The determination of trypsin activity in human urine is important for evaluating pancreatic disease. We designed an effective fluorescence sensing strategy based on a self-assembled amphiphilic pyrene/protamine complex system that provides an amplified fluorescence response for highly sensitive and selective detection of trypsin. In aqueous solution, the functionalized pyrene formed fluorescent, π-extended aggregates inside micelles, which were effectively quenched by protamine (a trypsin substrate). However, this quenched fluorescence was very sensitively recovered by the trypsin’s enzymatic reaction, and this was attributed to a marked reduction in enhanced exciton migration caused by protamine in π-delocalized pyrene aggregates. The devised sensing platform was successfully utilized to selectively and sensitively detect trypsin at very low concentrations (0.03–0.5 μg mL–1) in non-pretreated human urine and to screen for trypsin inhibitors at concentrations of 0.1–5.0 μg mL–1.

Real-time health monitoring technology in daily life requires mechanically robust and transparent electrodes for multimodal biosignal sensing from exposed human epidermis. Here, highly stretchable transparent electrodes comprising a water-dispersed conductive polymer, poly(3,4-ethylenedioxyth iophene):poly(styrenesulfonate) (PEDOT:PSS), and a protic ionic liquid (IL), 3-methylimidazolium:bis(trifluoromethylsulfonyl)amide (p-MIM:TFSI) are reported. Owing to the high water miscibility of p-MIM:TFSI and its favorable ion exchange capability with PEDOT:PSS, PEDOT:PSS/p-MIM:TFSI transparent electrodes show enhanced electrical conductivity (σ = 450 S cm −1 ) and thin-film stretchability represented by crack onset strain (ε c ) exceeding 50%. These electrodes outperform other PEDOT:PSS electrodes processed with an aprotic counterpart, 1-ethyl-3-methylimidazolium(EMIM):TFSI, or a traditional ionic salt, Li:TFSI. The PEDOT:PSS/p-MIM:TFSI thin-film electrodes are also biocompatible and conformally adhere to human skin; therefore, multimodal biosignals including electrocardiogram, electrooculogram, and electromyogram with high signal-to-noise ratios from exposed epidermis on human faces and arms under various measurement conditions mimicking daily activities are collected. Considering the importance of light penetration through human skin for stable biological activity during biosignal monitoring, the results can broaden the applicability of daily-use wearable biosignal sensors by applying them to exposed human skin.

Detection of heparin (HP) under physiological conditions is difficult due to the presence of biological obstructions including proteins and lipids. Thus, it is highly challenging to selectively detect HP and to increase its sensitivity in complex systems. Here, we report the detection of HP at nanomolar levels via efficient imidazolium-HP interaction-assisted fluorescence quenching amplification. The self-assembled pyrenyl aggregates are devised as a conduit for efficient exciton transport, which induces amplified fluorescence quenching for HP detection. This amplified quenching is enhanced by introducing an imidazolium receptor designed to have a high affinity to HP via electrostatic and/or additional interactions with C2 protons, resulting in a very high Stern-Volmer quenching constant of approximately 1.17 × 10 8 M À 1 .

No abstract