Self-cleaning and antibiofouling enamel surface by slippery liquid-infused technique.

The microbial biofilm is defined as a community of microbial cells attached to surfaces in natural and anthropogenic environments; such cells are embedded in a matrix of extracellular polymeric substance1. Mature biofilms are resistant to various antimicrobial treatments. Dental plaque is a typical biofilm that can accommodate a variety of flora2. Common dental diseases, such as dental caries and periodontal diseases, are caused by dental plaque. Furthermore, an association has been suggested between the oral microbiota and systemic diseases, such as diabetes, cardiovascular disease, atherosclerosis, and complications during pregnancy3,4. Treatment of adherent biofilm is difficult and costly. In clinic dentistry, dental plaque is usually controlled by meticulous mechanical oral hygiene. However, most individuals can hardly maintain the necessary standards of plaque control strictly for a long time. Additional approaches are being developed that are less dependent on the dexterity of the patient, and which augment conventional oral hygiene methods and keep plaque at levels compatible with oral health. Consequently, a wide range of antimicrobial agents, such as chlorhexidine, triclosan, metal salts, enzymes, and plant extracts, have been formulated into oral care products to enhance their plaque control potential5,6,7,8. However, following the prolonged and persistent usage of biocidal chemotherapeutics, oral bacteria can potentially acquire resistance to these agents. Most importantly, such agents may be harmful to the normal, resident oral microflora, possibly resulting in new problems9. Therefore, the approach that prevents the initial attachment of bacteria is likely to be better than the antimicrobial approach that aims at killing bacteria already attached. The prevention of biofilm formation without using biocidal agents rather than treatment of biofilm using antimicrobials is highly desirable. Dental plaque formation begins with the bacteria recognizing the salivary pellicle, which is an acquired pellicle for salivary proteins adsorbed onto the dental surface10. Thus, to prevent dental biofilm formation, scientists should focus on inhibiting bacterial adhesion and salivary protein adsorption on the dental surface. Common methods to construct the antibiofouling surface for medical devices and implants include functionalizing the surface chemical functional groups and then grafting poly (ethylene glycol) (PEG) or its analog, such as N-substituted glycine and polysarcosine11,12,13. However, none have yet proven ideal for long-term antibiofouling property. These antibiofouling surfaces are believed to be in solid forms. Permanent interactions between the solid surfaces and biological adhesives can eventually be established depending on the time scales of the adhesion processes, which then lead to stable attachment and biofouling14. Recently, a slippery liquid-infused porous surface (SLIPS) was introduced. The stabilized liquid interface possesses dynamic features down to the nanometer scale and may inhibit these permanent interactions, thereby significantly disrupting biological adhesion15,16,17. The antibiofouling effect of SLIPS is better than that of the PEGylated surface18. However, oral environment and oral bacterial flora are highly complex, and dental plaque formation exhibits distinctive behavior. To date, SLIPS on an enamel surface has not been reconstructed nor has its effect on inhibiting dental biofilm formation been evaluated. Thus, in the present study, we aimed to create a slippery liquid-infused enamel surface and evaluate its antibiofouling property.