Biomolecules adsorption to trigger the self-assembly of nanospheres and nanorods

The self-assembly (SA) of nanostructures triggered by the adsorption of biomolecules (BSA) is investigated as a platform to develop diagnostics and functional applications. Mixing nanostructures of different morphologies; SiO 2 nanospheres (NS) to a cellulose nanorod crystals (CNC) leads to the formation of short range ordered domains in the dried film. Adding biomolecules-treated SiO 2 NS into the CNC develop the long range ordered assembly in the composite film. The CNC-SiO 2 composite films were prepared by mixing CNC suspension (3 wt%) with the SiO 2 NS of different concentration (0.5-5 mg/mL) followed by drying at the ambient conditions. The CNC-SiO 2 @BSA films is prepared by first mixing the BSA (1 mg/mL) with the SiO 2 suspension of different concentrations. Later the SiO 2 @BSA suspension was mixed with the CNC and left for drying at the ambient conditions. The self-assembly mechanisms of CNC, SiO 2 and BSA are studied by combining SEM, DLS, UV-Vis, QCM-D and SAXS analysis. The SA mechanism of aqueous suspensions of CNC blended with SiO 2 NS pre-treated with BSA (by adsorption) is studied by a combination of small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), dynamic light scattering (DLS) and quartz crystal microbalance with dissipation (QCM-D). Both CNC and SiO 2 NS are negatively charged and have demonstrated self-assembly ability driven from a combination of long- and short- range order arrangement. Adding SiO 2 NS to a CNC suspension disrupts the original SA of both CNC and SiO 2 , which leads to the formation of small, short- range ordered domains of large polydispersity. Surprisingly, adding BSA-treated SiO 2 NS into the CNC network enhances the arrangement of CNC and NS towards a new system with long range ordered assembly. The SA mechanisms of cellulose-SiO 2 composites result from the balance of electrostatic repulsion and van der Waal attraction in the structure factor, radial distance distribution and potential of mean force. Understanding the effect of biomolecule adsorption on the self-assembling mechanisms of CNC nanorods with SiO 2 nanospheres enables the efficient engineering of catalysis, biosensors and diagnostics.