| 其他摘要 | Noble metal nanomaterial-based optical nanoprobes have been widely developed for easy quantification of species in environmental and biological analysis, attributing to their high sensitivity and high specificity. In this paper, we focused on the investigation of novel nanomaterial-based sensing methods and developed several new chemical and biological sensing strategies by integrating recognition units with talented gold/silver nanomaterials. These nanoprobes can transform the recoginition behavior of specific targets into optical signals such as colorimetry and fluorescence and show promising applications. The detail contents of this dissertation are as follows:
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N-1-(2-Mercaptoethyl) thymine modification of gold nanoparticles: a highly selective and sensitive colorimetric chemosensor for Hg2+.
In this work, an approach for mercury ions (Hg2+) sensing based on the Hg2+ induced aggregation of thymine (T)-SH functionalized gold nanoparticles (AuNPs) has been developed. The T-SH ligands that we synthesized can easily combined to the surface of AuNPs through Au–S bond and can recognize Hg2+ with high selectivity by forming T-Hg-T complex with strong affinity. The T-SH functionalized AuNPs (T-S–AuNPs) sensor, upon addition of Hg2+, the formation of T-Hg-T complex induces aggregation of T-S–AuNPs and results in significant change of color and UV-Vis absorption spectra. Under the optimum conditions, this method can be used for rapid, easy and reliable screening of Hg2+ in aqueous solution, with high sensitivity (2.8 nM) and selectivity over competing analytes, showing great potential for the sensing of Hg2+ in real environmental samples.
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A highly selective and sensitive colorimetric sensor for iodide detection based on anti-aggregation of gold nanoparticles.
In this work, a simple and rapid colorimetric iodide (I–) sensor based on the anti-aggregation of gold nanoparticles (Au NPs) was presented. This assay relied upon the distance-dependent optical properties of gold nanoparticles, the combination of mercapto-functionalized thymine on Au NPs, and the stronger affinity between I– and mercury ions (Hg2+). Hg2+ was employed as cross-linking agent for pairs of modified Au NPs by the coordination between Hg2+ and thymine. In the simultaneous presence of I– and Hg2+, the aggregation of Au NPs could not occur because of the preferential formation of HgI2 complex. Thus, the sensing of I– based on anti-aggregation of Au NPs was developed with the color of the Au NPs changing from blue to red, which was readily seen by the naked eye. The colorimetric sensor exhibited high sensitivity with a low detection limit of 10 nM. This simple and quick sensing method can selectively recognize I– in the presence of other halogen anions (F–, Cl–, Br–) and show possibilities for applying to environmental applications.
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Highly sensitive and selective colorimetric sensing of Hg2+ based on the morphology transition of silver nanoprisms.
In this work, a simple colorimetric approach for mercury ions (Hg2+) sensing was developed, which was based on the Hg2+-induced deprotection and morphology transition of 1-dodecanethiol (C12H25SH) capped silver nanoprisms (Ag NPRs) upon the presence of iodides at room temperature. The abstraction of thiols on the surface of Ag NPRs by Hg2+ led to their deprotection of Ag NPRs and the formation of complexation between bare silver ions and excess iodide ions. And the silver atoms were consumed and moved from the surface of Ag NPRs, accompanying the changes in particle morphology which resulted in the change of color and UV-Vis absorption spectra of colloid solution. With the increasing concentrations of Hg2+ from 10 to 500 nM, the surface plasma resonance spectra band of Ag NPRs emerged blue shift and exhibited a good linear relationship, and the limit of detection was 3.3 nM. The developed method could be applied for detecting Hg2+ in different real water samples with satisfying recoveries over 92%.
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A colorimetric nanosensor for sensitive detection of mercury species.
In this work, a novel colorimetric nanosensor strategy for mercury speciation was proposed for the first time, based on the analyte-induced aggregation of gold nanoparticles (Au NPs) with the assistance of thiol-containing ligand of diethyldithiocarbamate (DDTC). Upon addition of mercury species, since Hg-DDTC was more stable than Cu-DDTC, a place-displacement between Hg species and Cu2+ would occur and thereby the functionalized Au NPs would aggregate, resulting in a color change. Moreover, by virtue of masking effect of ethylenediaminetetraacetic acid (EDTA), the nanosensor could readily discriminate organic mercury and inorganic mercury (Hg2+), presenting high detectability such as up to 2.9 nM for Hg2+, 2.6 nM for methylmercury. This simple, rapid, and sensitive label-free colorimetric strategy shed some light on mercury speciation analysis providing an attractive alternative to conventional methods, which usually involve sophisticated instruments, time-consuming processes.
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FITC modified magnetic core-shell Fe3O4/Ag hybrid nanoparticle for selective determination of molecular biothiols.
In this work, a sensing strategy for chromogenic detection of molecular biothiols has been proposed based on fluorescein isothiocyanate (FITC) functionalized magnetic core-shell Fe3O4/Ag hybrid nanoparticles. Ag coated magnetic Fe3O4 nanoparticles were initially synthetized. FITC was subsequently conjugated on the surface of core-shell nanoparticles by Ag–SCN linkage and then the fluorescence of FITC was quenched. Upon addition of molecular biothiols, since the Ag–S bond is stronger than Ag–SCN, a place-displacement between thiols and FITC would occur and thereby the fluorescence of FITC would recover. Thus, a fluorescence “off-on” probe was attained by virtue of biothiols, so after magnetic separation, the fluorescence signal change of FITC in clear solution could be employed for quantitative determination of typical molecular biothiols such as glutathione (GSH) and cysteine (Cys). High sensitivity was obtained with the detection limits of 10 nM and 20 nM for GSH and Cys, respectively. As well as, this strategy presented excellent selectivity toward molecular biothiols against other amino acids, and show potentially applicable for imaging molecular thiols in biological systems. |
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