Mohammadhasan Hedayati

Ph.D. in Chemical Engineering

Biomaterials Microscopy Imaging

Surface Science Biophysics

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Education and Experience

Senior Scientist; R&D 2022 - Present

Intabio-Sciex

Postdoc 2021 - 2022

The University of Texas at Austin

Postdoc 2020 - 2021

Colorado State University

Ph.D. 2015 - 2020

Colorado State University

M.Sc. 2012 - 2014

Sharif University of Technology

B.Sc. 2006 - 2010

Amirkabir University of Technology

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Contact me:

hedayati.che@gmail.com

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Stem cell interactions with 3-D nanoporous protein crystal matrix

Dynamics of the protein interactions with nanostructured surfaces

Antifouling super slippery-hydrophilic surfaces

Nanostructured surfaces that mimic the vascular endothelial glycocalyx

Active antimicrobial and antiadhesive surfaces

Hydrogel’s molecular response to external mechanical forces

Research Experience

Designing blood-compatible materials through mimicking the vascular endothelial glycocalyx

Mimicking the nanoscale and macromolecular assembly of components of the vascular endothelium is a promising strategy for designing blood-compatible surfaces. In this project, we developed surfaces that mimic the chemistry and topography of the endothelial glycocalyx layer. Further, using single-molecule TIRF microscopy we demonstrated that these materials are capable of reducing blood protein adsorption and prevent fibrin network formation. This is an important step toward eliminating blood clots on artificial materials.

Vascular endothelium-mimetic surfaces that mitigate multiple cell-material interactions

Multifunctional surfaces are designed to mimic multiple features (both static and dynamic) of the vascular endothelium. These surfaces incorporate the release of the small molecule hormone nitric oxide (NO) with surface chemistry and nanotopography that mimic features of the vascular endothelial glycocalyx. They have features that interact with coagulation components, inflammatory cells, and bacterial cells. While a single surface feature alone may not be sufficient to achieve multiple functions, the release of NO from the surfaces along with their modification to mimic the endothelial glycocalyx synergistically improves platelet-, leukocyte-, and bacteria-surface interactions. These novel surfaces are better suited to deal with the complexity of material-blood interactions than surfaces designed with only a single feature or function.

Dynamics of protein interactions with biomaterial surfaces using single-molecule microscopy

Understanding the mechanisms of protein interactions with solid surfaces is critical to predict how proteins affect the performance of materials in biological environments. Low-fouling and ultra-low fouling surfaces are often evaluated in short-term protein adsorption experiments, where ‘short-term’ is defined as the time required to reach an initial apparent or pseudo-equilibrium, which is usually less than 600 s. However, it has long been recognized that these short-term observations fail to predict protein adsorption behavior in the long-term, characterized by irreversible accumulation of protein on the surface. This important long-term behavior is frequently ignored or attributed to slow changes in surface chemistry over time—such as oxidation—often with little or no experimental evidence. Here, we report experiments measuring protein adsorption on “low-fouling” and “ultralow-fouling” surfaces using single-molecule localization microscopy (TIRF microscopy) to directly probe protein adsorption and desorption.

A critical comparison of surface characterization techniques for measuring protein adsorption

Single-molecule microscopy techniques can resolve individual protein-surface interactions with high temporal and spatial resolution. This information can be used to tune the properties of surfaces to better resist protein adsorption. We demonstrate how combining surface plasmon resonance, X-ray photoelectron spectroscopy, atomic force microscopy, and single-molecule localization microscopy provides a more complete picture of protein adsorption on low fouling and ultralow fouling surfaces. A revision of the accepted definition of ultralow fouling surfaces is timely with the advent of time-resolved studies of protein adsorption kinetics at the single-molecule level, it is neither necessary nor sufficient to rely on a surface averaging techniques to qualify ultralow fouling surfaces.

Non-textured, all-solid, slippery hydrophilic surfaces

Slippery surfaces are sought after due to their wide range of applications in self-cleaning, drag reduction, enhanced condensation, biomedical implants, etc. However, virtually all of them are hydrophobic. In this work, we elucidate the systematic design of non-textured, all-solid, slippery hydrophilic surfaces by covalently grafting PEG brushes to smooth substrates. Furthermore, we postulate a plateau in slipperiness above a critical grafting density, which occurs when the tethered brush size is equal to the inter-tether distance. Our slippery hydrophilic (SLIC) surfaces demonstrate exceptional performance in condensation and anti-fouling compared to non-slippery hydrophilic surfaces and slippery hydrophobic surfaces. We firmly believe that slippery hydrophilic surfaces constitute an emerging class of surfaces with the potential to positively transform the technological landscape of thermofluidic and biofluidic devices.

Protein kinetics on low-fouling surfaces

Understanding the mechanisms of protein interactions on surfaces is critical to predict how proteins affect the performance of materials in biological environments. Single-molecule microscopy enables precise determination of both adsorption and desorption rates. The experimental data show anomalous desorption kinetics, evident as a surface dwell time that exhibits a power-law distribution, i.e. a heavy-tailed rather than the expected exponential distribution. Further analysis reveals that the observed anomalous desorption emerges due to the reversible formation of a small fraction of soluble protein multimers, such that each one desorbs from the surface with a different rate. The overall kinetics can be described by a series of elementary reactions, yielding simple scaling relations that predict experimental observations.

Polyelectrolyte multilayer scaffolds with antiadhesive and bactericidal properties

Nanostructured surfaces that reduce the adhesion, proliferation, and spread of bacteria have promise as a mean of preventing infections and reducing the use of antibiotics for biomedical applications. Scaffolds based on iota-carrageenan/chitosan, and pectin/chitosan polyelectrolyte multilayers (PEMs) have been proposed in this project. These PEMs have strong antiadhesive and bactericidal activities against Pseudomonas aeruginosa and Staphylococcus aureus. The iota-carrageenan/chitosan PEMs also impove the bone marrow-derived stem cells (BMSCs) adhesion, proliferation and spreading, confirming the potential use of these PEMs as coatings for tissue engineering.

Modulation of cell traction forces on highly ordered three-dimensional arrays of nanoporous scaffolds

Protein crystals are a unique nanomaterial with highly ordered and well-defined three-dimensional structures. Hexagonal crystals, with 13 nm-diameter nanopores (18 nm pore-center-to-center) that are aligned in along the z-axis, have been used as a nanoporous scaffold to modulate stem cell interactions.

Mechano-chemical signaling in heterogeneous extracellular fibrous networks

Fibrin plays an essential role in hemostasis, both as the main structural element of blood clots and the scaffold for cell recruitment in wound healing. Constituent proteins in fibrin networks have been shown to undergo α-helix to β-sheet transitions and stretch-induced bundling under tensile strain. The objective of this project is to understand how mechanical forces impact the molecular and chemical structure of fibrin proteins and how follow-on biochemical processes are affected. Here, we have used fluorescence lifetime microscopy (FLIM) to measure quantitative FRET between acceptor and donor dyes within fibrin networks to measure the molecular deformation of constituent proteins in fibrin networks under tensile strain.

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