title: Selective and sensitive detection of free bilirubin in blood serum using human serum albumin stabilized gold nanoclusters as fluorometric and colorimetric probe.
abstract: We report here a fluorescence quenching based non-enzymatic method for sensitive and reliable detection of free bilirubin in blood serum samples using human serum albumin (HSA) stabilized gold nanoclusters (HSA-AuNCs) as fluorescent probe. The fluorescence of the nanoclusters was strongly quenched by bilirubin in a concentration dependent manner by virtue of the inherent specific interaction between bilirubin and HSA. A strong binding constant of 0.55×10(6) L mole(-1) between the HSA-AuNC and bilirubin was discerned. The nano clusters each with size ~1.0 nm (in diameter) and a core of Au18 were homogeneously distributed in HSA molecules as revealed from the respective high resolution transmission electron microscopic and mass spectroscopic studies. The fluorescence quenching phenomena which obeyed a simple static quenching mechanism, was utilized for interference free detection of bilirubin with minimum detection limit (DL) of 248±12 nM (S/N=3). The fluorescence response of HSA-AuNCs against bilirubin was practically unaltered over a wide pH (6-9) and temperature (25-50 °C) range. Additionally, peroxidase-like catalytic activity of these nanoclusters was exploited for colorimetric detection of bilirubin in serum sample with a DL of 200±19 nM by following the decrease in absorbance (at λ440 nm) of the reaction and its rate constant (Kp) of 2.57±0.63 mL μg(-1) min(-1). Both these fluorometric and colorimetric methods have been successfully used for detection of free bilirubin in blood serum samples.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
authors.forename: Mallesh
authors.initials: M
authors.lastname: Santhosh
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
authors.forename: Somasekhar R
authors.initials: SR
authors.lastname: Chinnadayyala
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
authors.forename: Ankana
authors.initials: A
authors.lastname: Kakoti
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India. Electronic address: pgoswami@iitg.ernet.in.
authors.forename: Pranab
authors.initials: P
authors.lastname: Goswami
mesh_terms: D001663:Bilirubin / Q000097:blood*; D015374:Biosensing Techniques / Q000379:methods*; D003124:Colorimetry / Q000379:methods; D006046:Gold / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008958:Models, Molecular; D009195:Peroxidase / Q000737:chemistry; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D012709:Serum Albumin; D006046:Gold; D009195:Peroxidase; D001663:Bilirubin
keywords: Bilirubin encephalopathy; Fluorescence quenching; Free bilirubin; Gold nanoclusters; Human serum albumin; Tryptophan