Elevated levels of cytokines, toxins, or other proteins in the bloodstream can contribute to disease pathology and adverse immune responses. To address this, I propose a modular ferritin-based protein trap that leverages nanobody targeting to selectively bind and remove these damaging molecules. Ferritin self-assembles into nanoscale spherical particles, which I functionalize by fusing SpyTag or SpyCatcher domains to enable covalent attachment of nanobodies against desired targets. This creates a versatile "bio-sponge" system capable of sequestering specific proteins from solution. The platform can be adapted to different disease-relevant targets by simply swapping the nanobody component.
My initial proof-of-concept experiments focus on capturing GFP as a model antigen, with plans to expand to biologically relevant targets such as cytokines. I will design and express fusion proteins consisting of ferritin with SpyTag/SpyCatcher domains, and anti-GFP nanobodies with complementary SpyCatcher/SpyTag domains. These components will self-assemble through covalent isopeptide bond formation, creating a complex capable of binding target proteins. The binding capacity and efficiency will be assessed using fluorescence measurements with GFP as the model target. Long-term, this system could offer therapeutic applications for immunological disorders, sepsis, or toxin exposure, as well as diagnostic potential through protein capture from liquid biopsy samples.
When I was sick not too long ago, I remember the physical weight of illness and the sense that my body was carrying disease-inducing factors that were out of balance. This personal experience, combined with the scientific understanding that certain proteins—such as cytokines or toxins—can become dysregulated in patients' blood, motivated me to explore a strategy to remove these harmful molecules. There remains a significant clinical need for tools that can regulate or eliminate such proteins. The idea of creating a modular, adaptable platform to help meet this need is both scientifically compelling and personally meaningful. Current therapeutic approaches for managing protein-mediated pathologies often rely on antibodies that neutralize target proteins in circulation, but these don't physically remove the proteins and may form immune complexes that can exacerbate inflammation. Extracorporeal blood purification techniques like plasmapheresis can remove proteins non-specifically, but they're invasive, resource-intensive, and lack molecular specificity. A fundamental balance exists between selectivity and throughput in current removal technologies. Methods based on physical separation mechanisms such as centrifugation and simple ultrafiltration are generally robust and scalable but lack the specificity required to selectively target individual proteins or cell populations. Ferritin has previously been used as a drug delivery vehicle, where therapeutic agents are loaded into its protein shell and antibodies are conjugated to target specific cells. This demonstrates the platform's flexibility and biocompatibility (Hong et al., 2024, Bioconjugate Chemistry, 35(8):1142–1147). Separately, "bio-sponge" strategies have shown therapeutic potential in contexts such as wound healing by physically absorbing or neutralizing bioactive molecules (Tang et al., 2023, Int J Biol Macromol, 247:125754). Research has demonstrated that ferritin–polypeptide fusion constructs can successfully capture target proteins by anchoring nanobodies, thereby enabling modular and multivalent targeting. However, these two fields—nanoparticle delivery and protein trapping—have yet to be merged into a single, modular system for protein capture and removal. Based on a review of current literature, the idea of using a ferritin fused with SpyTag/SpyCatcher to attach a nanobody specifically for capturing target proteins from solution appears to be conceptually supported by the modular design strategies available but has not been explicitly demonstrated or reported in published works. This represents a significant gap in current technology that my project aims to address.
The overall vision of this project is to create a versatile, modular platform that can selectively capture and remove harmful proteins from biological fluids. If successful, this technology could revolutionize treatment options for a wide range of conditions characterized by protein dysregulation, including autoimmune disorders, cytokine storm syndromes, sepsis, and exposure to protein toxins.
Unlike current therapeutic antibodies that merely neutralize target proteins while leaving them in circulation, this ferritin-based system would physically sequester proteins, potentially preventing formation of immune complexes that can exacerbate inflammation. Compared to extracorporeal blood purification techniques like plasmapheresis, which are invasive and remove proteins non-specifically, this approach would provide molecular specificity while being potentially less invasive.
The modularity of the system means it could be rapidly adapted to emerging threats—whether pandemic viruses with specific protein signatures or novel bioterrorism agents—by simply swapping in appropriate nanobodies. This could dramatically reduce the development time for new therapeutic countermeasures in emergency situations. Additionally, the platform could serve as a valuable research tool for studying protein interactions in complex biological systems, or as a sensitive diagnostic technology for detecting low-abundance proteins in liquid biopsies.
In the long term, this technology could bridge the gap between therapeutic and diagnostic applications, enabling a new paradigm of "theranostic" approaches where protein capture serves both to identify disease markers and to remove pathogenic factors.
This project introduces a novel application of ferritin as a scaffold for nanobody-mediated protein trapping. Rather than serving as a cargo vehicle for drugs, ferritin is repurposed here as the core of a bio-sponge system designed to bind and sequester harmful proteins directly. The combination of ferritin's self-assembly properties with the modular, covalent SpyTag/SpyCatcher system and the high specificity of nanobodies creates a unique technological approach not previously described in the literature.
The innovation lies not just in combining these elements, but in creating a platform that can be rapidly reconfigured for different targets without redesigning the entire system. This represents a significant advance over current protein capture methods, which typically require complete redevelopment for each new target. The approach challenges the current paradigm in therapeutic protein modulation by moving beyond neutralization to physical removal, potentially offering more complete target elimination.
The development and deployment of a protein capture system using ferritin and nanobodies raises several important ethical considerations. The primary ethical principles at play include non-maleficence (avoiding harm), beneficence (promoting good), justice (fair distribution of benefits and risks), and respect for autonomy.
From a non-maleficence perspective, introducing engineered protein complexes into the human body carries risks of unintended consequences. These include potential immunogenicity of the ferritin-nanobody complexes, disruption of normal protein homeostasis by capturing beneficial proteins with structural similarities to targets, and risk of emboli formation if large aggregates form. The principle of non-maleficence requires thorough pre-clinical testing to identify such risks before human trials. Additionally, the ability to selectively remove proteins from circulation represents a powerful capability that could be misused to create targeted biological weapons, raising dual-use concerns.
To ensure ethical development and use of this technology, several measures should be implemented. First, rigorous safety testing in cell culture and animal models should precede any human applications, with particular attention to immunogenicity, off-target effects, and clearance mechanisms. Second, the platform should be developed with transparency and open-access principles to ensure broad availability and prevent monopolization by a single entity. Third, engagement with regulatory agencies early in development can help establish appropriate oversight frameworks. Fourth, community engagement and inclusion of diverse perspectives in clinical trial design can help ensure that future applications address needs across different populations. Finally, implementing technical safeguards against misuse—such as designing systems that can only function in controlled environments—could mitigate dual-use risks.
Potential unintended consequences include disruption of beneficial protein interactions, immune reactions to the ferritin platform, and creation of new disease states if protein homeostasis is significantly disturbed. Alternative approaches could include developing soluble, non-assembling protein binders that would be more readily cleared, or focusing exclusively on ex vivo applications like diagnostic testing rather than in vivo therapeutic use.