Ultrasensitive Detection Of Prostate Specific Antigens Using Surface Enhanced Raman Spectroscopy

Prostate cancer is a common malignant tumor in men.With the aggravation of China's population aging and lifestyle changes,prostate cancer patients are increasing day by day.There is an urgent need for timely and effective diagnosis and treatment.Prostate specific antigen?PSA?is a tumor marker of prostate cancer,which is widely used in the diagnosis and analysis of patients.With the development of medicine,people have gradually discovered that the slight changes in PSA content are closely related to the early detection of prostate cancer,the monitoring of treatment effects and the prediction of the risk of recurrence.So it is of great significance for the ultra-sensitive and highly time-sensitive detection of PSA.Surface-enhanced Raman spectroscopy?SERS?is a technique that uses noble metals to enhance Raman signals.When target molecules are distributed on the surface of nano-scale metal structures,the Raman signal will be greatly enhanced.SERS solves the problem of weak traditional Raman scattering signal.The SERS process requires a small sample volume and is not disturbed by water.According to the obtained Raman spectrum,it is possible to obtain rich information such as the target's structural state and substance content.This has prompted SERS to be widely used in biomedical and biophysics fields.In this article,we used SERS technology to conduct homogeneous ultra-sensitive detection of PSA to meet the gradually increasing detection requirements and no washing process.First,we design a pair of SERS probes that can recognize PSA.Both of these probes are modified with antibodies,which bind to different epitopes of PSA.The first probe is silver nanoparticles?AgNPs?modified with antibodies,namely AgNPs@Ab₁;the second probe is based on magnetic nanoparticles?MNs?,which modify another antibody and Raman reporter molecule 4-ABP,namely MNs@Ab₂/4-ABP.Two probes can combine with PSA to form an immune complex.At this time,AgNPs can greatly enhance the Raman signal of 4-ABP on adjacent MNs,thus achieving detect PSA.In the process of modifying antibodies on the surface of nanoparticles,it is possible to affect the antibody binding sites on the antigen.Therefore,by adding Domain Z,the antibodies are arranged on the nanoparticles in the same effective direction.It increases the effective coupling rate of the antibodies and improves the detection efficiency of the probe.In this experiment,we applied surface-enhanced Raman spectroscopy to successfully detect trace amounts of PSA,which showed a good linear relationship in the concentration range of 0.1 ng/mL¹?g/mL.The detection limit was as low as 0.1ng/mL.It is far lower than the general clinical testing needs,and can meet the requirements of a few cases such as the detection index of 0.1 ng/mL after prostatectomy.Under the modification of Domain Z,the SERS probe showed a more sensitive detection capability.Therefore,the detection method for PSA in this experiment is of great significance for the early detection and postoperative monitoring of prostate cancer.It also provides a reference for the detection of other tumor markers.