Synthesis of self-cleaning and photoreactive spherical layered double oxide/polymer composite thin layers: Biofouling and inactivation of bacteria

• Published in: Applied clay science 2022-10, Vol.228, p.106587, Article 106587
• Main Authors: Deák, Ágota, Janovák, László, Tallósy, Szabolcs Péter, Godič-Torkar, Karmen, Abram, Anže, Dékány, Imre, Sebők, Dániel, Bohinc, Klemen
• Format: Article
• Language: English
• Subjects: Bacterial adhesion; Composite layers; Layered double oxide (LDO); Photoreactive surfaces; Superhydrophobicity
• ISSN: 0169-1317; 1872-9053
• DOI: 10.1016/j.clay.2022.106587

Layered double oxide (LDO) photocatalyst microparticles were synthetized with special radial lamellar orientation. We presented that the 25.31 ± 2.34 μm LDO particles with rough surface can incorporated in fluoropolymer solution and resulted a composite layer with dual superhydrophobic and photocatalytic properties with high bacterial adhesion and inactivation ability. Next the LDO content in the composite layers were systematically increased (0, 20, 40, 60, 80 and 100 wt% LDO) which facilitated the surface adhesion of bacteria by electrostatic interactions. The structure of the initial LDO and LDO/fluoropolymer composites was verified by small angle X-ray scattering (SAXS), XRD and SEM measurements. We showed that the surface roughness and hydrophobicity increase with increasing LDO loading. At 80/20 wt% LDO/fluoropolymer ratio the apparent surface energy was low enough to obtain a superhydrophobic surface (θw= 156.3° and γstot= 2.7 mJ/m2). The bacterial adhesion extent on LDO/fluoropolymer composite layers increases with increasing LDO content because the adhesion takes place preferentially to LDO lamellae. The reason for this pronounced adhesion of negatively charged and hydrophilic bacteria onto positively charged and hydrophilic LDO surfaces is the electrostatic attraction between oppositely charged surfaces. The bacterial adhesion was detected by scanning electron and fluorescence microscopy and crystal violet staining assay. Finally, the adhered bacteria were inactivated by the LED-light illumination due to photoreactivity of LDO particles containing 12 wt% of ZnO phase. [Display omitted] •Photoreactive composite layers were synthesized with designed wetting properties.•LDO photocatalysts particles were ensured the adequate surface roughness.•The adhesion of bacteria was occurred on the photocatalyst (LDO) particles.•Surface hydrophobicity orientated bacteria were effectively inactivated by light.