Self-assembled hybrid nanocomposite films of carbon dots and hydrolyzed collagen

In the present work, hydrophilic carbon dots (CD) prepared by cotton cellulose were used in the building of self-assembled films with hydrolyzed collagen (CL) to verify their properties, especially molecular interactions and morphology. The materials were characterized by several techniques, such as AFM, FTIR and UV–Vis Spectroscopy, Surface Plasmon Resonance (SPR) and Calorimetric Titration. The interaction energy between the two components measured by isothermal calorimetry is higher at low pH due to higher electrostaticinteraction. It was observed, in all experimental conditions for the growth of the films, an increase in the amount of deposited material with the number of immersions performed. However, distinct conditions of the protein solutions produced films with different properties. In the CL/CD films, the amount of deposited nanoparticles, with the collagen solution at pH = 3.2, pH = 5 and pH 3.2/0.1 mol L−1 of NaCl, were 2.3 mg/m2, 5.9 mg/m2 and 4.1 mg/m2, respectively. In addition, the increase of the ionic strength of the collagen solution promoted fibrillogenesis of the biomolecule leading to the formation of self-assembled films with a fibrillated morphology. The presented results suggest that the structures of the films can be controlled by manipulating the conditions of the protein solutions. This study may contribute to the development of a future class of devices, such as sensors and photoactive surfaces.