Bacterial adhesion to biomaterials: What regulates this attachment? A review

Abstract

Bacterial attachment to biomaterials is of great interest to the medical and dental field due to its impact on dental implants, dental prostheses, and others, leading to the need to introduce methods for biofilm control and mitigation of infections. Biofilm adhesion is a multifactorial process and involves characteristics relevant to the bacterial cell as well as biological, chemical, and physical properties relative to the surface of biomaterials. Bacteria encountered different environmental conditions during their growth and developed interspecies communication strategies, as well as various mechanisms to detect the environment and facilitate survival, such as chemical sensors or physical detection mechanisms. However, the factors that govern microbial attachment to surfaces are not yet fully understood. In order to understand how bacteria interact with surfaces, as well as to characterize the physical-chemical properties of bacteria adhesins, and to determine their interrelation with the adhesion to the substrate, in recent years new techniques of atomic force microscopy (AFM) have been developed and helped by providing quantitative results. Thus, the purpose of this review is to gather current studies about the factors that regulate microbial adhesion to surfaces in order to offer a guide to studies to obtain technologies that provide an antimicrobial surface.

Keywords: AFM; Bacterial adhesion; Chemical interactions; Oral biofilms; Quorum sensing.

Fig. 1

Schematic representation of single-bacterial-contact probe atomic force microscopy. (A) The bacterial culture and the functionalizing coating are ready to be placed on the glass; (B) The glass is functionalized; (C) The bacterial cells are Immobilized on the functionalized glass; (D) The AFM probe is approached until a certain degree of indentation occurs on the cell surface; (E) Force spectra are typically captured as a cycle of tip approach and tip retraction. The tip is retracted from the surface; (F) Bacterium is attached to a tipless AFM cantilever.

Fig. 2

Stages of biofilm formation on (bio)materials surfaces. (A) Planktonic form of bacteria; (B) Bacteria adhere to the surface in a dynamic process; (C) Cells aggregating and bacterial attachment becomes irreversible; (D) Bacterial form microcolonies, and start secreting extracellular polymeric substance; (E) Cells form multi-layered clusters, and maturation of the biofilm occurs; (F) Biofilm reaches a critical mass and disperses planktonic bacteria that may colonize other surfaces.

Fig. 3

Schematic representation of bacteria proposed adhesion mechanisms. This image was adapted from Ref. [1].