Dual-probe (colorimetric and fluorometric) detection of ferritin using antibody-modified gold@carbon dot nanoconjugates
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ORIGINAL PAPER
Dual-probe (colorimetric and fluorometric) detection of ferritin using antibody-modified gold@carbon dot nanoconjugates Eepsita Priyadarshini 1 & Kamla Rawat 2 & Himadri B. Bohidar 3,4 & Paulraj Rajamani 1 Received: 8 April 2019 / Accepted: 7 September 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019
Abstract A dual-mode assay is described for immunological determination of the anemia biomarker ferritin. It is based on the use of a gold@carbon dot (Au@CD) nanoconjugate as a colorimetric and fluorescent probe. Au@CD is hydrophilic, easily surface modified and stable in aqueous solution. The Au@CD have a red color with blue-green fluorescence and were modified with antibody against ferritin. This allows bi-modal detection of ferritin. Assays can be performed in phosphate buffer and were also analyzed in (Bovine Serum Albumin) BSA and (Fetal Bovine Serum) FBS. Detection is based on antigen-antibody interaction underlying the classical sandwich model. Response to ferritin can be detected by spectrophotometry (at 570 nm) or fluorescence (at excitation/emission maxima of 354/454 nm). Under optimal conditions, the assay has a linear response in the 1 to 120 ngmL−1 ferritin concentration range and detection limits of 20 ng (colorimetrically) and 64 ng (fluorometrically). Keywords Bi-modal detection . Antigen-antibody . Immunoassay . Anemia . Nanoprobe . Diagnostic sensor . Binding efficiency . Dynamic light scattering . Aggregation . Quenching
Introduction The last decade has witnessed significant progress in synthesis and application of engineered nanomaterials in analytical platforms. The high surface volume ratio and ease of interaction with biomolecules forms the basis for development of versatile sensors, most of which utilize the optical, electronic and chemical characteristics of nanomaterials [1, 2]. Such nanomaterial based analytical devices have been used for detection of wide range of bio-molecules, heavy metals, Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-019-3802-1) contains supplementary material, which is available to authorized users. * Paulraj Rajamani [email protected]; [email protected] 1
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India
2
Department of Chemistry, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi 110062, India
3
School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
4
Special Centre for Nano Sciences, Jawaharlal Nehru University, New Delhi 110067, India
pesticides etc. Colorimetric and electrochemical detection have gained enormous popularity in detection of metal ions and environmental contaminates. Colorimetric based SPR is one of the most widely used mechanism in biosensor studies, due to its rapidity, real-time detection, but it becomes practically difficult to determine when the analyte concentration is low or of a small molecular weight [3]. On the contrary, quantum dots have gained significant intere
