title: [Effect of stiffness of polyelectrolyte multilayer on titanium surface on bacterium adhesion].
abstract: OBJECTIVE
  To provide a theoretical basis for surface modification of titanium implants, the effects of the stiffness of polyelectrolyte multilayer films on titanium surface on bacterium adhesion was explored.
  
  
  METHODS
  Via layer-by-layer technique, catechol functionalized polyelectrolyte multilayer film (cPEM) was constructed on titanium surface by using catechol functionalized hyaluronic acid (cHA) and lipopolysaccharide-amine nanopolymersomes (NP). The stiffness of cPEM was controlled by adjusting the catechol substitution degree of cHA (5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%). Titanium samples covered with cPEM were selected as test group, and the cPEM was constructed with the lowest, medium and highest stiffness. The polished titanium was used as a control. The surface topography of titanium before and after film construction was observed by scanning electron microscopy (SEM). At 1 and 24 h after incubation, the adhesion and clonal formation of Streptococcus mutans (S. mutans) on different titanium surfaces were quantified, and their morphology and survival status were observed by SEM and laser scanning confocal microscope (LSCM).
  
  
  RESULTS
  When the catechol grafting ratio was 5%, 30% and 70%, the lowest, medium and highest cPEM stiffness were obtained, and the cPEM stiffness were (10.69±4.54) GPa(cPEM-L), (20.99± 5.81) GPa (cPEM-M) and (32.57±6.93) GPa (cPEM-H) respectively, and the stiffness of polished titanium was (107.12±8.68) GPa (P<0.05). SEM observation showed that after cPEM coating, the titanium surface became smoother. After incubation for 1 and 24 h, the amount of adhesion and clonal formation of S. mutans on cPEM were higher than those on control titanium, and the difference was statistically significant (P<0.05). SEM images showed that for 1 h incubation, softer surfaces were beneficial for S. mutans adhering and agglomerating, while this difference nearly disappeared at 24 h. Observation under LSCM revealed that most of bacteria were alive on titanium disks at 1 h, and their amount decreased with the increase of stiffness. At 24 h, the living/dead bacterium ratios on cPEM-L and control titanium was higher than that on cPEM-M and cPEM-H, and cPEM-L surface was dominated by living bacteria, while stiffer cPEM-M and cPEM-H had more dead bacteria than living bacteria.
  
  
  CONCLUSIONS
  Increasing the stiffness of polyelectrolyte films on titanium limits the adhesion of S. mutans. As an independent factor, stiffness influences the bacterium adhesion.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University & Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Prosthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University & Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Teng
authors.affiliation: Key Laboratory on Assisted Circulation, Ministry of Health, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China.
authors.forename: Qinmei
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Oral and Maxillofacial Surgery, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University & Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China.
authors.forename: Hongzhang
authors.initials: H
authors.lastname: Huang
mesh_terms: D001422:Bacterial Adhesion; D002396:Catechols; D004548:Elasticity; D006820:Hyaluronic Acid; D008070:Lipopolysaccharides; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles; D011108:Polymers / Q000737:chemistry*; D013295:Streptococcus mutans / Q000502:physiology*; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*
chemical_list: D002396:Catechols; D008070:Lipopolysaccharides; D011108:Polymers; D006820:Hyaluronic Acid; D014025:Titanium; C034221:catechol