Chemiluminescence and Electrochemiluminescence Studies of Biomedical and Pharmaceutical Measurands

Abstract

Early stage diagnosis plays a very crucial role in disease counteract in its very early stage before the appearance of the symptoms. Physician diagnosis depends on the outcomes arise from bio-chemical/diagnostic tests. Therefore, diagnostic methods plays vital role in right diagnosis of diseases on right time and assessing the quality of the drugs. Currently, optical measurement and chromatography based diagnostic assays are mostly used clinically. However, these assays encompass laborious sample preprocessing, complex readout instrumentation, , non-portable, time-consuming and expensive labeling methods. In contrast, electro analytical methods particularly chemiluminescence (CL) and electochemiluminescence (ECL) is one of the approaches that fit perfectly to satisfy the need of desirable characteristics of new diagnostic method. In this project, CL and ECL experiments had been accomplished using a BPCL Ultra-Weak Luminescence Analyzer. The photomultiplier tube (PMT) had been used in the BPCL Ultra-Weak Luminescence Analyzer. PMT was operated in current mode. A conventional three-electrode cell was used with a CHI 600 voltammetric analyzer to carry out electrochemical measurements. The experiments including voltamety, amperometry, ECL analysis, CL-flow injection analysis, and parameters for method validations had been done. The CL studies were performed for detection of creatinine, an important biomarker, used in clinical diagnosis and biomonitoring programs. A strong chemiluminescence was observed when creatinine reacted with H2O2 in the presence of cobalt ions, without any luminophore, enzymes and chromatographic separation. This was presented via CL-FIA method exhibiting a promising strategy for the sensitive quantification of urinary creatinine in clinical and toxicological laboratories. Hence, the CL studies have developed a novel, sensitive and selective method for detection of creatinine, to be used in clinical diagnosis and biomonitoring programs. ECL studies were designed in two parts, The first part explores new coreactants (Tripropylamine and Glucosamine) for typical luminophores and second part design a novel ECL sensor for biomedical analysis. Tripropylamine (TPrA), an eminent coreactant of tris(2,2'-bipyridine)ruthenium ion Ru(bpy)32+ ECL. The most popular coreactant for most luminol studies is H2O2, though it is very unstable and more sensitive to metal ions. In this study, a more stable TPrA was exploited as the coreactant of luminol ECL for the first time. It is anticipated that luminol–TPrA ECL system may be an attractive alternative to luminol–H2O2 ECL system for bioanalysis, immunoassays, DNA probe assays and aptasensors. Glucosamine is a bioavailable amino sugar and helps to relieve the symptoms of osteoarthritis. Glucosamine lacks chromophores (or fluorophores) which enable the sensitive detection with UV (or fluorescence). So, most available analytical methods are expensive, time consuming and need complex sample preparations. Our study investigated a new method for Glucosamine ECL analysis using another luminophore, Ru(Phen)32+ (Tris(1,10-phenanthroline)ruthenium(II) chloride). The method was validated by quantitative testing of glucosamine contents in nutraceutical products in the market. So, It shows good sensitivity, selectivity, cost effective and very fast as compared with the currently used method. Second part of ECL studies leads to development of a novel cathodic ECL sensor. It was fabricated by introducing a unique facile immobilization method of Tris (4,7-diphenyl-1,10-phenanthroline) ruthenium (II) dichloride Ru(dpp)32+ using graphite powder asimmobilization matrix. This sensor has extended potential window for ECL detecting species (DNA probes, numerous analytes such as S2O82, oxalates and amine containing compounds)providing a novel approach for cathodic ECL as well as anodic ECL analysis in clinical chemistry and medical diagnostics. In conclusion, this project will contribute in the scientific world via a valuable addition of new analytical methods showing several logs of dynamic range, good sensitivity, fast and cost effectiveness. These characteristics provide advantages over assays that rely on radio isotopic labels, enzymatic activity, fluorescence, chromatographic and spectroscopic which have been applied in the biomedical testing and pharmaceutical analysis. However, it is foreseen that this project can be applied in the biomedical and pharmaceutical analysis for good quality and cost effective tests in future.