A series of eight novel siloxane-polyurethane fouling-release (FR) coatings were assessed for their FR performance in both the laboratory and in the field. Laboratory analysis included adhesion assessments of bacteria, microalgae, macroalgal spores, adult barnacles and pseudobarnacles using high-throughput screening techniques, while field evaluations were conducted in accordance with standardized testing methods at three different ocean testing sites over the course of six-months exposure. The data collected were subjected to statistical analysis in order to identify potential correlations. In general, there was good agreement between the laboratory screening assays and the field assessments, with both regimes clearly distinguishing the siloxane-polyurethane compositions comprising monofunctional poly(dimethyl siloxane) (PDMS) (m-PDMS) as possessing superior, broad-spectrum FR properties compared to those prepared with difunctional PDMS (d-PDMS). Of the seven laboratory screening techniques, the Cellulophaga lytica biofilm retraction and reattached barnacle (Amphibalanus amphitrite) adhesion assays were shown to be the most predictive of broad-spectrum field performance.

Novel, environmentally friendly antimicrobial coatings containing tethered biocide moieties derived from the ubiquitous biocide, triclosan, were synthesized and characterized using a high-throughput workflow. Triclosan was first modified with an acrylate functionality and, subsequently, copolymerized with hydroxyethyl acrylate and butyl acrylate using conventional free radical polymerization to form an array of acrylic polyol terpolymers. The polyols were characterized using nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and gel permeation chromatography. Arrays of urethane coatings were produced from the array of acrylic polyol terpolymers and, subsequently, characterized using parallel dynamic mechanical thermal analysis, surface energy measurements, and various biological assays. The results of the biological assays showed that the coatings were effective toward inhibiting Staphylococcus epidermidis biofilm retention without leaching triclosan or other toxic components from the coating. The level of antimicrobial activity was found to increase with the content of triclosan moieties incorporated into the coating matrix. These results indicate that triclosan moieties tethered to a polymer matrix can impart antimicrobial properties via a contact-active, nonleaching (i.e., environmentally friendly) mechanism. Since S. epidermidis is one of the primary microorganisms associated with infection and failure of implanted medical devices, such as prosthetic heart valves, urinary catheters, and a variety of orthopedic implants, these coatings may have good potential for commercialization in some of these applications.

Assessment and down-selection of non-biocidal coatings that prevent the adhesion of fouling organisms in the marine environment requires a hierarchy of laboratory methods to reduce the number of experimental coatings for field testing. Automated image-based methods are described that facilitate rapid, quantitative biological screening of coatings generated through combinatorial polymer chemistry. Algorithms are described that measure the coverage of bacterial and algal biofilms on coatings prepared in 24-well plates and on array panels, respectively. The data are used to calculate adhesion strength of organisms on experimental coatings. The results complement a number of physical and mechanical methods developed to screen large numbers of samples.

The effect of acrylic polyol composition on the properties of crosslinked siloxane-polyurethane coatings was explored. An acrylic polyol library was synthesized using batch solution polymerization and characterized using high-throughput gel permeation chromatography (Rapid-GPC) and differential scanning calorimetry (DSC). Siloxane-polyurethane coatings were prepared from 3-aminopropyl-terminated poly(dimethylsiloxane) (PDMS), the acrylic polyols and a polyisocyanate crosslinker. The siloxane-acrylic-polyurethane coatings were tested for mechanical and physical properties. The siloxane-polyurethane coatings had a systematic variation in glass transition temperature and had water contact angles ranging from 95° to 100°. Many of the coatings also showed a low-force of release in the pseudo-barnacle pull-off adhesion test. Performance testing of the fouling-release properties of the siloxane-polyurethane coatings on array panels with algae, namely the diatom Navicula and sporelings (young plants) of the green seaweed Ulva was also conducted.

The purpose of this study was to synthesize and characterize biodegradable and thermosensitive triblock copolymers for delivering protein at controlled rate in biologically active form for longer duration of time. A series of thermosensitive triblock copolymers with different block lengths (PLGA-PEG-PLGA) were synthesized by ring-opening polymerization of d,l-lactide and glycolide with polyethylene glycol (PEG) in the presence of stannous octoate. Compositions and molecular weight of triblock copolymers were characterized by 1H NMR spectrometry and gel permeation chromatography, respectively. A single test-tube inverting method was employed to determine the sol-gel transition temperature. Lysozyme was used as a model protein. Lysozyme solution formulation was prepared with different triblock copolymers for in vitro release. Lysozyme concentration and its biological activity in the released sample were determined using a standard MicroBCA method and bacterial cell lysis method, respectively. The effects of varying block lengths and concentrations of copolymers on the in vitro release of lysozyme were evaluated. The release profiles from formulations showed a higher initial release followed by slower release up to 4 weeks. Increasing the block lengths of copolymers decreased burst release of lysozyme from 41.2+/-5.4% to 16.1+/-3.9%. Increasing copolymer concentrations decreased the drug release. Lysozyme in the 4 weeks released samples retained most of its biological activity (>80%). It is feasible to deliver protein in biologically active form for longer duration by varying block lengths and concentrations of triblock copolymers.