Plant colorants driven diffusion inhibition and luminescence attenuation in cotton fabrics bloodstain detection

Cotton is a globally important economic and industrial crop. Cotton fiber serves as both the core raw material for textile processing and natural dyeing, and as a substrate for forensic bloodstain analysis. Luminol chemiluminescence is a key technique for bloodstain analysis. However, its performance is affected by carrier surface properties, especially interference from textiles dyed with natural colorants. Here, cotton fabrics were dyed with Sophora japonica and Rubia cordifolia . Combining surface characterization and chemiluminescence kinetics, a dual physical-chemical interference mechanism was revealed. The results revealed that physical inhibition, caused by a hydrophobic barrier, increased the blood contact angle by 2.32 times and reduced the spreading area by 45.1%. while chemical regulation, arising from polyphenol interactions, decreased hemoglobin release by 18.2% and quenched the luminescence intensity by 80%. Crucially, density functional theory (DFT) calculations elucidated the distinct molecular pathways of two representative components: rutin suppresses chemiluminescence via a dual pathway (scavenging both •OH and luminol radicals), whereas alizarin exhibits only weak inhibition through limited •OH scavenging. The physical barrier primarily restricts Hb accessibility, while the chemical scavenging and coordination predominantly govern the final luminescence signal loss. This study provides theoretical support for bloodstain detection and broader use of industrial crops in functional textiles.