Colorimetric assay of heparin in plasma based on the inhibition of oxidase-like activity of citrate-capped platinum nanoparticles.
We report citrate-capped platinum nanoparticles (Pt NPs) as oxidase mimetics for effectively catalyzing the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid), dopamine, and methylene blue in the presence of O2. To confirm oxidase-like activity of citrate-capped Pt NPs, their activity toward oxygen reduction reaction was studied using cyclic voltammetry and rotating ring-disk electrode method. The results obtained showed that Pt NP NPs can catalyze the oxidation of organic substrates to the colored product and the reduction of oxygen to water through a four-electron exchange process. Because the aggregation of Pt NPs can inhibit their oxidase-like activity and protamine can recognize heparin, we prepared the protamine-modified Pt NPs through direct adsorption on the surface of citrate-capped Pt NPs. The electrostatic attraction between heparin and protamine-stabilized Pt NPs induced nanoparticle aggregation, inhibiting their catalytic activity. Therefore, the lowest detectable heparin concentrations through UV-vis absorption and by the naked eye were estimated to be 0.3 and 60nM, respectively. Moreover, the proposed system enabled the determination of the therapeutic heparin concentration in a single drop of blood.
Department of Chemistry, National Sun Yat-sen University, Taiwan.
Jyun-Guo
JG
You
Department of Applied Physics and Chemistry, University of Taipei, Taiwan.
Yao-Wen
YW
Liu
Department of Biochemistry, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
Chi-Yu
CY
Lu
Department of Chemistry, National Sun Yat-sen University, Taiwan; School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Taiwan; Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, Taiwan. Electronic address: tsengwl@mail.nsysu.edu.tw.
Wei-Lung
WL
Tseng
Department of Applied Physics and Chemistry, University of Taipei, Taiwan. Electronic address: cheng-ju@utaipei.edu.tw.
Cheng-Ju
CJ
Yu
D000328:Adult; D000925:Anticoagulants / Q000097:blood*; D001560:Benzidines / Q000737:chemistry; D040761:Biomimetic Materials / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods; D002384:Catalysis; D019343:Citric Acid / Q000737:chemistry*; D003124:Colorimetry / Q000379:methods*; D006493:Heparin / Q000097:blood*; D006801:Humans; D057230:Limit of Detection; D008297:Male; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010984:Platinum / Q000737:chemistry*; D011479:Protamines / Q000737:chemistry; D055815:Young Adult
D000925:Anticoagulants; D001560:Benzidines; D011479:Protamines; D019343:Citric Acid; C021758:3,3',5,5'-tetramethylbenzidine; D010984:Platinum; D006493:Heparin; D010088:Oxidoreductases; D010100:Oxygen
Heparin; Oxidase mimic; Platinum nanoparticles; Protamine