FRONTIERS ARTICLE Measuring properties of nanoparticles in embryonic blood vessels: Towards a physicochemical basis for nanotoxicity Aisling A. Clancy, Yiota Gregoriou, Kristin Yaehne, David T. Cramb * Department of Chemistry, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, Canada T2N 1N4 article info Article history: Received 8 January 2010 In final form 9 February 2010 Available online 12 February 2010 abstract The developing field of nanotoxicology aims to relate the physical properties of nanomaterials to poten- tial risk when organisms are exposed to those materials. Regulators are interested in whether a nanofor- mulation would alter the risk of the native material. It may be that due to the physical nature of embryonic blood vessels (i.e. they are angiogenic and therefore leaky), embryos are at greater risk for bio- accumulation of nanoparticles (NPs) than mature organisms. To study the physicochemical nature of nanoparticle accumulation from embryonic blood vessels, one needs to measure the NP properties in situ, because these properties could be significantly dependent on environment. We have undertaken a study of the dynamics of CdSe/ZnS quantum dots and polystyrene nanospheres in the blood vessels of the chicken embryo chorioallantoic membrane (CAM). We show proof of principle that fluorescence cor- relation spectroscopy can be used in this system to determine the concentrations and hydrodynamic radii of NP solutions micro-injected into the CAM. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction The field of nanotechnology is rapidly growing and it is esti- mated that there will be USD $12 trillion invested in nanotechnol- ogy globally by 2012 [1]. Nanoparticles (NPs) (particles of diameter 10–500 nm) are already used in the cosmetics industry and are being developed for drug delivery, diagnostic imaging and tissue engineering, to name but a few applications. The increasing num- ber of NP applications also results in increased environmental and human exposure, and thus there is a need to investigate their potential detrimental effects. A global research effort is currently underway and focused on these so called Environmental, Health and Safety (EHS) concerns [2,3]. Currently, there is an international effort headed by organiza- tions such as the OECD (Organization for Economic Co-operation and Development, e.g. Working Party on Manufactured Nanomate- rials or WPMN) to develop research endpoints that will enable individual member states to implement sound, science-based reg- ulatory frameworks for the burgeoning nanotechnology industry. The inherent risk of NPs is the product of hazard and exposure. Hazard is the intrinsic toxicity of the NP, once in the organism. Exposure is the propensity of the NP to sequester in the organism (bioaccumulation), together with the likelihood of the organism encountering the NP. Important questions we seek to help answer are ‘If embryos are exposed to NPs, where will the NPs go? With what kinetics?’ and/or ‘Can we expect acute or chronic toxic responses?’ Furthermore, in the instance of accidental exposure, what response can be recommended? To help answer these ques- tions, federal governments have called for studies to establish the relationship of nanomaterial risk with their physical chemistry. There are as yet only a few systematic studies that relate NP properties to bioaccumulation in living organisms; and next to no nanotoxicity studies involving embryos have been conducted. Studies on the interactions of NPs with embryos are important since the problems associated with health of an adult organism could be due to exposure during the development process, and exposure may even affect embryonic viability. Indeed, there is a substantial knowledge gap with respect to NP risk assessment and policy/regulation development. With the boom in NP development there is an increasing possi- bility of environmental and/or occupational exposure. A recent study has shown that NP in aquatic systems can work their way up the food chain via ingestion [4]. It is clear that potential risk needs to be evaluated, particularly by regulatory agencies. The most likely path of NPs into embryonic organisms is through their parents. For mammals this would result from crossing the placen- tal barrier, for avian and aquatic vertebrate species this would oc- cur in egg generation. Young organisms could be exposed through food ingestion or through their skin. Once inside an immature organism, NPs can trigger toxicity through a variety of pathways, but the most common are: reactive oxygen generation, membrane disruption, release of toxic components and immunological re- sponses [5,6]. A significant difference between embryonic and mature organisms is that embryos undergo a large degree of new blood 0009-2614/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.cplett.2010.02.016 * Corresponding author. E-mail address: dcramb@ucalgary.ca (D.T. Cramb). Chemical Physics Letters 488 (2010) 99–111 Contents lists available at ScienceDirect Chemical Physics Letters journal homepage: www.elsevier.com/locate/cplett