The document summarizes a study that functionalized polydimethylsiloxane (PDMS) and stainless steel (SS) surfaces with two disinfectants, benzalkonium chloride (BZK) and chlorhexidine (CHX), using a mussel-inspired coating strategy. This immobilization of BZK and CHX onto the surfaces rendered them with antimicrobial properties and a low propensity for bacterial resistance development. Testing showed the coated surfaces reduced bacterial adhesion and viability of Staphylococcus aureus and S. epidermidis. The results highlight the potential of this approach for designing antimicrobial coatings for clinical settings.

1. Functionalization of polydimethylsiloxane and
stainless steel surfaces with disinfectants
Diana Alves, Carla Faria, Patrick Borges and Maria Olivia Pereira
University of M inho
School of Engineering
This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European
Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. The authors also acknowledge the support by FCT and the European Community fund FEDER, through Program COMPETE, under the scope of the Project AntiPep PTDC/SAU-SAP/113196/2009
(FCOMP-01-0124-FEDER-016012) and the PhD Grant of Diana Alves (SFRH/BD/78063/2011) . The authors also acknowledge COST AMiCI for the invitation.
Figure 1. (A) Contac-killing ability of surfaces functionalized with benzalkonium chloride (BZK) and chlorhexidine (CHX) and their leaching from the surfaces . (B) Number of adhered cells of S. aureus (black) and S.
epidermidis (blue) to unmodified stainless steel (SS), pDA-coated SS (pDA) and pDA-coated SS surfaces functionalized with chlorhexidine (CHX). (C) Metabolic activity of cells of S. aureus (black) and S.
epidermidis (blue) adhered to unmodified PDMS, pDA-coated PDMS (pDA) and pDA-coated PDMS surfaces functionalized with benzalkonium chloride (BZK). (D) MIC and MBC values of benzalkonium chloride (BZK)
against planktonic and adhered S. aureus recovered from unmodified PDMS, pDA and pDA further functionalized with BZK after 10 days of exposure.
q A mussel-inspired coating strategy was successfully applied to immobilize two disinfectants (BZK and CHX)) onto PDMS and SS surfaces and render them with
antimicrobial properties.
q A low propensity for developing bacterial resistance after their immobilization was found for BZK.
q Overall results highlight the promising potential of BZK and CHX to be used in the design of antimicrobial coatings for clinical settings.
Methods
Results
Conclusions
Main Goals
Introduction
Centre of Biological Engineering, LIBRO – Laboratory of Research in Biofilms Rosário Oliveira
University of Minho, Campus de Gualtar, 4700-057 Braga, Portugal
Cells
MIC (µg/mL) MBC (µg/mL)
PDMS pDA BZK PDMS pDA BZK
Adhered 2.5 2.5 2.5 5 5 5
Planktonic 1.25 5
(A)
(B)
(C)
(D)
Bacteria/
Antimicrobial
S. aureus S. epidermidis
Contact-killing Leaching Contact-killing Leaching
BZK Yes No Yes No
CHX Yes Yes Yes Yes
LeachingNo Leaching
PDMS pDA BZK
0.0
0.5
1.0
1.5
2.0
S. aureus
S. epidermidis
OD(490nm)
SS pDA CHX
0
2
4
6
8
Log(CFU/mL)
S. aureus
S. epidermidis
Microbial adhesion onto surfaces is at the root of serious problems in many areas, often compromising the
disinfection practices. In clinical settings, microorganisms can colonize abiotic surfaces, equipment and medical
devices. This problem is aggravated when microorganisms adopt a sessile lifestyle and live in biofilms. The best
approach to prevent the occurrence of cell adhesion and biofilm formation, with subsequent spread of
microorganisms between equipment and people, relies on the development of materials able to resist their
colonization in first place.
To prevent Staphylococci attachment to polydimethylsiloxane
(PDMS) and stainless steel (SS) surfaces, through
immobilization of benzalkonium chloride (BZK) and
chlorhexidine (CHX).
Polydopamine film
(pDA)
1.Dip coat in
dopamine-HCl
2. Immobilize
antimicrobial
OH
OH
OH
OH
Antimicrobial surface
(BZK/CHX)
Polydimethylsiloxane
(PDMS) or stainless
steel (SS)
Surface modification
***
***
Resistance Development
24 h, 120 rpm, 37 oC
Cells detachedSonication +
vortex
10 passages