The Genetic Code Kit: An Open-Source Cell-Free Platform for Biochemical and Biotechnology Education

At-Home, Cell-Free Synthetic Biology Education Modules for Transcriptional Regulation and Environmental Water Quality Monitoring

As the field of synthetic biology expands, the need to grow and train science, technology, engineering, and math (STEM) practitioners is essential. However, the lack of access to hands-on demonstrations has led to inequalities of opportunity and practice. In addition, there is a gap in providing content that enables students to make their own bioengineered systems. To address these challenges, we develop four shelf-stable cell-free biosensing educational modules that work by simply adding water and DNA to freeze-dried crude extracts of non-pathogenic Escherichia coli. We introduce activities and supporting curricula to teach the structure and function of the lac operon, dose-responsive behavior, considerations for biosensor outputs, and a "build-your-own" activity for monitoring environmental contaminants in water. We piloted these modules with K-12 teachers and 130 high-school students in their classrooms─and at home─without professional laboratory equipment. This work promises to catalyze access to interactive synthetic biology education opportunities.

Development of Solid-State Storage for Cell-Free Expression Systems

The fragility of biological systems during storage, transport, and utilization necessitates reliable cold-chain infrastructure and limits the potential of biotechnological applications. In order to unlock the broad applications of existing and emerging biological technologies, we report the development of a novel solid-state storage platform for complex biologics. The resulting solid-state biologics (SSB) platform meets four key requirements: facile rehydration of solid materials, activation of biochemical activity, ability to support complex downstream applications and functionalities, and compatibility for deployment in a variety of reaction formats and environments. As a model system of biochemical complexity, we utilized crudeEscherichia colicell extracts that retain active cellular metabolism and support robust levels of in vitro transcription and translation. We demonstrate broad versatility and utility of SSB through proof-of-concepts for on-demand in vitro biomanufacturing of proteins at a milliliter scale, the activation of downstream CRISPR activity, as well as deployment on paper-based devices. SSBs unlock a breadth of applications in biomanufacturing, discovery, diagnostics, and education in resource-limited environments on Earth and in space.

Virtual reality for biochemistry education: the cellular factory

Virtual Reality (VR) involves the coupling of visual communication hardware and software. The technology is capable of offering transformative educational practice and is increasingly being adopted within the biochemistry domain to better understand complex biochemical processes. This article documents a pilot study for the efficacy of VR in biochemistry education at undergraduate university level, focusing on the citric acid cycle: a central process for extracting energy in most cellular life forms. 10 participants were equipped with a VR headset and electrodermal activity (EDA) sensors, then immersed within a digital environment where they were able to learn the 8 main steps of the citric acid cycle within a virtual lab by completing 8 levels of activity. Post and pre surveys were taken, along with EDA readings throughout the students' interaction with VR. Research findings support the hypothesis that VR increase students' understanding, particularly if students feel engaged, stimulated and intend to use the technology. Moreover, EDA analysis indicated that the majority of participants demonstrate enhanced engagement in the education-based VR-experience as measured by elevated levels of skin conductance, a marker for autonomic arousal and a measure of engagement in an activity.

Cell Extracts from Bacteria and Yeast Retain Metabolic Activity after Extended Storage and Repeated Thawing

Cell-free synthetic biology enables rapid prototyping of biological parts and synthesis of proteins or metabolites in the absence of cell growth constraints. Cell-free systems are frequently made from crude cell extracts, where composition and activity can vary significantly based on source strain, preparation and processing, reagents, and other considerations. This variability can cause extracts to be treated as black boxes for which empirical observations guide practical laboratory practices, including a hesitance to use dated or previously thawed extracts. To better understand the robustness of cell extracts over time, we assessed the activity of cell-free metabolism during storage. As a model, we studied conversion of glucose to 2,3-butanediol. We found that cell extracts from Escherichia coli and Saccharomyces cerevisiae subjected to an 18-month storage period and repeated freeze-thaw cycles retain consistent metabolic activity. This work gives users of cell-free systems a better understanding of the impacts of storage on extract behavior.

At-home, cell-free synthetic biology education modules for transcriptional regulation and environmental water quality monitoring

As the field of synthetic biology expands, the need to grow and train science, technology, engineering, and math (STEM) practitioners is essential. However, the lack of access to hands-on demonstrations has led to inequalities of opportunity and practice. In addition, there is a gap in providing content that enables students to make their own bioengineered systems. To address these challenges, we develop four shelf-stable cell-free biosensing educational modules that work by just-adding-water and DNA to freeze-dried crude extracts of Escherichia coli . We introduce activities and supporting curricula to teach the structure and function of the lac operon, dose-responsive behavior, considerations for biosensor outputs, and a 'build-your-own' activity for monitoring environmental contaminants in water. We piloted these modules with K-12 teachers and 130 high school students in their classrooms - and at home - without professional laboratory equipment or researcher oversight. This work promises to catalyze access to interactive synthetic biology education opportunities.

Characterizing and Improving pET Vectors for Cell-free Expression

Cell-free protein synthesis (CFPS) is an in vitro process that enables diverse applications in research, biomanufacturing, point-of-care diagnostics, therapeutics, and education using minimal laboratory equipment and reagents. One of the major limitations of CFPS implementation is its sensitivity to plasmid type. Specifically, plasmid templates based on commonly used vector backbones such as the pET series of bacterial expression vectors result in the inferior production of proteins. To overcome this limitation, we have evaluated the effect of expression cassette elements present in the pET30 vector on protein production across three different CFPS systems: NEBExpress, PURExpress, and CFAI-based E. coli extracts. Through the systematic elimination of genetic elements within the pET30 vector, we have identified elements that are responsible for the poor performance of pET30 vectors in the various CFPS systems. As a result, we demonstrate that through the removal of the lac operator (lacO) and N-terminal tags included in the vector backbone sequence, a pET vector can support high titers of protein expression when using extract-based CFPS systems. This work provides two key advances for the research community: 1) identification of vector sequence elements that affect robust production of proteins; 2) evaluation of expression across three unique CFPS systems including CFAI extracts, NEBexpress, and PURExpress. We anticipate that this work will improve access to CFPS by enabling researchers to choose the correct expression backbone within the context of their preferred expression system.

Simple Extract Preparation Methods for E. coli-Based Cell-Free Expression

Cell-free protein synthesis (CFPS) is a powerful platform for synthetic biology, allowing for the controlled expression of proteins without reliance on living cells. However, the process of producing the cell extract, a key component of cell-free reactions, can be a bottleneck for new users to adopt CFPS as it requires technical knowledge and significant researcher oversight. Here, we provide a detailed method for implementing a simplified cell extract preparation workflow using CFAI media. We also provide a detailed protocol for the alternative, 2x YPTG media-based preparation process, as it represents a useful benchmark within the cell-free community.

Constructing Cell-Free Expression Systems for Low-Cost Access

Cell-free systems for gene expression have gained attention as platforms for the facile study of genetic circuits and as highly effective tools for teaching. Despite recent progress, the technology remains inaccessible for many in low- and middle-income countries due to the expensive reagents required for its manufacturing, as well as specialized equipment required for distribution and storage. To address these challenges, we deconstructed processes required for cell-free mixture preparation and developed a set of alternative low-cost strategies for easy production and sharing of extracts. First, we explored the stability of cell-free reactions dried through a low-cost device based on silica beads, as an alternative to commercial automated freeze dryers. Second, we report the positive effect of lactose as an additive for increasing protein synthesis in maltodextrin-based cell-free reactions using either circular or linear DNA templates. The modifications were used to produce active amounts of two high-value reagents: the isothermal polymerase Bst and the restriction enzyme BsaI. Third, we demonstrated the endogenous regeneration of nucleoside triphosphates and synthesis of pyruvate in cell-free systems (CFSs) based on phosphoenol pyruvate (PEP) and maltodextrin (MDX). We exploited this novel finding to demonstrate the use of a cell-free mixture completely free of any exogenous nucleotide triphosphates (NTPs) to generate high yields of sfGFP expression. Together, these modifications can produce desiccated extracts that are 203-424-fold cheaper than commercial versions. These improvements will facilitate wider use of CFS for research and education purposes.

Characterizing and Improving Reaction Times for E. coli-Based Cell-Free Protein Synthesis

Cell-free protein synthesis (CFPS) is a platform biotechnology that has enabled the on-demand synthesis of proteins for a variety of applications. Numerous advances have improved the productivity of the CFPS platform to result in high-yielding reactions; however, many applications remain limited due to long reaction times. To overcome this limitation, we first established the benchmarks reaction times for CFPS across in-house E. coli extracts and commercial kits. We then set out to fine-tune our in-house extract systems to improve reaction times. Through the optimization of reaction composition and titration of low-cost additives, we have identified formulations that reduce reaction times by 30-50% to obtain high protein titers for biomanufacturing applications, and reduce times by more than 50% to reach the sfGFP detection limit for applications in education and diagnostics. Under optimum conditions, we report the visible observation of sfGFP signal in less than 10 min. Altogether, these advances enhance the utility of CFPS as a rapid, user-defined platform.

Analysis of the Innovation Trend in Cell-Free Synthetic Biology

Cell-free synthetic biology is a maturing field that aims to assemble biomolecular reactions outside cells for compelling applications in drug discovery, metabolic engineering, biomanufacturing, diagnostics, and education. Cell-free systems have several key features. They circumvent mechanisms that have evolved to facilitate species survival, bypass limitations on molecular transport across the cell wall, enable high-yielding and rapid synthesis of proteins without creating recombinant cells, and provide high tolerance towards toxic substrates or products. Here, we analyze ~750 published patents and ~2000 peer-reviewed manuscripts in the field of cell-free systems. Three hallmarks emerged. First, we found that both patent filings and manuscript publications per year are significantly increasing (five-fold and 1.5-fold over the last decade, respectively). Second, we observed that the innovation landscape has changed. Patent applications were dominated by Japan in the early 2000s before shifting to China and the USA in recent years. Finally, we discovered an increasing prevalence of biotechnology companies using cell-free systems. Our analysis has broad implications on the future development of cell-free synthetic biology for commercial and industrial applications.

The Fold-Illuminator: A low-cost, portable, and disposable incubator-illuminator device

Fluorescent reporters have revolutionized modern applications in the fields of molecular and synthetic biology, enabling applications ranging from education to point-of-care diagnostics. Past advancements in these fields have primarily focused on improving reaction conditions, the development of new applications, and the broad dissemination of these technologies. However, field and classroom-based applications have remained limited in part due to the nature of fluorescent signal detection, which often requires the use of costly lab equipment to observe and quantify fluorescence readouts. Users without access to laboratory equipment rely on qualitative assessments of fluorescence, a process that remains highly variable from user-to-user even within the same classroom. To overcome this challenge, we have developed a foldable illuminator and incubator device to support field-applications of synthetic biology-based biosensors for education and diagnostics. The Fold-Illuminator is an affordable, portable, and recyclable device that allows for the visible detection of fluorescent biomolecules. The Fold-Illuminator's design allows for assembly in under 10 min, a user can then utilize the optional heating element to incubate biochemical reactions and visualize fluorescence outputs in a defined and light-controlled environment. Interchangeable LED strips and light-filtering screens provide modularity to pair with the fluorescence wavelengths of interest. The user can then unfold the device for convenient storage, transport, or even recycling. The cost for the Fold-Illuminator is $5.58 USD and is compatible with an optional heating element for an additional $3.98 cost, with potential for further reductions in cost for larger quantities. Open-source templates for cutting device parts from paper stock are provided for both printing and cutting by hand; cutting can also be achieved with consumer-grade smart cutting machines such as the Cricut®. Combined with the broad applications of fluorescent reporters, the Fold-Illuminator has the potential to improve access to fluorescence visualization and quantification for new users as well as emerging field applications.

Activation of Energy Metabolism through Growth Media Reformulation Enables a 24-Hour Workflow for Cell-Free Expression

Cell-free protein synthesis (CFPS) platforms have undergone numerous workflow improvements to enable diverse applications in research, biomanufacturing, and education. The Escherichia coli cell extract-based platform has been broadly adopted due to its affordability and versatility. The upstream processing of cells to generate crude cell lysate remains time-intensive and technically nuanced, representing one of the largest sources of cost associated with the biotechnology. To overcome these limitations, we have improved the processes by developing a long-lasting autoinduction media formulation for CFPS that obviates human intervention between inoculation and harvest. The cell-free autoinduction (CFAI) media supports the production of robust cell extracts from high cell density cultures nearing the stationary phase of growth. As a result, the total mass of cells and the resulting extract volume obtained increases by 400% while maintaining robust reaction yields of reporter protein, sfGFP (>1 mg/mL). Notably, the CFAI workflow allows users to go from cells on a streak plate to completing CFPS reactions within 24 h. The CFAI workflow uniquely enabled us to elucidate the metabolic limits in CFPS associated with cells grown to stationary phase in the traditional 2× YTPG media. Metabolomics analysis demonstrates that CFAI-based extracts overcome these limits due to improved energy metabolism and redox balance. The advances reported here shed new light on the metabolism associated with highly active CFPS reactions and inform future efforts to tune the metabolism in CFPS systems. Additionally, we anticipate that the improvements in the time and cost-efficiency of CFPS will increase the simplicity and reproducibility, reducing the barriers for new researchers interested in implementing CFPS.