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White light reflectance spectroscopy biosensing system for fast quantitative prostate specific antigen determination
Georgios Koukouvinos1, Aristea Metheniti2, Chrysoula-Evangelia Karachaliou3
1Immunoassay/Immunosensors Lab, Institute of Nuclear&Radiological Sciences&Technology, Energy&Safety, NCSR "Demokritos", GR-15341 Aghia Paraskevi, Greece; Forensic Science Division, Hellenic Police, Athens, Greece.
A novel label-free biosensor uses white light reflectance spectroscopy to detect prostate-specific antigen (PSA) in forensic samples. This rapid, sensitive assay enables detection of minute semen quantities, aiding forensic investigations.
Area of Science:
- Forensic Science
- Biomedical Engineering
- Analytical Chemistry
Background:
- Prostate-specific antigen (PSA) is a key biomarker for semen identification in forensic investigations.
- Accurate and rapid detection of PSA is crucial for forensic sample analysis.
- Existing methods may lack sensitivity, speed, or require complex instrumentation.
Purpose of the Study:
- To develop and validate a label-free biosensor for sensitive and rapid determination of PSA in forensic samples.
- To assess the performance of the biosensor in terms of detection limit, linear range, accuracy, and specificity.
- To evaluate the biosensor's utility in real forensic casework scenarios.
Main Methods:
- Development of a biosensor utilizing white light reflectance spectroscopy.
- Implementation of a two-step immunoassay with anti-PSA antibodies and streptavidin signal enhancement.
- Assay optimization for a 10-minute total reaction time.
- Validation using PSA calibrators, semen dilutions, and analysis of forensic samples.
Main Results:
- Achieved a detection limit of 0.5 ng/mL and a linear response range up to 500 ng/mL.
- Quantification limit of 1.0 ng/mL allows detection of nanoliter quantities of semen.
- Demonstrated high accuracy (89.6-106% recovery) and linearity across wide semen dilutions (5000-360,000).
- Confirmed lack of interference from other bodily fluids (blood, urine, saliva).
- Excellent agreement with established methods (immunoradiometric assay, membrane strip test, spermatozoa, and Y chromosome detection) in 51 forensic samples.
Conclusions:
- The developed label-free biosensor offers a rapid, sensitive, and accurate method for PSA determination in forensic samples.
- Its small size and excellent analytical performance make it a valuable tool for on-site forensic evidence screening.
- The biosensor shows significant potential for improving semen detection in forensic investigations.
