<br/>The process of Layer by Layer (LbL) assembly is a simple and robust surface functionalization techniques. It has the potential to form nanometer thin films in which the final surface properties such as homogeneity and roughness could be controlled during the LbL process by optimizing the factors that affect the assembly. Using CNF and polyelectrolytes as building blocks of the LbL assembly has been shown to have application in biomedicine like cancer diagnostics. It has been shown that a microfluidic chip modified with a CNF-polyelectrolyte LbL assembly developed for efficient immunoaffinity cancer cell capturing in which the cells were released by enzymatic digestion. Here the characterization methods that have potential use with LbL assembly containing cellulose will be discussed. AFM imaging performed on LbL assembly prepared on silica wafer as a proof of concept. The images show that LbL assembly that is constructed with low molecular weight polyelectrolytes and in DI water has shown more uniformity and lower roughness of the surface which is more ideal for uniform anti-body conjugation and improved circulating tumor cell (CTC) capturing afterwards. Fluorescence microscopy imaging of samples are performed using Carbotrace™ 680, a quantitative and non-destructive fluorescent tracer selective for cellulose. It is shown that higher concentration of CNF could lead to lower uniformity of the surface coating. Also, it is demonstrated that increasing of the number of bi-layers that are prepared in 10 mM NaCl could lead to more clusters and lower homogeneity comparing to samples prepared in DI water. GISAX measurements could verify the validity of the results achieved by AFM and fluorescence microscopy. It is concluded that multiple factors playing role in the LbL assembly such as solvent and dispersion media, their pH, concentration and molecular weight of polyelectrolytes and time of incubation; all have effects on the final CNF layer homogeneity and roughness. It is also observed that all these factors could affect the final layer properties simultaneously and one should optimize the parameters all together for desired final properties.

Cellulose nano fibril- polyelectrolyte layer by layer coating on PDMS microfluidic chips: Characterization and bio applications

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.