# Micro-Nanobubble Technology in Surface Cleaning and Defouling
## 4 Biofouling Mitigation and Advanced Cleaning Technologies
### Healthcare and Biofilm Remediation  
In healthcare applications, NBs and their byproducts, including ozone ultrafine bubble water (OUFBW), have become effective instruments for surface cleaning and biofilm removal. Without sacrificing the integrity of the material, these bubbles improve disinfection, break up biofilms, and inhibit microbiological adhesion [89]. Studies have demonstrated their adaptability. OUFBW efficiently lowers _Candida albicans_ (_C. albicans_) biofilms and suppresses metabolic activity, maintaining the quality of materials such as denture resins. By promoting mass transfer and biofilm breakdown, NBs enhance the structural soundness and performance of biological systems including anammox granular sludge (AnGS) [104]. Furthermore, breakthroughs such as graphene/carbon nanotube membranes that electrochemically produce NBs have strong self-cleaning capabilities, successfully tackling biofouling. Additionally, by improving skin oxygenation and biofilm control, NB hydrotherapy has demonstrated potential in the treatment of complicated diseases such as harlequin ichthyosis (HI). These uses, along with their low toxicity and broad-spectrum bactericidal effectiveness, make NBs revolutionary tools for improving surface cleaning and biofilm control in both industrial and clinical contexts [105]. [PERSON] et al. [89] examined the impact of OUFBW at concentrations of 6, 9, and 11 ppm in conjunction with controls on the development and biofilm formation of _C. albicans_ on denture base oils. Fluorescence microscopy demonstrated living cells in all groups, and SEM showed fewer fungi and reduced biofilm structures in the treated groups, indicating that OUFBW at 9 and 11 ppm significantly broke down established biofilms and gradually inhibited biofilm formation. Moreover, OUFBW at 11 ppm down-regulated important adhesion genes involved in biofilm formation and suppressed the metabolic activity of _C. albicans_. The Vickers hardness and surface roughness of the acrylic resin were unaffected by the immersion in OUFBW. Overall, the study found that OUFBW successfully prevents the growth of _C. albicans_ and the formation of biofilms without sacrificing the integrity of the denture base resin, indicating the possibility of additional research into its mechanisms and clinical uses for denture wearers. [PERSON] et al. [106] discussed the function of NBs in preserving the stability and structure of AnGS systems, filling in knowledge gaps brought on by the intricacy of the system and analytical difficulties. This study showed that after 300 min at 30 \({}^{\circ}\)C, dissolved gas supersaturation in AnGS produced NBs at a concentration of 2.75 \(\times\) 10\({}^{8}\) bubbles/mL. The stable NBs, which ranged in wavelength from 150 nm to 400 nm, showed increased stability over time by increasing the absolute value of the zeta potential. Given the increased space and pressure between cells brought about by NB formation, cell clusters were disrupted, and granules underwent advantageous microstructural changes that stopped flotation and disintegration owing to excessive extracellular polymeric substance secretion. To promote high-porosity structures and effective mass transfer within the AnGS, the formation and stability of NBs facilitated the formation of nanopores both inside and outside the cell clusters. Overall, this study provided insightful information for controlling AnGS's operation and determining its level of biological gas production. [PERSON] et al. [107] described a carbon nanotube/graphene membrane that uses electrochemical bubble generation for self-cleaning to prevent biofouling during membrane-based filtration processes. Within 10 min, the membrane achieved a 95.2% reduction in extracellular polymeric substances and over 4-log removal of viable biofilm cells, demonstrating high stability at voltages up to 15 V (Figure 15).