Microfluidic Paper-Based Preconcentration and Retrieval for Rapid Ribonucleic Acid Biomarker Detection and Visualization

Abstract

Microfluidic paper-based analytical devices (μPADs) have attracted significant attention in the field of pointof-care (POC) diagnostics. However, the heterogeneous structure of the paper often impairs the limit of detection (LOD) for lowabundance targets when those targets are directly analyzed. One viable solution to bypass this limitation is to elevate the target concentration above the LOD on-site to reach a valid readout. Here, we developed a 3D μPADs preconcentrator (3D-μP 2 ) to increase sample concentration by electrokinetic trapping and demonstrated its application in increasing the LOD of a downstream colorimetric assay. The three-dimensional (3D) structure of this device was composed of a loading pad, a vertical fluid path formed by stacked absorbent pads, and an ion-selective membrane of PEDOT:PSS. This novel design facilitates fast preconcentration, high capacity in sample processing, and easy target retrieval. The concentration of an exemplary target, a single-stranded DNA sequence, was increased up to 170-fold within 80 s. The LOD of the colorimetric assay to verify the DNA target was increased 3 orders of magnitude with a preconcentrated sample compared to the control. The device and its analysis equipment used in this study were all cheap and portable. Thus, the 3D-μP 2 can be a powerful POC tool for sample pretreatment in resource-limited areas.

Office paper and laser printing: a versatile and affordable approach for fabricating paper-based analytical devices with multimodal detection capabilities

“…Some examples include pen-on-paper strategies, 43,44 stamping, 45,46 spraying, 47 3D printing, 48 laser cutting, 49 printing cutting, 50 screen-printing, 51 die-cutting, 52 embossing, 53 thermal transfer printing, 54 or laser printing. 55,56 Laser printing has been used to develop microfluidic devices since 2003 when do Lago and coworkers proposed using a laser printer to deposit toner layers on a polyester surface.…”

“…42 In this context, many alternative techniques with lower instrumental requirements have been developed as candidates to replace wax printing protocols. Some examples include pen-on-paper strategies, 43,44 stamping, 45,46 spraying, 47 3D printing, 48 laser cutting, 49 printing cutting, 50 screen-printing, 51 die-cutting, 52 embossing, 53 thermal transfer printing, 54 or laser printing. 55,56…”

3D Paper-Based Origami Device for Programmable Multifold Analyte Preconcentration

“…This integrated platform enabled the 170-fold target preconcentration, on a filter paper pad, that resulted in a LOD of 100 pM, i.e., 3−4 orders of magnitude higher compared to the simple colorimetric assay. 19 All of the aforementioned preconcentration methods require external and additional equipment, such as isotachophoretic devices and pumps for sample delivery, which introduces numerous limitations that need to be addressed. At this point, it is important to note how the exploitation of paper-based devices offers several advantages over conventional preconcentration devices, including lower costs, ease of use, versatility, and capillary action without the need for external driving forces.…”

“…In another reported work, a three-dimensional microfluidic paper-based device exploiting electrokinetic trapping for the colorimetric detection of single-stranded DNA was introduced. This integrated platform enabled the 170-fold target preconcentration, on a filter paper pad, that resulted in a LOD of 100 pM, i.e., 3–4 orders of magnitude higher compared to the simple colorimetric assay …”

A Paper-Based Photoelectrochemical Sensing Platform Based on In Situ Grown ZnO/ZnIn2S4 Heterojunctions onto Paper Fibers for Sensitively Detecting AFP

“…To meet the criterion in demanded for cost-effective POC diagnostic devices, various substrates with advantage of macro- and mesoporous structures, ease of folded manufacturing, and well-established surface modification, have been widely explored [ 6 , 7 , 8 ]. Among them, a microfluidic paper-based analytical device ( μ PAD) has become one of the most generally employed POC assay devices applied in many areas, such as, pregnancy testing, drug abuse, and blood infection diagnoses, which is attribute to the intrinsic merits of cellulose paper, including easy functionalization, good biodegradability, and acceptable biocompatibility, in the construction of portable diagnostic devices [ 9 , 10 , 11 , 12 , 13 ]. So far, regarding the amount of appealing properties of paper substrate, the μ PAD integrated with different analytic technologies, such as colorimetric, electrochemiluminescence, and fluorescence, have been successfully exploited to produce paper-based colorimetric biosensing platform, enzyme-based paper biosensing platform, paper-based electrochemical biosensing platform, and even self-powered paper-based analytical device for revolutionizing clinic diagnostics [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ].…”