Quantifying Protein Adsorption on Dhvar5-Chitosan

Protein adsorption to Dhvar5-chitosan coatings was evaluated using a QCM-D system (Q-Sense E4 instrument; Biolin Scientific, Gothenburg, Sweden) and gold-coated QCM-D sensors with a fundamental frequency of 5 MHz (Biolin Scientific), as previously described [35 (link)]. Briefly, after cleaning, the sensors were prepared as described above (Section 2.2) [14 (link)]. Adsorption of bovine serum albumin (BSA) to Dhvar5-Chitosan surfaces was followed in real-time by the frequency and dissipation shifts of the sensors. A baseline was established by pre-incubating samples with phosphate-buffered saline (PBS, pH = 7.4) for 15 min at a flow rate of 0.1 mL/min. Then, a BSA solution at 4 mg/mL in PBS was injected into the system at a flow rate of 25 µL/min until saturation was achieved (2 h). PBS was then used to remove loosely attached proteins. The temperature was kept at 37 °C throughout the assay. The resulting data was treated with the Voigt model. Three replicates per sample were analyzed in three independent assays (n = 3).