Berberine and cyclodextrin based supramolecular assembly for the detection of a cancer biomarker in complex biomatrices via indicator displacement assay

Abstract

Spermine, an aliphatic tetramine plays a vital role in the growth and proliferation of cells. When tissues undergo growth-promoting hormonal stimulation, the concentration of spermine increases within the body. However, an elevated level of spermine in biological matrices like urine and serum is considered to be an effective indicator of various physiological disorders, specially the presence of malignant tissues within the body. Therefore, it is highly rewarding to accurately determine the concentration of spermine by an instant, label free, user friendly method. Herein, we present a supramolecular assembly of berberine (BBR) and sulfobutylether beta cyclodextrin (SBE10βCD) as fluorescent probe for the quantification of spermine in complex bio-media. Formation of the BBR-SBE10βCD supramolecular assembly upon incorporation of BBR into the SBE10βCD cavity results in a significant increase in fluorescence intensity of the dye due to the reduction in its non-radiative decay channels. While spermine is introduced into the complex solution, it strongly binds with the polyanionic host, displacing BBR from the host cavity. This causes a dramatic reduction of the fluorescence intensity, which follows a linear trend as a function of spermine concentration. Thus, from the linear regression analysis of such fluorescence response, limit of detection (LOD) of spermine has been determined to be 0.8 µM and 1.49 µM, in 1% serum and 50% urine matrices respectively. This outcome showcases the practicality and suitability of the investigated system in the field of bio-sensing. Furthermore, excellent biocompatibility of both BBR and SBE10βCD, emission in the green region of the electromagnetic spectrum, well separated absorption and emission profiles make the studied supramolecular assembly a preferred choice for the initial diagnosis of malignant tissues within the body via indicator displacement assay (IDA).