Formation and characteristics of mixed lipid/polymer membranes on a crystalline surface-layer protein lattice

Abstract

The implementation of self-assembled biomolecules on solid materials, in particular, sensor and electrode surfaces, gains increasing importance for the design of stable functional platforms, bioinspired materials, and biosensors. The present study reports on the formation of a planar hybrid lipid/polymer membrane on a crystalline surface layer protein (SLP) lattice. The latter acts as a connecting layer linking the biomolecules to the inorganic base plate. In this approach, chemically bound lipids provided hydrophobic anchoring moieties for the hybrid lipid/polymer membrane on the recrystallized SLP lattice. The rapid solvent exchange technique was the method of choice to generate the planar hybrid lipid/polymer membrane on the SLP lattice. The formation process and completeness of the latter were investigated by quartz crystal microbalance with dissipation monitoring and by an enzymatic assay using the protease subtilisin A, respectively. The present data provide evidence for the formation of a hybrid lipid/polymer membrane on an S-layer lattice with a diblock copolymer content of 30%. The hybrid lipid/polymer showed a higher stiffness compared to the pure lipid bilayer. Most interestingly, both the pure and hybrid membrane prevented the proteolytic degradation of the underlying S-layer protein by the action of subtilisin A. Hence, these results provide evidence for the formation of defect-free membranes anchored to the S-layer lattice.

Polymer–Lipid Hybrid Materials

“…Czernohlavek et al 172,174 supported hybrid bilayers composed of PBD 12 -b-PEO 9 and DOPC onto a crystalline surface-layer (S-layer) protein lattice and monitored the bilayers deposition process by QCM-D. Small amounts of DMPE lipids were chemically anchored to the crystalline protein lattice followed by rapid solvent exchange (RSE) techniques to form the polymer−lipid hybrid bilayers supported onto the lattice. 172 The DMPE anchoring is to stabilize the supported hybrid bilayers on the S-layer and facilitate the bilayers deposition. The RSE method uses an osmotic shock to rupture the hybrid vesicles, leading to a formation of PBD 12 -b-PEO 9 /DOPC hybrid bilayers on support.…”

“…The RSE method uses an osmotic shock to rupture the hybrid vesicles, leading to a formation of PBD 12 -b-PEO 9 /DOPC hybrid bilayers on support. Even though the PBD-b-PEO/DOPC hybrid bilayers membrane at 3:7 molar ratio should display phase separation (as observed in vesicles), Czernohlavek et al 172 could not detect lateral membrane morphology due to the innate limitation of QCM-D measurements. The authors brought light to promising bioinspired systems of the planar S-layer supported hybrid polymer−lipid membrane for biosensors, field effect transistors, optic and electronic screening, drug delivery, and many more applications.…”

“…The authors brought light to promising bioinspired systems of the planar S-layer supported hybrid polymer−lipid membrane for biosensors, field effect transistors, optic and electronic screening, drug delivery, and many more applications. 172,174 In addition to the work by Czernohlavek et al, 172,174 Paxton et al 169 also investigated the formation of PBD 37 -b-PEO 22 / DOPC hybrid bilayers supported onto planar vs nonplanar substrates, particularly mesoporous silica nanoparticles (MSNPs). Hybrid bilayer deposition on planar silica surfaces was investigated by CLSM, AFM, and QCM-D, and it was found that continuous homogeneous hybrid membranes form at 10 and 25 mol % polymer contents.…”

Recent Advances in Hybrid Biomimetic Polymer-Based Films: from Assembly to Applications

“…All these methods are based on physical interactions (hydrophobic/hydrophilic) between the lipid, the polymer, and the substrate, which drive their self-assembly into membranes [356]. Vesicle fusion results in the deposition of vesicles onto solid support that fuses into a bilayer planar membrane [351,357]. Due to the simultaneous influence of various parameters, such as pH, ionic strength, the chemical composition of the polymer, or size and distribution of the vesicles, it is challenging to control the properties of the films obtained using this method [297,352].…”

Electrochemical Biosensors Based on S-Layer Proteins

“…Thus, the two before mentioned examples constitute proof-of-principle studies for the feasibility to utilize membrane-active peptides and membrane proteins reconstituted in SsLMs as electrochemical biosensor. The ability to reconstitute integral membrane proteins in defined structures like pure lipid bilayers [9,[132][133][134][135], block copolymer bilayers [136,137], and recently lipid bilayers blended with block copolymers [138,139] on electrode and sensor surfaces is one of the most important concerns in designing biomimetic sensing devices in future [9,10,[140][141][142].…”