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Colorimetric detection of L-histidine based on the target-triggered self-cleavage of swing-structured DNA duplex-induced aggregation of gold nanoparticles

DOI:10.1007/s00604-018-2987-z
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Yunfei Jiao
Yunfei Jiao
Yunfei Jiao
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Qingyun Liu
Qingyun Liu
Qingyun Liu
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Hong Qiang
Hong Qiang
Hong Qiang
  • This person is not on ResearchGate, or hasn't claimed this research yet.
Zhengbo Chen at Capital Normal University
Zhengbo Chen
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Abstract and Figures

A rapid, highly sensitive and selective colorimetric assay is presented for visually detecting L-histidine. It is based on L-histidine-triggered self-cleavage of DNA duplex-induced gold nanoparticle (AuNP) aggregation. The citrate-capped AuNPs easily aggregate in a high concentration of salt environment. However, in the presence of L-histidine aptamers (DNA1 and DNA2), the partial strands of DNA1 and DNA2 hybridize to form a DNA duplex with a swing structure. The swing-like DNA duplexes are adsorbed on the surface of AuNPs to improve the stability of AuNPs, and the AuNPs also are better dispersed in high-salt media. When L-histidine is added to the solutions, it catalyzes the self-cleavage of DNA1 to form many single-stranded DNA (ssDNA) fragments. These ssDNA segments are adsorbed on the AuNPs and weaken the stability of AuNPs. Hence, the AuNPs aggregate in high-salt environment, and this results in a red-to-blue color change. Under the optimized conditions, L-histidine can be determined with a limit of detection of 3.6 nM. In addition, the sensor was successfully applied to the determination of L-histidine in spiked serum samples. Graphical abstractSchematic of a rapid and homogeneous colorimetric L-histidine assay. It combines L-histidine-triggered self-cleavage of the swing-like DNA duplexes and self-cleavage of DNA-induced AuNP aggregation.
The structure of DNA duplex. DNA1 is a sequence-specific nuclease acting on a single-stranded DNA substrate containing a single, sessile ribo-adenine (indicated by arrows in Fig. 1). The catalytic strand (DNA2) is composed of a functional domain of 24 deoxynucleotides flanked by 5′ and 3′ substrate-recognition domains of 8 nucleotides each
The structure of DNA duplex. DNA1 is a sequence-specific nuclease acting on a single-stranded DNA substrate containing a single, sessile ribo-adenine (indicated by arrows in Fig. 1). The catalytic strand (DNA2) is composed of a functional domain of 24 deoxynucleotides flanked by 5′ and 3′ substrate-recognition domains of 8 nucleotides each
… 
a Plot of L-histidine concentration vs absorbance ratio (A625 nm/A523 nm) for the target L-histidine assay. Inset: photograph showing colorimetric responses of the solutions in the absence and presence of various concentrations of target L-histidine (0, 10 nM, 150 nM, 400 nM, 3 μM, 8 μM, 20 μM, and 50 μM). b UV-vis absorption spectra for AuNP solution in the absence and presence of different concentrations of L-histidine. c The linear relationship between the A625 nm/A523 nm and the L-histidine concentration in the range of 0 to 400 nM. d The calculation of LOD of L-histidine according to 3 times the standard derivation of a blank solution. The error bars represent standard deviation obtained from three independent measurements. Experimental condition: DNA1 concentration: 1 μM, DNA2 concentration: 1 μM, AuNP concentration: 8.68 nM
a Plot of L-histidine concentration vs absorbance ratio (A625 nm/A523 nm) for the target L-histidine assay. Inset: photograph showing colorimetric responses of the solutions in the absence and presence of various concentrations of target L-histidine (0, 10 nM, 150 nM, 400 nM, 3 μM, 8 μM, 20 μM, and 50 μM). b UV-vis absorption spectra for AuNP solution in the absence and presence of different concentrations of L-histidine. c The linear relationship between the A625 nm/A523 nm and the L-histidine concentration in the range of 0 to 400 nM. d The calculation of LOD of L-histidine according to 3 times the standard derivation of a blank solution. The error bars represent standard deviation obtained from three independent measurements. Experimental condition: DNA1 concentration: 1 μM, DNA2 concentration: 1 μM, AuNP concentration: 8.68 nM
… 
TEM images of AuNPs in the (a) absence and presence of target L-histidine (b) 400 nM, and (c) 50 μM. DNA1 concentration: 1 μM, DNA2 concentration: 1 μM, AuNP concentration: 8.68 nM
TEM images of AuNPs in the (a) absence and presence of target L-histidine (b) 400 nM, and (c) 50 μM. DNA1 concentration: 1 μM, DNA2 concentration: 1 μM, AuNP concentration: 8.68 nM
… 
The colorimetric response (A625 nm/A523 nm) of the solutions treated with different amino acids. The concentration of the other interfering amino acids (0.5 mM) is 50-fold higher than that of L-histidine (10 μM). Inset: color change. The error bars represent standard deviation obtained from three independent measurements. Experimental condition: DNA1 concentration: 1 μM, DNA2 concentration: 1 μM, AuNP concentration: 8.68 nM
The colorimetric response (A625 nm/A523 nm) of the solutions treated with different amino acids. The concentration of the other interfering amino acids (0.5 mM) is 50-fold higher than that of L-histidine (10 μM). Inset: color change. The error bars represent standard deviation obtained from three independent measurements. Experimental condition: DNA1 concentration: 1 μM, DNA2 concentration: 1 μM, AuNP concentration: 8.68 nM
… 
The absorbance change (A625 nm/A523 nm) of AuNPs after interaction with different concentrations of L-histidine from 10 to 400 nM in serum samples and Tris-HCl buffer solution, respectively. The error bars represent standard deviation obtained from three independent measurements. Experimental condition: DNA1 concentration: 1 μM, DNA2 concentration: 1 μM, AuNP concentration: 8.68 nM
+1
The absorbance change (A625 nm/A523 nm) of AuNPs after interaction with different concentrations of L-histidine from 10 to 400 nM in serum samples and Tris-HCl buffer solution, respectively. The error bars represent standard deviation obtained from three independent measurements. Experimental condition: DNA1 concentration: 1 μM, DNA2 concentration: 1 μM, AuNP concentration: 8.68 nM
… 
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ORIGINAL PAPER
Colorimetric detection of L-histidine based on the target-triggered
self-cleavage of swing-structured DNA duplex-induced aggregation
of gold nanoparticles
Yunfei Jiao
1
&Qingyun Liu
2
&Hong Qiang
1
&Zhengbo Chen
1
Received: 8 August 2018 / Accepted: 29 August 2018 / Published online: 12 September 2018
#Springer-Verlag GmbH Austria, part of Springer Nature 2018
Abstract
A rapid, highly sensitive and selective colorimetric assay is presented forvisuallydetecting L-histidine. It is based onL-histidine-
triggered self-cleavage of DNA duplex-induced gold nanoparticle (AuNP) aggregation. The citrate-capped AuNPs easily aggre-
gate in a high concentration of salt environment. However, in the presence of L-histidine aptamers (DNA1 and DNA2), the partial
strands of DNA1 and DNA2 hybridize to form a DNAduplex with a swing structure. The swing-like DNA duplexes are adsorbed
on the surface of AuNPs to improve the stability of AuNPs, and the AuNPs also are better dispersed in high-salt media. WhenL-
histidine is added to the solutions, it catalyzes the self-cleavage of DNA1 to form many single-stranded DNA (ssDNA) frag-
ments. These ssDNA segments are adsorbed on the AuNPs and weaken the stability of AuNPs. Hence, the AuNPs aggregate in
high-salt environment, and this results in a red-to-blue color change. Under the optimized conditions, L-histidine can be
determined with a limit of detection of 3.6 nM. In addition, the sensor was successfully applied to the determination of L-
histidine in spiked serum samples.
Keywords Self-cleavage of DNA .Colorimetric assay .L-Histidine detection .Gold nanoparticle aggregation .Swing-like
duplex .Ratiometric assay .Visible color change .Serum samples .Catalysis
Introduction
L-Histidine (L-His), an essential amino acid in human and
mammal species, plays an essential role in the mammalian
central nervous system, the repair and growth of tissue, min-
imizing internal bleeding from microtrauma, and controlling
the transport of metals in biologically important bases [1,2].
An abnormal L-histidine level is an index of some diseases
including acute liver failure, rheumatoid arthritis, AIDS,
chronic kidney disorder, Alzheimer’s disease, and cancer
[3–8]. Therefore, the determination of L-histidine is extremely
important in biological fluids.
There are a number of methods for the detection of L-his-
tidine, such as including high performance liquid chromatog-
raphy (HPLC) [9], electrophoresis [10,11], mass spectrome-
try [12], fluorescence [13], and electrochemistry [14,15].
These approaches, while most successful, most of them show
poor selectivity, require time-consuming pre-treatment or so-
phisticated detection systems such as the use of organic sol-
vents. To circumvent these disadvantages, colorimetric
methods as a promising analytical technology, have been ex-
tensively used due to their simplicity, low cost, rapid/direct
readout with the bare eye, and no need to use expensive ana-
lytical instruments [16–24]. Therefore, it is still necessary and
important todevelop a low-cost, highly sensitive and selective
colorimetric method for scaling L-histidine.
Previous reports have demonstrated that single-stranded
DNA (ssDNA) can be absorbed on gold nanoparticle
A colorimetric assay for detecting L-histidine based on target L-histidine-
triggered self-cleavage of DNA duplex-induced AuNP aggregation.
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s00604-018-2987-z) contains supplementary
material, which is available to authorized users.
*Hong Qiang
13691076492@163.com
*Zhengbo Chen
czb979216@sina.com
1
Department of Chemistry, Capital Normal University,
Beijing 100048, China
2
College of Chemical and Environmental Engineering, Shandong
University of Science and Technology, Qingdao 266590, China
Microchimica Acta (2018) 185: 452
https://doi.org/10.1007/s00604-018-2987-z
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Numerous methods are known for the determination of His. They are based on various approaches, such as liquid chromatography [5,6], capillary electrophoresis [7,8], electrochemistry [9,10], surface-enhanced Raman scattering [11], chemiluminescence [12], colorimetry [13][14][15], fluorimetry [4,[16][17][18][19][20][21], and molecularly imprinted photonic hydrogels [22]. Among of them, fluorimetry can provide striking merits including relatively easy to operate, high sensitivity, wide linear range, low detection limit, and ability to real-time monitoring, etc., which render it superior compared to many of other conventional methods and evolves to be one of the most effective analyzing technologies [3,4]. ...
... Duing to the distinctive optical properties of innorganic nanoparticles (NPs), metal NPs such as Ag NPs [3] and Au NPs [14], metal oxide including ZnO [25,26] and carbon dots (C-dots) [19][20][21], etc. have been used as probes for bioanalytes sensing. However, the applications of noble metal NPs are limited by cost, precursor scarcity, and poor stability [27]. ...
... C [His] + 20.2301 (R 2 = 0.9924). The limit of detection (LOD) for His detecting is calculated to be 14.3 nM at a signal-to-noise ratio of 3. Besides, we compare the linear concentration range and LOD value for His of this system with other relevant previous work, including electrochemistry [9,10], colorimetry [13,14], MIPH-based optical sensor [22] and fluorimetry [3,[17][18][19][20][30][31][32]. The corresponding results are displayed in Table 1. ...
Fluorimetric determination of histidine by exploiting its inhibitory effect on the oxidation of thiamine by cobalt-containing Prussian Blue nanocubes
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A fluorometric assay for histidine (His) is described. It is based on the inhibitory effect of His on nanocubes consisting of cobalt-containing Prussian Blue analog (CoFe NCbs), which have a strong oxidation effect on thiamine (THI) in the presence of NaOH. THI is nonfluorescent but the oxidized form (thiochrome; ThC) has a strong blue fluorescence, with excitation/emission maxima at 370/445 nm. His inhibits the oxidation effect of the CoFe NCbs due to the strong interaction between its imidazole side chain and the amino groups of the CoFe NCbs. This method is fast and has good sensitivity and selectivity. The lower detection limit is 14.3 nM of His, the linear range extends from 0.05 to 2.5 μM, and the relative standard deviation is calculated to be 1.5%. The method was successfully employed to quantify His in spiked serum samples. Graphical abstractSchematic representation of cobalt-containing Prussian Blue nanocubes (CoFe NCbs)-thiamine (THI)-based fluorometric assay for Histine (His). His inhibits the generation of thiochrome (ThC; the oxidized form of THI). The detection limit is 14.3 nM with the linear range of 0.05–2.5 μM.
View
... Interestingly, Jiao et al. investigated the opposite behavior of DNA-based detection platform while assessing L-histidine. [314] In this assay without histidine, DNA1 and DNA2 as histidine aptamers were partially hybridized to form a swing-like unique structure which helped the DNA duplex absorption on AuNPs and make them dispersed. L-histidine was determined with a LOD of 3.6 nM when sessile phosphodiester of the DNA1 was cleaved into two parts via self-cleavage due to catalytic action of histidine which disturbed the swing structure of duplex and created ssDNA segments. ...
Gold Nanoparticles-Based Colorimetric Assays for Environmental Monitoring and Food Safety Evaluation
Article
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Recent years have witnessed an exponential increase in the research on gold nanoparticles (AuNPs)-based colorimetric sensors to revolutionize point-of-use sensing devices. Hence, this review is compiled focused on current progress in the design and performance parameters of AuNPs-based sensors. The review begins with the characteristics of AuNPs, followed by a brief explanation of synthesis and functionalization methods. Then, the mechanisms of AuNPs-based sensors are comprehensively explained in two broad categories based on the surface plasmon resonance (SPR) characteristics of AuNPs and their peroxidase-like catalytic properties (nanozyme). SPR-based colorimetric sensors further categorize into aggregation, anti-aggregation, etching, growth-mediated, and accumulation-based methods depending on their sensing mechanisms. On the other hand, peroxidase activity-based colorimetric sensors are divided into two methods based on the expression or inhibition of peroxidase-like activity. Next, the analytes in environmental and food samples are classified as inorganic, organic, and biological pollutants, and recent progress in detection of these analytes are reviewed in detail. Finally, conclusions are provided, and future directions are highlighted. Improving the sensitivity, reproducibility, multiplexing capabilities, and cost-effectiveness for colorimetric detection of various analytes in environment and food matrices will have significant impact on fast testing of hazardous substances, hence reducing the pollution load in environment as well as rendering food contamination to ensure food safety.
View
... Literature review brings many analytical procedures for His determination in pure form or in pharmaceutical formulations, as well as in biological samples: colorimetry (Newman and Turnbull, 1960, Jiao et al., 2018, Razavi and Khajehsharifi, 2021, spectrophotometry (Patel Vandana et al., 2009), spectrofluorimetry (Ambrose et al., 1969, Gerber, 1970, Alevridis et al., 2020, chemiluminescence (Zhu et al., 2002, Kiba et al., 2006, Hun, 20159, voltammetry (Jaselskis, 1958, Moreira and Fogg, 1991, Farias et al., 2008, microbiology (Horn et al., 1948), kinetic spectrophotometry (Mitić et al., 2004), potentiometry (Staden andHolo, 2007, Abbaspour et al., 2004) and cation-exchange chromatography (Stampina, 2021). ...
Kinetic–spectrophotometric approach to the ampicillin hydrolytic degradation applied for the histidine determination
Article
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  • Dec 2022
The objective of this research was to develop a kinetic-spectrophotometric method for the determination of microquantities of L-histidine in pure form and dietary supplements. The method was based on the kinetics of ampicillin degradation by Ni(II) ion as a catalyst in the presence of L-histidine in a strongly alkaline medium. The rate of this reaction was monitored spectrophotometrically by measuring the increase in absorbance at 265 nm as a function of time. The same approach was used for the investigation of the reaction rate in the absence of histidine. A differential variant of the tangent method was used to process the kinetic data. Beer’s law was obeyed in the interval of histidine concentration from 1.24 μg/ml to 11.63 μg/ml with the relative standard deviation ranging from 8.1% to 0.7%. The detection limit of 0.46 μg/ml was estimated based on the 3S0 criterion. The interference effects of some metal ions, anions, and other molecules on the reaction rate were studied to assess method selectivity. Herein described method was applied for the quantification of histidine in dietary supplements. The point hypothesis test confirmed that there was no significant difference between the proposed and the reference method.
View
... It's over expression could cause variety of diseases including histidinemia, advanced liver cirrhosis and asthma [13]. Many analytical techniques have been employed for L-histidine assay in biological fluids such as capillary electrophoresis [14], voltammetry [15], liquid chromatography [16], colorimetry [17] and fluorimetry [18]. Among these methods, fluorimetric detection is reported to be most favourable one in the detection of histidine due to their sensitivity, stability and reliability [19]. ...
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A benzimidazole derived probe [(6-(1H-indol-3-yl)-5,6-dihydrobenzo[4], [5]imidazo [1,2-c]quinazoline) (IDBIQ)] was synthesized and structurally characterized by single-crystal X-ray diffraction analysis and spectroscopic methods. The probe IDBIQ crystallizes in a monoclinic P21/c space group which is found to be highly sensitive and also selective towards the analytes HgII, F⁻ and histidine. The probe exhibits turn-off fluorescence for HgII and histidine while it is ratiometric towards F⁻ ions. These quenching and ratiometric fluorescent changes have been further explored by ¹H NMR titrations and DFT/TD-DFT calculations. The limit of detection of the probe towards the analytes was found to be in nano-molar range and the receptor was observed to bind with the analytes in 1:1 stoichiometric manner.
View
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Recent progress of 0D optical Nanoprobes for Application in Sensing of (Bio)analytes in the Prospect of Global Health Monitoring with Detailed Mechanistic Insights
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Continuous monitoring of a variety of biomolecules and bio-relevant ions is of tremendous importance to maintain the physiological balance and evaluation of metabolic parameters. Therefore, development of fast, selective, sensitive...
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A novel electrochemical sensor for determination of Histidine based on molecularly imprinted copolymer
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The present study aimed to report a novel electrochemical sensor through electropolymerization of o-aminophenol (o-AP) and m-dihydroxy benzene (m-DB) as monomers on the surface of the glassy carbon electrode (GCE) for the determination of histidine (His) as a template molecule. The developed sensor exhibited satisfactory sensitivity and high selectivity, and also offered a linear range between 0.005 and 10.0 μM with a detection limit of 0.9 nM. Finally, it is worth mentioning that we also aimed at employing the proposed sensor for the detection of His in blood serum samples.
View
Surface Plasmon Resonance Sensor for Novel Detection of Histidine Based on the Hg2+ Induced Aggregation of AuNPs Followed by Preconcentration with Chitosan Gel as Solid Phase Biosorbent
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This research work aims to propose an extraction method using chitosan as the sorbent and gold nanoparticles (AuNPs) as the colorimetric sensor for the development of a simple, cost-effective, rapid, sensitive, and selective detection method for histidine. The colorimetric assay is based on the aggregation of AuNPs in the presence of Hg2+ ions and histidine. The state of AuNPs generally changes from dispersion to aggregation. The change in state is accompanied by a corresponding change in color (from red wine to blue). Therefore, the solid phase extraction (SPE) method using chitosan as the sorbent was used to extract the AuNPs to improve the sensitivity of detection. It was found that the extraction by means of a sensor system using chitosan could increase the detection signal for histidine by 10 times. The calibration curve, which is the plot of absorbance ratio (A650/A528) against the concentration of histidine, shows a linear relation in the concentration range of 100 - 800 nM. The limit of detection (LOD) and limit of quantitation (LOQ) of the method were found to be 99.88 and 107.45 nM, respectively. Good recoveries were also obtained (range: 99.75 - 104.43%) with relative standard deviations (RSDs) below 5.89% in real water samples. Moreover, this method can be used for the selective detection of histidine even in the presence of other amino acids. The proposed method has been successfully used in the determination of histidine in mineral water samples.
View
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An extremely sensitive and highly selective sensing assay for histidine (His) in biological sample is demonstrated through the N-acetyl-cysteine (NAC) functionalized gold nanoparticles (AuNPs). To improve the detection efficiency, the external conditions of temperature and pH value are optimized. We assume that three main forces of hydrogen bond, electrostatic attraction, and hydrophobic force between His and NAC cause the formation of close crosslinking, resulting in the aggregation of AuNPs accompanied by an obvious color change. Thus, the assay is highly sensitive for His with a fast readout within 10 s and the detection limit of 176 pM which is the lowest one from what's been reported in the colorimetric detection. Furthermore, due to the special imidazole ring in His structure, the assay exhibits the high selectivity of His sensing among 18 common amino acids. Besides, the system has been successfully used for His detection in spiked urine and serum samples. This novel colorimetric sensor significantly improves the analytical merit of His sensing and applies in the biological sample detection.
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View
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Article
  • Aug 2017
A highly sensitive sensor for detection of histidine (His) based on the nitrogen-doped graphene quantum dots (N-GQDs)-Cu2 + system has been designed. The N-GQDs were synthesized by one-step hydrothermal approach according to previous report. The fluorescence of N-GQDs can be effectively quenched by Cu2 + due to the binding between Cu2 + and functional groups on the surface of N-GQDs. The high affinity of His to Cu2 + enables Cu2 + to be dissociated from the surface of N-GQDs and recovering the fluorescence. The sensor displayed a sensitive response to His in the concentration range of 0–35 μmol L− 1, with a detection limit of 72.2 nmol L− 1. The proposed method is successfully applied to detect His in samples with a recovery range of 96–102%.
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Lanthanide coordination polymer nanoparticles as a turn-on fluorescence sensing platform for simultaneous detection of histidine and cysteine
Article
In this work, we propose a strategy for the fluorescence assay of histidine (His) and cysteine (Cys) by using lanthanide coordination polymer nanoparticles (Ln-CPN) as a fluorescent probe. The Ln-CPN were prepared by self-assembly of adenosine monophosphate (AMP) with Tb(3+), i.e. AMP-Tb. The nonluminescent AMP-Tb could be efficiently sensitized by 5-sulfosalicylic acid (SSA). The fluorescence of AMP-Tb-SSA can be remarkably quenched by Cu(2+), and that of the resulting Cu/SSA/AMP-Tb can be significantly enhanced by His and Cys. Thus, a specific fluorescence "turn-on" assay for His and Cys was developed by using Cu/SSA/AMP-Tb as a sensing platform. The enhanced fluorescence intensity was proportional to the His and Cys concentration in the range from 0.2 to 150 μM and 0.5 to 200 μM, respectively, with the detection limits of 70 nM and 100 nM. Additionally, taking advantage of a masking agent for His, the differentiation of His from Cys was achieved in our system. Furthermore, the protocol can also work well for analyzing His and Cys in practical plasma samples with recovery in the range of 100.3-104.1%.
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Amino acid-mediated ‘turn-off/turn-on’ nanozyme activity of gold nanoclusters for sensitive and selective detection of copper ions and histidine
Article
  • Jan 2017
Herein, we presented a facile strategy for highly sensitive and selective detection of both Cu²⁺ and histidine (His) by combining the peroxidase-like nanozyme activity of gold nanoclusters with amino acid's ambidentate nature. The peroxidase-like catalytic ability of histidine-Au nanoclusters (His-AuNCs) can be inhibited by the addition of Cu²⁺. The sensitivity of this probe to Cu²⁺ is significant with a linear range of 1–100 nM, and a low detection limit of 0.1 nM. More interestingly, His-AuNC/Cu²⁺ undergoes recovery of the activity upon exposure to free His, because His/Cu²⁺ complex is more stable due to the participation of the imidazole ring of His. The method displays a good selectivity toward histidine over all the other amino acids, with a wide linear relationship in the range of 20 nM–2 μM, and a low detection limit of 20 nM. The feasibility of the probe for the rapid analysis of copper ion and His in human serum has been demonstrated with satisfactory results. With the merits of high sensitivity and selectivity, simplification, low cost, and visual readout with the naked eye, this novel 'turn-off/turn-on' sensing approach based on the amino acid's ambidentate nature is potentially applicable to metal ions, amino acids and peptides in biological and environmental areas.
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Montmorillonite-loaded ceria nanocomposites with superior peroxidase-like activity for rapid colorimetric detection of H2O2
Article
An efficient novel colorimetric sensor for H2O2 based on peroxidase-like CeO2-montmorillonite (MMT) nanocomposites that were successfully prepared by a facile one-pot approach, was realized. In comparison with other nanomaterials as peroxidase mimics, the catalytic reaction by the well-dispersed CeO2-MMT nanocomposites was in accordance with typical Michaelis–Menten kinetics, which exhibited a higher affinity to 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2, bringing about a superior peroxidase-like activity (a distinct blue color change was observed rapidly within 30 s, by the naked eye.) than that of pure CeO2 nanoparticles, MMT and their hybrid materials, respectively. Under the optimized conditions, CeO2-MMT nanocomposites were used to establish a colorimetric biosensor for the detection of H2O2 in a relative wide range of 9 × 10⁻⁶ M to 5 × 10⁻⁴ M with a lower detection limit of 7.8 × 10⁻⁶ M. The sensor was successfully applied in H2O2 detection in milk samples.
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