In this work, cellulosic nanomaterials were investigated for application as fluidic and sensing platforms. These platforms were used for humidity measurement, biosensors, and immunoassays, which are relevant to the areas of diagnostics, printed electronics, and smart packaging. A systematic investigation was carried out to study the interactions between water and protein molecules with cellulosic materials, which was facilitated by advanced techniques such as quartz microgravimetry, surface plasmon resonance, and confocal microscopy. Humidity responsive and electroactive composite films were developed using hybrid materials composed of nanocellulose and carbon nanotubes. The changes in relative humidity of air were monitored by measuring the shift in electroacoustic admittance and electrical resistivity of composite films upon water uptake. Other systems that incorporated mineral particles and nano-and microcellulose were used for lateral flow assays (LFA) based on fluidic wicking. For this purpose, inkjet printing was used to produce hydrophobic channel sidewalls on nanopaper. Alternatively, stencil printing of the fluid-wicking element was applied on hydrophobic supports. These wicking systems showed the potential as new types of LFA devices with excellent sensitivity. Glucose, non-specific protein, and antigen detection were demonstrated by colorimetric sensing at clinically relevant concentrations. A new type of cellulose nanomaterial, cellulose II nanoparticles, was introduced as a substrate for controlled protein adsorption. The interactions and protein accessibility to surfaces treated with such cellulose II nanoparticles, which formed a hydrogel film, were investigated in detail. Cationic cellulose II nanoparticles (NPcat) showed one of the highest levels of accessibility recorded, following both specific and non-specific protein interactions, and suggested NPcat suitability as a new immobilizing agent for biomolecular sensing. Oppositely charged anionic cellulose II nanoparticles (NPan) were used for surface passivation and indicated a great potential as a blocking agent that can be deposited on substrates to minimize non-specific molecular interactions. Both cellulose nanospheres, NPcat and NPan were deployed in protein-accessible and protein-repellent materials, respectively, and facilitated the design of a rapid antigen sensing system for SARS-CoV-2 nucleocapsid.
|Award date||5 May 2022|
|Publication status||Published - 5 May 2022|
|MoE publication type||G5 Doctoral dissertation (article)|
- surface interactions