On the Nanomechanical and Viscoelastic Properties of Coatings Made of Recombinant Sea Star Adhesive Proteins

Abstract

To attach to surfaces in the sea, sea stars produce proteinaceous adhesive secretions. Sfp1 is a major constituent of this adhesive, where it is present in the form of four subunits (named Sfp1α to δ) displaying specific protein-, carbohydrate- and metal-binding domains. Recently, two recombinant proteins inspired from Sfp1 have been produced: one corresponding to the C-terminal part of Sfp1β and the other to the full-length Sfp1δ. Adsorption ability tests showed that both recombinant proteins were able to adsorb and to form coatings on different surfaces in artificial seawater as well as in Tris buffer supplemented with NaCl or CaCl2. In this study, we used Atomic Force Microscopy (AFM) to characterize the nanomechanical properties of these coatings with an emphasis on functional characteristics such as adhesive properties and modulus of elasticity. We used AFM techniques which are the most appropriate to characterize the coating microstructure combined with the mapping of its nanomechanical properties.

Extracellular Matrix-Mimetic Intrinsic Versatile Coating Derived from Marine Adhesive Protein Promotes Diabetic Wound Healing through Regulating the Microenvironment

“…Meanwhile, the nanomechanical properties of coating were characterized by peak force quantitative nanomechanical property mapping . As exhibited in Figure S6, the adhesion force was 4.1 nN for Sbp9 Δ coating and 0.8 nN for Sbp9 Δ protein alone, indicating that the coating possess decent biomechanical compliance for diabetic wounds and will avoid the terrible pain caused by adhesive dressings during removal …”

“…Moreover, the morphology and physical properties of coatings that follow this assembly mode can be easily regulated by according to structural domains. 54,55 Sbp9 Δ Coating Exhibits Satisfactory Wet Adsorption Ability and Good Biocompatibility. DFUs constantly secrete exudates, making the reliable adsorption of dressings in humid environments a prerequisite for treatment.…”

“…Furthermore, we found that the metal ions-mediated assembly mode has advantages, such as the sea star adhesive protein rSfp1, as they can be triggered by truncated functional domains to interact with metal ions. Moreover, the morphology and physical properties of coatings that follow this assembly mode can be easily regulated by according to structural domains. , …”

Exploration of a superior water-resistant protein coating with inherent functionality inspired by scallop byssus

“…The measured moduli were 146 MPa for the Sbp9 ∆ coating and 42 MPa or the Sbp9 ∆ protein. Similar to the sea star Sfp1 nanocoating, the scallop Sbp9 ∆ coating certainly belonged to the category of soft materials, thus proving to be a decent mechanical microenvironment for in situ body-attachable soft matrices 50 .…”

Insights into Mechanical Dynamics of Nanoscale Interfaces in Epoxy Composites Using Nanorheology Atomic Force Microscopy

“…Over the past few years, various AFM-based dynamic modes have been developed for quantitative measurements of mechanical dynamics of soft materials at nanoscale, − among which the nanorheological approaches, also called nanoscale dynamic mechanical analysis (nDMA), have been proven capable of detecting local polymer viscoelasticity in nanostructured systems at rheologically relevant frequencies, that is, from ∼0.1 to ∼100 Hz. − However, because a sample-driving system is commonly used for performing rheological measurements in most of these approaches, it is only suitable for viscoelastic measurements of soft materials at room temperature. To circumvent this problem, a new design in which a piezo based probe-driving system is placed near the base of an AFM probe has been recently developed, − enabling the use of a heater/cooler stage beneath the sample for controlling the sample temperature.…”