Effect of pH on Electrochemical Impedance Response of Tethered Bilayer Lipid Membranes: Implications for Quantitative Biosensing
Arun Prabha Shivabalan,
Filipas Ambrulevicius,
Martynas Talaikis
et al.
Abstract:Tethered bilayer lipid membranes (tBLMs) are increasingly used in biosensor applications where electrochemical impedance spectroscopy (EIS) is the method of choice for amplifying and recording the activity of membrane-damaging agents such as pore-forming toxins or disrupting peptides. While the activity of these biological agents may depend on the pH of the analytes, there is increasing evidence that the sensitivity of tethered bilayer sensors depends on the pH of the solutions. In our study, we addressed the … Show more
“…Specifically, for pMPC- b -pADOPMA, a frequency upshift of 40–50 cm –1 was observed for water band components at −0.4 V, suggesting the potential-induced withdrawal of water molecules engaged in weaker hydrogen bonding. 83 , 84 In conclusion, SEIRAS and contact angle measurements demonstrate that under varying external electric potentials, the copolymer with unprotected catechol groups pMPC- b -pDOPMA significantly outperforms its acetonide-protected counterpart in attracting water molecules, likely due to the exposed phosphorylcholine groups.…”
Amphiphilic diblock copolymers containing a block of 2-methacryloyloxyethyl phosphorylcholine (MPC) with unique properties to prevent nonspecific protein adsorption and enhance lubrication in aqueous media and a block of dopamine methacrylamide (DOPMA) distinguished by excellent adhesion performance were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization for the first time. The DOPMA monomer with an acetonide-protected catechol group (acetonide-protected dopamine methacrylamide (ADOPMA)) was used, allowing the prevention of undesirable side reactions during polymerization and oxidation during storage. The adsorption behavior of the diblock copolymers with protected and unprotected catechol groups on gold surfaces was probed using attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectroscopy, surface-enhanced infrared absorption spectroscopy (SEIRAS), and reflection−absorption infrared spectroscopy (RAIRS). The copolymers pMPC-b-pADOPMA demonstrated physisorption with rapid adsorption and ultrasound-assisted desorption, while the copolymers pMPC-b-DOPMA exhibited chemical adsorption with slower dynamics but a stronger interaction with the gold surface. SEIRAS and RAIRS allowed proving the reorientation of the diblock copolymers during adsorption, demonstrating the exposure of the pMPC block toward the aqueous phase.
“…Specifically, for pMPC- b -pADOPMA, a frequency upshift of 40–50 cm –1 was observed for water band components at −0.4 V, suggesting the potential-induced withdrawal of water molecules engaged in weaker hydrogen bonding. 83 , 84 In conclusion, SEIRAS and contact angle measurements demonstrate that under varying external electric potentials, the copolymer with unprotected catechol groups pMPC- b -pDOPMA significantly outperforms its acetonide-protected counterpart in attracting water molecules, likely due to the exposed phosphorylcholine groups.…”
Amphiphilic diblock copolymers containing a block of 2-methacryloyloxyethyl phosphorylcholine (MPC) with unique properties to prevent nonspecific protein adsorption and enhance lubrication in aqueous media and a block of dopamine methacrylamide (DOPMA) distinguished by excellent adhesion performance were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization for the first time. The DOPMA monomer with an acetonide-protected catechol group (acetonide-protected dopamine methacrylamide (ADOPMA)) was used, allowing the prevention of undesirable side reactions during polymerization and oxidation during storage. The adsorption behavior of the diblock copolymers with protected and unprotected catechol groups on gold surfaces was probed using attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectroscopy, surface-enhanced infrared absorption spectroscopy (SEIRAS), and reflection−absorption infrared spectroscopy (RAIRS). The copolymers pMPC-b-pADOPMA demonstrated physisorption with rapid adsorption and ultrasound-assisted desorption, while the copolymers pMPC-b-DOPMA exhibited chemical adsorption with slower dynamics but a stronger interaction with the gold surface. SEIRAS and RAIRS allowed proving the reorientation of the diblock copolymers during adsorption, demonstrating the exposure of the pMPC block toward the aqueous phase.
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