a PerkinElmer lambda 35 photometer
with PTP (Peltier Temperature Programmer) and Julabo AWC 100 recirculating
cooler.
solutions were prepared
by dissolving compounds
DMSO (10 mM). 1980 μL of PBS buffer (pH 7.4), 12 μL of
DMSO, and 8 μL of stock solution were mixed to obtain a final
concentration of 40 μM. Immediately, UV–vis spectra were
recorded hourly over 48 h with a PerkinElmer lambda 35 photometer
with PTP (Peltier Temperature Programmer) and Julabo AWC 100 recirculating
cooler.
4
Hydrogel Rheological Characterization
5
Rheological Characterization of Thermoreversible Gels
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All samples for rheometry were prepared to the required concentration in deionised water or VFS and refrigerated overnight before measurements were taken. Rheology was performed on an AR 1500ex rheometer by TA instruments (USA) with a Julabo AWC100 cooling unit and a 40 mm parallel plate geometry with a gap of 650 mm. Rheological measurements were taken in triplicate.
Oscillatory stress sweeps were performed at 1 Hz between 1 and 1000 Pa at 37 1C. Frequency sweeps were measured at 37 1C between 0.1 and 10 Hz at a shear stress of 1 Pa. Temperature ramps were performed at a frequency of 1 Hz and a shear stress of 1 Pa. The temperature was increased at a rate of 2 1C min À1 , from 15 to 50 1C.
Reversibility of the phase transition was assessed by rheological measurement at 25 1C for 1 min, followed by 37 1C for 1 min, which was repeated once more. A 2 min equilibration period was included between temperature changes and the measurements were recorded at 1 Pa and 1 Hz.
To determine the gelation time, the temperature of the Peltier plate was held at 25 1C for 1 min, then increased to 37 1C and held for a further 4 min. All measurements were made at a constant shear stress of 1 Pa and a frequency of 1 Hz. The time taken for G 0 to exceed G 00 at 37 1C was taken as the gelation time.
Oscillatory stress sweeps were performed at 1 Hz between 1 and 1000 Pa at 37 1C. Frequency sweeps were measured at 37 1C between 0.1 and 10 Hz at a shear stress of 1 Pa. Temperature ramps were performed at a frequency of 1 Hz and a shear stress of 1 Pa. The temperature was increased at a rate of 2 1C min À1 , from 15 to 50 1C.
Reversibility of the phase transition was assessed by rheological measurement at 25 1C for 1 min, followed by 37 1C for 1 min, which was repeated once more. A 2 min equilibration period was included between temperature changes and the measurements were recorded at 1 Pa and 1 Hz.
To determine the gelation time, the temperature of the Peltier plate was held at 25 1C for 1 min, then increased to 37 1C and held for a further 4 min. All measurements were made at a constant shear stress of 1 Pa and a frequency of 1 Hz. The time taken for G 0 to exceed G 00 at 37 1C was taken as the gelation time.
6
Structural Analysis of Protein Conformations
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The secondary structure of native a-La and Lys protein and a-LaeLys supramolecular structures were assessed by circular dichroism (CD). CD spectra were obtained with a J-810 spectropolarimeter (Jasco Corporation, Japan) equipped with a temperature controller Peltier PFD 425S (Jasco Corporation, Japan) coupled to a thermostatic bath AWC 100 (Julabo, Germany). The spectra were collected at 25 C, under constant nitrogen flush, using a quartz cuvette of 10 mm path length (Hellma Analytics, Germany), from 200 to 260 nm wavelength range with a data pitch of 0.2 nm and accumulation of 3 scans. The response time, scan rate and bandwidth were 1 s, 200 nm min À1 , and 1 nm, respectively. These parameters were used based in the procedure adopted by Diniz et al. (2014) and optimized by Monteiro (2014) . CD spectra were baseline-corrected by subtracting blank spectra of the corresponding solutions, at the same concentration but without heat treatment and pH adjustment. At least, ten replicates of each sample were carried out.
7
Circular Dichroism Analysis of Lf-GMP Nanohydrogels
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The secondary structures of the Lf-GMP nanohydrogels and the effect of chitosan coating was evaluated by circular dichroism. CD spectra were obtained with a Jasco J-810 spectropolarimeter (Jasco Corporation, Japan) equipped with a Peltier temperature controller (PFD 425 S, Jasco, Japan) coupled with a thermostatic bath (AWC 100, Julabo, Germany). The spectra was obtained at 25 C using a 10 mm quartz cuvette (Hellma Analytics, Germany) at wavelength range of 190 nme260 nm. Deionized water was used as a blank.
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