Ultrathin alumina sol-gel-derived films: allowing direct detection of the liver fibrosis markers by capacitance measurement.
A capacitive immunoassay based on antibody-embedded ultrathin gamma-alumina sol-gel films (approximately 20 to 40 nm) was successfully prepared in this work. The nanofilms greatly increased the capacitance change initiated by the recognition between the immobilized antibody and the target antigen, which allowed capacitive measurements capable of directly determining the antigen more sensitive than that of thick films. Meanwhile, the inorganic films with high permittivity significantly increased the time constant (i.e., RC value) of the films, which rendered the potentiostatic step method with acceptable S/N ratio. These two advantages enabled the immunosensor to be readily employed in a multichannel capacitance analysis system. An eight-channel hIgG capacitive sol-gel-derived immunoassay based on this system was constructed to illustrate the application. Compared with the detection limits of SiO2 sol-gel-derived hIgG capacitive immunosensors or the conventional ELISA immunoassay, the immunoassay based on thin alumina gel film showed a lower detection limit of 1 ng mL(-1). The novel immunoassay was employed to co-determine two liver fibrosis markers (hyaluronan and laminin) in mixed samples from approximately 0.5 to 50 ng mL(-1). The little derivation caused by the interfered antigen indicated that the sensitive, specific, low-cost sol-gel-derived multichannel immunosensors might be a promising approach in the application of screening disease markers.
Jiang
Dechen
D
Department of Chemistry, Fudan University, Shanghai 200433, PR China.
Tang
Jia
J
Liu
Baohong
B
Yang
Pengyuan
P
Kong
Jilie
J
D000537:Aluminum Oxide / Q000737:chemistry*; D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D015415:Biomarkers / Q000032:analysis; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D025802:Electric Capacitance; D005782:Gels / Q000737:chemistry; D006801:Humans; D007118:Immunoassay; D008103:Liver Cirrhosis / Q000175:diagnosis*; D010100:Oxygen / Q000737:chemistry; D012828:Silicones / Q000737:chemistry; D013997:Time Factors
D000906:Antibodies; D015415:Biomarkers; D005782:Gels; D012828:Silicones; D000537:Aluminum Oxide; D010100:Oxygen