title: Chitosan adsorption to salivary pellicles.
abstract: The salivary pellicle is a negatively charged protein film, to which oral bacteria readily adhere. Chitosans are cationic biomolecules with known antimicrobial properties that can be modified in different ways to enhance its antimicrobial activity. Here, we determined the changes in surface chemical composition using X-ray photoelectron spectroscopy (XPS), in hydrophobicity by analyzing water contact angles, in charge through measuring streaming potentials, and evaluated morphology using atomic force microscopy (AFM), of salivary pellicles upon adsorption of different chitosans. The adsorption of chitosans to pellicles was chemically evident from altered carbon functionalities and the presence of an N(1s) peak at 401.1 eV as a result of protonated amines in XPS. Chitosan adsorption made the pellicle (zeta potential of untreated pellicles 29 mV) positively charged and more hydrophobic. A chemically modified chitosan (CL) and an unmodified chitosan (UC) caused aggregation of adsorbed salivary proteins, and AFM revealed clumps of protein after treatment with these chitosans, yielding an increase in pellicle surface roughness from 5.1 nm to between 16.3 and 35.6 nm for CL and UC, respectively. In summary, chitosans have a clear tendency to adsorb to salivary pellicles with a profound effect on the surface properties of the pellicle. Therefore, chitosans may provide anchoring molecules to affix antimicrobials to pellicle surfaces.
authors: Department of Biomedical Engineering, University Medical Center Groningen and University of Groningen, 9700 AD Groningen, The Netherlands. h.c.van.der.mei@med.umcg.nl
authors: Henny C
authors: HC
authors: van der Mei
authors: Eefje
authors: E
authors: Engels
authors: Joop
authors: J
authors: de Vries
authors: Rene J B
authors: RJ
authors: Dijkstra
authors: Henk J
authors: HJ
authors: Busscher
mesh_terms: D000327:Adsorption; D000704:Analysis of Variance; D000890:Anti-Infective Agents / Q000493:pharmacokinetics*; D002244:Carbon / Q000032:analysis; D048271:Chitosan / Q000493:pharmacokinetics*; D044622:Dental Pellicle / Q000737:chemistry / Q000187:drug effects* / Q000648:ultrastructure; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D009584:Nitrogen / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D012463:Saliva / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties
chemical_list: D000890:Anti-Infective Agents; D002244:Carbon; D048271:Chitosan; D009584:Nitrogen; D010100:Oxygen