By Gabriel Paijo 
Researchers at the Massachusetts Institute of Technology (MIT) and the Scripps Research Institute have announced a significant breakthrough in the manufacturing of therapeutic nanoparticles, potentially clearing a major hurdle in the transition from laboratory research to human clinical trials. By leveraging advanced microfluidic technology, the team has developed a streamlined, scalable method for producing layer-by-layer (LbL) nanoparticles, which are designed to deliver potent anti-cancer drugs directly to tumor sites while minimizing the systemic toxicity often associated with traditional chemotherapy.
The study, published today in the journal Advanced Functional Materials, addresses a decade-long challenge in nanomedicine: the "scalability gap." While polymer-coated nanoparticles have shown remarkable efficacy in animal models, particularly in treating aggressive forms of ovarian cancer, the labor-intensive nature of their production has historically limited their use to small-scale laboratory experiments. The new microfluidic mixing device allows for the sequential addition of polymer layers as particles flow through a microchannel, eliminating the need for time-consuming purification steps and enabling the production of clinical-grade materials in a fraction of the time.
The Evolution of Layer-by-Layer Nanotechnology
The concept of layer-by-layer assembly for drug delivery was pioneered over ten years ago in the laboratory of Paula Hammond, an MIT Institute Professor, Vice Provost for Faculty, and a prominent member of the Koch Institute for Integrative Cancer Research. The technique involves constructing a nanoparticle by alternately exposing a core material to positively and negatively charged polymers. Through electrostatic attraction, these polymers form thin, highly controlled films around the core.
This architecture is uniquely advantageous for oncology. Each layer can be precisely engineered to serve a specific function: one layer may contain a therapeutic payload, such as a chemotherapy drug or a cytokine, while the outermost layer can be decorated with targeting ligands that recognize specific proteins on the surface of cancer cells. This "smart" delivery system ensures that the drug remains sequestered until the nanoparticle reaches its destination, thereby protecting healthy tissues from exposure.
Despite the elegance of the design, the original manufacturing process was arduous. For every layer applied, the particles had to be centrifuged—a process of high-speed spinning to separate the nanoparticles from excess, unreacted polymer. This step-wise approach required manual intervention and significant time, making it nearly impossible to produce the large quantities required for human trials, which often demand thousands of doses manufactured under strict regulatory standards.
Overcoming the Production Bottleneck
The research team, led by senior authors Paula Hammond and Darrell Irvine, a professor of immunology and microbiology at the Scripps Research Institute, sought to modernize this workflow. Previous attempts to streamline the process included tangential flow filtration (TFF), a technique that improved upon centrifugation but still remained a batch-oriented process with inherent limitations in scale and complexity.
The breakthrough came with the integration of microfluidics. In the new system, nanoparticles flow through a series of microchannels within a specialized chip. As they move through the device, polymer solutions are introduced at precise intervals. By calculating the exact stoichiometric amount of polymer needed to coat the particles, the researchers eliminated the excess material that previously required removal.
"Separations are the most costly and time-consuming steps in these kinds of systems," Professor Hammond explained. "By using a microfluidic mixing device, we can sequentially add new polymer layers as the particles flow. This eliminates the need to purify the particles after each addition."
The efficiency gains are substantial. Using the traditional centrifugation method, creating 15 milligrams of nanoparticles—roughly equivalent to 50 doses for a mouse study—would take approximately one hour of intensive manual labor. With the microfluidic system, that same quantity is produced in just a few minutes. Furthermore, the process is continuous; to produce more material, operators simply keep the device running, making it inherently scalable for industrial applications.
Clinical Implications and GMP Compliance
A critical aspect of the new manufacturing technique is its alignment with Good Manufacturing Practice (GMP) standards. GMP is a system enforced by regulatory bodies like the U.S. Food and Drug Administration (FDA) to ensure that pharmaceutical products are consistently produced and controlled according to quality standards.
Traditional batch processing is prone to operator error and batch-to-batch variability, which are significant red flags during the FDA approval process. The microfluidic device utilized by the MIT team is already an established tool in the pharmaceutical industry, having been used for the GMP manufacturing of lipid nanoparticles, such as those found in mRNA-based COVID-19 vaccines.
"With the new approach, there’s much less chance of any sort of operator mistake or mishaps," said Ivan Pires, PhD ’24, a lead author of the study and currently a postdoc at Brigham and Women’s Hospital. "This is a process that can be readily implemented in GMP, and that’s really the key step here. We can create an innovation within the layer-by-layer nanoparticles and quickly produce it in a manner that we could go into clinical trials with."
Case Study: Treating Ovarian Cancer with IL-12
To validate the efficacy of nanoparticles produced via the new method, the researchers focused on ovarian cancer, a disease often diagnosed at an advanced stage with a high rate of recurrence. They loaded the nanoparticles with interleukin-12 (IL-12), a potent cytokine known to stimulate the immune system’s "natural killer" cells and T-cells to attack tumors.
Systemic administration of IL-12 is notoriously toxic to humans, often causing severe inflammatory responses. However, when delivered via LbL nanoparticles, the cytokine is localized within the tumor environment. In the study, the microfluidically manufactured nanoparticles demonstrated a unique behavior: they bound to the surface of cancer cells in the abdominal cavity but did not enter them. Instead, they remained on the exterior, acting as a beacon to activate the local immune response.
The results in mouse models were promising. The treatment led to significant delays in tumor growth and, in several instances, complete remissions. Crucially, the nanoparticles produced via the high-speed microfluidic method performed identically to those produced via the slower, traditional methods, proving that the gain in speed did not come at the cost of therapeutic quality.
Chronology of Development
The journey toward this manufacturing milestone has spanned over a decade of interdisciplinary research:
- 2012–2015: Hammond’s lab perfects the electrostatic assembly of LbL nanoparticles, demonstrating their ability to carry multiple drugs and target specific receptors in early animal models.
- 2016–2019: Research shifts toward immunotherapy, identifying IL-12 as a primary candidate for LbL delivery. Early mouse studies show potential for treating late-stage ovarian cancer.
- 2020–2022: The team experiments with Tangential Flow Filtration (TFF) to replace centrifugation. While TFF improves speed, the process remains difficult to scale for large-scale clinical supply.
- 2023–2024: The team successfully adapts microfluidic mixing chips for LbL assembly. They prove that "on-the-fly" coating without intermediate purification is chemically viable and biologically effective.
- Current Status: The researchers have filed for a patent on the microfluidic assembly process and are collaborating with MIT’s Deshpande Center for Technological Innovation to explore commercialization and the formation of a startup.
Broader Impact and Future Horizons
While the initial focus of the study is on abdominal cancers like ovarian cancer, the implications of scalable LbL production extend across the field of oncology. The researchers noted that the same technology could be adapted for glioblastoma, an aggressive form of brain cancer that is notoriously difficult to treat due to the blood-brain barrier and the need for localized, sustained drug release.
The ability to manufacture complex, multi-layered nanoparticles at scale could also lower the entry barrier for personalized medicine. If the manufacturing process is digitized and automated through microfluidics, it becomes theoretically possible to "print" custom batches of nanoparticles tailored to the specific genetic profile of a patient’s tumor.
The financial and logistical burden of drug development is another area where this innovation may provide relief. By reducing the "separations" phase—which Professor Hammond identified as the most expensive part of the process—biotech companies can reduce the capital expenditure required to bring a new nanomedicine to market.
As the team moves toward commercialization, the next steps involve long-term stability testing and expanded safety profiles in non-human primates. With the manufacturing bottleneck effectively bypassed, the transition from the laboratory bench to the patient’s bedside has never looked more attainable for layer-by-layer nanotechnology.
The research was supported by a diverse coalition of institutions, including the U.S. National Institutes of Health (NIH), the Marble Center for Nanomedicine, and the Koch Institute Support (core) Grant from the National Cancer Institute. The involvement of the Deshpande Center underscores the project’s high potential for real-world economic and clinical impact.