(696h) Development of a High-Throughput Workflow for the Synthesis of CdSe Nanocrystals Using a Sonochemical Materials Acceleration Platform

Semi-automated and fully automated platforms, in combination with data-science principles and artificial intelligence, have become an emerging paradigm for accelerated materials discovery[1]. The combination of high-throughput experimentation and minimal human interactions with the system have allowed faster material synthesis, characterization, and analysis. However, many initiatives of materials acceleration platforms (MAPs) are still too costly to be implemented. In this context, open hardware principles (i. e. distribution of design files, schematics, drawings and source codes for hardware projects) have made the use of laboratory automation more accessible and more easily implemented for a variety of applications. Here we present the use of a repurposed open-hardware and software 3D printing platform, Jubilee (https://github.com/machineagency/jubilee), as a plate handling lab automation device for sonochemical applications. The system, called sonication station, is an open-source flexible automation platform with a sonication horn attachment which allows for an array of automated experiments through the easy modification of several sonication parameters. Building upon the sonochemical synthesis of quantum dots and magic-sized clusters (MSCs) [2], a fully automated protocol was developed to demonstrate the synthesis of CdSe nanocrystals using sonochemistry and different combinations of sample conditions, including precursor ratio and ligand composition. The sonication station was used in combination with a liquid handling robot OT2 (Opentrons) for the sample preparation, to further automate the workflow for nanocrystal synthesis. The system allows to investigate and process upwards of 96 different samples, with a total sample volume of as little as 0.5 mL. The size of our quantum dots was obtained by applying an effective mass approximation equation, based on the first peak position in the absorption spectra. The calculated QDs diameter obtained in all our experimental conditions ranged between 1.35 and 2.12 nm. Polydispersity, QD shape and optical properties largely varied depending on the concentration of ligands present in solution. Furthermore, we propose a data analysis approach to corroborate the qualitative relationships observed from the optical characterization of the samples with quantitative approaches using Bayesian graphical and Causal models. The proposed workflow uses low-budget systems (< $10k for both robotic platforms) and the reduced volume allows for a more cost-efficient experimentation, increasing the accessibility of this MAP. Thanks to the high-throughput capabilities of the automated sonication platform, the ease in scalability of the system, and the modularity of the protocol, the overall workflow is adaptable to a variety of studies, including other nanocrystal design spaces, emulsions and re-dispersions.

[1] “Materials Acceleration Platforms: On the way to autonomous experimentation”. Flores-Leonar, M. M., Mejía-Mendoza, L. M., Aguilar-Granda, A., Sanchez-Lengeling, B., Tribukait, H., Amador-Bedolla, C., & Aspuru-Guzik, A. , Current Opinion in Green and Sustainable Chemistry, 25, 100370 (2020)

[2] “On-Demand Sonochemical Synthesis of Ultrasmall and Magic-Size CdSe Quantum Dots in Single-Phase and Emulsion Systems”, R Kastilani, B. Bishop, V. Holmberg, LD Pozzo, Langmuir, 35 (50), 16583 (2019)