Polymer Microarrays for High Throughput Discovery of Biomaterials

Abstract

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format 1 . Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2 . This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion [3][4][5] . Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction 6 . HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials 5,3 . Video LinkThe video component of this article can be found at https://www.jove.com/video/3636/ Protocol 1. Preparation of low-fouling background 1. Weigh out 2 g of poly(hydroxyethyl methacrylate) (pHEMA) (Sigma -cell culture tested) into a 50 mL centrifuge tube. Dissolve in 50 mL of 95% (v/v) ethanol in water. This typically takes 24 hrs of sonication. 2. Dip-coat epoxy-functional glass slide (Genetix) with the pHEMA solution. The epoxy groups will rapidly form covalent linkages with the pHEMA coating. Dip-coating is achieved by holding the glass slide with tweezers and dipping the slide into the solution. Typically 5 mm of the slide is left uncoated, which is useful for orientating the slide and can also act as a positive control as an adhering surface. The slide is then withdrawn from the pHEMA solution over a period of 1 s, inverted and left to dry in a near horizontal position for 10 min before placing in a slide holder. 3. The pHEMA coated slides are then left at atmospheric conditions for 1 week to allow the complete evaporation of the solvent. Preparation of monomer solution1. Weigh 120 mg of the photoinitiator 2,2-dimethoxy-2-phenyl acetophenone and add to 3 mL of dimethylformamide (DMF) to make a 4% (w/v) photoinitiator solution. This is best done fresh before each print run, so the mass and volume of the solution made can be varied to suit how much photoinitiator solution is required. The solution is stable up to a...

Bacterial Attachment to Polymeric Materials Correlates with Molecular Flexibility and Hydrophilicity

“…Polymer microarrays were formed as previously described. [ 10 , 29 ] Briefly, microarrays were prepared using a XYZ3200 dispensing workstation (Biodot). Printing conditions were O 2 < 1300 ppm, 25 °C, 30–40% humidity.…”

ToF-SIMS analysis of a polymer microarray composed of poly(meth)acrylates with C6derivative pendant groups

“…This is particularly relevant when large libraries of materials or material gradients are being assessed as these systems allow the response of a certain environment to large groups or populations of materials to be assessed, and hence provide a robust insight into underlying interactions . The polymer microarray format has become a key enabling tool for materials discovery and development, whereby hundreds to thousands of unique polymers are printed onto a single glass slide allowing for parallel screening. Further to the identification of novel materials, the large number of biological–material interactions that can be assessed using high‐throughput screening methodologies can be used to provide new insight into structure–function relationships.…”

Analysis and prediction of defects in UV photo-initiated polymer microarrays

“…Polymer microarrays were formed using a XYZ3200 pin printing workstation (Biodot) as described previously. 33,34 Printing conditions were O 2 <1300 ppm, 25 °C, 40% humidity. Slotted metal pins (946MP6B, Arrayit) with a diameter of 220 μm were used to transfer approximately 2.4 nL of polymerisation solution onto 10 substrates before slides were irradiated with a long wave UV source for 10 s. Polymerisation solution was composed of 75% (v/v) monomer in dimethylformamide with 1% (w/v) photoinitiator 2,2-dimethoxy-2-phenylacetophenone.…”