Protein Induced Aggregation of Conjugated Polyelectrolytes Probed with Fluorescence Correlation Spectroscopy: Application to Protein Identification

Abstract

The interaction of a series of water-soluble conjugated polyelectrolytes with varying backbone structure, charge type (cationic and anionic), and charge density with a set of seven different proteins is explored by using fluorescence correlation spectroscopy (FCS). The FCS method affords the diffusion time for a particular CPE/protein pair, and this diffusion time is a reflection of the aggregation state of the polymer/protein in the solution. The diffusion time is larger for oppositely charged CPE/protein combinations, reflecting the tendency toward the formation of CPE/protein aggregates in these systems. However, by careful analysis of the data, other factors emerge, including possible effects of hydrophobic interaction in specific CPE/protein systems. The final diffusion time for each CPE/protein mixture varies and the diffusion time response pattern created by the six-CPE array for a typical protein is unique, and this effect was leveraged to develop a sensor array for protein identification by using linear-discriminant analysis (LDA) methods. By application of multimode linear discrimination analysis, the unknown protein samples have been successfully identified with a total accuracy of 93%.

Evaluation of Discrimination Performance in Case for Multiple Non-Discriminated Samples: Classification of Honeys by Fluorescent Fingerprinting

“…Adding fluorophores to samples proved to be an efficient way of improving the discrimination performance using fluorescent fingerprinting when the samples are not intensely fluorescent or are not well discriminated by their intrinsic fluorescence [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. The discrimination performance should be quantitatively characterized.…”

“…Most fluorimetric fingerprinting classification methods use intrinsic fluorescence of samples [ 1 , 2 ]. A less developed approach is based on adding fluorophores to samples [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], which promises their better discrimination because of the interaction of fluorophore(s) with non-fluorescent components of the sample and corresponding changes in the spectrum. If more than one fluorophore is added to samples, we can talk about fluorescent sensor arrays [ 4 , 5 , 8 , 10 , 11 , 15 , 17 , 20 ].…”

Modification of fatty acid vesicle using an imidazolium-based surface active ionic liquid: a detailed study on its modified properties using spectroscopy and microscopy techniques $$^{\S }$$ §

“…[34][35][36] Several efforts have been made to understand the aggregation behavior of surfactants, polymers, proteins and ionic liquids in aqueous and non-aqueous media using FCS as a potential alternative technique. [38][39][40][41] It has recently been demonstrated that FCS can be used as an efficient tool to determine the size, size distribution and polydispersity of various surfactant assemblies. [42][43][44][45][46][47][48] In this work, we have investigated the diffusion properties of different self-assemblies of oleic acid/ [C 16 mim]Cl system such as micelles, large unilamellar vesicles and vesicles with varying pH using FCS technique.…”

Selective recognition of biologically important anions using a diblock polyfluorene–polythiophene conjugated polyelectrolyte

“…1,2 This improved solubility makes them highly desirable as optical sensors for a range of biological systems, 3,4 with the ionic terminal groups additionally serving as analyte recognition sites. 5,6 This approach has been elegantly demonstrated for various large bioanalytes such as DNA, 7,8 proteins, 9 lipids 10 and enzymes. 11 Ionic polythiophenes have been developed for a wide range of biosensing platforms due to their excellent optical properties and the possibility for self-assembly.…”