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Switch-on Near Infrared Emission in Albumin Behind Dark Fabric: Toward Application in Forensic Latent Bloodstain Detection

NCJ Number
RSC Advances Volume: 13 Dated: 2024
Date Published

In this paper, the authors discuss their research methodology, noting synthetic design photophysical studies, and near infrared photography; they also provide analysis of their findings, experimental details, and conclusions, specifically, that a novel heptamethine indolizine-cyanine dye, SO3C7, appended with sulfonate groups to enable albumin–sensing was synthesized and shown to have a longer wavelength emission than previous materials in the literature.


Latent bloodstain detection remains imperative for crime scene investigators. Widely used luminol offers high sensitivity to human blood but can produce untrustworthy results from a bleach-cleaned crime scene or in a room not dark enough. Furthermore, dark pigments impede imaging bloodstains covered by dark materials with previously reported bloodstain detection agents. A novel on/off human albumin–sensing dye (SO3C7) is reported herein with a longer emission wavelength (942 nm) than previous materials that allows imaging behind ∼5 mm of black fabric. The switch-on emission of SO3C7 is selective and sensitive to human albumin and lasts longer than luminol (24–48 hours). Emission studies, transient absorption spectra (TAS), and near-infrared (NIR) photographs herein describe the albumin sensing properties of the dye. (Published Abstract Provided)

Date Published: January 1, 2024