| With the development in both production and social life activities, the chemical explosive2,4,6-trinitrotoluene (TNT) was more and more used in the fields of mining, military security, and national defense industry, etc. However, many negative effects were caused with regard to the pollution of environment or the potential threat to human health. In recent years, the rapid and sensitive detection of TNT has become a hot topic and attracted more and more attentions in the research field. With the merits of simpleness, intuition, high selectivity of detecting the TNT explosive, the colorimetry has come into the researchers’ vision. This method is mainly based on the ligand-capped nanoparticles optical probe, which produces a visible color change to achieve the sensing of target analytes. In addition, on the basis of colorimetric method, surface enhanced Raman scattering (SERS) is the widely used technique because of its high sensitivity and the fingerprint analysis. Currently, the development of novel nano-materials sensor for TNT detection progressed fast, nevertheless there are still some bottlenecks with regard to (1) Environmental interference resistance ability of the optical probe detection of TNT is not high; its detection limit needs to be further improved.(2) The repeatability and stability of SERS measurements is very poor and remains to be further improved.(3) Enhancement effect of SERS substrate is not perfect and needs to continue to explore. This paper focused on these several problems and the main research contents are as follows:1) The use of ethylenediamine (EDA) for chemical modification of gold nanoparticles (Au NPs) constructed a novel optical probe for detecting the TNT explosive. This Au NPs@EDA optical probe has several advantages with regards to simplicity, stability, low cost, high sensitivity, and the low detection limit, which can realize the trace detection of TNT. Among them, the Au NPs@EDA ultrasensitive colorimetric probe in aqueous solution can be detected in the400pM levels of TNT. In addition, the use of ultraviolet-visible absorption spectrometer and dynamic light scattering (DLS) instrument can implement40pM and0.4pM levels of TNT ultrasensitive detection.2) A novel SERRS platform for fast and sensitive detection of TNT was developed. A cationic surfactant, cetylpyridinium chloride (CPC) was modified on the surface of silver sols (CPC-capped Ag). CPC not only can act as the surface seeking species to trap sulfite-sulfonated TNT, but also undergoes complexation with it, causing the arising of two charge-transfer bands at467and530nm, respectively. This chromophore absorbs the visible light that matches with the incident laser and plasmon resonance of Ag sols by the use of a532.06nm laser, and offered a highly resonance Raman enhancement. This SERRS platform evidenced a fast and accurate detection of TNT with a detection limit of5×10-11M under a low laser power (200μW) and a short integration time (3s). The CPC-capped Ag also provides remarkable sensitivity and reliable repeatability.3) A one-step synthesis and controlled assembly of Au nanoparticles (NPs) on X.-DNA scaffolds by an in-situ photoreduction method was developed aimed at the TNT sensing. The interpaticle gaps of the Au NPs attached on DNA can be fine regulated by controlling the R values (denoted as the ratio of Au (Δ) ions added per DNA base pairs). Empirical enhancement factor above1×109is observed when the R value is in a fairly broad range of10-60under785nm excitation. Moreover, this substrates have a good reproducibility at different sites on a substrate, with a standard deviation of<15%. These results indicate that the photoreduced Au NPs on DNA scaffolds can be used as SERS-active substrates which exhibit high and reproducible SERS activity. This DNA-Au hybrid has potential applications in chemical and biological SERS analysis. Through the above researches, several optical nanoprobes were developed and realized the trace detection of TNT, and these probes have a great application prospect in the field of analytical chemistry, environmental analysis. |
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