A circular framework connecting cell-free systems, synthetic cells, material integration, and space applications into a continuous design cycle.
Cell-free protein synthesis (CFPS) offers significant advantages over in vivo systems in terms of flexibility and control.
Most importantly for my research, CFPS allows the exploration of non-standard outputs, such as pigment production pathways, without the metabolic burden of living cells.
Together, these recreate a minimal biological system capable of producing visible material outputs (pigments).
Pigment production pathways are energy-intensive. Without ATP regeneration, the system quickly stops.
Example:
This is critical when expressing multi-enzyme pigment pathways.
Prokaryotic CFPS (E. coli)
Eukaryotic CFPS
Membrane proteins are difficult because they require a lipid environment.
Challenges:
Solutions:
This becomes relevant if designing transport systems for pigment secretion.
Weak DNA expression
→ optimize promoter / codons
Energy depletion
→ improve ATP regeneration
Metabolic burden (very relevant for pigments)
→ reduce expression strength or stage expression
I propose a synthetic minimal cell that produces a visible pigment in response to an environmental signal.
This extends beyond fluorescence: instead of emitting light, the system generates material color.
Input:
Output:
System behavior:
Signal → gene activation → multi-enzyme pathway → pigment accumulation → visible color
Yes, the pigment pathway could be expressed in a bulk cell-free system.
However, encapsulation is critical because:
Yes, bacteria can produce pigments naturally.
However, synthetic cells offer:
They act as designable units, not organisms.
The system remains inactive until exposed to the input signal, after which it gradually produces a visible pigment.
This creates a time-based and spatially distributed color response, which is highly relevant for responsive environments.
Membrane:
Inside:
Genes:
Optional:
A bacterial (E. coli) system is sufficient because:
Small molecules (input signals) enter through:
Pigment remains inside → visible localized color
This system shifts biological output from signal to substance.
Fluorescence communicates.
Pigment materializes.
This is critical for my research, where color is not an indicator, but a material property embedded within the system itself.
From biochemical signal to material color.
I propose an interior space surface embedded with freeze-dried cell-free reactions that activate with moisture and produce visible color changes to indicate environmental stress, contamination, or human metabolic presence.
The concept is a bio-responsive wall or panel system containing freeze-dried cell-free reactions distributed throughout a porous or layered material. When activated by tempature, humidity, or a defined triggering solution, the embedded reactions begin expressing a visible reporter such as a fluorescent protein or, in a more advanced version, a pigment-producing pathway. In this way, the material itself becomes an active sensing surface rather than a passive substrate.
The system could be designed to respond to specific molecules associated with environmental change, such as pH shifts, pollutants, or metabolites related to human activity. Rather than relying on conventional electronic sensors, the surface would function as a biological sensing layer, translating chemical information into a visible spatial output.
From a design perspective, this allows architecture to move beyond static materiality toward surfaces that can sense, signal, and communicate. The wall becomes an interface that reveals invisible environmental conditions through color or pattern.
This concept addresses the growing need for responsive and low-energy environmental monitoring in built environments. Buildings increasingly require systems that can indicate air quality, moisture intrusion, contamination, or human occupancy in real time.
A cell-free sensing surface could provide a lightweight and low-cost alternative for situations where conventional sensing technologies are too expensive, too energy-intensive, or too visually intrusive. It also opens opportunities for future adaptive spaces in health, education, and public environments.
Cell-free systems have important limitations, including the need for activation with water, limited stability after activation, and one-time use in many cases. I would address these challenges by designing the material as a replaceable or modular sensing layer rather than a permanent system.
The freeze-dried reactions could be embedded in cartridges, patches, or sealed microcapsules within the surface so that activation occurs only when needed. Moisture-triggered activation could be strategically used as part of the sensing logic rather than treated only as a limitation. For longer-term applications, the material could be designed as a periodically renewed layer, similar to how filters, coatings, or maintenance components are already replaced in architecture.
In this way, the system would not imitate the durability of conventional building materials, but instead introduce a new category of temporary, responsive biological interfaces.
Long-duration spaceflight creates highly constrained living environments where real-time monitoring of biological conditions is essential. Moisture accumulation, microbial growth, and shifts in environmental chemistry can pose serious risks to astronaut health and habitat stability. A compact, low-energy, and easy-to-use biosensing system would therefore be highly valuable. Freeze-dried cell-free reactions are especially promising for space because they are lightweight, portable, and do not require maintaining living cells. This proposal explores how the BioBits® cell-free protein expression system could be used to create a visible reporter system for detecting environmental changes relevant to closed habitat conditions.
A moisture- or metabolite-responsive reporter system using cell-free expression of sfGFP as a visible indicator of environmental chemical change.
In spacecraft and other closed habitats, small environmental changes can quickly become important because air, water, and surface systems are tightly coupled. A reporter system that visibly indicates the presence of a target chemical signal would provide a simple way to detect potentially harmful environmental shifts without relying on large instruments. The molecular target in this proposal is not a pathogen itself, but a measurable environmental signal that can be translated into a fluorescent output using BioBits®. This makes the system suitable as a lightweight first-step diagnostic tool for monitoring habitat conditions in space.
My hypothesis is that a freeze-dried cell-free reaction can be activated under controlled conditions to produce a visible fluorescent output in response to a defined environmental signal, demonstrating the feasibility of lightweight biological sensing in space.
The research goal is not to build a fully operational space diagnostic platform, but to test whether a compact cell-free system such as BioBits can serve as a simple and interpretable environmental sensor under constrained conditions. This is important because space missions require technologies that are low-mass, low-energy, easy to transport, and safe to operate. Cell-free systems are promising because they avoid the complexity of maintaining living cells while still enabling biological sensing and reporting. If successful, this kind of platform could support future monitoring of habitat health, crew environments, and resource systems in space exploration.
I would prepare BioBits reactions containing a fluorescent reporter construct and compare activated versus non-activated samples. The experiment would include:
Samples would be incubated using the miniPCR thermal cycler if needed, and fluorescence would be measured using the P51 Molecular Fluorescence Viewer. The main data collected would be visible fluorescence intensity across conditions. This would allow comparison of whether the reporter system responds specifically and reliably to the chosen input under compact, space-relevant experimental conditions.