title: Self-Assembled Templates of Aromatic Pentapeptides for Synthesis of CdS Quantum-Dots to Detect the Trace Amounts of Hg(2+) in Aqueous Solutions.
abstract: Molecular self-assembly has become a popular tool to prepare nanomaterials with potential applications, such as ion-responsive detection of Hg(2+) in aqueous solutions. In this study, FFACD aromatic pentapeptides, whose N-terminuses were protected by carboxyl (Ac-FFACD) or a 9-fluorenylmethoxycarbonyl group (Fmoc-FFACD), were chosen as building blocks to produce nanostructures in solutions. Based on the preliminary determination of the critical aggregation concentration (CAC) of Ac-FFACD and Fmoc-FFACD aromatic pentapeptides in water, the order of magnitude of which is 10(-5) mol·L(-1), self-assembled spiral and networked nanowires can be easily obtained over a range of concentrations. These nanowires were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The self-assembled spiral and networked nanowires were designed to be used as templates for preparing CdS quantum dots (QDs) in-situ at room temperature. The peptide-functionalized, nanowire-encapsulated CdS QDs can be used for rapid, sensitive, and selective detection of trace amounts of mercuric ions (Hg(2+)) in aqueous solutions. This method enables rapid, linear detection (the linear correlation coefficients are 0.9972 of ΔF = 257.09 + 3.58 cHg(2+) for Ac-FFACD and 0.9994 of ΔF = 48.13 + 32.96 cHg(2+) for Fmoc-FFACD) with the Hg(2+) limit of detection at 300.85 ng·L(-1) and 32.09 ng·L(-1) for Ac-FFACD and Fmoc-FFACD, respectively. The supramolecular, self-assembled nanowires, fabricated from the two aromatic pentapeptides and having encapsulated QDs, exhibit superior properties attributable to the large loading capacity and the coordination sites of these peptides with Hg(2+). These structures can serve as novel Hg(2+) sensors and have possible applications for detection of various targets in scientific and engineering systems.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Shandong University, Ministry of Education.
authors.forename: Min
authors.initials: M
authors.lastname: Meng
authors.forename: Yingying
authors.initials: Y
authors.lastname: Dou
authors.forename: Wenlong
authors.initials: W
authors.lastname: Xu
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Hao
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D008628:Mercury / Q000032:analysis*; D015394:Molecular Structure; D009812:Odorants; D009842:Oligopeptides / Q000737:chemistry*; D045663:Quantum Dots; D012996:Solutions; D013440:Sulfides / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D019187:Cadmium Compounds; D009842:Oligopeptides; D012996:Solutions; D013440:Sulfides; D014874:Water Pollutants, Chemical; C034939:cadmium sulfide; D008628:Mercury