Rheology advantage software

Oscillatory (dynamic) analyses were performed at 37 °C on all formulations using a TA system AR2000 rheometer. Rheological analyses were conducted using either a 6 cm or 4 cm parallel stainless-steel plate (gap size 1000 µm); again, the choice of geometry was determined via sample consistency. Samples to be analysed were applied to the lower plate and allowed fifteen minutes to equilibrate to negate any stresses induced during sample application. For each sample, the LVR (linear viscoelastic region) was determined via a stress sweep at a fixed frequency. The LVR was identified as the region in which the stress and the strain were directly proportional and where the storage modulus (G′) remained constant. Once determined, a frequency sweep from 0.1 to 10 Hz was performed at a strain value selected from within the LVR. The storage modulus (G′), loss modulus (G″), dynamic viscosity (η′), and the loss tangent (tan δ) were then determined using Rheology Advantage software provided by T.A. Instruments. The dynamic rheological properties of at least five replicates were determined.
The relationship between storage modulus and oscillatory frequency was determined using the power law model as follows: $$G^{\prime }=k{f}^n$$
where G′ is the storage modulus, f is the oscillatory frequency, n is the rheological index, and k is the gel strength.

To compare the rheologic properties of the optimized hydrogel to the previously published hydrogel, a TA Instruments AR-G2 rheometer was used. A 40 mm parallel plate geometry was used with a 500 micron gap distance; a Peltier unit was used to control temperature. First, a time sweep was performed over 10 min; the temperature was set to 15 °C for loading the samples and warmed to 37 °C to induce gelation while measuring oscillatory moduli (storage modulus (G’) and loss modulus (G”)) at the fixed angular frequency of 1 rad/s and strain of 5%. Following gelation, a frequency sweep was performed at 37 °C, from 100 to 0.1 rad/s at fixed 5% strain; G’ and G” were measured to calculate complex viscosity for each gel. Three different batches of gels were tested from each decellularization protocol (homogenized and optimized), rat-tail collagen type I (Corning, Corning, NY) was used as a control for comparison. All gels were prepared at a concentration of 8 mg/mL. Data was collected and analyzed with Rheology Advantage software (TA Instruments, New Castle, DE), and graphs were created with Prism 6 for Windows (GraphPad Software, Inc.). Each protocol was assessed using three biological replicates, each of a different batch of gel from a different donor.

The viscoelasticity of the sample crystallized in the SSHE and stored at 25 °C for 48 h was measured using an AR-G2 Rheometer (TA Instruments, New Castle, Delaware) operating with air purge (30 psi). Measurements were performed using a 40 mm standard steel parallel plate and a 5,000 μm gap. The instrument was operated by the Rheology Advantage Instrument Control software, where viscoelastic properties such as elastic (G′) and viscous (G″) moduli were measured using a strain sweep oscillation from 0.0008 to 10% strain at 25 °C. The frequency was kept constant at 1 Hz and G’ reported are means of the values obtained in the linear viscoelastic region (LVR). The Rheology Advantage software (TA Instruments, New Castle, Delaware) was used for data analysis. All experiments were performed in quadruplicate for each run.

JASX solutions at concentrations ranging from 0.25 to 2.0% (w/v) were made by soaking dried samples in Milli-Q water or 0.5 M NaCl solutions for 4 h (at room temperature) and gently stirring until full dissolution. After that, samples were kept at 4 °C for 48 h to achieve a fully water-swelling polymer (biopolymer hydration) and to remove bubbles.
Rheological measurements on JASX solutions were carried out with a rheometer AR-2000 (TA Instrument, Great Britain, Ltd. New Castle, DE, USA ) fitted with a 40 mm cone-plate geometry (54 microns gap) and a Peltier heating system for precise control. To prevent solvent evaporation during rheological analysis, samples were covered with a thin layer of hexadecane (oil film) after structure recovery and temperature equilibration (15 min). The TA Instrument Rheology Advantage software was used to collect and analyze the data (V5.7.0).

The rheological behavior of niosomes based on formulations 1, 2 and 3 was conducted using the Advanced Rheometer AR1000 equipment (TA instruments, New Castle, DE, USA). A flat plate with 20 mm of diameter was used. The concentration of the niosome formulations was 1 mg/mL and the GAP was settled at 1200 µm. The shear stress and the viscosity data were obtained at shear rates from 10 to 1000 s⁻¹ with 10 points per decade. Data were collected and processed using the Rheology Advantage™ software (TA instruments, New Castle, DE, USA).