Label-Free Imaging of Fibronectin Adsorption at Poly-(l-lysine)-Decorated Liquid Crystal Droplets

Abstract

Interactions and subsequent structural organization of fibronectin (FibN) (major component of an extracellular matrix) molecules in contact with chemically modified surfaces form an essential basis to the understanding of the regulation of matrix assembly in pathological states and to the development of new biomedical devices. Here, using poly-L-lysine (PLL)-coated liquid crystal (LC) droplets, we present a simple but fruitful advance of an experimental system that can report label-free imaging of adsorption of FibN at the LC−aqueous interface. We observed that the interfacial intermolecular interactions of anionic FibN molecules and cationic PLL residues is accompanied by a director configuration transition of the LC droplets from radial to bipolar/preradial, giving a distinct optical output. Specifically, it is found that the ordering transitions of LC can be effectively tuned by blocking the anionic sites of FibN with divalent cations (Ca 2+ ). Combination of fluorescence measurements, circular dichroism, and atomic force microscopy further revealed that PLL induces significant conformational changes in FibN at the aqueous−LC interface. This report provides a simple method based on LC droplets to understand polymer−protein interactions at membrane interfaces which would have potential applications in biomedical and interfacial systems.

Self-assembled fibrinogen–fibronectin hybrid protein nanofibers with medium-sensitive stability

“…It is known, however, that z Pot does not depend on the particle size. 42,43 This is conrmed by z Pot values of pure PNFs which correspond to the reported z Pot values of FN 44,45 and FG 46 molecules. An important factor inuencing the z Pot is the surface charge of a material.…”

Protein Microgel-Stabilized Pickering Liquid Crystal Emulsions Undergo Analyte-Triggered Configurational Transition

“…Extensive research efforts have been made to address these issues, ranging from studies on LC emulsions stabilized by amphiphilic polymer adsorption [20][21][22][23][24][25][26] and layer-by-layer deposition of polyelectrolyte 6,16 to LC infusion into the preformed and semipermeable polymer microcapsules. 7,27,28 Recently, gel film dispersed LC droplets have been developed as a simple and label-free optical probe to report the presence of chemical and biological analytes.…”

“…Extensive research efforts have been made to address these issues, ranging from studies on LC emulsions stabilized by amphiphilic polymer adsorption − and layer-by-layer deposition of the polyelectrolyte , to LC infusion into the preformed and semipermeable polymer microcapsules. ,, Recently, gel film-dispersed LC droplets have been developed as a simple and label-free optical probe to report the presence of chemical and biological analytes. , This strategy involves embedding LC droplets within a gel matrix that limits droplet mobility and thus delays their coalescence. These approaches permit the formation of large populations of stable LC droplets, mediate tuneable LC responses to analytes, and hinder the interactions between droplets and glass surfaces.…”

Surfactin-Laden Aqueous–Liquid Crystal Interface Enabled Identification of Secondary Structure of Proteins

“…In recent years, liquid crystals (LCs) have been significantly recognized as stimuli-responsive materials that hold technological applications in optical bioimaging and diagnostics. − In particular, orientations of LCs, owing to their weak anchoring energy of the order 1–10 μJ m –2 , are highly sensitive to the molecular events occurring at the fluidic interface formed between LC and aqueous media. This orientational order of LC, which can be amplified over 100 μm from the interface, gives rise to the anisotropic optical properties which in turn enable its label-free characterization under polarized light. , Previously, LC–aqueous interfaces have been utilized for amplification and transduction of highly specific molecular interactions such as antibody–antigen binding assay and DNA hybridization …”