A Selective Ratiometric Fluorescent Probe for No-Wash Detection of PVC Microplastic

Abstract

Microplastics (MP) are micrometric plastic particles present in drinking water, food and the environment that constitute an emerging pollutant and pose a menace to human health. Novel methods for the fast detection of these new contaminants are needed. Fluorescence-based detection exploits the use of specific probes to label the MP particles. This method can be environmentally friendly, low-cost, easily scalable but also very sensitive and specific. Here, we present the synthesis and application of a new probe based on perylene-diimide (PDI), which can be prepared in a few minutes by a one-pot reaction using a conventional microwave oven and can be used for the direct detection of MP in water without any further treatment of the sample. The green fluorescence is strongly quenched in water at neutral pH because of the formation dimers. The ability of the probe to label MP was tested for polyvinyl chloride (PVC), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), poly methyl methacrylate (PMMA) and polytetrafluoroethylene (PTFE). The probe showed considerable selectivity to PVC MP, which presented an intense red emission after staining. Interestingly, the fluorescence of the MP after labeling could be detected, under excitation with a blue diode, with a conventional CMOS color camera. Good selectivity was achieved analyzing the red to green fluorescence intensity ratio. UV–Vis absorption, steady-state and time-resolved fluorescence spectroscopy, fluorescence anisotropy, fluorescence wide-field and confocal laser scanning microscopy allowed elucidating the mechanism of the staining in detail.

Local detection of pH-induced disaggregation of biocompatible micelles by fluorescence switch ON

“…2a, clearly shows the typical vibration structure of the lowest energy absorption band of the PDI monomer with a maximum at 526 nm ( ε ∼80 000 M −1 cm −1 ). 26,27 A similar vibrational structure is observed for the fluorescence band upon excitation at 470 nm as shown in Fig. 2b.…”

“…The absorption spectrum of m1 in CH 2 Cl 2 (1x10 -6 M), shown in Figure 2a, clearly shows the typical vibration structure of the lowest energy absorption band of the PDI monomer with a maximum at 526 nm (ε~80000 M -1 cm -1 ). 26,27 A similar vibrational structure is observed for the fluorescence band upon excitation at 470 nm as reported in Figure 2b. This is the expected emission of the monomer, with a maximum at 535 nm and a fluorescence quantum yield Φ=90%.…”

“…22,23 Perylene diimides (PDI) constitute an important class of organic dyes that present ideal features for the design of systems which response is based on the fluorescence signal switching ON or OFF upon aggregationdisaggregation processes. [24][25][26][27][28] In fact, PDI dyes, which are very strongly fluorescent, exhibit a very low fluorescent quantum yield in the aggregated form. 29 As one of the main prerequisites for bio-application is the high biocompatibility of the probe, organic assemblies, consisting of a fluorescent core made by an organic emitter and a shell made by biocompatible/biodegradable polymers, are very promising candidates.…”

Photothermal motion: effect of low-intensity irradiation on the thermal motion of organic nanoparticles

“…This molecule belongs to the family of PDI, a wellknown class of photostable dyes with high ε that, upon π-π stacking, undergo a large decrease of the high fluorescence QY and a huge red-shift of the fluorescence band. [29][30][31][32][33][34] Owing to these properties, PDI aggregates (and NP) present large Stokes shifts, as well as fast and efficient non-radiative deactivation while still maintaining a QY high enough to allow their detection. In particular, we succeeded in preparing fluorescent NP by nanoprecipitation of P in water in the absence of any stabilizing agent.…”

In Situ Fluorescent Illumination of Microplastics in Water Utilizing a Combination of Dye/Surfactant and Quenching Techniques

“…For these observations, staining MPs using fluorescent dyes is an essential step to visualize and identify MPs ( Table S1, see Supplementary Materials ) [ 33 , 34 , 35 ]. To facilitate incorporation into a nonpolar polymer matrix, lipophilic nonpolar dyes are generally employed.…”