All ETDs from UAB

Advisory Committee Chair

Rakesh Kapoor

Advisory Committee Members

Christopher Lawson

Sergey Mirov

Upender Manne

Xincheng Yao

Xujing Wang

Document Type

Dissertation

Date of Award

2012

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

A combination tapered fiber-optic biosensor (CTFOB) dip-probe for rapid and cost effective quantification of proteins in serum samples has been developed. This device relies on diode laser excitation and a charged coupled device (CCD) spectrometer, and functions on a technique of sandwich immunoassay. As a proof-of-principle, this technique was applied in a quantitative estimation of interleukin (IL-6) and Carcinoembyonic antigen (CEA) in human sera. The probes detected IL-6 at picomolar levels in serum samples obtained from a patient with lupus, an autoimmune disease, and a patient with lymphoma. The estimated concentration of IL-6 in lupus sample was 5.9 +/- 0.6 pM and in lymphoma sample it was below detection limit. These concentrations were verified by a procedure involving bead-based xMAP technology. A similar trend in the concentrations was observed. The specificity of the CTFOB dip-probes was assessed by analysis with receiver operating characteristics (ROC). This analysis suggests that the dip-probes can detect 5pM or higher concentration of IL-6 in these samples with specificities of 100%. The probes detected CEA also at picomolar levels in three non-CEA serum samples added 300pM, 400pM and 500pM of CEA purified from human colon carcinoma. The estimated concentration of each serum samples were 96 +/- 6.2 pM, 325 +/- 91.9 pM, and 536 +/- 158.7 pM. The cause of the mismatch of first serum sample detection were verified and suggested that the lower detection value of CEA was caused by the low association constant in the serum sample. Furthermore the ROC analysis suggested that our CTFOB dip-probe can detect 100pM or higher concentration of CEA in these samples with 100% specificities. The results provide information for guiding further studies in the utilization of these probes to quantify other analytes in body fluids with high specificity and sensitivity.

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