Fast Proton Conduction in Denatured Bovine Serum Albumin-Coated Nafion Membranes

Abstract

Bovine serum albumin (BSA) is a globular soluble protein, which has been extensively used in biochemical engineering. BSA materials possess abundant hydrophilic charged amino acids, H-bonded networks, and various secondary structures, which has great potential in facilitating proton transfer. Herein, BSA−N117 (BSA−Nafion 117) membranes are conveniently and eco-friendly prepared by utilizing the adsorption and denaturation of BSA on the Nafion 117 surface. The morphology and secondary structures of the BSA layer are studied with field-emission scanning electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. BSA−N117 membranes show highly increased proton conductivity under various conditions, which could be attributed to the improved wettability, water uptake, and the denaturation of BSA. The in-plane proton conductivity of BSA−N117-5 reaches 0.3 and 0.06 S cm −1 under 80 °C95% RH and 100 °C40% RH, respectively. The denaturation of BSA leads to the unfolding of α-helix structures and the formation of β-sheet structures. β-Sheet structures are more beneficial to proton conduction since β-sheet structures have stronger interactions with water molecules and protons could transport more directly in the parallel H-bonded network. Moreover, the denatured BSA modification layer could effectively help BSA−N117 membranes to possess higher selectivity and overcome the "trade-off" effect between proton conductivity and methanol resistance. The methanol permeability of BSA− N117 membranes is 1 order of magnitude lower than that of Nafion 117.

A Review on Ion-Exchange Membranes Fouling during Electrodialysis Process in Food Industry, Part 2: Influence on Transport Properties and Electrochemical Characteristics, Cleaning and Its Consequences

“…Using the proposed algorithm, Park et al [146] concluded that bovine serum albumin, BSA (whose molecules in the working solution were charged negatively), does not enter the electrostatic interactions with the negatively charged CMX surface, but, nevertheless, partially screens it. Since BSA contains aromatic amino acids [158,159], it can be assumed that the reason for this screening was π-π (stacking) interactions and the formation of hydrogen bonds between the membrane surface and the foulant [56,160]. Electrostatic interactions between the positively charged AMX surface and the negatively charged BSA species cause more significant screening of the AEM surface than the CEM surface [146].…”

Protein-coated cobalt oxide–hydroxide nanospheres deliver photosensitizer IR780 iodide for near-infrared light-triggered photodynamic/photothermal/chemodynamic therapy against colon cancer

“…BSA has been widely used as a protective agent or carrier in biochemical experiments, owing to its excellent biostability, biosecurity, and solubility. 39,40 This protective coating contributed to blood circulation and tumor aggregation, significantly compensating for the biological defects of IR780. 41 Overall, this novel approach shows great promise for the intelligent application of antineoplastic drug delivery nanoplatforms.…”

Anomalous Proton Transport across Silica Nanochannel Membranes Investigated by Ion Conductance Measurements

“…In addition, fast proton transport is also important in fuel cell membranes. A variety of artificial proton exchange membranes, such as Nafion and Nafion-like organic polymers, − metal–organic frameworks (MOFs), − and coordination polymers (CPs), have recently drawn enormous attention. Although abundant experiments and molecular dynamics (MD) simulations have been carried out to investigate the proton transport, − the underlying mechanism responsible for fast proton transport in nanoscale structures with confinement effect remains marginally understood due to the biological complexity and associated experimental limitations .…”