Magnetically Driven Microrobots: A Revolutionary Breakthrough in Intracranial Tumor Therapy
On May 1, 2025, a groundbreaking research paper titled Magnetically-driven biohybrid blood hydrogel fibres for personalized intracranial tumour therapy under fluoroscopic tracking was published online in Nature Biomedical Engineering, one of the world’s top journals in biomedical engineering. The study, led by Researcher Xu Tiantian from the Shenzhen Institutes of Advanced Technology (SIAT) of the Chinese Academy of Sciences, in collaboration with Associate Professor Wang Ben from Shenzhen University and Professor Zhang Li from the Chinese University of Hong Kong, introduced a novel magnetically driven biohybrid blood hydrogel fibre (BBHF) microrobot. This millimeter-scale "biological robot" crafted from the patient’s own blood has achieved precise targeted drug delivery for deep intracranial tumors in animal experiments, opening an unprecedented non-invasive therapeutic pathway for the treatment of intracranial tumors that have long plagued the medical community.
Intracranial tumors, especially deep-seated gliomas and tumors adjacent to vital functional brain areas, have long been a clinical treatment conundrum. Traditional surgical resection carries a high risk of irreversible nerve damage due to the brain’s complex anatomical structure and delicate neural tissue. Radiotherapy often causes radiation necrosis of normal brain tissue surrounding the tumor, while chemotherapy struggles to cross the blood-brain barrier, failing to reach effective drug concentrations at the tumor site and leading to severe systemic side effects. Additionally, existing medical microrobots face bottlenecks such as immune system rejection, difficulty navigating narrow intracranial spaces, and imprecise drug release, making it hard to balance therapeutic efficacy and safety.
The BBHF microrobot developed by the research team breaks through these limitations with three core innovative "bionic designs", redefining the paradigm of intracranial tumor targeted therapy. First, it features ultra-high biocompatibility using the patient’s own blood as the raw material: the microrobot is fabricated by mixing the patient’s blood with magnetic nanoparticles and clotting agents, retaining the natural fibrin network structure of blood. With a diameter of only 1 mm and a length of up to 5 cm, it has an elastic modulus of about 100 kPa—softer than intestinal tissue yet more tough than cartilage. This "invisible cloak" design completely evades immune system recognition and rejection, and the microrobot degrades automatically in the body after completing its therapeutic mission, eliminating the need for a second surgical removal.
Second, it achieves multi-modal bionic movement adapted to the complex intracranial environment. Inspired by the slender shape and adaptive wave motion of nematodes in nature, the research team embedded magnetic particles in the blood hydrogel fibers and realized precise control of the microrobot through an externally programmable magnetic field. The BBHF can perform flexible bionic movements such as swinging, crawling, and rolling, and can switch movement modes in real time according to the curvature of the intracranial space—even navigating through subarachnoid spaces narrower than its own diameter without causing mechanical damage to the delicate brain tissue. Abandoning the traditional vascular delivery route, the team leverages cerebrospinal fluid, which flows 100 times slower than blood, as a "natural waterway" for the microrobot, enabling stable and accurate navigation in the brain’s intricate sulci and gyri.
Third, it integrates fluoroscopic real-time tracking and magnetically responsive intelligent drug release. The microrobot is tracked in real time via X-ray fluoroscopy during delivery, acting like a "GPS-guided torpedo" to ensure precise positioning to the tumor site. Encapsulated with chemotherapeutic drugs such as doxorubicin, the BBHF remains structurally stable with no drug leakage under a low-frequency weak magnetic field (intensity <20 mT, frequency <6 Hz) during transportation. Once it reaches the tumor focus, a high-intensity rotating magnetic field (50 mT, 24 Hz) triggers mechanical fragmentation of the fiber, breaking the millimeter-scale microrobot into micron-sized fragments and releasing the drugs in a concentrated manner. This physical field-responsive drug release strategy avoids the biological toxicity of traditional chemical triggers, and the release rate can be dynamically adjusted by modifying magnetic field parameters, creating a high local drug concentration at the tumor site while minimizing systemic side effects.
The research team validated the therapeutic efficacy and safety of the BBHF microrobot in a rigorous preclinical study on 18 miniature pigs with established glioma models, divided into a blank control group, a sham operation group (implanted with non-drug-loaded BBHF), and a treatment group (implanted with doxorubicin-loaded BBHF). The results were striking: 26 days after treatment, the tumor volume in the BBHF treatment group was 60% smaller than that in the control group (four times smaller), and the tumor growth was significantly inhibited. More importantly, the blood cell counts and biochemical marker levels of the pigs in the treatment group remained within the normal range with minimal fluctuations, and no immune response or tissue damage was detected. In contrast, fibers made from donor blood triggered significant inflammatory reactions, fully demonstrating the importance of personalization and the excellent safety profile of the self-blood-based BBHF.
"This biohybrid microrobot innovatively combines multi-modal bionic movement, fluoroscopic real-time tracking, and magnetically responsive intelligent drug release, providing a transformative solution for the non-invasive, precise, and efficient treatment of deep intracranial tumors or those adjacent to functional areas," said Xu Tiantian, the corresponding author of the paper. She added that the technology not only addresses the key clinical pain points of intracranial tumor therapy but also sets a new example for the application of microrobots in automated medical treatment. The research has been supported by multiple National Natural Science Foundation of China projects, laying a solid foundation for its subsequent clinical translation.
For the global medical community, the birth of the BBHF magnetically driven microrobot marks a major leap in the field of minimally invasive intracranial therapy. It breaks the technical bottlenecks of traditional tumor treatment and existing microrobots, and its personalized design based on the patient’s own blood greatly improves the clinical applicability of medical microrobots. The research team stated that the next step will focus on optimizing the microrobot’s structure, improving the precision of motion control, and enhancing its therapeutic functions—expanding its adaptability in complex brain environments, conducting further preclinical studies, and accelerating the process of clinical trials and industrialization. In the future, this technology is expected to be extended to complex medical scenarios such as boundary infiltration therapy of gliomas and relay drug delivery for multiple lesions, bringing new hope to millions of intracranial tumor patients worldwide.
