Single‐Step Reagentless Laser Scribing Fabrication of Electrochemical Paper‐Based Analytical Devices

A single‐step laser scribing process is used to pattern nanostructured electrodes on paper‐based devices. The facile and low‐cost technique eliminates the need for chemical reagents or controlled conditions. This process involves the use of a CO₂ laser to pyrolyze the surface of the paperboard, producing a conductive porous non‐graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well‐suited for electrochemical purposes. As a proof‐of‐concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices.     

A Biomimetic Phosphatidylcholine‐Terminated Monolayer Greatly Improves the In Vivo Performance of Electrochemical Aptamer‐Based Sensors

The real‐time monitoring of specific analytes in situ in the living body would greatly advance our understanding of physiology and the development of personalized medicine. Because they are continuous (wash‐free and reagentless) and are able to work in complex media (e.g., undiluted serum), electrochemical aptamer‐based (E‐AB) sensors are promising candidates to fill this role. E‐AB sensors suffer, however, from often‐severe baseline drift when deployed in undiluted whole blood either in vitro or in vivo. We demonstrate that cell‐membrane‐mimicking phosphatidylcholine (PC)‐terminated monolayers improve the performance of E‐AB sensors, reducing the baseline drift from around 70 % to just a few percent after several hours in flowing whole blood in vitro. With this improvement comes the ability to deploy E‐AB sensors directly in situ in the veins of live animals, achieving micromolar precision over many hours without the use of physical barriers or active drift‐correction algorithms.