Synthesis and Characterization of Surface-Grafted Polyacrylamide Brushes and Their Inhibition of Microbial Adhesion

Abstract

A method is presented to prevent microbial adhesion to solid surfaces exploiting the unique properties of polymer brushes. Polyacrylamide (PAAm) brushes were grown from silicon wafers by atom transfer radical polymerization (ATRP) using a three-step reaction procedure consisting of immobilization of a coupling agent γ-aminopropyltriethoxysilane, anchoring of an ATRP initiator 4-(chloromethyl)benzoyl chloride, and controlled radical polymerization of acrylamide. The surfaces were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ellipsometry, and contact-angle measurements. The calculated grafting density pointed to the presence of a dense and homogeneous polymer brush. Initial deposition rates, adhesion after 4 h, and detachment of two bacterial strains (Staphylococcus aureus ATCC 12600 and Streptococcus salivarius GB 24/9) and one yeast strain (Candida albicans GB 1/2) to both PAAm-coated and untreated silicon surfaces were investigated in a parallel plate flow chamber. A high reduction (70−92%) in microbial adhesion to the surface-grafted PAAm brush was observed, as compared with untreated silicon surfaces. Application of the proposed grafting method to silicone rubbers may offer great potential to prevent biomaterials-centered infection of implants.

Microbial adhesion to surface‐grafted polyacrylamide brushes after long‐term exposure to PBS and reconstituted freeze‐dried saliva

“…All strains were cultured as detailed before. 20 Microbial adhesion to noncoated and PAAm brush-coated silicone wafer was observed in a parallel plate flow chamber as reported previously. 20 …”

“…20 Subsequently, surface modification was done following the reaction procedure as described previously. 19 First, aminosilanization was carried out in a toluene solution (2% v/v) of c-aminopropyltriethoxysilane.…”

“…Second, the amino groups were reacted with 4-(chloromethyl)benzoyl chloride in dichloromethane solution (2% wt/v) to introduce the initiator and, finally, the atom transfer radical polymerization (ATRP) of acrylamide was carried out as described before. 20 The brush length and grafting density was calculated using ellipsometry as described previously. 20 Collection of saliva and exposure of PAAm brushes From at least 20 healthy volunteers of both sexes, human whole saliva was collected into ice-chilled cups.…”

“…20 The brush length and grafting density was calculated using ellipsometry as described previously. 20 Collection of saliva and exposure of PAAm brushes From at least 20 healthy volunteers of both sexes, human whole saliva was collected into ice-chilled cups. After the saliva was pooled and centrifuged at 10,000g for 5 min at 10 C, phenylmethylsulfonylfluoride was added to a final concentration of 1 mM as a protease inhibitor.…”

Three‐dimensional Arrangement of Short DNA Oligonucleotides at Surfaces via the Synthesis of DNA‐branched Polyacrylamide Brushes by SI‐ATRP

“…Following Cringus and Funderanu's approach, SI-ATRP was carried out in solution and the resulting DNA-acrylamide polymer was purified by repeated precipitation. [33] Figure 2(B) presents the mass spectra obtained under ionization conditions favorable to the fragmentation of the acrylamide backbone (i.e., ditranol/K). Under these experimental conditions, the spectra obtained correspond to that of a polymer with a fragmentation mass difference of 72 m/z, attributable to the acrylamide monomer units, and an average molecular weight of 1845 g Á mol À1 , i.e., approximately 23 acrylamide units.…”