Dual-mode Lab-on-paper Sensing Device For Heavy Metal Ions

With the rapid development of economy and industry,heavy metal ion pollution has become more and more serious.As a class of common toxic contaminants,heavy metal ions have strong potential destructiveness which given rise to human health threat and even restricted sustainable development of society due to the undegradable and bioaccumulative nature.As a consequence,it is of great significance to complete point-of-care testing of heavy metal ions.Nowadays,the emerging lab-on-paper inspection device has become the most promising technical means for point-of-care detection due to its property of low cost and portability.It can meet the needs of non-professional technicians who monitor the heavy metal ion contamination in resource-limited regions.In this work,multifunctional lab-on-paper devices were developed using paper cellulose as substrate material based on the research work of microfluidic paper chips by our research group.Hydrophilic channel can be constructed through wax printing and screen printing technologies.The establishment of paper-based colorimetric and electrochemical dual-mode sensing system will facilitate the application of microfluidic lab-on-paper devices in the point-of-care testing field.The paper mainly includes the following three parts:（1）A cross-shaped dual-mode origami-based lab-on-paper equipment was designed independently based on the specific biorecognition between the target and DNAzyme.Through growthing of flower-like AuNPs layers on cellulose fibers,visual prediction and precise ECL quantification can be realized with the help of P2-rGO-Pd Au-GOx multifunctional cleavable probe to complete the oxidation of 3,3’,5,5’-tetramethylbenzidine and glucose.（2）A novel paper-based device consisted of seven pads was designed.Au/HRP labeled oligonucleotide was used as multifunctional cleavable probe.The separation of cleavable probe can be achieved on account of the size difference between cellulose pores and as-prepared MOF materials.Distance-based measurements can be established in virtue of the efficient oxidation of 3,3’-diaminobenzidine by HRP.Meanwhile,Au/HRP can quench the ECL signal of the Cd S and simultaneously catalyzed H₂O₂to enhance the ECL intensity of luminol to construct ratiometric ECL detection.（3）The electrochemical sensing interface for rapid and highly sensitive diagnose was constructed using polypyrrole as functional monomers.Urchin-like AuNPs and prussian blue nanocomposites serving as low-potential redox mediator and electron transfer carrier was electrodeposited on an indium/tin oxide glass to achieve signal synergistic amplification,which lays a foundation for the functionalization technology of the paper-based device and the high-sensitivity of electrochemical signal conversion.