title: Comparative effectiveness of NiCl2, Ni- and NiO-NPs in controlling oral bacterial growth and biofilm formation on oral surfaces.
abstract: OBJECTIVE
  Oral ailments are often treated with antibiotics, which are rendered ineffective as bacteria continue to develop resistance against them. It has been suggested that the nanoparticles (NPs) approach may provide a safer and viable alternative to traditional antibacterial agents. Therefore, nickel (Ni)- and nickel oxide (NiO)-NPs were synthesized, characterized and assessed for their efficacy in reducing oral bacterial load in vitro. Also, the effects of bulk compound NiCl2 (Ni ions), along with the Ni- and NiO-NPs on bacterial exopolysaccharide (EPS) production and biofilm formation on the surface of artificial teeth, and acrylic dentures, were investigated.
  
  
  METHODS
  Total bacteria from a healthy male were collected and adjusted to 4×109cells/ml for all the tests. Effect of the NPs on growth, biofilm formation, EPS production and acid production from glucose was tested using standard protocols.
  
  
  RESULTS
  Data revealed that the Ni-NPs (average size 41.23nm) exhibited an IC50 value of 73.37μg/ml against total oral bacteria. While, NiO-NPs (average size 35.67nm) were found less effective with much higher IC50 value of 197.18μg/ml. Indeed, the Ni ions exhibited greater biocidal activity with an IC50 value of 70μg/ml. Similar results were obtained with biofilm inhibition on the surfaces of dental prostheses. The results explicitly suggested the effectiveness of tested Ni compounds on the growth of oral bacteria and biofilm formation in the order as NiCl2>Ni-NPs>NiO-NPs.
  
  
  CONCLUSIONS
  The results elucidated that Ni-NPs could serve as effective nanoantibiotics against oral bacteria.
authors.affiliation: Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia. Electronic address: shamsalig@yahoo.com.
authors.forename: Shams Tabrez
authors.initials: ST
authors.lastname: Khan
authors.forename: Maqusood
authors.initials: M
authors.lastname: Ahamed
authors.forename: Hisham A
authors.initials: HA
authors.lastname: Alhadlaq
authors.forename: Javed
authors.initials: J
authors.lastname: Musarrat
authors.forename: Abdulaziz
authors.initials: A
authors.lastname: Al-Khedhairy
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D017266:Dental Prosthesis / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D009055:Mouth / Q000187:drug effects / Q000382:microbiology*; D053758:Nanoparticles / Q000737:chemistry / Q000627:therapeutic use*; D009532:Nickel / Q000494:pharmacology / Q000627:therapeutic use*; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification; D016459:Prosthesis-Related Infections / Q000188:drug therapy*; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D011135:Polysaccharides, Bacterial; D009532:Nickel
keywords: Biofilm; Dental hygiene; Nanoparticles; Nickel; Oral bacteria