This document discusses optical immunoassay, which is a type of immunoassay that uses optical techniques like fluorescence, luminescence, or absorbance to detect antigen-antibody binding. It describes the principles of optical immunoassays, including the binding of antigens to antibodies and detection of this binding using light-based signals. Some common types of optical immunoassays are ELISA, fluorescence immunoassays, and chemiluminescence immunoassays. The document provides an example of an optical immunoassay developed for snake venom detection based on changes in thickness of molecular thin films on an optical chip. Optical immunoassays have applications in clinical diagnostics, pharmaceutical development, environmental monitoring, and food safety.

1. OPTICAL IMMUNOASSAY
Presented By
Name – Kedarnath Behera
Reg No – 23MPH010
M. Pharm 1st Sem
Department of Pharmaceutical Analysis
Institute of Pharmacy and Technology
Salipur, Cuttack

2. AGENDA
Introduction to Immunoassay
Optical Immunoassay
Principles of Optical Immunoassay
Types of Optical Immunoassay
Applications
Advantages and Disadvantages
Conclusion

3. INTRODUCTION
Immunoassay are bioanalytical method in which the quantitation of the analyte depends
on the reaction of an antigen (analyte) and an antibody.
 Types of Immunoassay -
a. Enzyme immunoassay
b. Fluoro immunoassay
c. Luminescence immunoassay
d. Optical immunoassay
e. Radio immunoassay

4. Optical Immunoassay
 Optical immunoassay is based on the interaction of antigen-antibody complexes on inert surfaces.
Specific binding of antibody increases the thickness of the reactants on the surface and changes the
colour of light reflected from the surface.
 ANTIGEN
 An antigen is a substance that triggers the immune system to produce antibodies
against it. Antigens can be molecules from pathogens like bacteria, viruses, or fungi, as
well as non-infectious substances such as toxins, allergens, or cells from transplanted
organs.
 ANTIBODY
 An antibody, also known as an immunoglobulin, is a protein produced by the immune
system in response to the presence of antigens. Antibodies bind to specific antigens,
marking them for destruction by other immune cells or neutralizing their harmful
effects. They are crucial in the body’s defence against pathogens and foreign substances.

5.  A sensitive and specific optical immunoassay (OIA) has
been developed for snake venom detection. The assay is
based on the principle of detection of physical changes
in thickness of molecular thin film resulting from
specific binding events on an optical silicon chip
(SILASTM-1, ThermoBioStar, Colorado, USA). The
reflection of white light through the thin film results in
destructive interference of a particular wavelength of
the light from gold to purple-blue depending on the
thickness of the thin film formed or the amount of
venom in the test sample.

6.  Principles of Optical Immunoassays
 Antibody-Antigen Binding.
 Signal Detection using Light-Based Techniques (Fluorescence, Luminescence, Absorbance).
Types of Optical Immunoassays-
 Enzyme-Linked Immunosorbent Assay (ELISA)
 Fluorescence Immunoassays
 Chemiluminescence Immunoassays
 Surface Plasmon Resonance (SPR)
 Other Optical Detection Methods

7. APPLICATIONS
• Clinical Diagnostics (Disease Biomarkers, Pathogen Detection).
• Pharmaceutical Development (Drug Discovery, Therapeutic Monitoring).
• Environmental Monitoring and Food Safety.
• For snake toxin and venom detection.
• Detection of Streptococcal Pharyngitis.

8.  Advantages of Optical Immunoassays-
• High Sensitivity and Specificity
• Rapid Results
• Automation and High Throughput
 Limitations and Challenges-
• Cross-reactivity
• Sensitivity to Environmental Conditions
• Cost and Equipment Requirements

9. CONCLUSION
• Immunoassays are bioanalytical methods have been widely used in many important areas of
pharmaceutical analysis such as diagnosis of diseases, therapeutic drug monitoring, clinical
pharmacokinetic and bioequivalence studies in drug discovery and pharmaceutical
industries.
• The importance and widespread of immunoassay methods
in pharmaceutical analysis are attributed to their
inherent specificity, high- throughput,
and high sensitivity for the analysis of wide range
of analytes in biological samples.

10. REFERENCES
1. Le Van Dong, Khoo Hoon Eng, Le Khac Quyen, P Gopalakrishnakone,
Optical immunoassay for snake venom detection, Biosensors and Bioelectronics, Volume 19, Issue 10,2004, Pages
1285-1294, ISSN 0956-5663,
https://doi.org/10.1016/j.bios.2003.11.020.
2. John F. Place, Ranald M. Sutherland, Claus Dähne,
Opto-electronic immunosensors: A review of optical immunoassay at continuous surfaces, Biosensors,
Volume 1, Issue 4, 1985, Pages 321-353, ISSN 0265-928X,
https://doi.org/10.1016/0265-928X(85)80004-3.
3. Darwish, Ibrahim A. “Immunoassay Methods and their Applications in Pharmaceutical Analysis: Basic
Methodology and Recent Advances.” International journal of biomedical science : IJBS vol. 2,3 (2006): 217-35.