Journal article Open Access
Leskinen, Timo; Witos, Joanna; Valle-Delgado, Juan José; Lintinen, Kalle; Kostiainen, Mauri; Wiedmer, Susanne K.; Österberg, Monika; Mattinen, Maija-Liisa
Coating of colloidal lignin particles (CLPs), or lignin nanoparticles (LNPs), with proteins was investigated in order to establish a safe, self-assembly-mediated modification technique to tune their surface chemistry. Gelatin and poly- L-lysine formed the most pronounced protein corona on the CLP surface, as determined by dynamic light scattering (DLS) and zeta potential measurements. Spherical morphology of individual protein coated CLPs was confirmed by transmission electron (TEM) and atomic force (AFM) microscopy. A mechanistic adsorption study with several random coiled and globular model proteins was carried out using quartz crystal microbalance with dissipation monitoring (QCM-D). The three-dimensional (3D) protein fold structure and certain amino acid interactions were highly dependent on the protein adsorption on the lignin surface. The main driving forces of protein-lignin affinity were electrostatic, hydrophobic, and Van der Waals interactions, and hydrogen bonding. The relative contributions of these interactions were highly dependent on the ionic strength of the surrounding medium. Capillary electrophoresis (CE) and Fourier transform infrared spectroscopy (FTIR) provided further evidence about the adsorption-enhancing role of specific amino acid residues such as serine and proline. These results have high impact on the utilization of lignin as colloidal particles in biomedicine and biodegradable materials, as the protein corona enables tailoring of the CLP surface chemistry for intended applications.