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9. Au nanoparticle‐catalyzed electron transfer from ammonia‐borane to Ru(NH3)63+ for sensitive biosensing.

Author

Park, Seonhwa, Bhatia, Aman, Nandhakumar, Ponnusamy, Kim, Jihyeon, and Yang, Haesik

Subjects
*CHARGE exchange, *PROSTATE-specific antigen, *IMMUNOGLOBULIN G, *SERUM albumin, *REDUCING agents, *METAL nanoparticles
Abstract

Metal nanoparticle (NP)‐catalyzed electron transfer (ET) from a reducing agent to a metal complex is useful for signal amplification in biosensors. For efficient ET, the metal complex must undergo rapid outer‐sphere reactions, be highly water‐soluble, and effectively penetrate bio/organic layers on metal NPs. Our study identifies Ru(NH3)63+ as well‐suited for this purpose. Among reducing agents, ammonia‐borane (AB) enables rapid metal NP‐catalyzed ET, with Au, Pt, and Pd NPs displaying similar catalytic activities. The pseudo second‐order rate constant for 20‐nm Au NP‐catalyzed ET from AB to Ru(NH3)63+ (1.4 × 108 M−1 s−1) approaches the diffusion‐controlled rate constant. Despite immunoglobulin G and bovine serum albumin passively adsorbed on Au NPs, catalytic activity remains largely unaffected. Applying Au NP‐catalyzed ET to prostate‐specific antigen detection in human serum achieves a low detection limit of 10 pg/mL. These findings highlight the potential of Ru(NH3)63+ and AB in designing biosensors based on rapid catalytic reaction. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Molten-Salt Processed Potassium Sodium Niobate Single-Crystal Microcuboids with Dislocation-Induced Nanodomain Structures and Relaxor Ferroelectric Behavior

Author

Park, Seonhwa, primary, Choi, Hyunsu, additional, Hwang, Geon-Tae, additional, Peddigari, Mahesh, additional, Ahn, Cheol-Woo, additional, Hahn, Byung-Dong, additional, Yoon, Woon-Ha, additional, Lee, Jung Woo, additional, Park, Kwi-Il, additional, Jang, Jongmoon, additional, Choi, Jong-Jin, additional, and Min, Yuho, additional

Published
2022
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24. Solid-phase recombinase polymerase amplification using an extremely low concentration of a solution primer for sensitive electrochemical detection of hepatitis B viral DNA

Author

Ichzan, Andi Muhammad, primary, Hwang, Sang-Hyun, additional, Cho, Hyejin, additional, Fang, Chiew San, additional, Park, Seonhwa, additional, Kim, Gyeongho, additional, Kim, Jihyeon, additional, Nandhakumar, Ponnusamy, additional, Yu, Byeongjun, additional, Jon, Sangyong, additional, Kim, Kwang-sun, additional, and Yang, Haesik, additional

Published
2021
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34. Selective Phase Control of Dopant-Free Potassium Sodium Niobate Perovskites in Solution

Author

Park, Seonhwa, primary, Peddigari, Mahesh, additional, Kim, Jung Hwan, additional, Kim, Eunae, additional, Hwang, Geon-Tae, additional, Kim, Jong-Woo, additional, Ahn, Cheol-Woo, additional, Choi, Jong-Jin, additional, Hahn, Byung-Dong, additional, Choi, Joon-Hwan, additional, Yoon, Woon-Ha, additional, Park, Dong-Soo, additional, Park, Kwi-Il, additional, Jeong, Chang Kyu, additional, Lee, Jung Woo, additional, and Min, Yuho, additional

Published
2020
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35. Wash-Free Amperometric Escherichia coliDetection via Rapid and Specific Proteolytic Cleavage by Its Outer Membrane OmpT

Author

Park, Seonhwa, Park, Kiryeon, Cho, Hyejin, Kwon, Jungwook, Kim, Kwang-sun, and Yang, Haesik

Abstract

Various methods have been developed for the detection of Escherichia coli(E. coli); however, they are complex and time-consuming. OmpT─a cell membrane endopeptidase of E. coli─strongly embedded in the outer membrane of only E. coli, exposed to external solutions, with high proteolytic activity, could be a suitable target molecule for the rapid and straightforward detection of E. coli. Herein, a wash-free, sensitive, and selective amperometric method for E. colidetection, based on rapid and specific proteolytic cleavage by OmpT, has been reported. The method involved (i) rapid proteolytic cleavage of consecutive amino acids, after cleavage by OmpT, linked to an electrochemical species (4-aminophenol, AP), by leucine aminopeptidase (LAP, an exopeptidase), (ii) affinity binding of E. colion an electrode, and (iii) electrochemical-enzymatic (EN) redox cycling. OmpT cleaved the intermediate peptide bond of a peptide substrate containing alanine-arginine-arginine-leucine-AP (−A-R-R-L-AP), forming R-L-AP, followed by the cleavage of two peptide bonds of R-L-AP sequentially by LAP, to liberate an electroactive AP. Affinity binding and EN redox cycling, in addition to rapid proteolytic cleavage by OmpT and LAP, enabled high electrochemical signal amplification. Two-sequential-cleavage was employed for the first time in protease-based detection. The calculated detection limit for E. colicells in tap water (approximately 103CFU/mL after 1 h incubation) was lower than those obtained without affinity binding and EN redox cycling. The detection method was highly selective to E. colias OmpT is present in only E. coli. High sensitivity, selectivity, and the absence of wash steps make the developed detection method practically promising.

Published
2022
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37. Trypsin Detection Using Electrochemical Reduction‐based Redox Cycling.

Author

Shin, Jeonghwa, Park, Kiryeon, Park, Seonhwa, and Yang, Haesik

Subjects
TRYPSIN, OXIDATION-reduction reaction, HORSERADISH peroxidase, CYTOCHROME c, ELECTROLYTIC reduction, PEPTIDE bonds
Abstract

It is more difficult to obtain high signal‐to‐background ratios in biosensors using electrochemical reduction than using electrochemical oxidation. Here, we present a method for trypsin detection using electrochemical reduction‐based redox cycling. Electrochemical‐enzymatic (EN) redox cycling and electrochemical‐chemical (EC) redox cycling for trypsin detection were tested and compared. Trypsin cleaves a peptide bond in an electrochemically inactive p‐aminophenol (AP)‐conjugated oligopeptide, and this cleavage results in the release of electrochemically active AP, which is involved in EN and EC redox‐cycling reactions. Horseradish peroxidase and cytochrome c (Cyt c) were tested as redox enzymes for EN redox cycling involving a redox enzyme and H2O2. Cyt c was better than horseradish peroxidase, as its use resulted in lower background levels. The trypsin detection based on the EN redox cycling involving Cyt c and H2O2 (~50 ng/mL) exhibited lower detection limits than the detection based on EC redox cycling involving IO3− (~100 ng/mL), because of higher signal levels. [ABSTRACT FROM AUTHOR]

Published
2021
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38. Washing- and Separation-Free Electrochemical Detection of Porphyromonas gingivalisin Saliva for Initial Diagnosis of Periodontitis

Author

Park, Seonhwa, Park, Kiryeon, Na, Hee Sam, Chung, Jin, and Yang, Haesik

Abstract

Indirect detection of Porphyromonas gingivalisin saliva, based on proteolytic cleavage by an Arg-specific gingipain (Arg-gingipain), has traditionally been used for simple, initial diagnosis of periodontitis. To accurately detect P. gingivalisusing a point-of-care format, development of a simple biosensor that can measure the exact concentration of P. gingivalisis required. However, electrochemical detection in saliva is challenging due to the presence of various interfering electroactive species in different concentrations. Here, we report a washing- and separation-free electrochemical biosensor for sensitive detection of P. gingivalisin saliva. Glycine–proline–arginine conjugated with 4-aminophenol (AP) was used as an electrochemical substrate for a trypsin-like Arg-gingipain, and glycylglycine was used to increase the Arg-gingipain activity. The electrochemical signal of AP was increased using electrochemical–chemical (EC) redox cycling involving an electrode, AP, and tris(2-carboxyethyl)phosphine, and the electrochemical charge signal was corrected using the initial charge obtained before a 15 min incubation period. The EC redox cycling combined with the matrix-corrected signal facilitated a high and reproducible signal without requiring washing and separation steps. The proteolytic cleavage of the electrochemical substrate was specific to P. gingivalis. The calculated detection limit for P. gingivalisin artificial saliva was 5 × 105colony-forming units/mL, and the concentration of P. gingivalisin human saliva could be measured. The developed biosensor can be used as an initial diagnosis method to distinguish between healthy people and patients with periodontal diseases.

Published
2021
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39. Enhanced Electron Transfer Mediated by Conjugated Polyelectrolyte and Its Application to Washing-Free DNA Detection

Author

Park, Seonhwa, Jeong, Ji-Eun, Le, Van Sang, Seo, Jeongwook, Yu, Byeongjun, Kim, Da-Young, Kwon, Se-Hun, Jon, Sangyong, Woo, Han Young, and Yang, Haesik

Abstract

Direct electron transfer between a redox label and an electrode requires a short working distance (<1–2 nm), and in general an affinity biosensor based on direct electron transfer requires a finely smoothed Au electrode to support efficient target binding. Here we report that direct electron transfer over a longer working distance is possible between (i) an anionic π-conjugated polyelectrolyte (CPE) label having many redox-active sites and (ii) a readily prepared, thin polymeric monolayer-modified indium–tin oxide electrode. In addition, the long CPE label (∼18 nm for 10 kDa) can approach the electrode within the working distance after sandwich-type target-specific binding, and fast CPE-mediated oxidation of ammonia borane along the entire CPE backbone affords high signal amplification.

Published
2024
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41. Trypsin Detection Using Electrochemical Reduction‐basedRedox Cycling

Author

Shin, Jeonghwa, Park, Kiryeon, Park, Seonhwa, and Yang, Haesik

Abstract

It is more difficult to obtain high signal‐to‐background ratios in biosensors using electrochemical reduction than using electrochemical oxidation. Here, we present a method for trypsin detection using electrochemical reduction‐based redox cycling. Electrochemical‐enzymatic (EN) redox cycling and electrochemical‐chemical (EC) redox cycling for trypsin detection were tested and compared. Trypsin cleaves a peptide bond in an electrochemically inactive p‐aminophenol (AP)‐conjugated oligopeptide, and this cleavage results in the release of electrochemically active AP, which is involved in EN and EC redox‐cycling reactions. Horseradish peroxidase and cytochrome c(Cyt c) were tested as redox enzymes for EN redox cycling involving a redox enzyme and H2O2. Cyt c was better than horseradish peroxidase, as its use resulted in lower background levels. The trypsin detection based on the EN redox cycling involving Cyt c and H2O2(~50 ng/mL) exhibited lower detection limits than the detection based on EC redox cycling involving IO3−(~100 ng/mL), because of higher signal levels. Electrochemical reduction‐based electrochemical‐enzymatic redox cycling and electrochemical‐chemical redox cycling for trypsin detection were tested and compared.

Published
2021
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