Ovarian cancer is one of the most lethal gynecological conditions among women today. Having around a 50% survival rate, it has been the 5th leading cause for cancer-related deaths for women. Delayed manifestation of symptoms with late stage diagnosis has been a major factor for relatively high mortality. The 5-year survival rate for the early stage is over 90%; therefore, early detection of cancer is essential to improve the survival rate. Even though technology has improved today, early detection has not improved, and still it has been posing challenges. In addition to the clinical practices in diagnosis, scientists are looking for other novel promising methods to detect it at the early stage that would be inexpensive and user-friendly. Currently, cancer antigen 125 (CA125), a type of biomarker that can become elevated in a patient’s blood serum, is recommended mostly for clinical tests in the screening of ovarian cancer. However, because of the lack of sensitivity and specificity associated with CA125, the search for new potential biomarkers is a research priority to diagnose cancer at a localized stage.In this work, I report a nano/micro particle labeled immunoassay method for the detection of ovarian cancer biomarker CA125 in a Phosphate-Buffered Saline (PBS) medium. Here, a sandwich type immunoassay method is presented. For this goal, CA125 biomarkers are immobilized on a solid surface (magnetic beads) using a bioconjugation technique. In order to specifically target CA125, antibody and aptamer molecules are used. Here, the elemental nano/micro particles are used to label the antibody and aptamer. This labeled immunoassay is subjected to surface enhanced Raman spectroscopy (SERS) and laser induced breakdown spectroscopy (LIBS) for the detection of CA125. I establish a calibration curve by acquiring the spectroscopic signal for the known concentration of CA125. In addition to the detection part, other spectroscopic techniques such as attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), UV-Vis spectroscopy, dynamic light scattering (DLS) and scanning electron microscopy (SEM) are employed to study the bioconjugation steps. In this regard, chapter 1 gives a general overview about ovarian cancer with necessary statistics. In chapter 2, I have given necessary background information on bioconjugation techniques for immunoassay methods, particularly in the perspective of my experiments. Chapter 3 covers the antibody-based immunoassay using Raman labeled gold nanoparticles. It describes how to build a nano/micro particle based sandwich type immunoassay for CA125 detection and the corresponding results. Chapter 4 describes a similar immunoassay method to chapter 3, using aptamers instead of antibodies for specifically targeting CA125. In both chapters, SERS is employed for detection. In chapter 5, I use LIBS for the detection of an aptamer based assay. Following a similar technique in the previous chapter, I use silica microparticles to label the aptamer instead gold nanoparticles. Chapter 6 focuses on the computational aspect of our experimental work, detailing the molecular docking process and presenting preliminary results regarding the interactions of the antibody and aptamer with the CA125 antigen. Chapter 7 offers a summary of my findings along with the relevant background information.