Bacteria adhesion

In many liquid-phase applications, the bacterial colonization of activated carbons can occur quite readily [67]. This colonization [68] is considered to result from (i) the adsorptive properties of carbon, which produce an increase in the concentration of nutrients and oxygen as well as the removal of disinfectant compounds (ii) the pore texture of the carbon particles, which provides the bacteria with a protective environment (iii) the presence of a large variety of functional groups on the carbon surface, which enhances the adhesion of microorganisms and (iv) the nature of the mineral matter content of the carbon, which can favor bacteria adhesion. In general, bacteria attached to carbon particles are very resistant to disinfectants. 

Koh WG, Revzin A, Siminian A, Reeves T, Pishko M (2003) Control of mammalian cell and bacteria adhesion on substrates micropattemed with poly(ethylene glycol) hydrogels. Biomed Microdev 5 11-19... 

Despite the criticisms above, the vOCG approach has been frequently and successfully used over recent years to interpret polymer solubility in water [14] (this is not possible using the y approach ), protein adsorption on clays [57] and conducting polymers (see Section IV.A.2 below), cell adhesion to copolymer surfaces [65], yeast-yeast and yeast-bacteria adhesion [72], fiber-matrix adhesion [69], and the hydrodynamic detachment of colloidal particles from glass plates [70]. 

Infection has been reported to often occur when a biomaterial is implanted in a body or inserted in tubular organs as a catheter. Such infection seems to be a result of adhesion of infectious bacteria onto the biomaterial surface. If bacteria adhesion is similar to adhesion of other cells like fibroblasts, occurrence of infection through the material surface may be reduced by modifying the material surface so as to minimize cell adhesion. Such a surface can be obtained by surface grafting of water-soluble polymer chains. However, producing a hydrophilic biomaterial surface by plasma treatment only leads to enhanced cell adhesion as shown in Figure 10 (16). 

Figure 2 SEM picture of bacteria adhesion on untreated and hydrolyzed Neem seed extract treated (by HT/HP method) PET (washed sample)...

Morisaku et al. support this h3 othesis. The phosphoiylcholine groups were found to possess a hydrophobic hydration layer that did not disturb the hydrogen bonding between the water molecules. PMB-30 is a promising polymer for use in the modification of a wide variety of substrates, providing a stable polymer layer that is resistant to protein adsorption and cell/bacteria adhesion, and can initiate an anti-inflammatory response. The polymer has been filed in the Master Access File of the FDA, USA ( MAF2103, 2012) as LIPIDURE-CM5206, NOF Co., Japan. 

It is important to note that antimicrobial and biofilm resistance are two different characteristics though some materials show both properties at the same time. Antimicrobial materials do not automatically prevent biofilm formation and vice versa. Antimicrobial surfaces could kill bacteria on contact but if dead bacteria cell debris blocks the active biocidal surface, biofilm formation could eventually occur. For example, quaternary anunonium polymers can effectively kill bacteria but when the surface is fouled with dead bacteria debris, biofilm formation is inevitable [188]. Materials with antibiofilm properties will repel the bacterial adhesion very effectively but may not kill the bacteria when they do colonize the surface. PEG surfaces are well known to repel bacteria adhesion. However, PEG surfaces show little antimicrobial activity. Quantitative antibiofilm efficacy tests can be divided into two categories static (minimum biofilm eradication concentration assay, MBEC) and dynamic (flow cell assay). In addition, SEM is a semiquantitative assay, which is discussed in Section 2.5. 

The literature review revealed some deficiency in studies dedicated to the polymer basis effect on bacteria adhesion, especially with regard to an excessive amount of works devoted to the biofilm itself. In summary, the purpose of this research to analyze the distinctions in behavior of the elucidated devices with regard to bacteria adhesion, relying on investigated factors of bacteria adhesion to polymeric materials, and to provide recommendations on the developing composites based on BSTPE with improved properties, which are capable to supersede the established materials functioning in microbiota media. 

Thus, with regard to nontoxicity and moderate bacteria adhesion to material surface, BSTPE could be recommended for producing medical devices. Further on, the issues related to modifying BSTPE to improve its bacteria fouling resistance will be addressed. The recommendations for medical devices can be actual only after conducting the clinical trials. 

It is clear from the above studies that low EET efficiency between the bacteria and the anode often limits the practical applications of MFCs and another critical challenge is to overcome the low bacterial loading capacities. Note that graphene is hydrophobic and in order to try and improve bacteria adhesion and biofilm formation the decoration of graphene surfaces with hydrophilic conducting polymers (such as the use of polyaniline (PANI)) has been attempted [120]. 

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