OTTO is an open-source automated liquid handler that can be fabricated at a cost of $1,500 using off-the-shelf and 3D-printable parts as an alternative to commercial devices. Open-source approaches have been applied to build syringe pumps, centrifuges, and other laboratory equipment. These devices are affordable but generally rely on a single motor to perform simple operations and thus do not fully utilize the potential of the Maker Movement. Open-source linear actuators and microcontrollers enable the fabrication of more complex laboratory instruments that rely on 3D positioning and accurate dispensing of fluids, such as automated liquid handlers. These instruments can be built rapidly and affordably, thereby providing access to highly reproducible sample preparation for common biological assays such as qPCR. We applied the design principles of speed and accuracy, unattended automation, and open-source components to build an automated liquid handler that controls micropipetting of liquids in 3D space at speeds and positional resolutions required for qPCR. In benchmarking studies, OTTO showed accuracy and sample preparation times comparable to manual qPCR. The ability to control linear motion and liquid dispensing using affordable off-the-shelf and 3D-printable parts can facilitate the adoption of open-source automated liquid handlers for qPCR, bioplotting, and other bioinstrumentation applications. At the onset of a viral outbreak, quantitative polymerase chain reaction (qPCR) tests are commonly employed to screen patients for disease 1. Compared to serology tests, which search for antibodies that are reactive to the virus, qPCR-based tests are more sensitive and can be implemented faster but have longer turnaround times 2-5. During the COVID-19 outbreak, health care officials promptly recruited technicians to run qPCR on samples from patients who experienced an exposure event to detect the presence of viral RNA 6. However, preparing samples for qPCR is prone to human error and time consuming 7-9 , resulting in decreased reproducibility and increased costs 10-12. These limitations have been mitigated in part by robotic liquid handlers that are more precise and faster than their human counterparts. However, commercial liquid handlers are expensive systems with recurring maintenance contracts that the majority of laboratories cannot afford 13. The rarity of these instruments may have contributed in part to hospitals being overwhelmed by the large number of patient samples during the COVID-19 pandemic. The Maker Movement is an educational initiative that focuses on the innovative application of open-source technologies to solve problems at multiple scales. This movement was enabled by the advent of additive manufacturing (i.e., 3D printing), a process for converting a digital model into a physical part that provides affordable access to digital fabrication. The Maker Community has a history of generating solutions for public health problems, such as the design of low-cost and readily manufacturable ventilators and ...

When breast cancer metastasizes to bone, treatment options are limited. Failure to treat bone metastases is thought to be due to therapy-resistant features of the bone marrow microenvironment. Using a murine model of bone metastatic mammary carcinoma, we demonstrate that systemic delivery of polymer nanoparticles loaded with cyclic dinucleotide (CDN) agonists of stimulator of interferon genes (STING) inhibited tumor growth and bone destruction after 7 days of treatment. Each dose of STING-activating nanoparticles (STING-NPs) trafficked to the bone marrow compartment and was retained within the tumor microenvironment for over 24 h, enhancing antitumor immunity through proinflammatory cytokine production and early T cell activation. While acquired resistance mechanisms, including increased levels of immunosuppressive cytokines and the infiltration of regulatory T cells, ultimately limited antitumor efficacy after two weeks of treatment, bone protective effects remained. Overall, these studies demonstrate that STING pathway activation, here enabled using a nanomedicine approach to enhance CDN delivery to bone metastatic sites, can reprogram the immune contexture of the bone marrow to an antitumor phenotype that inhibits bone colonization of metastatic breast cancer cells and protects from tumor-mediated bone destruction.

<p>Supplementary Figure 4: Effects of STING-NP on mouse weights.</p>

<p>Supplementary Figure 2: Gating scheme for T cell activation flow panel.</p>