Sigma 300 vp field emission sem

Electrochemical measurements such as CV, differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) were carried out with a BASi Palmsens-4 potentiostat (PalmSens B.V., Houten, The Netherlands). A three-electrode system was used for all electrochemical measurements, wherein an MN electrode, platinum wire, and in-house Ag/AgCl reference electrode (composition delineated vide infra) were used as the working, counter, and reference electrodes, respectively. To fabricate the in-house Ag/AgCl reference electrode, silylated needles were first infused with a homogenous suspension comprising 1 mg/mL of CNT, 4 mg/mL of CNC, and 5 mg/mL of AgNPs at a flow rate of 15 µL/min. The CNT/CNC/AgNP-modified needles were then immersed in 0.5% NaClO bleach at room temperature overnight, and rinsed with DI water. FTIR spectra were recorded using a Bruker Tensor 27 FTIR instrument fitted with diamond-attenuated total reflectance (ATR). Scanning electron microscope (SEM) images were acquired from a Zeiss Sigma 300 VP field emission SEM. The HPLC was performed by an Agilent 1260 II Analytical-Scale LC Purification System with 6530 LC/Q-TOF system (Agilent Technologies Inc., Santa Clara, CA, USA). Separation was performed on a Superlco^® analytical Ascentis^® C18 column (Sigma-Aldrich Inc., St. Louis, MI, USA, 15 cm × 2.1 mm, 3 µM).

Immediately after crosslinking, hydrogel samples were flash-frozen in liquid nitrogen to maintain the internal structure of the scaffold. Once frozen, the samples were lyophilized, cryo-fractured, and sputter-coated with 10 nm of Au–Pd prior to imaging. Scanning electron micrographs (Zeiss Sigma 300 VP Field-Emission SEM, Oberkochen, Germany) were used to qualitatively characterize the internal structure of the crosslinked scaffolds and confirm an interconnected porous network.