Selective Near-Infrared Blood Detection Driven by Ionic Liquid–Dye–Albumin Nanointeractions

Abstract

Due to its abundance in blood, a great deal of research has been undertaken to develop efficient biosensors for serum albumin and provide insight into the interactions that take place between these biosensing molecules and the protein. Nearinfrared (NIR, >700 nm) organic dyes have been shown to be effective biosensors of serum albumin, but their effectiveness is diminished in whole blood. Herein, it is shown that an NIR sulfonate indolizine-donor-based squaraine dye, SO 3 SQ, can be strengthened as a biosensor of albumin through the addition of biocompatible ionic liquids (ILs). Specifically, the IL choline glycolate (1:1), at a concentration of 160 mM, results in the enhanced fluorescence emission ("switch-on") of the dye in the presence of blood. The origin of the fluorescence enhancement was investigated via methods, including DLS, ITC, and molecular dynamics. Further, fluorescence measurements were conducted to see the impact the dye−IL system had on the fluorescence of the tryptophan residue of human serum albumin (HSA), as well as to determine its apparent association constants in relation to albumin. Circular dichroism (CD) spectroscopy was used to provide evidence that the dye−IL system does not alter the secondary structures of albumin or DNA. Our results suggest that the enhanced fluorescence of the dye in the presence of IL and blood is due to diversification of binding sites in albumin, controlled by the interaction of the IL−dye−albumin complex.

Virtual Special Issue Honoring the Legacy of Dr. Bettye Washington Greene

“…This section of the VSI includes articles that describe a variety of different liquid colloidal solutions. Edgehouse et al and Han et al both describe the characterization of various ionic liquids, Darlington et al report on the use of biocompatible ionic liquids to improve blood detection, and Birrer et al describe ionic liquid-in-water emulsions. Wang et al and Norouzi et al report on liquid crystals, while Piñeres-Quiñones et al characterize emulsions of thermotropic liquid crystals.…”

“…Dr. Phillips’ reflection provides a unique perspective on the lasting influence and legacy of Dr. Greene. Following this personal reflection, we present invited research articles submitted to this VSI to honor Dr. Greene and further recognize the importance of her work in advancing the discipline. − We then include selected recent articles published in Langmuir that showcase advances within research areas related to those that Dr. Greene devoted her scientific career to advancing. − This collection of articles is divided into four sections that reflect the breadth of topics influenced by Dr. Greene’s accomplishments (Table ).…”

Turn-On Fluorescent Probe for BSA Detection Constructed by Supramolecular Assembly

“…Bovine serum albumin (BSA), which exhibits high structural homology with human serum albumin and is more readily available, has been extensively studied as a model protein in various fields. − Over the years, numerous methods, including electrochemical impedance spectroscopy, near-infrared diffuse reflectance spectroscopy, capillary electrophoresis, and UV spectroscopy, have been developed for BSA detection. Although these methods offer high selectivity and sensitivity, they suffer from drawbacks such as inaccurate measurement results, complex operational procedures, poor reproducibility, and time-consuming measurements. − In contrast, the fluorescence probe method, characterized by its ease of use, accuracy, and excellent reproducibility, has emerged as an ideal detection method, gaining increasing attention from analysts. − …”