Near-infrared-emitting persistent luminescent nanoparticles modified with gold nanorods as multifunctional probes for detection of arsenic(III).

Near infrared (NIR)-emitting persistent luminescent nanoparticles (PLNPs) have advantages such as long afterglow, high photostability and deep tissue spectral penetration. A NIR-emitting inner filter effect (IFE) probe for arsenic(III) is described here. It is composed of polyethyleneimine-coated PLNPs and gold nanorods (AuNPs) coated with dithiothreitol. The probe can detect arsenic(III) (= arsenite) selectively even in the presence of interfering substances. The PLNPs and AuNPs were prepared by a hydrothermal method combined with high-temperature calcination and seed-mediated growth mechanism, respectively. The PLNPs show excellent NIR luminescence (with excitation/emission peaks at 254/695 nm) and long afterglow (lifetime >1200 s). The use of polyethyleneimine improves water solubility and provides positive surface charges for the PLNPs. On exposure to arsenite ions, the luminescence of the probe at 695 nm is restored. Under the optimum conditions, the method can detect As(III) in the 0.067 to 13.4 μmol·L-1 concentration range with good linear relationship (R2 = 0.99734), and the detection limit (at S/N = 3) is 55 nmol·L-1. The precision of this method was demonstrated by 11 replicate detections of 2 μmol·L-1 As(III), and the relative standard deviations (RSD) is 2.1%. The practicality was evaluated by the analyses of real water samples and recoveries for the water samples spiked with 2, 5 and 10 μmol·L-1 of As(III) were 89.8%-100.1% with RSDs ranging from 3.0-5.7%. Graphical abstract A near infrared-emitting inner filter effect (IFE) inhibition probe is presented. It is based on the combination of polyethyleneimine (PEI)-coated NIR-emitting persistent luminescent nanoparticles (type Zn1.25Ga1.5Ge0.25O4: Cr3+, ZGGO) (PLNPs-PEI) with dithiothreitol (DTT)-coated gold nanorods (AuNPs) (DTT-AuNPs) to detect arsenite.