4D-STEM atomic structure determination of beam-sensitive soft biopolymers

Project Description

Considering the advances in polymer science, the diversity of biodegradable polymer approved for clinical use is very limited. From the chemical perspective it is imperative to study these bio-compatible materials at atomic scale to better understand their local phases which will lead to design of better futuristic materials with medical applications. Poly (lactic-co-glycolic acid) (PLGA), a class of bio-compatible and bio-degradable polymer has found applications in various medical implants and drug delivery and dominated the market in products that gained regulatory approval. These biopolymers have diverse order-disorder region that influence their properties such as biocompatibility and biodegradability. However, these bio-compatible polymers are very sensitive and prone to damage under characterization conditions such as high energy electron beam. Four-dimensional scanning transmission electron microscopy (4D-STEM) provide the real time access to the dynamic behavior of surfaces, interfaces and nano systems hence producing maps of local crystal orientation, structural distortions, crystallinity or mixtures of different structural classes. The total fluence of the incident beam can be easily controlled in 4D-STEM. Minimizing the localized electron dose minimizes the beam damage hence 4D-STEM is a flexible and powerful approach to elucidate structure from “soft” materials such as biopolymers that are challenging to image in the conventional transmission electron microscopy (TEM) because of strong electron beam damage. This works aims to study the biopolymer PLGA using high-end 4D-STEM method on Spectra-300C instrument at UCLA, which will involve a methodology development for sample preparation, data acquisition, data processing and analysis. This study aims to establish a workflow for 4D-STEM characterization on bio-degradable polymer PLGA on Spectra-300C, the insights gained from this study will be helpful to understand and design better materials, also it’ll open a niche for the application of this techniques to other polymeric materials on Spectra-300C.

Instruments