ABSTRACT
The poor fluorescence properties of magneto-fluorescent paramagnetic-ion (Gd, Mn, or Co) doped I-III-VI quantum dots (QDs) at higher paramagnetic-ion doping concentrations have limited their use in magnetic-driven water-based applications. This work presents, for the first time, the use of stable magneto-fluorescent Gd-doped AgInS2 QDs at high Gd mole ratios of 16, 20, and 30 for the fluorescence detection and adsorption of Ag+ ions in water environments. The effect of pH, initial concentration, contact time, and adsorbent dosage were systematically evaluated. The AgInS2 QDs with the least Gd mole ratio (16) exhibited the best fluorescence characteristics (LOD = 0.88, R2 = 0.9549) while all materials showed good adsorption properties under optimized conditions (pH of 2, initial concentration of 30 ppm, contact time of 10 min and adsorbent dosage of 0.02 g) and a pseudo 2nd order reaction was followed. The adsorption mechanism was proposed to be a combination of ion-exchange, electrostatic interaction, complexation, and diffusion processes. Application in environmental wastewater samples revealed complete removal of Ag + ions alongside Ti2+ Pb2+, Ni2+, Cr3+, and Zn2+ ions.
ABSTRACT
The utility of a low-cost biocompatible material for the detection of pollutants in water is highly essential to ensure safety and economic efficiency. In this paper, solutions of two viscous alkaline glucose syrups (AGS@22-sheet and AGS@60-rod), obtained under two different temperature conditions (22 °C and 60 °C) were used to detect low levels of humic acid (HA), a carcinogen pro-molecule and metal-complexing agent in an aqueous solution. The AGS materials were characterized using ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). By evaluation, a detection limit (LOD) as low as 4.6 × 10-5 mg L-1 was obtained. The sensing capability of the new technology was further extended to the detection of HA in a real water sample (tap water) using the standard addition method with 98 and 100.05% recoveries. The sensing was improved in the presence of sodium acetate and sodium citrate and was found to follow a pseudo-first order reaction. These findings show that the as-synthesized glucose syrups have the potential to detect humic acid in water and thus may be employed for the quantification of HA in water treatment plants or textile industry.
ABSTRACT
Specially designed functionalized nanomaterials such as superparamagnetic iron oxide, gold, quantum dots and up- and down-conversion lanthanide series nanoparticles have consistently and completely revolutionized the biomedical environment over the past few years due to their specially inferring properties, such as specific drug delivery, plasmonic effect, optical and imaging properties, therapeutic thermal energy productionand excellent irresistible cellular penetration. These properties have been used to improve many existing disease treatment modalities and have led to the development of better therapeutic approaches for the advancement of the treatment of critical human diseases, such as cancers and related malaise. In photodynamic therapy, for example, where the delivery of therapeutic agents should ideally avoid toxicity on nearby healthy cells, superparamagnetic iron oxide nanoparticles have been shown to be capable of making photodynamic therapy (PDT) prodrugs and their associative targeting moieties tumor-specific via their unique response to an external magnetic fields. In this review, the nanomaterials commonly employed for the enhancement of photodynamic therapy are discussed. The review further describes the various methods of synthesis and characterization of these nanomaterials and highlights challenges for improving the efficacy of PDT in the future.