All samples were obtained by irradiating polymer precursors with green LED at intensity of 100 mW/cm2 for 16 mins before the tests. An atomic force microscope (Agilent 5400) was used to measure the elastic moduli of hydrogel samples. For each sample, 12–20 indentation measurements were collected. All measurements were carried out in phosphate buffered saline (PBS). The gels were indented with a pyramid-tipped probe (nanoworld, PNP-TR-20) with cantilever spring constants of 0.125 N m-1, as measured by thermal calibration. Elastic moduli of the gels were calculated from force-displacement curves using a Hertz model (Carl and Schillers, 2008 ).
Pnp tr 20
Manufactured by NanoWorld
Sourced in Switzerland
The PNP-TR-20 is a laboratory instrument designed for thin-film deposition. It utilizes a plasma-enhanced physical vapor deposition (PEPVD) process to deposit thin films on substrates. The core function of the PNP-TR-20 is to enable the controlled deposition of thin films onto various surfaces.
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Lab products found in correlation
5 protocols using pnp tr 20
1
Measuring Hydrogel Elastic Moduli
2
Measuring Neutravidin-Biotin Binding Forces
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AFM cantilevers (PNP‐TR‐20, Nanoworld, Switzerland) were used to measure neutravidin‐biotin binding forces. Prior to measurements, cantilevers were functionalized with PEG‐biotin (QBD10200, Sigma‐Aldrich, MO, USA)[82
] and treated using oxygen plasma at 600 mTorr and 100 W for 10 min. For forming amino groups, cantilevers were immersed in a 5% APTMS and absolute ethanol solution for 12 h. After rinsing with toluene, cantilevers were incubated in 1 mg ml−1 PEG‐biotin in chloroform with 0.5% trimethylamine catalysts for 2 h. Neutravidin‐biotin binding forces were measured using an AFM (NX‐10, Park systems) under 0.1 µm −1s in a PBS more than 50 points.
] and treated using oxygen plasma at 600 mTorr and 100 W for 10 min. For forming amino groups, cantilevers were immersed in a 5% APTMS and absolute ethanol solution for 12 h. After rinsing with toluene, cantilevers were incubated in 1 mg ml−1 PEG‐biotin in chloroform with 0.5% trimethylamine catalysts for 2 h. Neutravidin‐biotin binding forces were measured using an AFM (NX‐10, Park systems) under 0.1 µm −1s in a PBS more than 50 points.
3
Atomic Force Microscopy of Dialysis Membranes
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Imaging was performed via a 3100 Dimension atomic force microscopy machine (DAFM-XYZ, Bruker Instruments, Billerica, MA, USA). The atomic force microscopy (AFM) scan was conducted in tapping and fluid modes using a Pyrex-Nitride probe (PNP-TR-20, NanoWorld, Neuchâtel, Switzerland) with a triangular cantilever (resonant frequency 17 kHz, force constant 0.08 N/m, thickness 500 nm, length 200 μm, tip radius 7–10 nm). A total of 6 tips were used, corresponding to the respective MW marker/imaging mode outlined in Table 6 . Nanoscope v6.13 (Bruker Instruments, Billerica, MA, USA) and Gwyddion v2.3 (Czech Metrology Institute, Brno, Czechoslovakia) were used as image analysis software, respectively.
Scan speed was established by setting a ratio of 512 pixels/line for a range of frequency of 0.1–0.2 Hz. The scan area ranged from 1 to 8.0 μm2. The pore sizes were feature-extracted at a constant scan area of 1 μm2. Images were obtained at 5 different locations for the tapping and 4 different locations for the fluid modes respectively, across the sample.
The dialysis tubing, stored in sodium azide to avoid biofouling, was cut in order to produce a 1 cm2 single ply sheath. For the tapping mode, samples were washed and allowed to equilibrate in filtered saline (0.9% w/v NaCl) for 30 min. For the fluid mode, the sample remained submerged in the saline throughout the scan.
Scan speed was established by setting a ratio of 512 pixels/line for a range of frequency of 0.1–0.2 Hz. The scan area ranged from 1 to 8.0 μm2. The pore sizes were feature-extracted at a constant scan area of 1 μm2. Images were obtained at 5 different locations for the tapping and 4 different locations for the fluid modes respectively, across the sample.
The dialysis tubing, stored in sodium azide to avoid biofouling, was cut in order to produce a 1 cm2 single ply sheath. For the tapping mode, samples were washed and allowed to equilibrate in filtered saline (0.9% w/v NaCl) for 30 min. For the fluid mode, the sample remained submerged in the saline throughout the scan.
4
Hydrogel Stiffness Characterization by AFM
5
Hydrogel Elasticity Modulation by Fibroblasts
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Other than cytokines, physical properties also play important roles in regulating endothelial cell sprouting into the hydrogels. In the experiments, three 100 μl hydrogel samples without MRC-5 cells and three 100 μl hydrogels samples with MRC-5 cells (106 cells/ml) are prepared in the wells punched by a 6 mm diameter biopsy punch on 1 mm thick PDMS coating layers inside the conventional 3.5 cm petri-dishes (93,040, TPP Techno Plastic Products AG) and cultured using the HUVEC medium for 72 h. The biological atomic force microscopy (Bio-AFM) (JPK NanoWizard 3, Bruker Nano GmbH, Berlin, Germany) is then exploited to measure the elasticities of the hydrogels cultured without and with the MRC-5 cells covered by the medium. In the measurement, a four-side pyramid tip (PNP-TR20, Nanoworld, Neuchâtel, Switzerland) is used under the QI mode of the Bio-AFM setup (JPK NanoWizard Control, Bruker Nano GmbH) as an indenter to scan across a 30✕30 μm2 area of the samples. To ensure accurate measurement of the elasticity, the maximum indentation depth of 4000 nm and maximum indentation force of 5 nN are set for the measurement. During the scanning, the force-displacement curve measured at each indentation pixel is collected and further used to calculate the Young's modulus of each position of the hydrogel samples by optimum curve fitting according to the Hertz model [23 ].
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