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1.
Biofouling ; 32(9): 1017-28, 2016 10.
Article in English | MEDLINE | ID: mdl-27560712

ABSTRACT

Silicone-oil additives are often used in fouling-release silicone coatings to reduce the adhesion strength of barnacles and other biofouling organisms. This study follows on from a recently reported active approach to detach barnacles, which was based on the surface strain of elastomeric materials, by investigating a new, dual-action approach to barnacle detachment using Ecoflex®-based elastomers incorporated with poly(dimethylsiloxane)-based oil additives. The experimental results support the hypothesis that silicone-oil additives reduce the amount of substratum strain required to detach barnacles. The study also de-coupled the two effects of silicone oils (ie surface-activity and alteration of the bulk modulus) and examined their contributions in reducing barnacle adhesion strength. Further, a finite element model based on fracture mechanics was employed to qualitatively understand the effects of surface strain and substratum modulus on barnacle adhesion strength. The study demonstrates that dynamic substratum deformation of elastomers with silicone-oil additives provides a bifunctional approach towards management of biofouling by barnacles.


Subject(s)
Biofouling/prevention & control , Dimethylpolysiloxanes/chemistry , Silicone Elastomers/chemistry , Silicone Oils/chemistry , Thoracica/physiology , Animals , Surface Properties
2.
Biomaterials ; 77: 77-86, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26584348

ABSTRACT

Biofilm removal from biomaterials is of fundamental importance, and is especially relevant when considering the problematic and deleterious impact of biofilm infections on the inner surfaces of urinary catheters. Catheter-associated urinary tract infections are the most common cause of hospital-acquired infections and there are over 30 million Foley urinary catheters used annually in the USA. In this paper, we present the design and optimization of urinary catheter prototypes capable of on-demand removal of biofilms from the inner luminal surface of catheters. The urinary catheters utilize 4 intra-wall inflation lumens that are pressure-actuated to generate region-selective strains in the elastomeric urine lumen, and thereby remove overlying biofilms. A combination of finite-element modeling and prototype fabrication was used to optimize the catheter design to generate greater than 30% strain in the majority of the luminal surface when subjected to pressure. The catheter prototypes are able to remove greater than 80% of a mixed community biofilm of Proteus mirabilis and Escherichia coli on-demand, and furthermore are able to remove the biofilm repeatedly. Additionally, experiments with the prototypes demonstrate that biofilm debonding can be achieved upon application of both tensile and compressive strains in the inner surface of the catheter. The fouling-release catheter offers the potential for a non-biologic, non-antibiotic method to remove biofilms and thereby for impacting the thus far intractable problem of catheter-associated infections.


Subject(s)
Biofilms , Urinary Catheters , Bacterial Adhesion , Biofilms/growth & development , Catheter-Related Infections/prevention & control , Equipment Contamination , Equipment Design , Escherichia coli/physiology , Finite Element Analysis , Humans , Models, Theoretical , Pressure , Proteus mirabilis/physiology , Stress, Mechanical , Urinary Catheterization , Urinary Tract Infections/prevention & control
3.
ACS Appl Mater Interfaces ; 7(46): 25586-91, 2015 Nov 25.
Article in English | MEDLINE | ID: mdl-26554418

ABSTRACT

We present a method for dual-mode-management of biofouling by modifying surface of silicone elastomers with zwitterionic polymeric grafts. Poly(sulfobetaine methacrylate) was grafted from poly(vinylmethylsiloxane) elastomer substrates using thiol-ene click chemistry and surface-initiated, controlled radical polymerization. These surfaces exhibited both fouling resistance and triggered fouling-release functionality. The zwitterionic polymers exhibited fouling resistance over short-term (∼hours) exposure to bacteria and barnacle cyprids. The biofilms that eventually accumulated over prolonged-exposure (∼days) were easily detached by applying mechanical strain to the elastomer substrate. Such dual-functional surfaces may be useful in developing environmentally and biologically friendly coatings for biofouling management on marine, industrial, and biomedical equipment because they can obviate the use of toxic compounds.


Subject(s)
Biofouling , Polymers/chemistry , Silicone Elastomers/chemistry , Bacteria/drug effects , Bacterial Adhesion , Biofilms/drug effects , Ions , Photoelectron Spectroscopy , Polymerization , Polyvinyls/pharmacology , Siloxanes/pharmacology , Spectroscopy, Fourier Transform Infrared , Surface Properties
4.
Biofouling ; 31(3): 265-74, 2015.
Article in English | MEDLINE | ID: mdl-25917206

ABSTRACT

Many strategies have been developed to improve the fouling release (FR) performance of silicone coatings. However, biofilms inevitably build on these surfaces over time. Previous studies have shown that intentional deformation of silicone elastomers can be employed to detach biofouling species. In this study, inspired by the methods used in soft-robotic systems, controlled deformation of silicone elastomers via pneumatic actuation was employed to detach adherent biofilms. Using programmed surface deformation, it was possible to release > 90% of biofilm from surfaces in both laboratory and field environments. A higher substratum strain was required to remove biofilms accumulated in the field environment as compared with laboratory-grown biofilms. Further, the study indicated that substratum modulus influences the strain needed to de-bond biofilms. Surface deformation-based approaches have potential for use in the management of biofouling in a number of technological areas, including in niche applications where pneumatic actuation of surface deformation is feasible.


Subject(s)
Biofilms , Biofouling/prevention & control , Materials Testing , Silicone Elastomers/chemistry , Bacteria/growth & development , Elastic Modulus , Seawater , Surface Properties
5.
Adv Healthc Mater ; 3(10): 1588-96, 2014 Oct.
Article in English | MEDLINE | ID: mdl-24668920

ABSTRACT

Infectious biofilms are problematic in many healthcare-related devices and are especially challenging and ubiquitous in urinary catheters. This report presents an on-demand fouling-release methodology to mechanically disrupt and remove biofilms, and proposes this method for the active removal of infectious biofilms from the previously inaccessible main drainage lumen of urinary catheters. Mature Proteus mirabilis crystalline biofilms detach from silicone elastomer substrates upon application of strain to the substrate, and increasing the strain rate increases biofilm detachment. The study presents a quantitative relationship between applied strain rate and biofilm debonding through an analysis of biofilm segment length and the driving force for debonding. Based on this mechanism, hydraulic and pneumatic elastomer actuation is used to achieve surface strain selectively within the lumen of prototypes of sections of a fouling-release urinary catheter. Proof-of-concept prototypes of sections of active, fouling-release catheters are constructed using techniques typical to soft robotics including 3D printing and replica molding, and those prototypes demonstrate release of mature P. mirabilis crystalline biofilms (e.g., ≈90%) from strained surfaces. These results provide a basis for the development of a new urinary catheter technology in which infectious biofilms are effectively managed through new methods that are entirely complementary to existing approaches.


Subject(s)
Biofilms , Equipment Design/methods , Urinary Catheters/microbiology , Catheter-Related Infections/microbiology , Catheter-Related Infections/prevention & control , Proteus mirabilis/physiology , Robotics , Silicone Elastomers , Surface Properties
6.
ACS Appl Mater Interfaces ; 5(19): 9295-304, 2013 Oct 09.
Article in English | MEDLINE | ID: mdl-24041191

ABSTRACT

Model surfaces with switchable functionality based on nanopatterned, thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) brushes were fabricated using interferometric lithography combined with surface-initiated polymerization. The temperature-triggered hydration and conformational changes of nanopatterned PNIPAAm brushes reversibly modulate the spatial concealment and exposure of molecules that are immobilized in the intervals between nanopatterned brushes. A biocidal quaternary ammonium salt (QAS) was used to demonstrate the utility of nanopatterned PNIPAAm brushes to control biointerfacial interactions with bacteria. QAS was integrated into polymer-free regions of the substrate between nanopatterned PNIPAAm brushes. The biocidal efficacy and release properties of these surfaces were tested against Escherichia coli K12. Above the lower critical solution temperature (LCST) of PNIPAAm, desolvated, collapsed polymer chains facilitate the attachment of bacteria and expose QAS moieties that kill attached bacteria. Upon a reduction of the temperature below the LCST, swollen PNIPAAm chains promote the release of dead bacteria. These results demonstrate that nanopatterned PNIPAAm/QAS hybrid surfaces are model systems that exhibit an ability to undergo noncovalent, dynamic, and reversible changes in structure that can be used to control the attachment, killing, and release of bacteria in response to changes in temperature.


Subject(s)
Acrylic Resins/chemistry , Bacteria/drug effects , Nanoparticles/chemistry , Surface Properties , Acrylic Resins/pharmacology , Alkanes/chemistry , Humans , Polymerization , Quaternary Ammonium Compounds/chemistry , Temperature
7.
Nanoscale ; 5(9): 3632-7, 2013 May 07.
Article in English | MEDLINE | ID: mdl-23532384

ABSTRACT

We report convenient methods for synthesis of nanopatterned, thermally responsive brushes of poly(N-isopropyl acrylamide) over large areas (e.g., 1 cm(2)) to form model, dynamic, biofunctional surfaces. The new nanopatterned brush structure can be used to control (i) the rate of both nonspecific and biospecific adsorption processes at the polymer-graft-free regions of the substrate, and (ii) the rate of cell detachment. These capabilities have potential implications in a number of areas of biotechnology including biosensing, separations and cell culture.


Subject(s)
Acrylamides/chemistry , Polymers/chemistry , Acrylamides/metabolism , Acrylic Resins , Adsorption , Animals , Biosensing Techniques , Cattle , Cell Adhesion , Hydrogen-Ion Concentration , Light , Mice , NIH 3T3 Cells , Oxidation-Reduction , Polymers/metabolism , Serum Albumin, Bovine/chemistry , Serum Albumin, Bovine/metabolism , Surface Properties
8.
Adv Mater ; 25(10): 1430-4, 2013 Mar 13.
Article in English | MEDLINE | ID: mdl-23292960

ABSTRACT

Dynamic change of the surface area and topology of elastomers is used as a general, environmentally friendly approach for effectively detaching micro- and macro-fouling organisms adhered on the elastomer surfaces. Deformation of elastomer surfaces under electrical or pneumatic actuation can debond various biofilms and barnacles. The bio-inspired dynamic surfaces can be fabricated over large areas through simple and practical processes. This new mechanism is complementary with existing materials and methods for biofouling control.


Subject(s)
Biofouling , Animals , Biofilms , Elastomers/chemistry , Halomonadaceae/physiology , Surface Properties , Thoracica/physiology
9.
Biointerphases ; 7(1-4): 32, 2012 Dec.
Article in English | MEDLINE | ID: mdl-22589075

ABSTRACT

Stimuli responsive (or "smart") polymer brushes represent a non-toxic approach for achieving release of biofouling layers. Thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) polymer brushes have been shown to modulate bacterial adhesion and release through transition between temperatures above and below the lower critical solution temperature (LCST ~32 °C) of PNIPAAm in water. In this article, we describe a convenient method to synthesize grafted PNIPAAm brushes over large areas for biological studies using a relatively simple and rapid method which allows atom transfer radical polymerization (ATRP) in presence of air using the activator regenerated electron transfer (ARGET) mechanism. PNIPAAm brushes were characterized using X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy, Fourier transform infrared spectroscopy, ellipsometry, and contact angle measurements. Our studies demonstrate that uniform, high purity PNIPAAm brushes with controlled and high molecular weight can be easily produced over large areas using ARGET-ATRP. We also report the use of a spinning disk apparatus to systematically and quantitatively study the detachment profiles of bacteria from PNIPAAm surfaces under a range (0-400 dyne/cm(2)) of shear stresses.


Subject(s)
Acrylamides/chemistry , Bacteria/drug effects , Bacterial Adhesion , Polymers/chemistry , Surface Properties , Acrylic Resins , Dielectric Spectroscopy , Photoelectron Spectroscopy , Spectroscopy, Fourier Transform Infrared
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