Background: Adaptations and improvements have been made upon the paper-based Nanoceria Reducing Antioxidant Capacity (NanoCerac) assay, in order to create a high-throughput (HTP) analysis method to be used on large sample sets. Experimental: Modification made to the NanoCerac assay include: utilization of smaller sample volumes, simultaneous preparation of samples, simultaneous deposition of samples, and utilization of a novel customized MatLab program for rapid, automated analysis of digital NanoCerac sensor images. Our HTP version of the NanoCerac was validated through analysis of the effect of re-infusion on the antioxidant capacity of twenty-four commercial green teas; a study, which involved 432 samples. The popular oxygen radical absorbance capacity (ORAC) assay was used alongside the NanoCerac in this study, as a comparator measure of antioxidant capacity. Results: The NanoCerac and ORAC assays correlated moderately (R2 0.80 ± 0.19). NanoCerac assay modifications resulted in increased speed of analysis as well as reduced material requirements. This HTP method, capable of analyzing roughly forty-eight samples per hour, acts as a drastic improvement to the original method, which required two hours for each sample analyzed. A novel measure of sustained antioxidant capacity, the total inherent antioxidant capacity (TI-NanoCerac of TI-ORAC) was named following measurement of six repetitive infusions of varietal green teas. The average first-brew NanoCerac, TI-NanoCerac, first-brew ORAC and TI-ORAC were: 0.73 ± 0.1 GAE/g tea; 2.4 ± 0.70 mmol GAE/g tea; 1.0 ± 0.3 mmol TE/g tea and 2.1 ± 0.71 mmol TE/g tea respectively. Conclusions: This HTP adaptation of the original NanoCerac assay offers advantages over the ORAC assay, including portability and rapid analysis. While NanoCerac sensors are capable of identifying specific antioxidant compounds, using the published database of reference colors (Sharpe, et. al. 2014), this high-throughput version of the NanoCerac assay is best suited for analysis of large sample sets for antioxidant activity. The demonstrated measurement of total-inherent antioxidant capacity (TI-AOX) of a sample that is infused repetitively, offers a new approach to analyzing botanicals that may commonly be reused as part of their medicinal applications.

Modification of the paper-based NanoCerac antioxidant assay for high-throughput use: An analysis of twenty-four green teas for antioxidant activity throughout six consecutive infusions

253rd National Meeting (2017)

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