A novel and facile marine mussel-inspired surface modification approach for microcrystalline celluloses (MCC) and enhanced interfacial adhesion with the soy protein isolate (SPI) matrix were demonstrated in an effort to develop renewable composite films. The surface composition and micromorphology of the poly­(dopamine) (PDA)-modified MCC (PDMCC) were characterized by X-ray photoelectron spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The biomimetic adherent PDA layer was successfully coated onto the MCC surface via dopamine self-polymerization through a simple dip-coating method. As expected, the adlayer of PDA between the PDMCC and peptide chains greatly enhanced the mechanical properties of the resultant films. Because of the favorable interfacial adhesion between PDMCC and SPI, as certified by solid state 13C nuclear magnetic resonance and atomic force microscopy, the tensile strength of the PDMCC/SPI film was improved by 82.3%, and its water absorption was reduced by 31.3% in comparison to that of the unmodified SPI film.

Biopolymer products are widely used in our everyday life, however, the poor antimicrobial nature dramatically limits their applications. Therefore, it is essential to improve the antibiotic performance of these biopolymer products. In this study, soy protein isolate (SPI)-based films with antimicrobial and antifouling function were fabricated through a dip-coating method. Briefly, mussel-inspired polydopamine was coated onto the surface of SPI film, followed by depositing silver nanoparticles (AgNPs) on the film for yielding an antimicrobial film, named S-DA-Ag. Subsequently, octadecyltrichlorosilane (OTS) molecular was attached on the S-DA-Ag film. Elemental and morphological surface analyses verified the successful coating for each step. The S-DA film decorated only with AgNPs exhibited an effective antimicrobial activity against Escherichia coli and Staphylococcus aureus but failed to prevent bacterial attachment. However, the number of attached bacterial cells significantly decreased for the OTS-coated S-DA-Ag film.Additionally, the resultant SPI-based films displayed excellent mechanical performance and remarkably improved water resistance, dramatically benefiting their practical applications. This novel design can endow the antimicrobial and antifouling properties to the SPI-based films and enhance their mechanical properties and water resistance, which might expand their potential applications in the healthcare and biomedical fields. K E Y W O R D Sbiopolymers, coatings, films, proteins