Quantitative Detection of the Disappearance of the Antioxidant Ability of Catechin by Near-Infrared Absorption and Near-Infrared Photoluminescence Spectra of Single-Walled Carbon Nanotubes

Abstract

We succeeded in quantitatively detecting the disappearance of catechin antioxidant ability as a function of time using near-infrared (NIR) absorbance and NIR photoluminescence (PL) spectra of single-walled carbon nanotubes (SWNTs) wrapped with DNA molecules (DNA–SWNT hybrids). When 15 μg/mL of catechin was added to the oxidized hybrid suspension, the absorbance of SWNTs increased, according to the antioxidant ability of catechin, and the effect was maintained at least for 30 min. When catechin concentrations were less than 0.3 μg/mL, SWNT absorbance gradually decreased, although it increased when catechin is added. The results revealed that disappearance of the catechin effects could be quantitatively detected by NIR absorbance spectra. When NIR PL was employed, the disappearance of PL intensity was also observed in the case of low catechin concentrations. However, time-lapse measurement of the disappearance was difficult because the PL intensity was rapidly quenched. In addition, the optical responses were different due to different chirality of SWNTs. Our results suggested that both NIR absorbance and PL can detect disappearance of catechin antioxidant effects; in particular, slow response of NIR absorbance was effective to detect time dependence of the disappearance of the catechin effects. Contrarily, PL revealed huge and rapid responses in contrast to NIR absorbance. PL might be effective for reversible use of DNA–SWNT hybrids as a nanobiosensor.

Sensing of epigallocatechin gallate and tannic acid based on near infrared optical spectroscopy of DNA-wrapped single-walled carbon nanotube hybrids

“…7 When the amount of catechin was insufficient, the EG effects disappeared. 14 These results are consistent with previously reported findings. 7,14,32…”

“…10–12 Previous studies have detected and analyzed optical responses of SWNTs in the presence and absence of biochemicals. 7,13,14 In terms of biological applications, SWNT surfaces are usually wrapped in organic molecules such as DNA, surfactants, and proteins. 15,16 Since most biological applications are performed in aqueous conditions, the SWNTs used in this study were dispersed in aqueous solution.…”

“…A previous study demonstrated the antioxidant effects of epigallocatechin gallate (EG) using DNA-SWNT hybrids. 7,13,14,32 The disappearance of catechin’s antioxidant effect as a function of time could be quantitatively detected by both absorbance and photoluminescence at low catechin concentrations. It was found that when SWNTs were wrapped with cellulose and other artificial polymers, the optical responses were inhibited.…”

Optical Response Characteristics of Single-Walled Carbon Nanotube Chirality Exposed to Oxidants with Different Oxidizing Power

“…Semiconductor SWNTs have a unique diameter according to their chirality, and the bandgap energy changes because of the unique band structure [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Many studies have been conducted to apply the chirality-dependent redox characteristics to biosensors [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ].…”

Detection and Imaging of the Plant Pathogen Response by Near‐Infrared Fluorescent Polyphenol Sensors

“…In addition to the change in emission of PEG-PL-SWCNTs also E 11 absorption maximum was redshifted by % 10 nm (Supplementary Figure S2). Overall, such interplay indicates as ensing mechanism based on ac hange in fluorescence quantum yield, without dominant aggregation effects.I t furthermore suggests as trong interaction between sensor and analyte that goes beyond polyphenols acting as antioxidants [60,61] and might include changes in solvation that affects exciton diffusion. Hence,PEG-PL-SWCNTs showed the most promising response to plant polyphenols.…”