The rationale for the approach lies in the peculiar biology of glioblastoma. These tumors are notoriously oxygen-starved because their blood vessels are underdeveloped and chaotic. That hypoxia activates hypoxia-inducible factor 1, or HIF-1, a master transcription factor that drives angiogenesis, metabolic reprogramming, and drug resistance by upregulating efflux pumps. Photodynamic therapy, which uses a photosensitizer and light to generate reactive oxygen species that destroy tumor cells, makes the problem worse: it consumes oxygen and damages tumor microvessels, deepening the hypoxia and paradoxically boosting HIF-1 activity. Photothermal therapy, which kills cells with heat, triggers its own countermeasure in the form of heat shock proteins, particularly HSP70, which help tumor cells survive thermal stress and develop thermoresistance.

To exploit light-based therapy despite these obstacles, the team first optimized the ratio of IR780 to paclitaxel inside bovine serum albumin nanoparticles. Using the combination index method, a standard quantitative tool for drug synergy, they found that a 1:2 ratio of IR780 to paclitaxel yielded a combination index of 0.39, well below the threshold of 1 that indicates true synergism. The resulting nanoparticles measured roughly 168 nanometers in hydrodynamic diameter by dynamic light scattering, with polydispersity indices around 0.1, indicating a highly uniform population. Transmission electron microscopy revealed spherical particles of approximately 120 nanometers. Encapsulation efficiency was high, at 89.8 percent for IR780 and 84.4 percent for paclitaxel, and the particles remained colloidally stable for at least 72 hours at room temperature.

The photophysical performance of the encapsulated dye proved markedly superior to the free drug. Under 808-nanometer near-infrared irradiation, free IR780 raised solution temperature by about 18 degrees Celsius within five minutes before its effect collapsed, a consequence of photobleaching. The albumin-encapsulated version, by contrast, generated roughly 25 degrees of heating and sustained it for at least ten minutes without decline. The nanoparticles also withstood at least four heating-cooling cycles, while free IR780 survived only one. Ultraviolet-visible spectroscopy showed a red shift in the dye’s absorption peak from 770 to about 790 nanometers, attributed to molecular aggregation within the particles, which improved excitation at 808 nanometers. Reactive oxygen species generation, measured with the chemical probe DPBF, was equally robust, and adding paclitaxel did not diminish the dye’s photodynamic output.

In LN229 human glioma cells, the nanoparticles were taken up faster than free IR780, and the team traced the mechanism to albumin-specific pathways. Pretreating cells with free albumin competitively blocked nanoparticle internalization in a concentration-dependent manner, consistent with uptake mediated by proteins such as SPARC and gp60, both overexpressed in glioblastoma. Once inside, the nanoparticles localized to lysosomes, where near-infrared irradiation disrupted lysosomal membranes, as shown by acridine orange staining, facilitating the escape and release of paclitaxel. Irradiated cells loaded with the nanoparticles heated about 15 degrees Celsius in four minutes, compared with roughly 10 degrees for free dye, and produced visibly more reactive oxygen species.

But the irradiation also exposed the therapy’s Achilles heel. A hypoxia-sensitive fluorescent probe revealed that photodynamic treatment significantly increased oxygen deprivation in the cells, and western blotting showed HIF-1α expression rising by 56 percent after irradiation. Under simulated hypoxia, the potency of both phototherapy and chemotherapy dropped substantially: the half-maximal inhibitory concentration of the combined nanoparticles rose from 0.08 to 0.48 micrograms per milliliter of IR780 equivalent. This is precisely where acriflavine entered the picture. When added to the treatment, the drug, which binds the HIF-1α subunit and prevents its dimerization with HIF-1β, further reduced the inhibitory concentrations to 0.32 and 0.63 micrograms per milliliter for IR780 and paclitaxel respectively under hypoxic conditions, and drove apoptosis, measured by cleaved caspase-3, to its highest levels.

The most striking discovery came when the team examined heat shock protein expression. Acriflavine alone suppressed HSP70 by roughly 80 percent compared with controls, and when combined with the nanoparticles it brought HSP70 levels down even under photothermal stress. To the authors’ knowledge, this is the first report of acriflavine acting as a potent HSP70 inhibitor, meaning a single molecule simultaneously blocks the hypoxia response that undermines photodynamic therapy and the thermoresistance that blunts photothermal therapy. The combination also nearly abolished glioma cell migration and invasion in scratch and Transwell assays, an effect the researchers linked to acriflavine’s suppression of HIF-1 downstream targets including VEGF, GLUT-1, and MMP9, proteins that drive angiogenesis, glucose uptake, and metastasis.

In tumor-bearing mice, the nanoparticles accumulated preferentially in tumors after intravenous injection, peaking at 24 hours, while free IR780 showed far weaker tumor localization. Acriflavine was delivered differently: because it is highly water-soluble and clears quickly from the body, the team embedded it in sodium alginate that gels on contact with the physiological calcium found inside tumor tissue, releasing the drug for at least 72 hours. In the treatment study, nanoparticles plus acriflavine hydrogel under near-infrared irradiation suppressed tumor growth by essentially 100 percent from day six onward, and three of five mice in that group showed complete tumor elimination. Histology confirmed the most extensive cellular destruction and the highest apoptotic fractions in the combination group. Tumors heated by 17 degrees Celsius within five minutes of irradiation, and HSP70 expression in treated tumors fell below even the untreated control level.

Safety signals were encouraging. Body weights remained stable across all treatment groups, organ histology showed no lesions, hemolysis stayed below 5 percent even at high nanoparticle concentrations, and blood chemistry markers of liver and kidney function showed no significant differences between treated and control animals. The authors are candid about limitations: the efficacy studies used a subcutaneous model rather than an orthotopic brain tumor, which lacks the blood-brain barrier and invasive growth patterns of real glioma, and the two delivery systems remain separate formulations. Still, both platforms have clinical precedents, from the FDA-approved albumin-paclitaxel formulation Abraxane to carmustine wafers implanted in post-surgical brain cavities. By showing that one repurposed, clinically approved dye can neutralize both HIF-1 signaling and heat shock defenses at once, the study offers a compelling template for reinforcing combination therapy in hypoxic, treatment-resistant tumors.

Subject of Research: Albumin nanoparticle photochemotherapy with acriflavine-mediated HIF-1 and HSP70 inhibition for glioma treatment

Article Title: Acriflavine-empowered IR780-PTX albumin nanoparticles for reinforced synergistic photochemotherapy

Article References: Li, D., Wang, T., Liu, H., Yao, Y., Lu, T., Wang, R., Jiang, X., Zhang, X., Sun, M., Peng, Y., Yang, Y., Shao, N., Ding, D., & Zhi, F. (2026). Acriflavine-empowered IR780-PTX albumin nanoparticles for reinforced synergistic photochemotherapy. Advanced Biotechnology, 4(1), Article 10. https://doi.org/10.1007/s44307-026-00097-9

Image Credits: AI Generated

DOI: 10.1007/s44307-026-00097-9

Keywords: glioblastoma, albumin nanoparticles, photothermal therapy, photodynamic therapy, paclitaxel, IR780, acriflavine, HIF-1, HSP70, tumor hypoxia, drug delivery, combination therapy

The central problem the researchers set out to address is deceptively simple to state but notoriously difficult to study. When nanoparticles enter the bloodstream, the reticuloendothelial system, a network of macrophage-rich organs dominated by the liver and spleen, recognizes them as foreign material and clears them within minutes to hours. A nanoparticle that is removed from circulation before it can reach a tumor delivers little drug to the disease and much to healthy tissue, compounding toxicity while blunting efficacy. Both PEGylation and red blood cell membrane coating are designed to defeat this clearance, but they do so through entirely different chemistry. PEG is a hydrophilic synthetic polymer that forms a hydration shell around particles, sterically blocking the adsorption of opsonins, the blood proteins that flag foreign material for destruction. Red blood cell membranes, by contrast, carry native ‘self’ markers, most famously the CD47 protein, which engages an inhibitory receptor on macrophages and delivers a molecular ‘don’t eat me’ signal. Yet despite the popularity of both approaches, the field has lacked rigorous head-to-head comparisons in which the only variable is the coating itself.

That gap is precisely what the Fujian team, led by Han Lin, Xiaoqin Wang, and corresponding author Qing Hu, set out to close. Their experimental design hinged on a single, identical nanocarrier core: albumin nanoparticles loaded with doxorubicin, a widely used chemotherapy agent. Albumin has become an attractive scaffold for drug delivery because it is biocompatible, biodegradable, and has a natural affinity for tumors, which scavenger albumin as a nutrient source. Building on this shared platform, the researchers constructed three formulations that differed only in their outermost surface. The first was the bare doxorubicin-loaded albumin nanoparticle, designated DOX-BSA, serving as the unmodified control. The second, DOX-BSA@LPs, was cloaked in PEGylated liposomes, representing the synthetic stealth strategy. The third, DOX-BSA@RMs, was camouflaged with red blood cell membranes, representing the biomimetic strategy. Because all three shared the same core, the same drug payload, and the same underlying particle, any differences in biological behavior could be attributed to the coating rather than to confounding variations in size, charge, or drug loading.

The team then subjected all three formulations to a systematic evaluation spanning physicochemical characterization, cellular behavior, tumor accumulation, and therapeutic performance. The physicochemical work confirmed that the coatings had been successfully applied and that the formulations were suitable for comparison, while the biological assays probed the questions that matter most for nanomedicine: how readily tumor cells take the particles up, how deeply the particles penetrate into tumor-like tissue, how much drug actually accumulates in tumors relative to healthy organs, and ultimately how well the treatments shrink tumors in living animals.

The first headline result was that both stealth strategies clearly worked. Compared with the unmodified DOX-BSA nanoparticles, both the PEGylated liposome-coated and the red blood cell membrane-coated versions showed significantly enhanced tumor accumulation and significantly improved anti-tumor efficacy, with the differences reaching statistical significance at the P < 0.05 threshold. This confirms, on a controlled albumin platform, the core premise of stealth nanotechnology: disguising the surface of a nanocarrier allows it to evade immune clearance long enough to reach its target. For a field in which many comparisons are confounded by differences in particle design, this clean demonstration of the stealth effect itself is a valuable benchmark.

But the more provocative finding lay in the comparison between the two coatings. Across multiple endpoints, the red blood cell membrane formulation, DOX-BSA@RMs, showed marginal yet statistically significant advantages over its PEGylated counterpart, DOX-BSA@LPs. In three-dimensional tumor spheroids, laboratory models that mimic the dense, poorly vascularized architecture of real tumors, the membrane-camouflaged particles penetrated deeper than the PEGylated ones. Penetration depth is a critical variable in solid tumor therapy because chemotherapeutics must reach not just the cells at the tumor periphery but the inner mass, where hypoxic and quiescent cells often survive treatment and seed relapse. A coating that improves access to the tumor interior could therefore translate into more complete tumor kill.

Histological examination of treated tumors reinforced the pattern. Tumors from animals treated with the red blood cell membrane formulation displayed more extensive necrosis and apoptosis, the two hallmarks of effective chemotherapy response, than tumors treated with the PEGylated formulation. Consistent with this, the membrane-coated particles achieved a higher tumor inhibition rate overall, meaning they shrank tumors more effectively in vivo. The researchers also measured tumor-to-normal-tissue ratios, a pharmacokinetic metric that captures how selectively a formulation homes in on tumors versus healthy organs, and found the ratios were superior for the membrane-camouflaged particles, indicating higher tumor accumulation relative to off-target deposition. Higher selectivity is the holy grail of chemotherapy, since it promises greater efficacy with fewer of the dose-limiting side effects, such as cardiotoxicity, that plague conventional doxorubicin.

Why might a biological membrane outperform a synthetic polymer, even if only by a modest margin? The authors’ findings are consistent with mechanistic ideas that have been accumulating in the literature. PEG, despite its success in products such as the liposomal doxorubicin formulation Doxil, the first FDA-approved nano-drug, is not without liabilities. Anti-PEG antibodies exist in a substantial fraction of the population, likely owing to widespread exposure to PEG-containing products, and recent work has shown that such antibodies can become enriched in the protein corona that forms around PEGylated nanocarriers, potentially accelerating clearance and altering cellular uptake on repeated dosing. Red blood cell membranes, by contrast, present a native repertoire of self-markers, including CD47, whose role as a ‘marker of self’ on erythrocytes was established in landmark work published in Science in 2000. In addition, membrane coatings preserve the mechanical deformability that allows red blood cells to squeeze through narrow capillaries, a property that some studies suggest may aid circulation and tissue penetration in ways that rigid synthetic coatings cannot replicate.

The significance of the study lies as much in its methodology as in its results. By fixing the core and varying only the coating, the researchers established what they describe as a comparative paradigm for evaluating nano-coatings, one that removes the confounders that have made it difficult to judge competing stealth strategies on their merits. Previous reviews of the field, including a 2024 analysis of stealth coatings in cancer models published in ACS Applied Materials and Interfaces, have noted that direct comparisons under uniform conditions are rare, leaving formulators to choose between PEGylation and membrane coating largely on the basis of precedent rather than evidence. The Fujian study provides that evidence for the albumin-doxorubicin system, and its framework can be readily applied to other payloads and other coating chemistries, from macrophage membranes to platelet membranes to hybrid coatings that combine features of several cell types.

Caveats remain, as they always do in preclinical nanomedicine. The advantages of the red blood cell membrane coating, while statistically significant, were described by the authors as marginal in magnitude, and the study evaluated a single drug, a single core material, and a single tumor model. Red blood cell membrane coatings also raise practical questions about sourcing, standardization, and scale-up that synthetic polymers do not, and the long-term immunological behavior of membrane-cloaked particles in repeat-dose regimens will require further study. Nevertheless, the work marks an important step toward rational, evidence-based design of nanocarrier surfaces. As cancer nanomedicine matures from proof-of-concept demonstrations toward optimized clinical formulations, studies that isolate the contribution of each design choice, rather than changing everything at once, are exactly what the field needs. On the evidence assembled by the Fujian Medical University team, when it comes to hiding a nanoparticle from the immune system long enough to deliver a lethal payload to a tumor, nature’s own disguise appears to hold a slight but real edge over the best synthetic imitation.

Subject of Research: Comparison of PEGylation and red blood cell membrane stealth coatings on doxorubicin-loaded albumin nanoparticles for antitumor drug delivery

Article Title: Comparison of PEGylation versus red blood cell membrane camouflage strategies: in vivo and in vitro antitumor efficacy of doxorubicin-loaded albumin nanoparticles

Article References: Lin, H., Wang, X., Lin, Z., Dai, T., Qiu, X., Yu, X., Yu, Y., & Hu, Q. (2026). Comparison of PEGylation versus red blood cell membrane camouflage strategies: in vivo and in vitro antitumor efficacy of doxorubicin-loaded albumin nanoparticles. Journal of Pharmaceutical Investigation. https://doi.org/10.1007/s40005-026-00831-4

Image Credits: AI Generated

DOI: 10.1007/s40005-026-00831-4

Keywords: nanoparticles, drug delivery, PEGylation, red blood cell membrane, doxorubicin, albumin nanoparticles, stealth coating, tumor accumulation, cancer therapy, nanomedicine, biomimetic coating, CD47