Ultrathin Polydopamine Films with Phospholipid Nanodiscs Containing a Glycophorin A Domain

Abstract

Cellular membranes have long served as an inspiration for nanomaterial research. The preparation of ultrathin polydopamine (PDA) films with integrated protein pores containing phospholipids and an embedded domain of a membrane protein glycophorin A as simplified cell membrane mimics is reported. Large area, ultrathin PDA films are obtained by electropolymerization on gold surfaces with 10-18 nm thickness and dimensions of up to 2.5 cm 2 . The films are transferred from gold to various other substrates such as nylon mesh, silicon, or substrates containing holes in the micrometer range, and they remain intact even after transfer. The novel transfer technique gives access to freestanding PDA films that remain stable even at the air interfaces with elastic moduli of ≈6-12 GPa, which are higher than any other PDA films reported before. As the PDA film thickness is within the range of cellular membranes, monodisperse protein nanopores, so-called "nanodiscs," are integrated as functional entities. These nanodisc-containing PDA films can serve as semipermeable films, in which the embedded pores control material transport. In the future, these simplified cell membrane mimics may offer structural investigations of the embedded membrane proteins to receive an improved understanding of protein-mediated transport processes in cellular membranes.

Polydopamine Films with 2D-like Layered Structure and High Mechanical Resilience

“… 52 The mechanical properties of these films were investigated by micro-Brillouin light spectroscopy. 59 The authors reported a much higher Young’s modulus of ∼12 GPa, which allowed the easy transfer of the films.…”

Strategic Advances in Spatiotemporal Control of Bioinspired Phenolic Chemistries in Materials Science

“…Adding to this, PDA micropatterns further allow for site-specific immobilization of metal particles, chemical molecules, proteins, and cells, thus advancing applications, including but not limited to, biochips and biosensors. In this section, we summarize the repertoire of micro-/nanofabrication technologies for spatially controlled mussel-inspired patterning (Figure 12A), including photolithography, [27,46,100,[218][219][220] microcontact printing, [47,[221][222][223] inkjet printing, [48,224] electropolymerization, [225,226] microfluidics, [105,227] colloidal lithography, [228] and atomic force microscopy (AFM)-assisted lithography. [229]…”

“…Reproduced with open access permission from ref. [ 226 ] . a–c) Schematic of the evaporation‐driven convective particle self‐assembly at the liquid contact line of printed pattern.…”

“…Moreover, they demonstrated that these films could be delaminated and transferred to another substrate without disrupting their intactness (Figure 12E, a). [ 226 ] In addition, it offers the opportunity to embed nonconductive molecules or supramolecular structures into the PDA film. For instance, nonconductive phospholipid nanodiscs, with an integrated transmembrane domain of glycophorin A, were successfully embedded into the PDA films to form protein nanopores (Figure 12E, b).…”

In situ Sub‐Cellular Identification of Functional Amyloids in Bacteria and Archaea by Infrared Nanospectroscopy

“…[ 16a,h,17 ] Furthermore, as a major advance in the field, we have demonstrated that off‐resonance and short pulse AFM‐IR (ORS‐nanoIR) can acquire infrared maps and spectra to determine protein secondary structure down to the single protein molecule level. [ 15,18 ] The ultimate spatial resolution of maps and spectra acquisition in contact mode is in the order of 10–20 nm. [ 15 ] Its scanning properties also allow it to analyze complex mixtures with co‐existing species such as amyloid, amorphous aggregates and pre‐fibrillar aggregates, which differ in secondary structure.…”