Lakeshore 335 temperature controller

Atomic force microscopy (AFM) imaging of dry nanofilm samples was performed on a Dimension™ ICON with Nanoscope V controller (Bruker, Santa Barbara, CA) in TappingMode™ using Si cantilevers (OTESPA-R3, f₀ 300 ​kHz, k: 26 ​N/m, Bruker) as described previously [43 (link)]. To analyze the swelling behavior of the nanohydrogels, AFM measurements were performed in air as well as aqueous solutions using PeakForce Tapping™ mode and standard cantilevers for liquid imaging (Bruker SNL) with a nominal spring constant of 0.35 ​N/m. A PeakForce Tapping™ frequency of 2 ​kHz and amplitude of ∼100 ​nm was used. Before each measurement, the optical lever sensitivity and the spring constant were calibrated using the software of the AFM (Nanoscope 9.10). For the swelling/deswelling cycles, a PeakForce setpoint of 1 ​nN was applied, whereas for deformation measurements, 5 ​nN was used. After each measurement in water, the liquid was removed, and the protein nanohydrogel was dried in situ at 40 ​°C using a Bruker heater chuck connected to a LakeShore 335 temperature controller (Lake Shore Cryotronics). Data processing was performed using Nanoscope Analysis 1.40 (Bruker).

The temperature-dependent resistance of the rGO sheets
was measured using a conventional four-probe method. The sample was
loaded into a closed-cycle refrigerator cryostat, and the cryostat
was evacuated down to under 1 × 10^–5 Torr.
Then, we measured temperature-dependent resistance from 293 K to 8
K using a KEITHLEY 6211 direct current (DC) and an alternating current
(AC) source, a 2182 nanovoltmeter (KEITHLEY Instruments, Ohio, USA),
and a LakeShore 335 temperature controller (Lake Shore Cryotronics,
Ohio, USA).