Talanta 132 (2015) 457–462

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Nitrite sensing based on the carbon dots-enhanced chemiluminescence from peroxynitrous acid and carbonate Zhen Lin a,b, Xiangnan Dou b, Haifang Li b, Yuan Ma b, Jin-Ming Lin b,n a b

Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou 350004, China Beijing Key Laboratory of Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University, Beijing 100084, China

art ic l e i nf o

a b s t r a c t

Article history: Received 31 July 2014 Received in revised form 14 September 2014 Accepted 16 September 2014 Available online 7 October 2014

In this work, chemiluminescence (CL) from peroxynitrous acid (ONOOH)–carbonate system greatly amplified by carbon dots was observed. The CL mechanism of the ONOOH–carbonate–carbon dots system has been investigated and the results reveal that the carbon dots could serve as the energy acceptor, which gives us new insight into the optical properties of the new emerging carbon nanomaterial. There is a good linear relationship between the CL signal and the concentration of the nitrite using for ONOOH formation, which provides us a nitrite sensing method with sensitivity as high as 5.0  10  9 M (S/N¼3). The method has been successfully applied to the determination of nitrite in tap water with the recovery of 98%. The standard deviations are within 2.5%. & 2014 Elsevier B.V. All rights reserved.

Keywords: Chemiluminescence Carbon dots Peroxynitrous acid Carbonate

1. Introduction Peroxynitrite is a powerful oxidizing agent of biological importance, which exists in many forms, such as trans-peroxynitrous acid (ONOOH), cis-ONOOH, activated form of ONOOH, and peroxynitrous anion [1–3]. ONOOH, as a weak acid with a pKa of 6.8, is an important form of peroxynitrite [4]. In acid solution, ONOOH is an unstable compound with lifetime less than 1 s [5]. In basic solution, ONOOH could be converted to peroxynitrous anion (ONOO  ) that is fairly stable and can decompose slowly to nitrite and superoxide anion radical. The oxidation reaction by peroxynitrite is beneficial for destroying invading organism. However, peroxynitrite is also involved in protein and lipid nitration, which has been found to be an early event in the etiology of some pathologies. The study concerning peroxynitrite has attracted many attractions. Certain chemical reactions released their energy through light emission, which was called as chemiluminescence (CL). Large amount of excited species with short life are involved in CL reaction. Hence, CL could be a useful tool in reactive species investigation. Since 1999, Starodubtseva et al. had reported weak CL emission from excited ONOOH. ONOOH/ONOO  also oxidized pholasin [6], chloroquine [7,8] and bilirubin [9] to produce strong CL. There are some reports concerning the CL from the decomposition of ONOO  , which is enhanced by some energy acceptors,

n

Corresponding author. Tel./fax: þ 86 10 62792343. E-mail address: [email protected] (J.-M. Lin).

http://dx.doi.org/10.1016/j.talanta.2014.09.046 0039-9140/& 2014 Elsevier B.V. All rights reserved.

such as fluorescent compounds [10], CdTe quantum dots [11]. Materials, including Mg–Al–carbonate layered double hydroxides [12] and gold nanoparticles [13], could increase the CL from ONOOH related system. Carbonate solution was reported to react with ONOO  to produce ONOOCO2 that had a lifetime less than 3 ms and decomposed rapidly into NO2 and carbonate radical (CO3 )[14,15]. CO3 changed to carbon dioxide in its excited form that brought in the CL emission [16]. Carbon dots, as a new type of fluorescent carbonaceous nanoparticle, owned lots of advantages, such as environmental benign, optical stability, low cost and easy preparation. Nowadays, fluorescent carbon dots have been successfully applied in bioimaging for cells [17,18]. The new properties of carbon dots, such as catalytic activity [19,20], fluorescent probe [21,22] and photocatalyst [23,24], have been reported recently by several groups. The CL enhanced role of carbon dots was firstly reported in our group and the CL mechanism was revealed. There are several possible mechanisms explaining the enhancing effect of carbon dots: (1) Carbon dots have catalysis effect on the reaction [25]. (2) Carbon dots concentrated the excited CL emitter, which facilitated the CL emission [26]. (3) Carbon dots were involved in the CL reaction and the CL emission was through the annihilation of hole-injected and electron-injected carbon dots [27]. We firstly found that carbon dots had enhancing effect on the ONOOH system [27]. In the present work, we further find that carbon dots could greatly amplify the CL from ONOOH–carbonate system. Furthermore, the carbon dots–ONOOH–carbonate CL system has higher CL intensity than that from carbon dots–ONOOH system. More interestingly, a linear relationship between the

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nitrite for the formation of ONOOH and CL signal produced from the carbon dots–ONOOH–Na2CO3 system was found. Hence, the proposed method can be employed for the determination of nitrite with improved sensitivity. The CL enhanced mechanism of carbon dots on ONOOH–Na2CO3 system was also illustrated in details, and its role of energy acceptor was further discussed.

2. Experimental 2.1. Reagents and materials All chemicals were of analytical grade and were used as received. Sodium nitrite (NaNO2) was from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). Hydrogen peroxide (H2O2, 35%) was obtained from Alfa Aesar China Ltd. Serine and polyethylene glycol 1500 (PEG 1500) were purchased from Merck Company (Darmstadt, Germany). 5, 5-Dimethyl-1-pyrroline N-oxide (DMPO) was from Sigma-Aldrich Chemical Co. (St. Louis, USA). Sulfuric acid (H2SO4, 98%) and glycerine were bought from Beijing Chemical Reagent Co. (Beijing, China).

2.2. Apparatus Flow injection experiments were performed with a LumiFlow LF-800 detector (NITI-ON, Funabashi, Japan). Batch CL experiment was performed with a BPCL ultraweak CL analyzer (Institute of Biophysics, Chinese Academy of Science, Beijing, China). Two peristaltic pumps (SJ-1211, Atto, Tokyo, Japan) were used to deliver the solution into the spiral flow CL cell, which was installed in front of the photomultiplier tube (PMT). The fluorescent spectra were performed using a FL-7000 spectrofluorometer (Hitachi, Japan). Electron paramagnetic resonance (EPR) spectra were measured on a JEOL spectrometer (JES-FA200, Japan).

2.3. CL system Carbon dots were prepared by microwave heating of serine in the presence of 15 mL glycerine and 1.0 g PEG 1500 by microwave oven for 10 min. Carbon dots were dialyzed against pure water before the batch experiment. While in the flow injection experiment, carbon dots were used without any further treatment. CL kinetic curves were obtained by batch experiments, which were carried out in the glass cuvette. The CL profiles were displayed and integrated for 0.1 s interval. A microliter syringe was used for the injection of the solution from the upper injection port. The addition orders of the reagent were changed to investigate the interaction of the reagent and design the CL flow injection analysis system. The manifolds of the flow injection system were shown in Fig. S1. The solution of NaNO2 and H2O2 was mixed at the threeway channel, where HNOOH was produced and reached the flow cell through channel AB. Carbon dots and Na2CO3 were pumped by pumps 1 and 2 to mix with HNOOH in the flow cell. The CL signal was collected by the LF-800 detector. The peak height of the signal recorded was measured as CL intensity.

3. Results and discussions 3.1. CL from carbon dots–NaNO2–H2O2–Na2CO3 system by flow injection system Flow injection system with precise control of the sample volume, flow rate and mixing time of the reagent has been employed to compare the CL intensity from several systems. The manifolds of the flow injection system were shown in Fig. S1. The interaction of NaNO2 and H2O2 in acid medium produced ONOOH [28]. The solution of NaNO2 and H2O2 was mixed at the three way channel AB to generate HNOOH. Carbon dots enhanced the CL from ONOOH system, and its CL has been recorded in Fig. 1a. The baseline of curves b and c in Fig. 1 stands for the CL intensity caused by the reaction of ONOOH–NaOH and ONOOH–Na2CO3 systems. The introduction of carbon dots further increased the CL intensity from ONOOH–NaOH and ONOOH–Na2CO3 system (Fig. 1b and c). ONOOH, as a weak acid with pKa of 6.8 [4], is suggested to be turned to ONOO  related species in alkaline medium. The CL enhancement of carbon dots in alkaline medium is suspected to be attributed to the interaction between carbon dots and ONOO  related species [29]. Compared with the CL from carbon dots– NaNO2–H2O2–Na2CO3 system (Fig. 1d), the CL from carbon dots–H2O2–Na2CO3 system in the absence of NaNO2 was rather low, which confirmed the main role of nitrite and its related species (ONOOH, ONOO  , and ONOOCO2 ) in the CL reaction.

3.2. CL from carbon dots–NaNO2–H2O2–Na2CO3 system by batch experiment The CL dynamic curves under different reagent injection orders have been obtained by batch experiment. The injection of solution of Na2CO3 and carbon dots together into ONOOH was accompanied by very strong CL (Fig. 2), which was stronger than the CL intensity obtained when Na2CO3 and carbon dots were added in that order into ONOOH. In the absence of nitrite, very weak CL emission as low as 120 count was observed in Fig. 2, which further verified the important role of ONOOH, ONOO  and ONOOCO2 in the CL system. HNO2 þH2O2-ONOOHþ H2O

(1)

ONOOHþOH  -ONOO  þH2O

(2)

ONOO  þCO2-ONOOCO2

(3)

2.4. Sample preparation For the determination nitrite in tap water, the water was firstly filtered by 0.25 mm and then was passed through a cationexchange resin to eliminate interferences from metal cation.

Fig. 1. The CL signal in the flow injection system for carbon dots–NaNO2–H2O2, carbon dots–NaNO2 H2O2 NaOH, carbon dots–NaNO2–H2O2–Na2CO3 and carbon dots–H2O2–Na2CO3 systems. Conditions: 0.1 M H2O2 in 0.025 M H2SO4, 1.0  10  5 M NaNO2, 0.1 M Na2CO3, carbon dots with a dilution of 1: 1000.

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Fig. 2. CL kinetic curves of carbon dots–NaNO2–H2O2 system with different reagent mixing orders: (A) injecting Na2CO3 and carbon dots solution together into the mixture of H2O2 and NaNO2, (B) injecting carbon dots and Na2CO3 successively to NaNO2–H2O2 solution, (C) injecting Na2CO3 and carbon dots successively to NaNO2–H2O2 solution, and (D) Na2CO3 and carbon dots were injected simultaneously into H2O2 solution. Curve a in (B) stands for the CL caused by injecting Na2CO3 into NaNO2–H2O2 solution. Curve b in (B) is the CL resulting from the injection of carbon dots into the solution containing Na2CO3–NaNO2–H2O2. Conditions: 0.1 M H2O2 in 0.025 M H2SO4, 1.0  10  5 M NaNO2, 0.1 M Na2CO3, carbon dots with a dilution of 1: 1000.

3.3. The determination of nitrite The batch CL signals increased with the concentration of nitrite. Hence, this system can be developed as a flow injection analysis method for the determination of nitrite. To establish the optimal conditions for the analysis of nitrite, the effects of the pH on the CL reaction, the length of the channel as well as the flow rate of the solution on the CL analysis were investigated. It has been found that maximum CL intensity is observed in solution with pH value around 7.0, which is slightly higher than the pKa of ONOOH (6.8). It is known that ONOOH is generated from NaNO2 and H2O2 in acid medium. While only ONOOH in its anion (ONOO  ) form could react with CO2 to form ONOOCO2 [30]. Solution with the pH value around 7.0 is not only beneficial for the formation of ONOO  but also facilitates the generation of CO2. ONOOH is generated from NaNO2 and H2O2 in channel AB (Fig. S1). Short mixing channel could reduce the decomposition of ONOOH and brought in higher CL intensity. The flow rate of the solution affected the mixing efficiency of the reagent, the decomposition of unstable compound as well as the detection time in spiral CL detection cell. Fig. 3A showed that NaNO2 and H2O2 solution with flow rate as high as 4.5 mL min  1 could greatly reduce the decomposition of ONOOH and obtain optimal signal. The optimized flow rate for Na2CO3 and carbon dots solution is 2.4 mL min  1 (Fig. 3B). The CL intensity increased linearly with the nitrite concentration in the range of 1.0  10  7 to 1.0  10  5 M and the correlation coefficient is 0.9956 (Fig. 4). The relative standard deviations (R. S. D) (n ¼10) of the analysis were 1.8 %, 2.5 %, and 1.9 % for 1.0  10  7, 1.0  10  6, and 5.0  10  6 M nitrite, respectively. The limit of detection (S/N ¼3) for nitrite was 5.0  10  9 M.

The flow-injection CL analysis has been applied successfully to detect nitrite in tap water. The concentration of nitrite in the tap water from Haidian district (Beijing, China) is 1.8  10  7 M and the result is in good agreement with the value obtained by spectrophotometric method (1.9  10  7 M)[31]. The recovery calculated by spiking the tap water with 1.0  10  6 M nitrite is 98%. Some metal cations have positive interference on the CL detection. Cation-exchange resins could effectively eliminate the interferences from cations. With the using of cation-exchange resins, ions such as 1000-fold Na þ , Ca2 þ , F  , Cl  , Br  , NO3 , SO24  , 200-fold Mg2 þ , Fe2 þ , Fe3 þ , Zn2 þ and 100-fold Co2 þ have no interferences on the CL detection of 1.0  10  6 M nitrite. 3.4. CL mechanism Carbon dots could greatly enhance the CL in NaNO2–H2O2– carbonate system. In order to identify the enhanced mechanism of carbon dots, CL spectrum was measured by a fluorescence spectrometer with the xenon lamp turned off. The maximum CL spectrum for carbon dots–NaNO2–H2O2–carbonate system presented in Fig. 5A is around 500 nm, which is blue-shifted compared with maximum CL spectrum for carbon dots–NaNO2–H2O2 system (520 nm). ONOOCO2 and its related radical, CO3 , is suggested to be generated and is also confirmed by using DMPO as the trapping reagent (Fig. 6A) [32] in carbon dots–NaNO2–H2O2– Na2CO3 system. Carbon dioxide in its excited form, (CO2)n2 is suggested to be formed through CO3 (Reactions 4 and 5) [33,34]. (CO2)n2 could release to its basic ground with CL emission in 440 nm (Reaction 6). It could be found from the fluorescence spectrum of carbon dots whose emission wavelength was located at 500 nm with 440 nm as the excitation wavelength. Hence, it is

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Fig. 3. The effects of the flow rate of NaNO2 and H2O2 solution (A), Na2CO3 and carbon dots solution (B) on the flow-injection CL detection system.

Fig. 4. Flow injection signals (A) and standard curve (B) for the nitrite concentration ranging from 1.0  10  7 to 1.0  10  5 M. Experimental conditions: 0.5 M H2O2 in 0.05 M H2SO4, 0.1 M Na2CO3, carbon dots in a dilution of 1: 1000, high voltage:  800 V, and 100 mL samples were injected.

Fig. 5. (A) The CL spectrum of carbon dots–NaNO2–H2O2–Na2CO3 system and (B) the fluorescent spectra for carbon dots excited at wavelengths from 260 nm to 460 nm with 20 nm increment.

reasonable to deduce that carbon dots partially serve as the energy acceptor in the CL system (Reactions 7 and 8), which gives us new insight into the role of carbon dots. The EPR signal of carbon dots changed greatly in the presence of NaNO2–H2O2. The presence of carbonate in carbon dots-NaNO2-H2O2 system decreased the EPR signal changing of carbon dots, which further confirmed its energy acceptor role (Fig. 6B). ONOOCO2 -CO3 þ NO2

(4)

2(CO3 )-(CO2)n2 þO22 

(5)

(CO2)n2-2CO2 þhv (440 nm)

(6)

(CO2)n2 þR-CO2 þRna

(7)

Rna -Ra þhv(500

(8)

nm)

It is noted that CL spectrum for carbon dots–NaNO2–H2O2– carbonate system is partially overlapped with that from carbon dots–NaNO2–H2O2 system (520 nm). The overlapping indicated that the CL is partially aroused from the radiative electron–hole annihilation between hole-injected and electron-injected carbon dots (R þ and R  ) [35,36] (Reactions 13 and 14). Oxidant species

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Fig. 6. (A) EPR spectra of carbonate and hydroxyl radicals generated by reaction of DMPO probe in carbon dots–NaNO2–H2O2–Na2CO3 system and (B) EPR spectra of the carbon dots before and after the CL reaction.

Fig. 7. Schematic illustration of CL mechanism of carbon dots–NaNO2–H2O2–Na2CO3 system. CDs stand for carbon dots.

that existed in the carbon dots–NaNO2–H2O2–carbonate system, including ONOO  , OH and CO3 , could serve as the hole injector and convert carbon dots into R þ (Reactions 11and 12). O2 – generated from the decomposition of ONOO  could donate its electron to carbon dots to produce carbon dots with negative charge (Reactions 9 and 10) [37]. ONOO  -O2 þNO

(9)

R þ O2 -R  þ O2

(10)





R þONOO -R R þOH-R R



þR





þproduct

þOH



-Rnb

Rnb-Rb þhv (525 nm)

(11) (12) (13) (14)

The discussion above indicated that carbon dots could enhance the CL from NaNO2–H2O2–Na2CO3 system through two pathways (Fig. 7). Firstly, carbon dots acts as the energy acceptor in carbon dots–NaNO2–H2O2–Na2CO3 system. This kind of enhancement in the system is related with the excited species generated from ONOOCO2 and CO3 . With pH value above the pKa of ONOOH, ONOOH converted to its anion form (ONOO  ). ONOO  reacted

with CO2 that was generated from the protonation of carbonate to produce ONOOCO2 . The decomposition of ONOOCO2 resulted in the formation of CO3 and (CO2)n2. (CO2)n2 acted as the energy donor and donated its energy to carbon dots and excited the carbon dots, whose energy releasing brought in the CL emission (Route 1 in Fig. 7). CL is also partially generated from the radiative electron–hole annihilation between hole-injected and electroninjected carbon dots (Route 2 in Fig. 7).

4. Conclusion Carbon dots were found to have CL enhancement on NaNO2– H2O2–Na2CO3 system. The CL mechanism has been investigated. (CO2)n2 is suggested to be existing in the system and donates its energy to excite carbon dots to its excited form, which released their energy to ground-state by CL emission. The radiative electron–hole annihilation between hole-injected and electroninjected carbon dots also had contribution for the CL. The investigation not only gave us new insight into the characteristic of carbon dots but also showed a broad prospect for the application of carbon dots in CL system. With the advantage of the CL from carbon dots–NaNO2–H2O2–Na2CO3 system, a sensitive and

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simple flow-injection CL method for nitrite sensing has been developed. The established method has been successfully applied to the determination of nitrite in tap water with good recoveries and precision. Acknowledgments This work was supported by National Natural Science Foundation of China (Nos. 91213305, 21305015) and China Equipment and Education Resources System (No. CERS-1-75). Appendix A. Supporting information Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.talanta.2014.09.046. References [1] B. Alvarez, H. Rubbo, M. Kirk, S. Barnes, B.A. Freeman, R. Radi, Chem. Res. Toxicol. 9 (1996) 390–396. [2] Y.D. Liang, J.F. Song, J. Pharm. Biomed. Anal. 38 (2005) 100–106. [3] Y. Zhao, K. Houk, L.P. Olson, J. Phys. Chem. A. 108 (2004) 5864–5871. [4] W. Koppenol, J. Moreno, W.A. Pryor, H. Ischiropoulos, J. Beckman, Chem. Res. Toxicol. 5 (1992) 834–842. [5] M.N. Hughes, Biochimica et Biophysica Acta (BBA)-Bioenergetics. 1411 (1999) 263–272. [6] J. Glebska, W.H. Koppenol, Free Radical Biol. Med. 38 (2005) 1014–1022. [7] Y.D. Liang, J.F. Song, X.F. Yang, W. Guo, Talanta 62 (2004) 757–763. [8] Y.D. Liang, J.F. Song, X.F. Yang, Anal. Chim. Acta 510 (2004) 21–28. [9] C. Lu, J.M. Lin, C.W. Huie, Talanta 63 (2004) 333–337. [10] C. Lu, F. Qu, J.M. Lin, M. Yamada, Anal. Chim. Acta. 474 (2002) 107–114. [11] H. Zhang, L. Zhang, C. Lu, L. Zhao, Z. Zheng, Spectrochim. Acta Part A 85 (2011) 217–222. [12] Z. Wang, X. Teng, C. Lu, Analyst 137 (2012) 1876–1881.

[13] J. Li, Q. Li, C. Lu, L. Zhao, Analyst 136 (2011) 2379–2384. [14] S.V. Lymar, J.K. Hurst, J. Am. Chem. Soc. 117 (1995) 8867–8868. [15] M.G. Bonini, R. Radi, G. Ferrer-Sueta, A.M.D.C. Ferreira, O. Augusto, J. Biol. Chem. 274 (1999) 10802–10806. [16] C. Lu, J.-M. Lin, C.W. Huie, M. Yamada, Anal. Chim. Acta. 510 (2004) 29–34. [17] L. Cao, X. Wang, M.J. Meziani, F. Lu, H. Wang, P.G. Luo, Y. Lin, B.A. Harruff, L.M. Veca, D. Murray, J. Am. Chem. Soc. 129 (2007) 11318–11319. [18] S.T. Yang, L. Cao, P.G. Luo, F. Lu, X. Wang, H. Wang, M.J. Meziani, Y. Liu, G. Qi, Y.P. Sun, J. Am. Chem. Soc. 131 (2009) 11308–11309. [19] W. Shi, Q. Wang, Y. Long, Z. Cheng, S. Chen, H. Zheng, Y. Huang, Chem. Commun. 47 (2011) 6695–6697. [20] Y. Song, K. Qu, C. Zhao, J. Ren, X. Qu, Adv. Mater. 22 (2010) 2206–2210. [21] L. Zhou, Y. Lin, Z. Huang, J. Ren, X. Qu, Chem. Commun. 48 (2012) 1147–1149. [22] Y. Dong, R. Wang, H. Li, J. Shao, Y. Chi, X. Lin, G. Chen, Carbon 50 (2012) 2810–2815. [23] H. Li, X. He, Z. Kang, H. Huang, Y. Liu, J. Liu, S. Lian, C.H.A. Tsang, X. Yang, S. T. Lee, Angew. Chem. Int. Ed. 49 (2010) 4430–4434. [24] L. Cao, S. Sahu, P. Anilkumar, C.E. Bunker, J. Xu, K.A.S. Fernando, P. Wang, E.A. Guliants, K.N. Tackett, Y.P. Sun, J. Am. Chem. Soc. 133 (2011) 4754–4757. [25] M.L. Zhang, Q.F. Yao, W.J. Guan, C. Lu, J.-M. Lin, J. Phys. Chem. C. 118 (2014) 10441–10447. [26] Z. Lin, X.N. Dou, H.F. Li, Q.S. Chen, J.-M. Lin, Microchim. Acta. 181 (2014) 805–811. [27] Z. Lin, W. Xue, H. Chen, J.-M. Lin, Anal Chem. 83 (2011) 8245–8251. [28] M. Anbar, H. Taube, J. Am. Chem. Soc. 76 (1954) 6243–6247. [29] S. Goldstein, G. Czapski, J. Am. Chem. Soc. 120 (1998) 3458–3463. [30] S. Goldstein, G. Czapski, J. Lind, G. Merenyi, Chem. Res. Toxicol. 14 (2001) 1273–1276. [31] N.V.N. Sreekumar, B. Hegde, P. Manjunatha, B.R. Sarojini, B.K, Microchem. J. 74 (2003) 27–32. [32] R.G. Wolcott, B.S. Franks, D.M. Hannum, J.K. Hurst, J. Biol. Chem. 269 (1994) 9721–9728. [33] J.-M. Lin, M. Yamada, Anal. Chem. 71 (1999) 1760–1766. [34] S.X. Liang, L.X. Zhao, B.T. Zhang, J.M. Lin, J. Phys. Chem. A. 112 (2008) 618–623. [35] Z. Ding, B.M. Quinn, S.K. Haram, L.E. Pell, B.A. Korgel, A.J. Bard, Science 296 (2002) 1293–1297. [36] L. Zheng, Y. Chi, Y. Dong, J. Lin, B. Wang, J. Am. Chem. Soc. 131 (2009) 4564–4565. [37] P. Di Mascio, E.J.H. Bechara, M.H.G. Medeiros, K. Briviba, H. Sies, FEBS Lett. 355 (1994) 287–289.

Nitrite sensing based on the carbon dots-enhanced chemiluminescence from peroxynitrous acid and carbonate.

In this work, chemiluminescence (CL) from peroxynitrous acid (ONOOH)-carbonate system greatly amplified by carbon dots was observed. The CL mechanism ...
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