Oral bioavailability and sex specific tissue partitioning of quantum dots in fathead minnows, Pimephales promelas
The number of potential applications for manufactured nanomaterials (NMs) is growing exponentially around the world as is concomitant research into the possible consequences of inadvertent or purposeful releases into the environment. Fish and other aquatic organisms reside in bodies of water where many NMs may potentially be deposited, as these environments act as terminal sinks for many contaminants. A growing body of evidence suggests that some NMs, depending on their composition, size, and/or surface functionalization, can affect fish health by adversely interacting with gill function or by entering circulation through the digestive tract. The goal of this study was to investigate the role surface functionalization plays on oral bioavailability of NMs, using quantum dots (QDs) as a model. Three different surface functional groups, amino, carboxyl, and PEG were investigated. Additionally, two different exposure scenarios, a single dose or 5 sequential doses over 2 weeks, were used to determine which tissues were the sites of greatest accumulation over time. Results show QDs are able to enter the blood stream after ingestion, and accumulate in the intestine, liver, gonads, and other organs in female and male fathead minnows. Data from a repeated dosing experiment indicated that QDs were retained and accumulated in most tissues in a surface functionalization and sex specific manner. The carboxyl and amino QDs were found to be most readily taken up and the carboxyl QDs were found to be in the greatest concentration in the most number of tissues including the gonad, spleen and kidneys in both males and females.