Controllable synthesis of chiral hierarchical porous Co(OH)2 and its application in rapid chiral recognition and separation

Background

Chiral pollutants present significant environmental and health concerns, with neurotoxic amino acid analogs like β-N-methylamino-L-alanine (BMAA) demonstrating enantiomer-specific bioaccumulation in aquatic ecosystems. Current analytical approaches for chiral environmental contaminants rely predominantly on chromatographic techniques that require extensive sample preparation (typically 24 h), limiting field deployment and high-throughput screening capabilities. Detection thresholds for these compounds (0.1–10 μg/L) necessitate sensitive methodologies that maintain stereochemical integrity. This study addresses these analytical challenges through the rational design of chiral cobalt hydroxide (CF–Co(OH)₂) nanomaterials engineered for dual-mode detection and separation functionality.

Results

A hierarchical porous α-Co(OH)₂ with tunable chirality (R/S/RS configurations) and morphologies (square, rough surface, snowflake, flower-like) via micelle-templated growth strategies. The materials demonstrated dual functionality: (1) Rapid colorimetric amino acid discrimination within 5 min with precision (RSD = 4.9 %, n = 6), validated through urinary l-tryptophan quantification (17.1 ± 0.4 μg/mL); (2) Ultrasensitive BMAA separation via SPE-HPLC-MS/MS with significantly improved detection limits (LOD = 0.02 μg/kg) and processing speed (144 × faster than conventional methods). The colorimetric detection mechanism exploits BMAA's ability to form cobalt-amine complexes that produce concentration-dependent yellow coloration, enabling visual detection at 50 μg/kg in freshwater samples. Field testing successfully detected BMAA in crucian carp (0.39 ± 0.03 μg/kg), confirming food-chain biomagnification with excellent recovery (90.1–102.7 %) across diverse matrices. The system's chiral specificity exhibited distinct affinity patterns (BMAA: R–Co(OH)₂; DAB: S–Co(OH)₂) with 91.4 % enantiomeric excess in just 10 min through configuration-specific “three-point binding” mechanisms (intramolecular binding energy: 18.7 kcal/mol).

Significance

This research establishes morphology-programmable chiral materials as a versatile analytical platform for rapid on-site environmental monitoring and high-throughput toxin analysis. The developed methodology directly addresses World Health Organization guidelines for algal toxin detection in drinking water while providing a generalizable approach for chiral pollutant discrimination in complex environmental and biological samples.