Inkjet printed polyelectrolyte patterns for analyte separation on inherently porous microfluidic analytical designs

Colloids and Surfaces A: Physicochemical and Engineering Aspect

Bollström

et al. 2019

Self Cite

Printed, self-contained sensor designs based on capillary transport and microfluidic principles form a major part of current research in printed functionality. Previous work into such designs has mainly focused on cellulosic papers as base substrates. In this study, novel findings are presented employing alternative customdesigned functional pigment coated substrates, locally functionalised by inkjet printed polyelectrolytes, to separate or transport anionic or cationic molecules by surface chemistry tailoring. Both anionised and cationised coatings are tested and found to transport similarly charged model colorants successfully, while separating those of opposite charge, with the extent of separation depending on colorant concentration. Furthermore, surface chemistry reversal by cationic (polyethyleneimine, polyDADMAC) and anionic (carboxymethyl cellulose) polyelectrolyte inks is demonstrated as a complementary method for analyte separation or concentration. However, the deposition of the polyelectrolyte ink itself was found to affect the cationised coating by solubilising and re-depositing coating components, while the printed polyethyleneimine was found to be partially dissolved and transported by water elution, suggesting limited adsorption under tested conditions.

Section: Introductionmentioning

confidence: 99%

Investigating chromatographic interactions in porous pigment coatings between inkjettable polyelectrolytes and model colorant solutions

Colloids and Surfaces A: Physicochemical and Engineering Aspect

Bollström

et al. 2019

Self Cite

“…The surface of FCC consists of pores built from protruding hydroxyapatite platelet structures on a calcium carbonate particulate core, and, thus, while the particle pores are anionic, the edges of the platelets have a slight cationic charge capable of interacting with the anionic NADPH. To investigate further the impact of surface charge compared with the inherent zwitterionic nature of FCC, either anionic (sodium polyacrylate, NaPA) or cationic (polyDADMAC) polyelectrolyte solution was applied on FCC by inkjet printing to neutralize the inherent complementary charge . As expected, the chromatographic behavior of NADPH and umbelliferone when applied onto the cationic treatment was similar to that on bare FCC (Figure d).…”

Section: Resultsmentioning

confidence: 68%

“…The effects of surface charge modifiers on the enzyme activity were also examined with a view to possible use of the modifiers in eliminating non‐specific binding or in manipulating the separation chemistry of bare FCC. Two commonly used polyelectrolyte charge modifiers, cationic poly(diallyldimethylammonium chloride) (polyDADMAC) and anionic sodium polyacrylate (NaPA), that can both be applied onto FCC locally via inkjet printing, were characterized for their impact on CYP2A6 model activity by adding FCC modified, respectively, with each compound to the enzyme incubation solution. As a result, polyDADMAC was shown to reduce the enzyme activity by half, whereas addition of NaPA resulted in about 40% increase in enzyme activity compared with the control (Figure a).…”

Section: Resultsmentioning

confidence: 99%

“…The wetting properties and wicking kinetics of the coating can be tailored using different coating pigment porosities and acting permeability, as well as choosing suitable binders at controlled amounts . Surface chemistry, and thus functionality such as chromatographic retention as a function of surface area, can also be in‐built or readily added, for example, by printing anionic or cationic polyelectrolyte regions onto the coating . Furthermore, the thickness of the coating layer, can be chosen to steer application variables including the wicking rate, volumes applied and the detection sensitivity.…”

Section: Introductionmentioning

confidence: 99%

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Microfluidic Lateral Flow Cytochrome P450 Assay on a Novel Printed Functionalized Calcium Carbonate‐Based Platform for Rapid Screening of Human Xenobiotic Metabolism

Kiiski

et al. 2018

Adv Funct Materials

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Cytochrome P450 (CYP) is a superfamily of enzymes in charge of elimination of the majority of clinically used drugs and other xenobiotics.This study focuses on the development of a rapid microfluidic lateral flow assay to study human phase I metabolism reactions mediated by CYP2A6 isoenzyme, the major detoxification route for many known carcinogens and drugs, with coumarin 7-hydroxylation, as the prototype model reaction. Assay fabrication utilizes custom-designed porous functionalized calcium carbonate (FCC) coatings and inkjet-printed fluid barriers. All materials used are novel and carefully chosen to preserve biocompatibility. The design comprises separate zones for reaction, separation and detection, and an absorbent pad to keep the assay wet for extended periods (up to 10 min) even when heated to physiological temperature. The concept enables CYP assays to be made at lower cost than conventional well-plate assays, while providing increased selectivity at equally high speed, owing to the possibility for simultaneous chromatographic separation of the reaction products from the reactants on the FCC coating. The developed concept provides a viable rapid prediction of the interaction risks related to metabolic clearance of drugs and other xenobiotics, and exemplifies a novel coating technology illustrating the opportunity to broaden application functionality.

“…Furthermore, we have shown that our coatings are biocompatible and that they offer enhanced sensitivity compared to filter paper (Jutila et al 2019). We have also shown that the properties of the coating can be altered either completely (Jutila et al 2019) or locally (Koivunen et al 2017(Koivunen et al , 2019 with polyelectrolytes, affecting the transfer and separation of positively or negatively charged molecules on the coating, which may be useful for some microfluidic applications.…”

Section: Introductionmentioning

confidence: 81%

Fully inkjet-printed glucose assay fabricated on highly porous pigment coating

Bollström

et al. 2020

Microfluid Nanofluid

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A simple paper-based microfluidic device, fabricated on a highly porous coating consisting of functionalised calcium carbonate (FCC) pigment and a microfibrillated cellulose (MFC) and/or polyvinyl alcohol (PVOH) binder, was developed for glucose detection. Both the hydrophobic patterns, consisting of alkyl ketene dimer (AKD), and the enzyme ink, consisting of glucose oxidase (GOx), horseradish peroxidase (HRP) and an indicator containing 4-aminoantipyrine (4-AAP), and sodium 3,5-dichloro-2-hydroxy-benzenesulphonic acid (DHBS) were inkjet-printed. Multiple coating formulations were tested using two indicators, potassium iodide (KI) and 4-AAP/DHBS, to find the optimal formulation with regard to detection sensitivity and assay stability. Higher binder concentrations increased the enzyme activity, especially in the case of PVOH. Two coatings, containing either solely MFC or both MFC and PVOH were ultimately chosen for the glucose assay experiments. For the assays, a 42 nl volume of buffered enzyme solution, containing a total of 5.04 mU GOx and approximately 1.01 mU HRP, in combination with 4 mM 4-AAP and 8 mM DHBS, was printed, and a 1 µl glucose solution, made up over a range of concentrations, was applied onto the samples to evaluate the response. A good linearity was achieved between detection and glucose concentration between 0.1 and 0.6 mM with both coatings. The assays remained stable for four weeks when stored at − 20 °C. The results show that the functional coated substrates offer a viable alternative to cellulose-based substrates for microfluidic applications enabling the use of small reagent and sample volumes.