Professor Moein Moghimi
From Fundamental Science to Advanced Therapies
Advancing nanoparticle engineering for biological targeting, safe-by-design nanomedicines and engineering biology
For more than 30 years, Professor Moein Moghimi has rewritten the rules on how particulate drug delivery systems behave inside the human body. As a pioneer in nanomedicine, he designs engineered nanoparticles and non-viral vectors that can travel directly to diseased tissues, offering new hope for treating cancer, cardiovascular diseases, and brain disorders.
Moghimi's early breakthroughs, including co-proposing the landmark opsonin-dysopsonin hypothesis, changed how scientists understand how the immune system clears foreign particles from the blood. By mastering these immune interactions and by exploiting organ ultrastructure and microcirculatory pathways, he successfully engineered “splenotropic” (spleen-targeting) and “lymphotropic” (lymph node-targeting) nanocarriers. This foundational work mapping organ-specific targeting has served as a direct design inspiration for today’s advanced lipid nanoparticle targeting systems, which are used to build highly effective mRNA vaccines and organ-selective therapies.
By precisely tweaking a nanoparticle's shape, flexibility, and atomic-scale surface patterns, his team can effectively hide medicine from the body's defences and mitigate infusion-related adverse reactions. Among his most exciting breakthroughs are NanoLigand Carriers—which safely cross the strict blood-brain barrier to deliver gene therapies—and a new generation of CAR-T cell therapies engineered to fight complex cancers. His work further applies computational network knowledge of genomics and epigenomics to understand inter-individual variations in how patients respond to nanomedicines, pushing the boundaries of nanotherapies to a truly personalised level.
Nanoparticle-Immune System Interactions
The “Opsonin/Dysopsonin” Hypothesis
First formulated by Professor Moein Moghimi and H.M. Patel in 1989, the “opsonin-dysopsonin” hypothesis revolutionized systemic drug delivery by proving that a nanoparticle's survival in the bloodstream is dictated by a competitive molecular tug-of-war between blood proteins. While opsonins act as "red flags" that tag nanoparticles for rapid clearance by phagocytic cells, dysopsonins function as biological cloaks limiting phagocytic recognition. They also viewed dysopsonins as “protective agents” against over-ingestion of liposomes by macrophages, particularly those with lipid compositions more resistant to lysosomal esterases.
This paradigm-shifting framework proved that scientists could manipulate a nanocarrier's surface chemistry to deliberately recruit protective proteins, laying the foundational groundwork for the modern "protein corona" concept and a new framework for understanding stealth, long circulation and organ-specific distribution.
Nanoparticle-Complement Interaction
During the past two decades, Moghimi and his collaborators performed pioneering, definitive work in mapping the complement activation properties of nanoparticles, establishing a comprehensive blueprint for how the innate immune system senses engineered materials. This work demonstrated that the complement system—the blood's primary immunological tripwire—is exquisitely sensitive to a nanoparticle's surface topology. By systematically evaluating different nanocarrier architectures, it proved that subtle structural shifts, such as altering nanoparticle shape, deformability, surface polymer density, and even the Ångström-scale spacing arrangement of surface motifs, could dramatically alter complement sensing and drive C3 opsonization. Complement mapping eventually achieved the ultimate goal in nano-engineering: the rational design of entirely complement-evading nanoparticles without the need of complement inhibitors. By cracking the structural code of how the immune system senses foreign surfaces, Moghimi’s lab demonstrated that subtle, premeditated changes to a particle's physical blueprint could completely overcome complement activation pathways.
The Ångström-scale surface arrangement hypothesis
Professor Moghimi’s formulation of the Ångström-scale surface arrangement (ASSA) hypothesis introduced a profound shift in nanomedicine, proving that immune recognition depends not just on what chemical motifs are on a nanoparticle’s surface, but exactly how they are spatially patterned at the atomic level. Employing dendrimers, he demonstrated that by precisely manipulating the Ångström-scale spacing between surface polymers or surface motifs, one can structurally disrupt the binding geometry of complement-initiating complexes. Based on this study, he speculated that microbial pathogens might utilize an identical spatial mechanism to evade the human complement system. He proposed that successful pathogens likely orchestrate their surface motifs with precise Ångström-scale arrangements that prevent critical complement proteins from stably docking, effectively blindfolding the host's innate immune defenses. By bridging synthetic nanostructures with theoretical microbiology, this hypothesis established a universal architectural concept for immune evasion, offering a revolutionary blueprint for designing completely stealth therapeutics.
Infusion-Related Reactions
Infusion reactions remain a critical barrier in modern medicine, causing unpredictable and potentially life-threatening immune responses when patients receive advanced therapies like nanomedicines. Moghimi and colleagues established both operational and molecular solutions to mitigate infusion-related reactions to nanomedicines. First, optimising nanoparticle shape delayed macrophage clearance and overcame infusion-related reactions. Second, having identified complement opsonisation as a likely driver of this cascade, they used specific complement inhibitors to block immune sensing safely. By providing the exact rational engineering and clinical rules required to control these parameters, this collective research provided a definitive roadmap for delivering next-generation targeted therapeutics without triggering dangerous systemic immune responses.
Nanoparticle Engineering for Organ-Specific Targeting
Spleen-Selective Targeting
Professor Moein Moghimi’s principle for splenotropic (spleen-selective) targeting was inspired by how the spleen naturally traps rigid, malaria-infected red blood cells (spherocytes). In malaria, infected cells lose their flexibility and become mechanically filtered out because their rigidity and dimensions exceed the submicron size of the interendothelial cell slits in sinusoidal spleen. Moghimi translated this evolutionary bottleneck into a rational nanomedicine design. By applying high-density steric stabilization to his nanoparticles, he successfully minimised liver clearance, extending their blood half-life. Because of this prolonged systemic circulation, the nanoparticles encountered the splenic filtration grid much more frequently, allowing them to become predictably and safely entrapped within the narrow slits based purely on their rigid physical dimensions. Eventually, as the protective polymer coating was gradually lost over time, these physically entrapped particles were safely ingested by local splenic macrophages, completing an elegant combination of molecular stealth, biomimetic physics, and controlled cellular delivery.
The In Vivo Cloaking Principle
In a groundbreaking paradigm shift, Professor Moghimi demonstrated that "phagocyte-prone" nanoparticles could be converted into long-circulating or splenotropic entities entirely in vivo, completely bypassing the need for chemical surface modification prior to injection. He discovered that a pre-injection of free, non-ionic block copolymers (such as poloxamine-908) allowed these molecules to remain dynamically active in the bloodstream. When unmodified nanoparticles were subsequently introduced, they spontaneously acquired a protective coating of these circulating polymers and polymer-protein complexes directly within the blood. This prolonged circulation was a result of this spontaneous in vivo coating rather than a simple hepatic blockade or overwhelming of liver macrophages by the free polymer.
This immediate steric barrier blindfolded liver macrophages, allowing the nanoparticles to survive long enough to encounter the spleen's filtration grid. For rigid nanoparticles whose physical dimensions exceeded the interendothelial slits of the venous sinuses, this extended circulation resulted in precise splenotropic redirection, as they became mechanically entrapped within the spleen. By proving that a medicine's biological destiny could be reprogrammed inside a living organism rather than a test tube, this work revolutionized concepts of on-demand targeted nanotherapies.
Lymphotropic Nanoparticles
In collaboration with Professor S.S. Davis, Professor Moghimi applied the principle of steric stabilisation to overcome a major clinical hurdle in nanoparticle targeting of lymph nodes: particle aggregation at interstitial injection sites. Coating nanoparticles with specific block copolymers (like poloxamers and poloxamines) prevented local clumping and dramatically accelerated their drainage into lymphatic capillaries. Tightly coordinating nanoparticle size and polymer chain length, dictated their ultimate fate: shorter polymer coatings allowed local opsonization and massive capture by lymph node macrophages, while longer chains bypassed regional nodes entirely to reach the systemic bloodstream. Moghimi later translated these precise physical rules into liposome engineering, pairing specific lipids with PEG arrays to build highly adaptable, clinical-grade lymphatic delivery platforms. This breakthrough manipulation of surface physics laid the structural blueprint for modern Lipid Nanoparticles (LNPs), providing the exact engineering principles used today to route mRNA vaccines and immunotherapies directly to the lymph nodes to train the human immune system.
Macrophage Sensing of “Stealth”
In the mid-1990’s Moghimi challenged another foundational dogma by proving that under certain pathophysiological conditions, seemingly "stealth" nanoparticles can be rapidly recognised and cleared by macrophages of the reticuloendothelial system. He demonstrated that "stealth" status is never absolute; rather, it is a conditional state that can completely fail when encountering primed or activated macrophages. When the innate immune system is stimulated—such as during an ongoing inflammatory response, infection, or prior exposure to nanomedicines—these activated macrophages undergo profound changes in receptor expression and phagocytic capacity. This heightened immune state allows them to effectively "see through" protective steric barriers like PEG or poloxamers, rapidly engulfing the carriers despite their “stealthy” status. By exposing how macrophage activation state dictates nanomedicine performance, Moghimi highlighted critical biological parameters that must be accounted for to prevent sudden therapeutic failure in patient groups with active or primed immune profiles.
Gene Therapy
Crossing the Blood-Brain Barrier
Professor Moghimi’s development of NanoLigand Carriers (NLCs) represented a paradigm shift in overcoming the highly restrictive blood-brain barrier (BBB). Inspired by how bacteriophages might present display peptides in a hierarchical structure for target recognition, this platform marked the first demonstration of a functional nanocarrier self-assembled from a single peptide conjugate. Through the spatial configuration and surface display of peptidic motifs, NLCs uniquely target at least two separate receptors on cerebral endothelial cells (transferrin receptor and RAGE), driving safe, rapid, and highly efficient receptor-mediated transcytosis.
These self-assembling particles successfully delivered gene therapies directly to neurons and microglia with unprecedented efficacy and safety, completely avoiding toxicity and inflammation. By operating as an autonomous, self-navigating system, NLCs offer a powerful, non-toxic alternative capable of completely replacing barrier-penetrating viral vectors and modern lipid and polymeric nanoparticles, eliminating compositional complexity, multi-step chemical functionalization and batch-to-batch inconsistencies that slow down clinical translation.
Non-Viral Vector Design and Safety
Professor Moghimi’s research team provided a definitive resolution to a long-standing bottleneck in genetic medicine by uncovering the precise molecular basis of polycation toxicity. Non-viral gene delivery systems relying on cationic polymers (such as polyethylenimine) had been severely limited by their tendency to trigger widespread cell death, a phenomenon previously written off as non-specific cell membrane disruption. Moghimi’s research shattered this assumption by proving that polycation toxicity is driven by highly orchestrated, multifaceted intracellular pathways, mapping out how these positively charged polymers actively damage plasma membrane, mitochondrial membranes, manipulate electron transport systems, trigger the release of cytochrome c, unleashing a cascade of apoptotic, necrotic and necroptotic cell death. This mechanistic understanding has provided a blueprint for designing highly efficient, non-toxic polymeric vectors, fundamentally resolving the cell-death challenges that had stalled polycation-based gene therapies for decades.
CAR T-Cell Bio-Engineering
Expanding beyond classical nanotechnology, Professor Moghimi’s team has pioneered a paradigm-shifting approach to cancer immunotherapy through innovative oligoclonal VHH-directed Chimeric Antigen Receptor (CAR) T cell engineering. Traditional CAR-T therapies typically rely on single-antibody fragments (scFvs) that target a single tumor protein, leaving them highly vulnerable to antigen escape and tumor mutation. Moghimi’s lab overcame this barrier by harnessing oligoclonal VHH domains (single-domain antibodies derived from camelids) capable of simultaneous, multi-epitope targeting against complex cancer antigens like HER2. This multi-pronged architecture mimics the natural diversity of a polyclonal immune response, dramatically reducing the likelihood of tumour escape and enhancing therapeutic durability. By integrating deep engineering biology with synthetic immunology, his team has unlocked a next-generation cell therapy platform that solves the structural and clinical limitations of conventional CAR-T designs, opening a powerful new frontier in the eradication of heterogeneous and resistant solid tumors.