Week 1 HW: Final Project Ideas
Automation-Assisted Biomanufacturing of Hyaluronic Acid for Hydrogel Scaffolds in Neural Tissue Engineering Research
(1) What I would like to biomanufacture and why
I propose a conceptual workflow to produce hyaluronic acid (HA) using engineered bacteria and subsequently convert the purified HA into hydrogel scaffolds for neural tissue engineering research. The biologically manufactured product would be HA; the final research material would be an HA-based hydrogel prepared through additional material-processing steps.
A hydrogel is a water-rich polymer network. A scaffold is a material that provides a three-dimensional environment for cells. In this project, the hydrogel would serve as an experimental scaffold for researchers investigating neural cell behavior and potential approaches to tissue repair. Its suitability would need to be demonstrated experimentally.
HA is a component of the extracellular matrix of the central nervous system. HA-based hydrogels have been investigated as three-dimensional culture environments for neural stem/progenitor cells. Published work supports their potential while also showing that cell outcomes depend on the formulation [1]. My initial goal would be to investigate cell survival and growth in a candidate scaffold. The specific neural cell type and biological success criteria remain to be selected.
For the manufacturing estimate, I assume a final hydrogel volume of 100 µL per scaffold and an HA concentration of 1% mass/volume. These values define a preliminary design scenario; they are not an experimentally optimized formulation.
My motivation comes from my interest in neuroscience, neuroengineering, and neural tissue regeneration. This interest also has a personal foundation: my grandfather, who raised me, later developed a neurodegenerative disease. Experiencing its impact strengthened my desire to understand the nervous system and explore approaches that might eventually contribute to its repair.
As a biomedical engineering student beginning to learn biotechnology, I would use this project to connect biological production with automation, process control, and biomaterial design. The proposed output is a research scaffold, with no claim of established therapeutic efficacy.
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(2) What living system would I use?
The proposed manufacturing chassis is an engineered strain of Bacillus subtilis. Here, chassis means the organism used as a production platform. HA production has been demonstrated in genetically modified B. subtilis [2,3].
At a high level, the system would receive a carbon source, nutrients, water, and the oxygen supply appropriate to the cultivation process. The cells would use their metabolism to generate energy and the activated sugar precursors needed for HA synthesis. Hyaluronan synthase (HAS) would assemble those precursors into HA chains.
HA is a polysaccharide, rather than a protein. Its synthesis requires enzymes that make its precursors and assemble the polymer. The two activated sugar substrates are UDP-glucuronic acid and UDP-N-acetylglucosamine. Published engineering strategies include expressing HAS and increasing precursor availability [2].
The proposed workflow is:
- Supply nutrients to an engineered HA-producing B. subtilis culture.
- Allow cellular metabolism and HAS activity to produce HA.
- Recover HA from the culture broth and purify it.
- Select an appropriate functionalization and crosslinking approach.
- Form hydrogel scaffolds and evaluate their material and biological properties.
The strain, genetic stability, and production conditions would need to be specified during subsequent development.
Li et al. reported an engineered strain, WmB, with an HA titer of approximately 3.65 g/L at 32 °C in experiments using 5-L fermenters, with a 54-hour cultivation period [3]. Titer means product concentration in the broth. I use this result as a reference scenario, not as a guaranteed outcome for my proposed strain or equipment.
The bacteria would produce HA; conversion into a hydrogel would occur after recovery. Crosslinking chemistry and any additional scaffold components remain design choices.
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(3) How would I use automation?
I would use a desktop liquid-handling robot such as an Opentrons to assist with repetitive small-scale experimental preparation.
Candidate tasks include dispensing medium components, preparing nutrient variations, creating replicate samples, and preparing dilutions for analysis.
Cultivation would require suitable incubation and mixing equipment. Analytical measurements would require compatible instruments and assays. Testing several temperatures would require suitable independent temperature-control capacity. Available Opentrons modules add specific capabilities, which depend on the selected platform [4].
The purpose of automation would be to improve consistency and make replicated comparisons more practical. Measurements of HA concentration and quality would inform the next experimental design. Faster or more productive cultivation would have to be demonstrated rather than assumed.
For the proposed quantity, I would use an automated benchtop bioreactor with monitoring and control of temperature, pH, dissolved oxygen, agitation, and feeding as appropriate. This represents a laboratory production scenario, not a validated industrial process.
The liquid handler would support screening and sample preparation; the bioreactor would maintain the production culture. Larger-scale manufacturing would require additional development of mixing, oxygen transfer, recovery, and quality-control operations.
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(4) How much would I need to make, and how long would it take?
(a) How much?
I define a meaningful research-production target as enough HA for 10,000 experimental hydrogel scaffolds. This could supply repeated experiments across scaffold formulations and cell-culture conditions. It is a chosen planning target, rather than a measured demand forecast.
1 g HA / 100 mL final formulation = 10 mg/mL.
The HA mass per scaffold is:
100 µL = 0.1 mL
10 mg/mL × 0.1 mL = 1 mg HA/scaffold.
For 10,000 scaffolds:
10,000 scaffolds × 1 mg/scaffold = 10,000 mg = 10 g HA.
The total final hydrogel volume would be:
10,000 × 0.1 mL = 1,000 mL = 1 L.
Thus, 10 g refers to the HA incorporated into the scaffolds, not the total mass of the hydrated material.
To account for losses, I assume an effective recovery of 80% from broth HA to HA incorporated into usable scaffolds:
Required broth HA = 10 g / 0.80 = 12.5 g.
This effective recovery combines recovery, purification, and subsequent handling losses on an HA-equivalent basis. It excludes the mass of added crosslinkers or other components. The real recovery would need to be measured. If 80% were achieved only during purification, additional formulation losses would increase the required production.
(b) How long?
I use 54 hours, or 2.25 days, as the reference cultivation time [3]. This does not include culture preparation, purification, hydrogel fabrication, or release checks.
For a preliminary one-batch schedule, I assume the following operations occur sequentially:
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Operation Planning duration Basis
Preparation, seed culture, and reactor setup 12–24 h Unvalidated scheduling assumption
Production cultivation 54 h Reference experiment [3]
Recovery and purification 24–48 h Unvalidated scheduling assumption
Functionalization and hydrogel fabrication 12–24 h Unvalidated scheduling assumption
Initial material quality checks 12–24 h Unvalidated scheduling assumption
Total 114–174 h Sum of the assumed steps
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I would therefore budget approximately 5–8 days for this illustrative material-production workflow. Its feasibility depends on the selected purification, gel chemistry, and assays. These durations are placeholders for an engineering estimate, not measured process times.
This schedule excludes strain development, optimization, full biological validation, and extended cell-culture experiments. Preparing 10,000 individual scaffolds could itself become a bottleneck; the dispensing and gelation throughput remains to be determined.
If only 3 L of working volume were available and two batches were run sequentially, cultivation alone would take approximately 2 × 54 h = 108 h, plus turnaround and other processing.
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(5) What don’t I know yet?
What HA specifications and hydrogel formulation are needed?
I need to select a neural cell model and define the scaffold’s intended biological outcome. I would then investigate HA molecular-weight distribution, concentration, crosslinking, stiffness, degradation, and any required adhesion cues. These are candidate variables to evaluate, not established specifications for my material. Published neural culture work provides a starting point [1].
Can the production and recovery assumptions be reproduced?
The reference titer may not transfer to my strain, medium, or reactor. I would need to measure actual titer, effective recovery, molecular-weight distribution, purity, and variation between batches. Cultivation conditions can alter both HA quantity and molecular weight [3], so maximizing mass alone would not establish product suitability.
Can the workflow retain quality and adequate throughput at the target quantity?
I would need to evaluate whether mixing and oxygen supply remain adequate, whether purification preserves the required HA properties, and how reliably the formulation can be dispensed into 10,000 consistent scaffolds. Measurements of batch consistency, scaffold fabrication time, and material performance would determine whether the proposed schedule and scale are realistic.
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References
- Seidlits, S. K., et al. (2019). Peptide-modified, hyaluronic acid-based hydrogels as a 3D culture platform for neural stem/progenitor cell engineering. Journal of Biomedical Materials Research Part A, 107(4), 704–718. https://doi.org/10.1002/jbm.a.36603
- Widner, B., et al. (2005). Hyaluronic acid production in Bacillus subtilis. Applied and Environmental Microbiology, 71(7), 3747–3752. https://doi.org/10.1128/AEM.71.7.3747-3752.2005
- Li, Y., Li, G., Zhao, X., Shao, Y., Wu, M., & Ma, T. (2019). Regulation of hyaluronic acid molecular weight and titer by temperature in engineered Bacillus subtilis. 3 Biotech, 9, 225. https://doi.org/10.1007/s13205-019-1749-x
- Opentrons. (n.d.). Opentrons Modules. Official documentation. https://docs.opentrons.com/modules/
AI use disclosure
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AI client: ChatGPT, OpenAI.
Purpose of use: Brainstorming and refinement of the biomanufacturing concept, identification of relevant scientific literature, organization of the engineering calculations, and refine of the written response.
Prompts:
- I’m participating in the MIT Media Lab’s HTBAA course, and I’m completely new to the fields of biomanufacturing, biotechnology, and gene editing. I’ll need your help to develop my ideas and understand some concepts that aren’t clear to me.
- Research literature on automation and biomanufacturing related to neuronal regeneration.
- I would like to develop a final project combining these two areas; what titles do you suggest based on the sources I have attached?
- I am interested in the use of hyaluronic acid; let’s explore that idea.
- Based on this outline and the drafted text, help me refine my proposal.
- I feel like the scope is too broad; help me focus more on the biomanufacturing of HA initially.
AI Client: Consensus
Purpose of use: Literature research
Prompt:
- Help me find literature for my project proposal titled:
Automated Biomanufacturing of Hyaluronic Acid-Based Hydrogels for Neural Tissue Engineering