Detection Of Tumour Biomarkers In Human Blood Based On Triple-helix DNA-mediated SWNTs SERS Substrate

Surface-enhanced Raman scattering(SERS)effect is widely used in biomedical applications due to its high sensitivity.The noble metal nanomaterials,such as gold,silver and copper,with its superior surface plasmon resonance effect,become the best choice of SERS substrate.Facing various types of cancer caused by the deteriorating environment and serious food security problems,liquid biopsy as a non-invasive early diagnosis mode biopsy,which is different from traditional tissue biopsy,has gradually been concerned.At present,using noble metal nanomaterials as highly sensitive SERS substrate in liquid biopsy for early cancer research has yet to develop.Thus,this thesis was focused on the following two aspects works:(1)Detection of prostate specific antigen(PSA)in human blood via DNA-mediated surface-enhanced Raman spectroscopy of single-walled carbon nanotubes(SWNTs).To enhance the G band Raman signal of SWNTs,sandwich structure SERS substrate was constructed.First,universal triple-helix DNA probe covalently modified on the surface of gold film by Au-S bond.The loop portion of the universal triple-helix DNA was designed as a PSA aptamer.In the presence of PSA,triple-helix DNA probe broken,exposing single-stranded DNA(ssDNA)to capture SWNTs through ?-? stacking,and silver nanoparticles(AgNPs)grows on SWNTs in situ,forming ssDNA-mediated Au@SWNTs@AgNPs sandwich nanocomposites,generating a strongly enhanced Raman signal to achieve the detection of PSA.(2)Detection of circulating tumor DNA(ctDNA)in human blood via DNA-mediated surface-enhanced Raman spectroscopy of SWNTs).After detecting proteinaceous tumor biomaker in last work,DNA tumor biomarker detection was carried on.The loop portion of the universal triple-helix DNA was designed as the complementary DNA of ctDNA.In the presence of target DNA,triple-helix DNA probe broken,exposing T-rich ssDNA to capture SWNTs through ?-? stacking,and copper nanoparticles(CuNPs)grows on SWNTs in situ.To achieve ultra-low abundance ctDNA detection,enzyme amplification system was introduced to realize the highly sensitive detection of blood samples of cancer patients and healthy people.