Advancing the understanding of stability behavior and aggregation mechanisms of quantum dot (QD) nanoparticles in natural systems is fundamental to elucidate their fate and transport, bioavailability, environmental toxicity, and subsequent risks to environmental and public health. This study investigates the aggregation kinetics and colloidal stability of QDs as a function of pH and organic ligands—acetate, oxalate, and citrate. Results indicated an influence of solution chemistry upon both the aggregation kinetics and colloidal stability of QDs. The zeta potential of QDs, with a point of zero charge (pH_PZC) between pH 1.5 and 3.5, decreased (from positive to negative) with increasing solution pH. The diameter of QD aggregates was ~500 nm in the region of pH_PZC and decreased with pH when pH > pH_PZC to 40–50 nm. Organic ligands enhanced the negative zeta potentials of QDs at pH = 1.5 and pH = 3.5. The impact of ligands on the levels and rates of aggregation was pH dependent; furthermore, the presence of ligands increased the diameters of all QD nanoaggregates at pH 3.5 (e.g., 817 nm for 0.001 M citrate). QDs and organic ligand-QD nanoparticle complexes remained stable across pH values 5–9. In terms of environmental and toxicological risk assessments, results revealed that QDs and organic ligand-QD nanoparticle complexes remain stable across a significant range of pH values (5–9), indicating that this stability behavior could enhance the mobility, transport, and residence time of QDs in terrestrial and aqueous environments, and facilitate the bioavailability of QDs, therefore augmenting the adverse effects of QDs in the environment.

推进对量子点（QD）纳米粒子在自然系统中的稳定性行为和聚集机理的理解，对于阐明其命运和运输，生物利用度，环境毒性以及对环境和公共健康的后续风险至关重要。这项研究调查了QDs的聚集动力学和胶体稳定性与pH和有机配体（乙酸盐，草酸盐和柠檬酸盐）的关系。结果表明溶液化学性质对量子点的聚集动力学和胶体稳定性的影响。QD的零电势（pH _PZC）在pH 1.5和3.5之间时，其Zeta电位随溶液pH的增加而降低（从正到负）。在pH _PZC区域中QD聚集体的直径约为500 nm当pH> pH _PZC时，随pH降低到40–50 nm。在pH = 1.5和pH = 3.5时，有机配体增强了量子点的负ζ电势。配体对聚集水平和速率的影响取决于pH。此外，配体的存在增加了在pH 3.5（例如，对于0.001M柠檬酸盐为817nm）下所有QD纳米聚集体的直径。QD和有机配体-QD纳米颗粒复合物在5-9的pH值范围内保持稳定。在环境和毒理学风险评估方面，结果表明，QD和有机配体-QD纳米颗粒复合物在很大的pH值范围内（5-9）保持稳定，表明这种稳定性行为可以提高迁移率，运输和停留时间在陆地和水性环境中分离QD，并促进QD的生物利用度，因此增加了QD在环境中的不利影响。