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.

开发了一种简单的纸基微流控设备，该设备在由功能化碳酸钙（FCC）颜料和微纤化纤维素（MFC）和/或聚乙烯醇（PVOH）粘合剂组成的高度多孔涂层上制造，用于葡萄糖检测。由烷基烯酮二聚体（AKD）组成的疏水模式和由葡萄糖氧化酶（GOx），辣根过氧化物酶（HRP）和含有4-氨基安替比林（4-AAP）和3,5钠的指示剂组成的酶墨水喷墨印刷-二氯-2-羟基-苯磺酸（DHBS）。使用两种指标碘化钾（KI）和4-AAP / DHBS对多种涂料配方进行了测试，以找到关于检测灵敏度和测定稳定性的最佳配方。较高的粘合剂浓度会增加酶的活性，尤其是在PVOH的情况下。两层涂料 最终选择仅含有MFC或同时含有MFC和PVOH的葡萄糖进行实验。为了进行测定，打印了42 nl体积的缓冲酶溶液，其中包含5.04 mU GOx和约1.01 mU HRP，以及4 mM 4-AAP和8 mM DHBS，并制成1 µl葡萄糖溶液在一定浓度范围内，将其应用于样品以评估响应。两种涂层在检测和葡萄糖浓度在0.1和0.6 mM之间都实现了良好的线性。当储存在− 20°C下时，测定可保持稳定四周。结果表明，在微流体应用中，功能性涂层基材可替代纤维素基基材，从而可以使用少量试剂和少量样品。