Nucleation of calcium carbonate nanoparticles in alginate biomimetic matrix by CO2 diffusion using microfluidic devices

Contacts:
Simone Laganá, PhD – Student 
Kristian Mølhave, Assoc. Prof.
DTU Nanotech, DTU Cen, and DTU Chemistry
Group: Molecular Windows

Calcium carbonate is one of the most abundant biogenic mineral present on the earth. Understanding the principle which is behind its formation is one of the major topics related to a new generation of bio-inspired materials. In this work we would like to focus our attention on the diffusion of CO₂ in a thin alginate biopolymer film, to investigate how alginate will affect the resulting CaCO₃ nucleation. Nowadays, alginate is the most common cross-linked hydrogel used for biomedical industries in different kinds of applications like wound treatment, cell encapsulation and scaffold for tissue engineering¹. However, the nanoscale mechanism of how alginate and CaCO₃ are interacting has never being addressed so far even if CO₂ diffusion at high pressure is a well-established methodology². Charged biopolymers are well known as amorphous calcium carbonate phase stabilizers³. This work will use electron microscopy techniques such as ((S)TEM, cryo-TEM, EELS, Diffraction) and also combining a well-established approach to characterize (bio)polymer thin films with CaCO₃  precipitates.

The main task of this project will be:

Aim 1: Fabrication of micro milled microfluidic system for CO₂ injection into an alginate matrix

Challenge: To characterize CaCO₃ dispersed in a biomimetic matrix and establish a new way of its synthesis.

Approach: A micro milled PMMA system will be developed ensuring diffusion of CO₂ only through one small nanometric hole in a silicon nitride 50 [nm] suspended membrane. Possible characterizing methods to consider are TEM, EELS, Diffraction and Raman (in bulk system).

Impact: This work will propose a new way of CaCO₃ synthesis clarifying also which kind of interactions between a biopolymer (as alginate) and a bio mineral (as CaCO₃) could be occurring on the nanoscale.

Schematic drawing of the diffusion set up. b) Suspended 50 [nm] Silicon nitride on a round chip Ø = 3 [mm] 

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