On the importance of controlling film architecture in detecting prostate specific antigen

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift


Immunosensors made with nanostructured films are promising for detecting cancer biomarkers, even at early stages of the disease, but this requires control of film architecture to preserve the biological activity of immobilized antibodies. In this study, we used electrochemical impedance spectroscopy (EIS) to detect Prostate Specific Antigen (PSA) with immunosensors produced with layer-by-layer (LbL) films containing anti-PSA antibodies in two distinct film architectures. The antibodies were either adsorbed from solutions in which they were free, or from solutions where they were incorporated into liposomes of dipalmitoyl phosphatidyl glycerol (DPPG). Incorporation into DPPG liposomes was confirmed with surface plasmon resonance experiments, while the importance of electrostatic interactions on the electrical response was highlighted using the Finite Difference Time-Domain Method (FDTD). The sensitivity of both architectures was sufficient to detect the threshold value to diagnose prostate cancer (ca. 4 ng mL −1 ). In contrast to expectation, the sensor with the antibodies incorporated into DPPG liposomes had lower sensitivity, though the range of concentrations amenable to detection increased, according to the fitting of the EIS data using the Langmuir-Freundlich adsorption model. The performance of the two film architectures was compared qualitatively by plotting the data with a multidimensional projection technique, which constitutes a generic approach for optimizing immunosensors and other types of sensors.


  • Juliana Santos Graça
  • Celina Massumi Miyazaki
  • Flavio Makoto Shimizu
  • Diogo Volpati
  • J. R. Mejía-Salazar
  • Osvaldo N. Oliveira
  • Marystela Ferreira
Externa organisationer
  • Federal University of São Carlos
  • University of São Paulo
  • Mittuniversitetet


Sidor (från-till)1175-1182
Antal sidor8
TidskriftApplied surface science
StatusPublished - 2018 mar 15
Peer review utfördJa
Externt publiceradJa