Background: Rapid screening of acetylcholinesterase (AChE) inhibition is essential for monitoring exposure to organophosphate compounds, particularly in field settings where access to laboratory infrastructure is limited. This study aimed to develop a portable paper-based colorimetric biosensor for the semi-quantitative detection of AChE activity in blood samples. Methods: The biosensor was based on a pH-dependent color change adapted from the modified Edson method. The platform was first optimized using experimental models and then evaluated in human capillary blood samples collected under real field conditions. Reference serum cholinesterase activity was determined by a certified clinical laboratory and used for comparison with the colorimetric response of the biosensor. RGB (red, green, and blue) image analysis was performed in a subset of samples to digitally characterize the chromatic response of the device. Results: Samples with preserved AChE activity showed a visible color shift associated with substrate hydrolysis, whereas samples with reduced or inhibited activity maintained darker blue-dominant tones. RGB analysis of human samples revealed significant associations between AChE activity and the R and G channels, supporting the ability of the platform to distinguish between chromatic patterns associated with different ranges of enzymatic activity. Conclusions: The proposed platform demonstrated the feasibility of translating a pH-based AChE assay into a portable paper-based format for semi-quantitative visual and RGB-assisted screening. Its evaluation in human samples demonstrated the feasibility of its use under field conditions as a proof-of-concept. Further studies are needed to optimize its analytical performance and validate its application in larger and more diverse populations.

Background/Objectives: Maresin 1 (MaR1), a pro-resolving mediator derived from docosahexaenoic acid (DHA), differs from DHA in its C7/C14 hydroxylation pattern and double-bond arrangement. We compared their recognition by peroxisome proliferator-activated receptor α (PPARα), peroxisome proliferator-activated receptor γ (PPARγ), and retinoic acid receptor-related orphan receptor α (RORα) in the context of metabolic dysfunction-associated steatotic liver disease (MASLD). Methods: We validated Glide docking by redocking reference ligands and performed four independent 250 ns molecular dynamics simulations per complex (24 trajectories; 6.0 μs). We evaluated structural stability, replica-resolved contacts, oxygen distance profiles, and conformational sampling; relative energetic estimates were obtained using molecular mechanics/generalized Born surface area (MM-GBSA) calculations. Results: Redocking RMSDs were ≤1.5 Å, and the replicated trajectories showed no ligand dissociation. In PPARα, MaR1 showed recurrent C7-OH–Lys358 proximity and reproducible carboxylate-associated contacts with Tyr314 and Ser280. In PPARγ, the MaR1 carboxylate sampled Tyr473 in helix 12 and HIE323 with replica-dependent geometry, whereas DHA retained an Arg288-centered anchor. In RORα, MaR1 preferentially sampled an Arg370-centered arrangement, whereas DHA predominantly engaged Arg367; both ligands displayed replica-dependent alternative polar contacts. MaR1 showed more negative hydrogen-bonding, lipophilic, and van der Waals contributions and lower numerical total MM-GBSA scores than DHA across all three receptor pairs. Conclusions: MaR1 showed receptor-specific redistribution of polar contacts associated with alternative carboxylate positioning. Although the calculations do not establish binding affinity or receptor activation, these patterns, rather than a conserved direct C7-OH/C14-OH recognition motif, define testable interaction sites for matched-analog studies and functional assays.