title: Simple approach to study biomolecule adsorption in polymeric microfluidic channels.
abstract: Herein a simple analytical method is presented for the characterization of biomolecule adsorption on cyclo olefin polymer (COP, trade name: Zeonor(®)) substrates which are widely used in microfluidic lab-on-a-chip devices. These Zeonor(®) substrates do not possess native functional groups for specific reactions with biomolecules. Therefore, depending on the application, such substrates must be functionalized by surface chemistry methods to either enhance or suppress biomolecular adsorption. This work demonstrates a microfluidic method for evaluating the adsorption of antibodies and oligonucleotides surfaces. The method uses centrifugal microfluidic flow-through chips and can easily be implemented using common equipment such as a spin coater. The working principle is very simple. The user adds 40 L of the solution containing the sample to the starting side of a microfluidic channel, where it is moved through by centrifugal force. Some molecules are adsorbed in the channel. The sample is then collected at the other end in a small reservoir and the biomolecule concentration is measured. As a pilot application, we characterized the adsorption of goat anti-human IgG and a 20-mer DNA on Zeonor(®), and on three types of functionalized Zeonor: 3-aminopropyltriethoxysilane (APTES) modified surface with mainly positive charge, negatively charged surface with immobilized bovine serum albumin (BSA), and neutral, hydrogel-like film with polyethylene glycol (PEG) characteristics. This simple analytical approach adds to the fundamental understanding of the interaction forces in real, microfluidic systems. This method provides a straightforward and rapid way to screen surface compositions and chemistry, and relate these to their effects on the sensitivity and resistance to non-specific binding of bioassays using them. In an additional set of experiments, the surface area of the channels in this universal microfluidic chip was increased by precision milling of microscale trenches. This modified surface was then coated with APTES and tested for its potential to serve as a unique protein dilution feature.
authors.affiliation: Biomedical Diagnostics Institute (BDI), National Centre for Sensor Research (NCSR), Dublin City University, Dublin 9, Ireland. V.Gubala@kent.ac.uk
authors.forename: Vladimir
authors.initials: V
authors.lastname: Gubala
authors.forename: Jonathan
authors.initials: J
authors.lastname: Siegrist
authors.forename: Ruairi
authors.initials: R
authors.lastname: Monaghan
authors.forename: Brian
authors.initials: B
authors.lastname: O'Reilly
authors.forename: Ram Prasad
authors.initials: RP
authors.lastname: Gandhiraman
authors.forename: Stephen
authors.initials: S
authors.lastname: Daniels
authors.forename: David E
authors.initials: DE
authors.lastname: Williams
authors.forename: Jens
authors.initials: J
authors.lastname: Ducrée
mesh_terms: D000327:Adsorption; D000818:Animals; D000906:Antibodies / Q000737:chemistry; D002417:Cattle; D006041:Goats; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D046210:Microfluidic Analytical Techniques; D009841:Oligonucleotides / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011437:Propylamines; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012821:Silanes / Q000737:chemistry
chemical_list: D000906:Antibodies; D009841:Oligonucleotides; D011108:Polymers; D011437:Propylamines; D012821:Silanes; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; C477625:amino-propyl-triethoxysilane