We have devised a unique strategy for highly sensitive, selective, and colorimetric detection of mercury based on analyte-induced enhancement of the photocatalytic activity of TiO2–Au nanospheres (TiO2–Au NSs) toward degradation of methylene blue (MB). Through electrostatic interactions, Au nanoparticles are attached to poly-(sodium 4-styreneulfonate)/poly(diallyldimethylammonium chloride) modified TiO2 nanoparticles, which then form an Au shell on each TiO2 core through reduction of Au3+ with ascorbic acid. Notably, the deposition of Hg species (Hg2+/CH3Hg+) onto TiO2–Au NSs through strong Au–Hg aurophilic interactions speeds up catalytic degradation of MB. The first-order degradation rates of MB by TiO2–Au NSs and TiO2–Au–Hg NSs are 1.4 × 10−2 min−1 and 2.1 × 10−2 min−1, respectively. Using a commercial absorption spectrometer, the TiO2–Au NSs/MB approach provides linearity (R2 = 0.98) for Hg2+ over a concentration range of 10.0 to 100.0 nM, with a limit of detection (LOD) of 1.5 nM. On the other hand, using a low-cost smartphone app that records the color changes (ΔRGB) of MB solution based on the red–blue–green (RGB) component values, the TiO2–Au NSs/MB approach provides an LOD of 2.0 nM for Hg2+ and 5.0 nM for CH3Hg+, respectively. Furthermore, the smartphone app sensing system has been validated for the analyses of various samples, including tap water, lake water, soil, and Dorm II, showing its great potential for on-line analysis of environmental and biological samples.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
Tax calculation will be finalised during checkout.
Maxson PA. Global mercury production, use and trade. In: Pirrone N, Mahaffey KR, editors. Dynamics of mercury pollution on regional and global scales—atmospheric processes and human exposures around the world. New York: Springer; 2005. p. 25–50.
Roy P, Lin Z-H, Liang C-T, Chang H-T. Iron telluride nanorods-based system for the detection of total mercury in blood. J Hazard Mater. 2012;243:286–91.
Liu C-W, Huang C-C, Chang H-T. Control over surface DNA density on gold nanoparticles allows selective and sensitive detection of mercury(II). Langmuir. 2008;24(15):8346–50.
Park M, Seo S, Lee I-S, Jung J-H. Ultraefficient separation and sensing of mercury and methylmercury ions in drinking water by using aminonaphthalimide-functionalized Fe3O4@ SiO2 core/shell magnetic nanoparticles. Chem Commun. 2010;46(25):4478–80.
Wei B, Yang L. A review of heavy metal contaminations in urban soils, urban road dusts and agricultural soils from China. Microchem J. 2010;94(2):99–107.
Lewen N, Mathew S, Schenkenberger M, Raglione T. A rapid ICP-MS screen for heavy metals in pharmaceutical compounds. J Pharm Biomed Anal. 2004;35(4):739–52.
Palchetti I, Laschi S, Mascini M. Miniaturised stripping-based carbon modified sensor for in field analysis of heavy metals. Anal Chim Acta. 2005;530(1):61–7.
Placido T, Aragay G, Pons J, Comparelli R, Curri ML, Merkoçi A. Ion-directed assembly of gold nanorods: a strategy for mercury detection. ACS Appl. Mater Interfaces. 2013;5(3):1084–92.
Huang P-JJ, van Ballegooie C, Liu J. Hg2+ detection using a phosphorothioate RNA probe adsorbed on graphene oxide and a comparison with thymine-rich DNA. Analyst. 2016;141:3788–93.
Chiang C-K, Huang C-C, Liu C-W, Chang H-T. Oligonucleotide-based fluorescence probe for sensitive and selective detection of mercury (II) in aqueous solution. Anal Chem. 2008;80(10):3716–21.
Zhu Z, Su Y, Li J, Li D, Zhang J, Song S, et al. Highly sensitive electrochemical sensor for mercury(II) ions by using a mercury-specific oligonucleotide probe and gold nanoparticle-based amplification. Anal Chem. 2009;81(18):7660–6.
Kim HJ, Park DS, Hyun MH, Shim YB. Determination of HgII ion with a 1, 11-bis (8-quinoyloxy)-3, 6, 9-trioxaundecane-modified glassy carbon electrode using spin-coating technique. Electroanalysis. 1998;10(5):303–6.
Childress ES, Roberts CA, Sherwood DY, LeGuyader CL, Harbron EJ. Ratiometric fluorescence detection of mercury ions in water by conjugated polymer nanoparticles. Anal Chem. 2012;84(3):1235–9.
MacLean JL, Morishita K, Liu J. DNA stabilized silver nanoclusters for ratiometric and visual detection of Hg2+ and its immobilization in hydrogels. Biosens Bioelectron. 2013;48:82–6.
Wang C-W, Lin Z-H, Roy P, Chang H-T. Detection of mercury ions using silver telluride nanoparticles as a substrate and recognition element through surface-enhanced Raman scattering. Front Chem. 2013;1:1–5.
Huang C-C, Chang H-T. Selective gold-nanoparticle-based “turn-on” fluorescent sensors for detection of mercury (II) in aqueous solution. Anal Chem. 2006;78(24):8332–8.
Deng L, Ouyang X, Jin J, Ma C, Jiang Y, Zheng J, et al. Exploiting the higher specificity of silver amalgamation: selective detection of mercury (II) by forming Ag/Hg amalgam. Anal Chem. 2013;85(18):8594–600.
Huang C-C, Yang Z, Lee K-H, Chang H-T. Synthesis of highly fluorescent gold nanoparticles for sensing mercury(II). Angew Chem Int Ed Engl. 2007;46(36):6824–8.
Lin Y-W, Liu C-W, Chang H-T. DNA functionalized gold nanoparticles for bioanalysis. Anal Methods. 2009;1(1):14–24.
Lee JS, Han MS, Mirkin CA. Colorimetric detection of mercuric ion (Hg2+) in aqueous media using DNA-functionalized gold nanoparticles. Angew Chem. 2007;119(22):4171–4.
Liu D, Qu W, Chen W, Zhang W, Wang Z, Jiang X. Highly sensitive, colorimetric detection of mercury (II) in aqueous media by quaternary ammonium group-capped gold nanoparticles at room temperature. Anal Chem. 2010;82(23):9606–10.
Liu C-W, Hsieh Y-T, Huang C-C, Lin Z-H, Chang H-T. Detection of mercury(II) based on Hg2+-DNA complexes inducing the aggregation of gold nanoparticles. Chem Commun. 2008;19:2242–4.
Chen L-Y, Ou C-M, Chen W-Y, Huang C-C, Chang H-T. Synthesis of photoluminescent Au ND–PNIPAM hybrid microgel for the detection of Hg2+. ACS Appl Mater Interfaces. 2013;5(10):4383–8.
Salgueirino-Maceira V, Correa-Duarte MA, Farle M, López-Quintela A, Sieradzki K, Diaz R. Bifunctional gold-coated magnetic silica spheres. Chem Mater. 2006;18(11):2701–6.
Ravindranath R, Roy P, Periasamy AP, Chang H-T. Effects of deposited ions on the photocatalytic activity of TiO2–Au nanospheres. RSC Adv. 2014;4(100):57290–6.
Viscarra Rossel RA, Minasny B, Roudier P, McBratney AB. Colour space models for soil science. Geoderma. 2006;133(3–4):320–37.
Mahshid S, Askari M, Ghamsari MS. Synthesis of TiO2 nanoparticles by hydrolysis and peptization of titanium isopropoxide solution. J Mater Process Technol. 2007;189(1–3):296–300.
Chiang C-K, Chen W-T, Chang H-T. Nanoparticle-based mass spectrometry for the analysis of biomolecules. Chem Soc Rev. 2011;40(3):1269–81.
Mechiakh R, Sedrine NB, Chtourou R. Sol–gel synthesis, characterization and optical properties of mercury-doped TiO2 thin films deposited on ITO glass substrates. Appl Surf Sci. 2011;257(21):9103–9.
Aguado M, Cervera-March S, Giménez J. Continuous photocatalytic treatment of mercury (II) on titania powders. Kinetics and catalyst activity. Chem Eng Sci. 1995;50(10):1561–9.
Chang H, Su C, Lo C-H, Chen L-C, Tsung T-T, Jwo C-S. Photodecomposition and surface adsorption of methylene blue on TiO2 nanofluid prepared by ASNSS. Mater Trans. 2004;45(12):3334–7.
Xie J, Zheng Y, Ying JY. Highly selective and ultrasensitive detection of Hg2+ based on fluorescence quenching of Au nanoclusters by Hg2+–Au+ interactions. Chem Commun. 2010;46(6):961–3.
Lee J-S, Mirkin CA. Chip-based scanometric detection of mercuric ion using DNA-functionalized gold nanoparticles. Anal Chem. 2008;80(17):6805–8.
Xue X, Wang F, Liu X. One-step, room temperature, colorimetric detection of mercury (Hg2+) using DNA/nanoparticle conjugates. J Am Chem Soc. 2008;130:3244–5.
Li D, Wieckowska A, Willner I. Optical analysis of Hg2+ ions by oligonucleotide–gold-nanoparticle hybrids and DNA-based machines. Angew Chem. 2008;120(21):3991–5.
Huang C-C, Chang H-T. Parameters for selective colorimetric sensing of mercury (II) in aqueous solutions using mercaptopropionic acid-modified gold nanoparticles. Chem Commun. 2007;12:1215–7.
Darbha GK, Singh AK, Rai US, Yu E, Yu H, Chandra RP. Selective detection of mercury (II) ion using nonlinear optical properties of gold nanoparticles. J Am Chem Soc. 2008;130(25):8038–43.
Lin C-Y, Yu C-J, Lin Y-H, Tseng W-L. Colorimetric sensing of silver (I) and mercury (II) ions based on an assembly of tween 20-stabilized gold nanoparticles. Anal Chem. 2010;82(16):6830–7.
Yoon S, Miller EW, He Q, Do PH, Chang CJ. A bright and specific fluorescent sensor for mercury in water, cells, and tissue. Angew Chem Int Ed. 2007;46(35):6658–61.
Lee D-N, Kim G-J, Kim H-J. A fluorescent coumarinylalkyne probe for the selective detection of mercury (II) ion in water. Tetrahedron Lett. 2009;50(33):4766–8.
Li M, Wang Q, Shi X, Hornak LA, Wu N. Detection of mercury (II) by quantum dot/DNA/gold nanoparticle ensemble based nanosensor via nanometal surface energy transfer. Anal Chem. 2011;83(18):7061–5.
Peng H-P, Hu Y, Liu P, Deng Y-N, Wang P, Chen W, et al. Label-free electrochemical DNA biosensor for rapid detection of multidrug resistance gene based on Au nanoparticles/toluidine blue–graphene oxide nanocomposites. Sens Actuator B Chem. 2015;207:269–76.
Li M, Zhou X, Ding W, Guo S, Wu N. Fluorescent aptamer-functionalized graphene oxide biosensor for label-free detection of mercury (II). Biosens Bioelectron. 2013;41:889–93.
Wu D, Zhang Q, Chu X, Wang H, Shen G, Yu R. Ultrasensitive electrochemical sensor for mercury (II) based on target-induced structure-switching DNA. Biosens Bioelectron. 2010;25(5):1025–31.
Allibone J, Fatemian E, Walker PJ. Determination of mercury in potable water by ICP-MS using gold as a stabilising agent. J Anal At Spectrom. 1999;14(2):235–9.
Harrington CF, Merson SA, D’Silva TM. Method to reduce the memory effect of mercury in the analysis of fish tissue using inductively coupled plasma mass spectrometry. Anal Chim Acta. 2004;505(2):247–54.
Wang M, Feng W, Shi J, Zhang F, Wang B, Zhu M, et al. Development of a mild mercaptoethanol extraction method for determination of mercury species in biological samples by HPLC-ICP-MS. Talanta. 2007;71(5):2034–9.
Wang Y, Yang F, Yang X. Colorimetric detection of mercury(II) ion using unmodified silver nanoparticles and mercury-specific oligonucleotides. ACS Appl Mater Interfaces. 2010;2(2):339–42.
Zhou L, Lin Y, Huang Z, Ren J, Qu X. Carbon nanodots as fluorescence probes for rapid, sensitive, and label-free detection of Hg2+ and biothiols in complex matrices. Chem Commun. 2012;48(8):1147–9.
Li X, Liu L, Zhao J, Tan J. Optical properties of sodium chloride solution within the spectral range from 300 to 2500 nm at room temperature. Appl Spectrosc. 2015;69(5):635–40.
Muthukumaran S, Song L, Zhu B, Myat D, Chen J-Y, Gray S, et al. UV/TiO2 photocatalytic oxidation of recalcitrant organic matter: effect of salinity and pH. Water Sci Technol. 2014;70(3):437–43.
Yusa S-i, Fukuda K, Yamamoto T, Iwasaki Y, Watanabe A, Akiyoshi K, et al. Salt effect on the heat-induced association behavior of gold nanoparticles coated with poly (N-isopropylacrylamide) prepared via reversible addition-fragmentation chain transfer (RAFT) radical polymerization. Langmuir. 2007;23(26):12842–8.
Lévy R, Thanh NT, Doty RC, Hussain I, Nichols RJ, Schiffrin DJ, et al. Rational and combinatorial design of peptide capping ligands for gold nanoparticles. J Am Chem Soc. 2004;126(32):10076–84.
Ding N, Zhao H, Peng W, He Y, Zhou Y, Yuan L, et al. A simple colorimetric sensor based on anti-aggregation of gold nanoparticles for Hg2+ detection. Colloids Surf A Physicochem Eng Asp. 2012;395:161–7.
Nakayama S, Kelsey I, Wang J, Sintim HO. C-di-GMP can form remarkably stable G-quadruplexes at physiological conditions in the presence of some planar intercalators. Chem Commun. 2011;16:4766–8.
Khataee A, Kasiri MB. Photocatalytic degradation of organic dyes in the presence of nanostructured titanium dioxide: influence of the chemical structure of dyes. J Mol Catal A Chem. 2010;328(1):8–26.
Kumar A, Mathur N. Photocatalytic oxidation of aniline using Ag+-loaded TiO2 suspensions. Appl Catal A. 2004;275(1):189–97.
Szabó-Bárdos E, Czili H, Horváth A. Photocatalytic oxidation of oxalic acid enhanced by silver deposition on a TiO2 surface. J Photochem Photobiol A. 2003;154(2):195–201.
Pham T-D, Lee B-K. Feasibility of silver doped TiO2/glass fiber photocatalyst under visible irradiation as an indoor air germicide. Int J Environ Res Public Health. 2014;11:3271–88.
Zhuang J, Fu L, Tang D, Xu M, Chen G, Yang H. Target-induced structure-switching DNA hairpins for sensitive electrochemical monitoring of mercury (II). Biosens Bioelectron. 2013;39(1):315–9.
This work was funded by the Ministry of Science and Technology (MOST), Taiwan (grant no. 103-2923-M-002-002-MY3). P.R. and A.P.P. are grateful to MOST for a postdoctoral fellowship under the contract number MOST 104-2811-M-002-154 and MOST 104-2811-M-002-153, respectively. We would also like to thank Ms. S.-J. Ji and Ms. C.-Y. Chien of Precious Instrument Center (National Taiwan University) for their assistance in SEM and EDX analysis.
Conflict of interest
The authors declare no conflict of interest.
Electronic supplementary material
About this article
Cite this article
Ravindranath, R., Periasamy, A.P., Roy, P. et al. Smart app-based on-field colorimetric quantification of mercury via analyte-induced enhancement of the photocatalytic activity of TiO2–Au nanospheres. Anal Bioanal Chem 410, 4555–4564 (2018). https://doi.org/10.1007/s00216-018-1114-7
- Methylene blue
- Smartphone app
- TiO2–Au nanospheres