RESUMEN
Nanostructured titanium dioxide (TiO2 ) electrodes, prepared by anodization of titanium, are employed to probe the electron-transfer process of cytochrome b5 (cyt b5 ) by surface-enhanced resonance Raman (SERR) spectroscopy. Concomitant with the increased nanoscopic surface roughness of TiO2 , achieved by raising the anodization voltage from 10 to 20 V, the enhancement factor increases from 2.4 to 8.6, which is rationalized by calculations of the electric field enhancement. Cyt b5 is immobilized on TiO2 under preservation of its native structure but it displays a non-ideal redox behavior due to the limited conductivity of the electrode material. The electron-transfer efficiency which depends on the crystalline phase of TiO2 has to be improved by appropriate doping for applications in bioelectrochemistry.
Asunto(s)
Materiales Biocompatibles/química , Citocromos b5/química , Nanoestructuras , Titanio/química , Adsorción , Catálisis , Cristalización , Electrodos , Electrones , Hemo/química , Humanos , Nanotecnología , Oxidación-Reducción , Espectrofotometría , Espectrometría Raman , Propiedades de SuperficieRESUMEN
The overexpression of specific biomarkers in serum is closely related to diseases, and accurate and sensitive detection of them is beneficial for the early diagnosis and treatment of cancer. In this study, we developed a novel surface-enhanced Raman spectroscopy (SERS)-based aptasensor to detect the prostate-specific antigen biomarkers, consisting of total prostate-specific antigen (PSA) and free prostate-specific antigen (f-PSA). A composite structure containing arrays of polystyrene colloidal sphere @Ag shell (PS@Ag) was fabricated as a SERS-active chip. A complementary DNA probe (SH-DNA) and PSA aptamer (Apt) were immobilised stepwise on the chip, followed by the binding of a Raman reporter methylene blue (MB) to the guanine base of the aptamer. PSA-Apt recognition causes the release of MB-Apt and a decrease in the SERS intensity of MB on the chip, which correlates with the PSA concentration. The proposed biosensor has high spectral reproducibility, selectivity, and sensitivity and successfully determines the PSA levels in serum samples collected from prostate cancer patients, demonstrating great potential for clinical diagnosis.