A Nanomaterial’s Sample Life

Studies suggest that nanomaterials interact with their respective environments in unique ways. In order to capture and track these phenomena, the Nanomaterial Registry curates Instance of Characterization (IOC) information within each record. The IOC information defines the “when” or “where” a material was characterized in terms of a time point or environmental condition. A goal of tracking IOCs is not just for the comparison of nanomaterial measurements, but also to identify if two originally identical nanomaterials retain the properties that make them similar over the course of various processing and characterization steps. A second goal is to determine if nanomaterials that share certain physico-chemical characteristics (PCCs) have similar or predictive interactions with biological or environmental systems. To support these goals, substantial importance is placed on the IOC of each nanomaterial entry in the Registry.
Unique IOCs are curated with PCC and study data whenever reported. IOC designations speak to both the dynamic and kinetic state of a nanomaterial (see Figure 1). IOC designations are listed below:

  • As Synthesized – used when an investigator has characterized a nanomaterial after synthesis. This IOC often includes a manufacturer name, product name, lot #, and general description of synthesis.
  • As Received –used when an investigator has characterized a nanomaterial after receiving it from a manufacturer. This IOC often includes a manufacturer name and product name.
  • As Processed – used when an investigator has either received or synthesized a nanomaterial and then subjects it to a thermodynamic change (e.g., suspending a powdered nanomaterial in a media, sonicating a nanomaterial suspension, changing the media in which a nanomaterial is suspended, or changing the pH of a nanomaterial suspension). Each processing step is designated by a letter: for example, “As Processed A” and “As Processed B.”

Energy Time

Figure 1. Instances of Characterization of a nanomaterial undergoing dynamic and kinetic changes

Nanomaterial records in the Registry database may have one or many IOCs. Sometimes, these nanomaterials are characterized in various systems (thermodynamic analysis) or in one system at various times (kinetic analysis).

A nanomaterial can be characterized in isolated events, either by measuring different samples of the same batch or by processing a sample in a step-by-step method. A nanomaterial sample can also be characterized in a chronological fashion (measuring the same sample over time). The Registry indicates step-wise and chronological testing by displaying a predecessor IOC in the upper-right-hand corner of the data box.[MK1] If a predecessor is not listed, the record's IOCs are not step-wise or chronological but, rather, are isolated tests.

Because of the differential nature of information within each IOC, the Registry collects specific minimal information for each type of IOC. The collected meta-data is depicted in the IOC Description[m2]. By reporting this information (e.g., manufacturer, product name, Digital Object Identifier (DOI) of synthesis procedure, etc.), the Registry can be used to accurately track a nanomaterial sample's life. Table 1 lists several of the categories of minimal information requested for each IOC category.

Table 1. Minimal information curated for each Instance of Characterization category

Instance of Characterization Minimal Information Curated
As Synthesized Manufacturer or Laboratory Name
Product Name
Lot Number
General Synthesis Description
Digital Object Identifier (DOI) Citation of Synthetic Procedure
As Received Manufacturer
Laboratory Name
Product Name
Lot Number
As Processed Processing Details
(e.g., aerosolized, suspended, dried, milled, heated)

Figure 2 gives an example of how a nanomaterial’s degree of similarity can change when it is used by two different laboratories. At this time, the Registry uses simple, rule-based data matching to show the user how similar nanomaterials are to each other. As the depth and breadth of data in the Registry increase and as minimal information standards become more refined, nanomaterial matching will improve.

Figure 2. Examples of chronological Instances of Characterization and their respective descriptions for a purchased nanomaterial being processed in different ways indicate, in part, a decreasing degree of similarity of these nanomaterials over time

 


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