SYNTHESIS AND CHARACTERIZATION OF BIOCOMPATIBLE INORGANIC/ORGANIC NANOCOMPOSITES MATERIAL FOR SENSOR APPLICATIONS

Abstract

According to WHO report 2011, cardiovascular diseases (CVD) have been considered as the leading cause of death around the world which includes coronary heart disease, cerebrovascular disease, raised blood pressure, peripheral artery disease, rheumatic heart disease, congenital heart disease and heart failure. The symptoms typically associated with heart attacks and angina includes chest pain, pressure, shortness of breath, and/or nausea but they may also be seen with non-heart related conditions. Since the treatment for each previous condition differs, and most of them require urgent measures, it is necessary that physicians are provided with additional information in a short time basis, enabling them to carry out quick and accurate diagnosis. So far for diagnosis, prognosis, monitoring, and risk stratification of suspected heart attack patients with symptoms of acute myocardial infarction (AMI), cardiac biomarkers have been employed. Different laboratorial detection methods are used for the estimation of cardiac biomarkers that include sandwich immunoassay with secondary labeled antibodies, enzyme linked immunosorbent assay (ELISA) and fluorescence. However, they require laboratory equipments with proper instrument, multi-step processing of samples, and well-trained personnel, leading to considerable time consuming and expense to the overall detection. Therefore, there is a growing demand for a range of rapid and low cost device for the detection of CVD. Biosensors can play an important role in this regard, without having to rely on hospital visits, where expensive and time consuming laboratory tests are recommended. iv Among the different types of biosensors available, the biosensors based on electrochemical impedance spectroscopy (EIS) have emerged as the most commonly used biosensors as they have been found to overcome most of the disadvantages, which inhibits the use of other types of biosensors. EIS is a powerful method to analyze the complex electrical resistance of a system and is sensitive to surface phenomena and changes of bulk properties. Thus, in the field of biosensing, it is particularly suited for the detection of binding events and is sensitive to changes in interfacial impedance upon bio-recognition events occurring at the electrode/electrolyte interface. The basic characteristics of electrochemical biosensors are associated with their capability to detect a specific biomolecule with high specificity and sensitivity. Also, these characteristics are dictated by a better correlation between the biological component and the transducing element. Important advances in these aspects have been achieved with the utilization of several kinds of nanomaterials to improve electrochemical signal of bio-recognition events occurring at the electrode/electrolyte interface. The present thesis is an attempt towards the synthesis and characterization of biocompatible nanoparticles, i.e., ZnS/Pt and their nanocomposites with organic conducting polymer and inorganic graphene/silane materials for bio-sensing applications, especially for the quantitative detection of cardiac biomarkers e.g. myoglobin and Creactive protein. The main objective behind the utilization of these nanomaterials is to combine the high power of detection with preservation of the structural integrity of the biomolecules, for the development of biosensors with improved properties such as sensitivity and limit of detection.