title: Target-responsive DNAzyme cross-linked hydrogel for visual quantitative detection of lead.
abstract: Because of the severe health risks associated with lead pollution, rapid, sensitive, and portable detection of low levels of Pb(2+) in biological and environmental samples is of great importance. In this work, a Pb(2+)-responsive hydrogel was prepared using a DNAzyme and its substrate as cross-linker for rapid, sensitive, portable, and quantitative detection of Pb(2+). Gold nanoparticles (AuNPs) were first encapsulated in the hydrogel as an indicator for colorimetric analysis. In the absence of lead, the DNAzyme is inactive, and the substrate cross-linker maintains the hydrogel in the gel form. In contrast, the presence of lead activates the DNAzyme to cleave the substrate, decreasing the cross-linking density of the hydrogel and resulting in dissolution of the hydrogel and release of AuNPs for visual detection. As low as 10 nM Pb(2+) can be detected by the naked eye. Furthermore, to realize quantitative visual detection, a volumetric bar-chart chip (V-chip) was used for quantitative readout of the hydrogel system by replacing AuNPs with gold-platinum core-shell nanoparticles (Au@PtNPs). The Au@PtNPs released from the hydrogel upon target activation can efficiently catalyze the decomposition of H2O2 to generate a large volume of O2. The gas pressure moves an ink bar in the V-chip for portable visual quantitative detection of lead with a detection limit less than 5 nM. The device was able to detect lead in digested blood with excellent accuracy. The method developed can be used for portable lead quantitation in many applications. Furthermore, the method can be further extended to portable visual quantitative detection of a variety of targets by replacing the lead-responsive DNAzyme with other DNAzymes.
authors.affiliation: The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation, Innovation Center of Chemistry for Energy Materials, State Key Laboratory of Physical Chemistry of Solid Surfaces, the Key Laboratory for Chemical Biology of Fujian Province, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, Fujian, People's Republic of China.
authors.forename: Yishun
authors.initials: Y
authors.lastname: Huang
authors.forename: Yanli
authors.initials: Y
authors.lastname: Ma
authors.forename: Yahong
authors.initials: Y
authors.lastname: Chen
authors.forename: Xuemeng
authors.initials: X
authors.lastname: Wu
authors.forename: Luting
authors.initials: L
authors.lastname: Fang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhu
authors.forename: Chaoyong James
authors.initials: CJ
authors.lastname: Yang
mesh_terms: D003124:Colorimetry; D003432:Cross-Linking Reagents / Q000737:chemistry*; D021881:DNA, Catalytic / Q000737:chemistry* / Q000378:metabolism*; D006046:Gold / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D007854:Lead / Q000032:analysis* / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry; D046210:Microfluidic Analytical Techniques; D010984:Platinum / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D021881:DNA, Catalytic; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007854:Lead; D010984:Platinum; D006046:Gold