(CHEM) Planning Meeting Jonathan D. Nickels Dept. of Chemical and - - PowerPoint PPT Presentation

Center For Hierarchical Materials (CHEM) Planning Meeting

Jonathan D. Nickels

• Dept. of Chemical and Environmental Engineering,

University of Cincinnati Jonathan.Nickels@uc.edu August 3-4, 2020

Introduction

Tools

Inelastic Light Scattering Fluorescence / FRET / Polarization GPU Accelerated Workstations Small Scale MD Elastic Scattering / Structure SANS/SAXS Inelastic Scattering / Dynamics Direct / Backscattering / Neutron Spin Echo

Small to Big

N-methylacetamide

Small to Big

Comez et al Soft Matter 2016 Perticaroli et al. JACS 2017.

Phase Separation within Lyotropic Liquid Crystal Materials

Lyotropic Liquid Crystal Phases

Solvent dispersed liquid crystals with 1D or quasi 1D order

Baumgart, Hess, and Webb Nature (2003)

Phase behavior in mammalian model membrane mimics

POPC OPC DS DSPC Choles Cholester terol

• l

DSPC, POPC, and Chol, in a 39/39/22 ratio

Macromolecular structure - SANS

• Small angle neutron scattering – SANS

– Observe the angle at which neutrons are scattered from the sample. – Scattered intensity is related to the structure and composition of the sample. – 100’s nm to Å spatial resolution

 (q) = NpVp

2 (Δρ)2 P(q) S(q) + Binc # of scattering particles volume of one scattering particle neutron contrast form factor structure factor incoherent background, no Q-dependence

𝑟 =

4𝜌 sin 𝜄 𝜇

0.001 − 0.5 Å −1

Neutron Scattering - Contrast

• Neutron scattering length, b, is an

atomic property that varies by element and isotope.

• Neutrons are especially sensitive to

the isotopes of hydrogen.

• Lipids are hydrogen rich

– Good internal contrast – Available in deuterium substituted form.

 (Q) = NpVp

2 (Dρ)2 P(Q) S(Q) + Binc neutron contrast Neutron Scattering Length Density

ρ = σ 𝒄𝒋 𝑾

Castellanos et al. Comp. Struct. Bio. (2016)

Neutrons Scattering and Contrast Matching

 (Q) = NpVp

2 (Dd)2 P(Q) S(Q) + Binc # of scattering particles volume of one scattering particle neutron contrast form factor structure factor incoherent background, no Q-dependence

(Dd)2 = (dlipid - dwater)2 = 0 scattering (Dd)2 = (dlipid - dwater)2 = 0 no scattering

Solv. Lo Ld  (Q) = NpVp

2 (Dd)2 P(Q) S(Q) + Binc # of scattering particles volume of one scattering particle neutron contrast form factor structure factor incoherent background, no Q-dependence

Nickels et al. JACS 2015

Neutrons Scattering - Contrast

Avg.

0.02 0.1 93.5% D2O

I(q) [A.U.] q [Å

• 1]

50 C 40 C 30 C 20 C 10 C

Domains-LD

10 100 1

P(r) [A.U.]

LD Nanodomains (20C) Model PDF 3.2 nm bilayer thickness Model PDF 6.8 nm radius disc Model PDF 60 nm diam. vesicle 3 Component Fit

r [Å]

10 100 1

P(r) [A.U.] r [Å]

Domains-LD, 93.5% D2O, 20 C Domains, 100% D2O, 20 C

SANS – Structure of Raft-like Features

Neutrons Scattering - Contrast

 (Q) = NpVp

2 (Dd)2 P(Q) S(Q) + Binc

# of scattering particles volume of one scattering particle neutron contrast form factor structure factor incoherent background, no Q-dependence

Summary

Methods to investigate coexisting lyotropic phases based on scattering contrast. Lead to new design principles to drive material properties.

An invitation

Jonathan D. Nickels PhD Assistant Professor

• Dept. of Chemical and Environmental Engineering

University of Cincinnati

An invitation

NickelsLab.com