Enzyme-free electrochemical immunosensor based on methylene blue and the electro-oxidation of hydrazine on Pt nanoparticles.
Enzyme-free electrochemical sensors enable rapid, high sensitivity measurements without the limitations associated with enzyme reporters. However, the performance of non-enzymatic electrochemical sensors tends to suffer from slow electrode kinetics and poor signal stability. We report a new enzyme-free electrochemical immunosensor based on a unique competitive detection scheme using methylene blue (MB), hydrazine and platinum nanoparticles (Pt NPs). This scheme is coupled with a robust immunosandwich format employing a MB-labelled detection antibody as a non-enzymatic reporter. In the presence of the target antigen, surface-immobilized MB consumes interfacial hydrazine thereby diminishing the electro-oxidation of hydrazine on Pt NPs. Thus, the concentration of the antigen is directly proportional to the reduction in the electrochemical signal. For proof-of-concept, this sensor was used to detect Plasmodium falciparum histidine-rich protein 2 (PfHRP2), an important malaria biomarker, in unadulterated human saliva samples. Chronocoulometric measurements showed that this platform exhibits pM-range sensitivity, high specificity and good reproducibility, making it well suited for many biosensing applications including noninvasive diagnostic testing.
Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824, USA.
Gorachand
G
Dutta
Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA; Centre for Drug Discovery and Development, Sathyabama University, Chennai, Tamil Nadu 600119, India.
Sureshbabu
S
Nagarajan
Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA.
Lisa J
LJ
Lapidus
Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824, USA. Electronic address: lillehoj@egr.msu.edu.
Peter B
PB
Lillehoj
D000913:Antibodies, Protozoan / Q000737:chemistry / Q000276:immunology; D015374:Biosensing Techniques / Q000379:methods; D055664:Electrochemical Techniques / Q000379:methods*; D006801:Humans; D006834:Hydrazines / Q000737:chemistry; D007118:Immunoassay / Q000379:methods; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000469:parasitology; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008751:Methylene Blue / Q000737:chemistry; D008958:Models, Molecular; D010963:Plasmodium falciparum / Q000276:immunology / Q000302:isolation & purification*; D010984:Platinum / Q000737:chemistry*; D011506:Proteins / Q000032:analysis* / Q000276:immunology; D015800:Protozoan Proteins / Q000032:analysis* / Q000276:immunology; D015203:Reproducibility of Results; D012463:Saliva / Q000469:parasitology*; D000099053:Histidine-Rich Glycoprotein
D000913:Antibodies, Protozoan; D006834:Hydrazines; D011506:Proteins; D015800:Protozoan Proteins; D000099053:Histidine-Rich Glycoprotein; C029424:hydrazine; D010984:Platinum; D008751:Methylene Blue
Electrochemical immunosensor; Enzyme-free; Hydrazine; Methylene blue; Pt nanoparticles