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Biomaterials Science

Royal Society of Chemistry (RSC)

Preprints posted in the last 7 days, ranked by how well they match Biomaterials Science's content profile, based on 24 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

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A fibril-inducing support-bath enables embedded 3D printing of aligned collagen-rich constructs

Gonnella, G.; Milazzo, R.; Gibney, R.; Kelly, D.

2026-08-31 bioengineering 10.64898/2026.08.30.748057 medRxiv
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Embedded extrusion printing can process collagen-rich bioinks, but their low viscosity and slow fibrillogenesis compromise print fidelity and post-deposition stability. Here, we developed a collagen fibril-inducing support bath (FIB) that combines mechanical support for embedded printing with biochemical induction of collagen assembly. Microfibrillated or nanofibrillated cellulose was incorporated into a fibril-inducing buffer, and formulations were screened at 37 degrees Celsius for rheological behaviour and optical transparency. The selected FIB was evaluated by printing 1% and 5% (w/v) articular cartilage-derived extracellular matrix (ECM) inks at 10-20 mm/s and compared with a cellulose-only control bath. FIB exhibited yield-stress, shear-thinning and rapid recovery behaviour that supported reproducible filament deposition. Unlike the control bath, FIB enabled intact construct retrieval following stabilisation and promoted the formation of fibrillar collagen within the printed strands. Scanning electron microscopy revealed D-banded collagen fibrils preferentially oriented along the deposition direction, with dominant orientation peaks within +/- 10-15 degrees. The platform supported the fabrication of 15 x 15 x 1.5 mm sheets and 6 x 6 x 6 mm scaffolds whose macroscopic dimensions were retained after processing. Constructs produced from 5% ECM inks exhibited approximately fourfold higher ramp and relaxation moduli than those produced from 1% ECM inks. Extracts from both formulations caused no detectable reduction in cell metabolic activity after 24 h or 72 h. Mesenchymal stem/stromal cells (MSCs) seeded onto printed sheets became markedly elongated and aligned by day 3, with approximately 80% of cells having an aspect ratio exceeding 1.5, significantly greater than cells seeded onto casted ECM controls, with a mean deviation of ~9 degrees from the filament print direction. These findings establish FIB as a bioactive support bath that couples embedded printability with collagen fibrillogenesis, enabling recoverable collagen-rich constructs with aligned fibrillar architecture that directs early cellular organisation.

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Extracellular matrix composition is associated with tissue-specific decellularization susceptibility and mechanical remodeling across human urogenital tissues

Bolduc, S.; Chabaud, S.; Droit, A.; Fourcassie, V.; Roux-Dalvai, F.; Sahuc, Y.; Sueters, J. J.

2026-08-31 bioengineering 10.64898/2026.08.28.747607 medRxiv
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Decellularized extracellular matrices (ECMs) are widely used in regenerative medicine, yet current evaluation criteria prioritize cellular removal rather than preservation of the ECM characteristics that govern tissue behavior. Here, we demonstrate that efficient decellularization is achieved across a broad range of chemical conditions, whereas preservation of structurally and biologically relevant ECM components is confined to narrow, tissue-specific windows defined by coupled detergent interactions. Quantitative proteomics revealed that intrinsic ECM composition is strongly associated with tissue-specific susceptibility to decellularization-induced damage and provided molecular context for the distinct preservation responses between tissues. Optimized matrices retained major structural ECM components and supported tissue-specific cellular organization and cell-mediated mechanical reinforcement following cellular repopulation despite uniformly low residual DNA across protocols. Together, these findings support a shift in decellularization quality assessment from DNA-based evaluation toward preservation of biologically relevant ECM and establish a composition-driven strategy for the rational design of regenerative biomaterials with tissue-relevant biological and mechanical properties.

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3D Printed X-ray Compatible Microfluidics for Online Characterization of Hexosomes: A Synchrotron SAXS-on-Chip Study with Molecular Dynamics Insights

Babaie, Z.; Valerio, M.; Schuhmann, F.; Dimaki, M.; Rezaei, B.; Pezeshkian, W.; Keller, S. S.; Svendsen, W. E.; Souza, P. C. T. d.; Yaghmur, A.

2026-09-01 biophysics 10.64898/2026.08.31.748233 medRxiv
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Online structural characterization during microfluidic lipid self-assembly is important for understanding and controlling the formation of nonlamellar liquid crystalline nanodispersions. Here, we report a 3D-printed, X-ray-compatible hydrodynamic flow-focusing microfluidic chip with variable channel dimensions, integrated with synchrotron small-angle X-ray scattering (SAXS), for position-resolved SAXS-on-chip monitoring of Ca2+-triggered hexosome formation. Hexosomes were produced under continuous flow by mixing ethanolic solutions of docosahexaenoic acid monoglyceride (MAG-DHA), the negatively charged phosphatidylglycerol DOPG, and -tocopherol with Ca2+-containing PIPES buffer. Online SAXS-on-chip measurements detected three Bragg reflections characteristic of the internal inverse hexagonal (H2) phase on a tens-of-milliseconds residence-time scale, revealing rapid structural evolution during microfluidic mixing. Complementary ex situ SAXS identified the DOPG/Ca2+ molar ratio as a key parameter modulating the direct vesicle-to-hexosome transformation and the compactness of the internal H2 nanostructures. Dynamic light scattering showed that the flow-rate ratio modulated nanoparticle size, yielding hexosomes with mean hydrodynamic diameters in the range of approximately 120-175 nm and polydispersity index values down to 0.14 at a total flow rate of 200 {micro}L min-1. Cryo-TEM revealed coexistence of hexosomes and vesicular nanostructures, highlighting morphological heterogeneity, while Coarse-Grained Molecular Dynamics simulations supported a central role of Ca2+-DOPG association in promoting a direct lamellar-H2 phase transition. Overall, this work shows that 3D-printed SAXS-compatible microfluidics can integrate continuous production with online structural characterization, providing a basis for future formulation and process optimization of drug-loaded cubosomes, hexosomes, and related nonlamellar liquid crystalline nanodispersions.

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Development and pharmacological evaluation of an intranasal liposomal norbinaltorphimine formulation for the prevention of pain-induced negative affect

Lorente, J. D.; Campos-Jurado, Y.; Martinez-Navarrete, M.; Cuitavi, J.; Cervera-Sospedra, M.; Higginbotham, J. A.; Melero, A.; Polache, A.; Guillot, A. J.; Moron, J.; Hipolito, L.

2026-09-01 neuroscience 10.64898/2026.08.26.747378 medRxiv
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Chronic pain is frequently accompanied by negative affect and motivational deficits due to dysregulated mesocorticolimbic dopamine and kappa opioid receptor (KOR) signalling. Although intracranial KOR antagonism prevents pain-induced negative affect in preclinical models, systemic KOR antagonists can produce adverse off-target effects in the periphery, thereby limiting its clinical utility. Consistent with this, we found that systemic administration of KOR antagonist norbinaltorphimine (NorBNI), exacerbated motivational deficits in rats with persistent inflammatory pain. We hypothesized that maximizing central and minimizing peripheral KOR antagonism could overcome these limitations. To test this, we engineered an intranasal liposomal NorBNI formulation incorporated into an in-situ forming mucoadhesive hydrogel to enable selective nose-to-brain delivery (Nor-BNILV-HG). We characterized its physicochemical properties and functional efficacy in rats with inflammatory pain produced by Complete Freund's Adjuvant (CFA). NorBNI-loaded liposomes exhibited high drug entrapment efficiency, nanometric size, and suitable surface charge for intranasal administration. The selected thermosensitive hydrogel demonstrated appropriate gelation properties and sustained drug release. Intranasal administration of NorBNI-LV-HG produced negligible systemic NorBNI levels compared with intraperitoneal delivery. In vivo microdialysis showed that NorBNI-LV-HG prevented KOR agonist-induced reductions in nucleus accumbens (NAc) dopamine release, confirming functional central KOR blockade. Behaviourally, intranasal NorBNI-LV-HG attenuated pain-induced impairments in sucrose motivation. Importantly, unlike systemic NorBNI, repeated intranasal NorBNI-LV-HG did not alter mechanical nociceptive thresholds in pain-naive animals, suggesting this strategy mitigates unwanted peripheral nociceptive effects. Together, these findings demonstrate that intranasal NorBNI-LV-HG achieves functional brain KOR antagonism while minimizing systemic exposure and off-target effects. Selective nose-to-brain delivery of KOR antagonists therefore represents a promising therapeutic strategy to prevent and potentially reverse the affective and motivational consequences of pain and may overcome key translational barriers associated with systemic KOR treatments.

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Novel Dissymmetric Ionizable Lipid-Assembled Lipid Nanoparticles for Delivery of Ferroptosis-Related siRNA in Diabetic Treatment

Zhang, H.; Liu, Y.; He, F.; Xue, G.; Kang, Y.; Zhang, Z.; Ma, J.; Xiao, J.; Meng, Q.

2026-09-01 pharmacology and toxicology 10.64898/2026.08.26.747432 medRxiv
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Small interfering RNA (siRNA) enables precise post-transcriptional gene silencing for refractory diseases, yet its clinical translation remains limited by the lack of safe and efficient delivery vectors. Inspired by the dissymmetric alkyl chain architecture of natural membrane phospholipids, we designed and synthesized 34 novel ionizable lipids with dissymmetric hydrophobic tails and formulated them into lipid nanoparticles (LNPs). Through systematic physicochemical and biological assessments, we established clear structure-activity relationships and identified two lead LNPs (O14-LNP, H18a-LNP) with superior endosomal escape capacity, enhanced in vivo gene silencing potency, and favorable biosafety relative to the clinical benchmark MC3-LNP. In both streptozotocin-induced and spontaneous db/db type 2 diabetes (T2D) mouse models, lead LNPs delivering ferroptosis-related siRNAs effectively ameliorated glucose and lipid metabolic disorders, restored islet function, and alleviated hepatic steatosis. This study not only lays a theoretical foundation for the rational design of novel ionizable lipids, but also validates the therapeutic potential of siRNA therapy targeting ferroptosis, providing a versatile delivery platform and targeted therapeutic strategy for the treatment of T2D.

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Multilayered extracellular matrix derived scaffolds direct progenitor cell differentiation in vitro and osteochondral-tissue formation in vivo.

Gonnella, G.; Strong, O.; Sularea, V. M.; Soares Kronemberger, G.; Karam, A. S.; Kelly, D.

2026-08-31 bioengineering 10.64898/2026.08.28.747815 medRxiv
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Osteochondral repair requires restoration of zonally organised articular cartilage and subchondral bone, yet translatable implants rarely reproduce this spatial complexity. Here, we developed an off-the-shelf, cell-free multilayer scaffold comprising a superficial 2% (w/v) articular cartilage extracellular matrix (AC-ECM) phase, an intermediate 5% AC-ECM phase and a basal 6% bone ECM (BN-ECM) phase. The scaffold formed continuous interfaces, displayed regionally distinct pore sizes and resisted permanent deformation during cyclic compression. In vitro, constructs seeded with caprine mesenchymal stromal and articular cartilage progenitor cells supported cell expansion and the accumulation of sulfated glycosaminoglycan- and collagen-rich matrix, with regional differences in collagen I, II and X deposition. Following eight weeks of subcutaneous implantation, cell-seeded scaffolds contained more collagenous matrix than unseeded controls, while vascularisation preferentially localised to the BN-ECM phase. The scaffold was then evaluated against empty defects in a caprine osteochondral model for six months. Scaffold treatment significantly improved macroscopic and histological repair, increased chondral tissue fill (~60% versus ~40%), limited cartilage-like tissue extension into the subchondral region and generated a more native-like superficial collagen organisation. Repair tissue further exhibited greater collagen II immunoreactivity, increased ACAN and COL2A1 expression and reduced COL1A2 expression relative to empty defects, although deeper bone repair was not significantly improved. These findings demonstrate that tissue-specific ECM layering can spatially guide endogenous repair and substantially improve cartilage restoration without exogenous cells or growth factors in a clinically relevant large-animal model, while identifying subchondral bone regeneration as the remaining design challenge for complete osteochondral repair.

7
Amyloid Polymorphism of Lysozyme Governs Cross-Seeding of Insulin Aggregation

Metkar, S.; Eerati, V.; Ramamoorthy, A.

2026-08-30 biophysics 10.64898/2026.08.26.747312 medRxiv
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Amyloid fibrils are highly ordered protein aggregates characterized by a conserved cross-{beta}-sheet architecture despite originating from structurally diverse precursor proteins. Growing evidence suggests that interactions between different amyloidogenic proteins can modulate aggregation pathways through heterologous cross-seeding; however, the influence of seed polymorphism on the structure and biological properties of cross-seeded fibrils remains poorly understood. Here, we investigated the cross-seeding of native human insulin by two structurally distinct polymorphs of hen egg-white lysozyme (HEWL): flexible fibrils (FFs) and rigid fibrils (RFs). Native insulin remained stable under physiological conditions and underwent spontaneous fibrillation only under acidic conditions. In contrast, both HEWL polymorphs efficiently induced insulin aggregation at physiological pH, bypassing the nucleation barrier. Thioflavin T fluorescence, circular dichroism spectroscopy, and transmission electron microscopy revealed that lysozyme FFs templated the formation of insulin flexible fibrils (IFFs), whereas lysozyme RFs produced insulin rigid fibrils (IRFs), demonstrating that the structural characteristics of the parental HEWL polymorphs were propagated during heterologous cross-seeding. The toxicity of the resulting insulin fibrils was evaluated in SH-SY5Y neuronal cells and CCF-STTG1 astrocytes. IFFs exhibited minimal cytotoxicity and only subtle morphological alterations, whereas IRFs caused modest reductions in cell viability accompanied by more pronounced cellular damage. These findings demonstrate that the structural polymorphism of HEWL fibrils governs both the architecture and biological activity of cross-seeded insulin fibrils, highlighting amyloid polymorphism as an important determinant of heterologous amyloid propagation and a potential design principle for engineering functional amyloid-based biomaterials and protein delivery platforms.

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A Tunable Flat-Jet Hydro-Debridement Device: Clinical Feasibility for Soft Tissue Wound Management

DATTA, A.; Majumder, R.; Biswas, I.; Ganguly, R.; Santra, A. K.; Sarkar, S.; Gumta, M. K.; Sarkar, S.

2026-09-04 surgery 10.64898/2026.09.01.26361120 medRxiv
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Background: Chronic wounds, ulcers, and lacerations require staged debridement and irrigation to promote healing. However, conventional techniques of debridement, such as surgical, chemical, or autolytic, struggle to fully remove residual necrotic tissue, slough, and unhealthy granulation from wound sites, especially when lodged within wound clefts and cavities, and in wounds with exposed structures. This promotes polymicrobial biofilms, delays wound closure, and causes significant discomfort with increased morbidity. Objective: To demonstrate the feasibility of using an indigenously developed tunable flat-jet hydro-debridement device (presently termed as CleanseJet), a frugal wound debridement system designed for deployment in resource-constrained clinical settings. Methods: An open-label, interventional, single-centre, parallel-group pilot randomized controlled trial was conducted to clinically evaluate an indigenously developed tunable flat-jet hydro-debridement device in patients with wounds of varied aetiology. The device provided adjustable spray impact force and coverage area tailored to wound characteristics. Outcomes were compared with a control group receiving standard wound care alone, with time to complete granulation serving as the primary healing endpoint. Outcomes were compared with a control cohort receiving standard of care alone. Results: The removal of loose devitalized tissue, slough, and biofilms from the wound bed improved the healing, which were monitored using the SINBAD scoring system. No adverse events were reported, supporting the feasibility and safety of CleanseJet. Conclusion: While commercial hydro-debridement systems are effective, they are often costly, rely on disposable components, and require specialized training. In contrast, CleanseJet provides a low-cost, easy-to-use alternative that can be operated with minimal training, making it suitable for broader clinical use without observed adverse effects.

9
Vascularizing neurospheroids to probe vascular contributions to α-synuclein pathology in Parkinson's disease

Alim, A.; Lwin, S.; Saha, P.; Baek, Y.; Lee, M.; Paek, J.

2026-08-31 bioengineering 10.64898/2026.08.28.747883 medRxiv
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Neurodegenerative diseases are increasingly associated with vascular dysfunction beyond progressive neuronal degeneration, yet how vascular pathology contributes to disease progression remains poorly understood, largely due to the lack of a neurodegenerative disease model capable of capturing neuronal pathology alongside associated vascular dysfunction. Here, we developed a microengineered 3D vascularized brain tissue model that integrates neurospheroids with a self-assembled, perfusable vascular network to recapitulate key features of the neurovascular interface. Using this model, we investigated the vascular contribution to Parkinson's disease pathology by introducing -synuclein preformed fibrils into the engineered vasculature. Intravascular -syn fibril exposure induced endothelial barrier disruption, vascular leakage, inflammation, and vascular regression. Notably, this vascular insult was accompanied by intraneuronal -synuclein aggregation within neurospheroids, suggesting that vascular dysfunction may facilitate the exposure of neural tissue to pathogenic -synuclein. Our neurodegenerative disease modeling approach establishes a versatile and tractable platform for investigating vascular contributions to neurodegenerative disease progression.

10
Low-Density Lipoprotein Modulates Plasma Fibrin Network Architecture and Impairs Fibrinolysis

Nameny, A.; DeSmet, A.; Cai, C.; R. Baker, S.; Bonin, K.; E. Hudson, N.; E. Bannish, B.; Guthold, M.

2026-09-01 biophysics 10.64898/2026.08.31.748310 medRxiv
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Low-density lipoprotein (LDL) is a major atherogenic lipoprotein, yet its potential to directly modify the fibrin scaffold of blood clots is incompletely understood. Here, we investigated how LDL alters plasma fibrin network architecture and internal fibrinolysis across defined fibrinogen/thrombin conditions. Pooled normal human plasma was supplemented with LDL and clotted with controlled concentrations of fibrinogen and thrombin. Fibrin architecture was visualized by confocal microscopy and quantified by pore-size analysis; clot formation and lysis were monitored turbidimetrically in the presence of tissue plasminogen activator (tPA). Increasing LDL produced a pronounced reduction in fibrin-network pore size across the tested fibrinogen/thrombin conditions. The LDL dependence of pore diameter was well described by a power-law relationship, D_pore=(6.54 +/- 0.11)[LDL]^(-0.12 +/- 0.02) , (R^2 = 0.90), with a significant negative LDL exponent (p = 4 x 10^5). Increasing LDL also prolonged clot lysis time and altered turbidity kinetics. These findings extend epidemiologic and clinical associations between ApoB-containing lipoproteins and hypofibrinolytic clot phenotypes by demonstrating, in a controlled plasma system, that LDL itself can modify fibrin network architecture and fibrinolytic susceptibility. The results support a structure-function role for LDL within the fibrin biomaterial and motivate direct tests of LDL incorporation, protofibril packing, fibrinolytic-protein binding, and single-fiber mechanics.

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Postoperative analgesia and recovery after minimally invasive cardiac surgery

Note, H.; Kajiura, T.; Muramatsu, A.; Inagaki, Y.; Takahashi, T.; Sato, K.; Nakamura, K.; Sadatoshi, T.; Sakurai, Y.; Tochii, M.; Watanuki, H.; Matsuyama, K.; Okamoto, S.

2026-08-31 intensive care and critical care medicine 10.64898/2026.08.27.26361580 medRxiv
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Introduction Postoperative analgesic management after minimally invasive cardiac surgery (MICS) should facilitate early recovery while providing adequate pain control. However, direct evidence comparing postoperative remifentanil- and fentanyl-based analgesic strategies after MICS remains limited. We compared these strategies and explored their associations with postoperative recovery, postoperative nausea and vomiting (PONV), and pain management. Methods This retrospective single-center observational cohort study included patients who underwent MICS via a right mini-thoracotomy between January 2023 and June 2026. Patients were categorized according to postoperative remifentanil- or fentanyl-based analgesia in the intensive care unit. Outcomes included time to extubation, PONV, postoperative pain assessed using the numerical rating scale (NRS), additional analgesic use, and intensive care unit length of stay. Multivariable logistic regression examined the association between postoperative opioid strategy and PONV, adjusting for age, sex, and smoking history. Results PONV occurred less frequently in the remifentanil group than in the fentanyl group (20.6% vs 45.0%, P = 0.004), and this association remained significant after adjustment (adjusted odds ratio, 0.23; 95% confidence interval, 0.10-0.56; P = 0.001). Time to extubation was shorter with remifentanil (median, 179 [interquartile range, 134-240.5] vs 247 [190.2-276.5] min; P < 0.001). In contrast, NRS pain scores on postoperative day 0 were higher with remifentanil (3 [1-6] vs 1 [0-2]; P < 0.001), and additional analgesics were used more frequently (80.6% vs 33.3%; P < 0.001). Pain scores on postoperative day 1 did not differ significantly between groups. Conclusion Postoperative remifentanil-based analgesia after MICS was associated with less PONV and earlier extubation but also with greater early postoperative pain and more frequent additional analgesic use than fentanyl-based analgesia. Appropriate transition to longer-acting analgesics with multimodal analgesia may help preserve the potential benefits of remifentanil while maintaining adequate postoperative pain control.

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Elevated hydrostatic pressure modulates endothelial junctional mechanotransduction through VE-cadherin remodelling and altered association with YAP1, EPS8: an endothelium-on-chip study

Vasanthi Bathrinarayanan, P.; Abadie, T.; Vigolo, D.; Simmons, M. J. H.; Grover, L. M.

2026-09-01 bioengineering 10.64898/2026.08.31.748221 medRxiv
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Endothelial dysfunction is a hallmark of numerous vascular pathologies and is strongly influenced by mechanobiological forces within the vascular microenvironment. While the effects of shear stress have been extensively investigated, the mechanisms by which elevated hydrostatic pressure regulates endothelial junctional organisation remain sparsely investigated. Here, we employed a microfluidic platform to investigate the combined effects of low shear stress (1.4 dyne/cm2) and elevated hydrostatic pressure (~3972 Pa) on endothelial junctional dynamics. Elevated hydrostatic pressure induced marked remodelling of VE-cadherin junctions, characterised by formation of serrated, finger-like structures accompanied by increased YAP1 nuclear localisation and reduced YAP1-VE-cadherin cytoplasmic colocalisation compared to shear stress alone conditions. Further, elevated hydrostatic pressure also demonstrated an increase in cytoplasmic accumulation of EPS8, an actin adaptor protein, and increased cytoplasmic EPS8-VE-cadherin colocalisation. These observations were accompanied by functional changes marked by increased endothelial permeability, and enhanced THP-1 monocyte adhesion, thus suggesting activation of mechanosensitive pathways linked to dynamic junctional reorganisation. Inhibition of PI3K at elevated hydrostatic pressure exhibited a thin VE-cadherin patterning and increased cytoplasmic EPS8-VE-cadherin colocalisation, thus demonstrating a prominent role for PI3K signalling in regulating the junction organisation. Interestingly, Piezo-1 activation using Yoda1 produced context-dependent effects. Under shear stress alone, Yoda1 promoted YAP1 nuclear translocation, reduced YAP1-VE-cadherin colocalisation, increased endothelial permeability but strikingly did not impact THP-1 adhesion compared to shear stress alone conditions. In contrast, under elevated hydrostatic pressure conditions, Yoda1 significantly reduced both endothelial permeability and THP-1 adhesion while increasing YAP1-VE-cadherin colocalisation and decreasing YAP1 nuclear accumulation. Collectively, these findings identify a previously underappreciated elevated hydrostatic pressure-Piezo-1-PI3K signalling axis that regulates endothelial barrier integrity and pro-adhesive endothelial activation through coordinated regulation of VE-cadherin, YAP1, and EPS8. These results highlight elevated hydrostatic pressure as a unique mechanobiological stimulus, distinct from that of shear stress alone and provide novel insights into mechanisms underlying microvascular dysfunction.

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Spatial Geometry and Prevalence of Tunneling and Undermining in Pressure Ulcers

Frade, S.; Tunyiswa, Z.; Shin, M.; Dirks, R.

2026-09-01 dermatology 10.64898/2026.08.28.26361615 medRxiv
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Background: Pressure ulcers often develop complex three-dimensional morphologies that extend beyond the visible wound surface. Subsurface extensions such as tunneling and undermining create hidden cavities that complicate clinical assessment and wound management. Despite their clinical relevance, the prevalence and spatial characteristics of these subsurface wound morphologies have not been well characterized at scale. Methods: We performed a registry-based analysis using data from the LIFT-OFF Pressure Ulcer Registry, which captures longitudinal clinical documentation of pressure ulcers treated in routine care. The registry included approximately 18,000 patients with 32,000 documented pressure ulcers. Spatial characteristics of tunneling and undermining were analyzed using measurements recorded during routine wound assessments, including tract length, direction, and circumferential extent. Directional and circumferential distributions of subsurface defects were examined to characterize wound geometry. Results: Tunneling was present in 764 of 14,700 full-thickness pressure ulcers (5.2%), whereas undermining occurred in 2,293 wounds (15.6%). Tunneling tracts were typically short and exhibited directional clustering relative to the wound bed. In contrast, undermining demonstrated broader circumferential distributions and frequently involved larger subsurface separations beneath the wound margin. Both morphologies demonstrated distinct spatial patterns across anatomical locations and wound stages. Conclusion: Tunneling and undermining are common subsurface features of pressure ulcers and exhibit distinct spatial geometries. Whereas tunneling manifests as directional tract-like extensions, undermining more frequently produces circumferential tissue separation beneath wound margins. Improved characterization of subsurface wound architecture may enhance assessment of wound complexity and provide information not captured by surface measurements alone. Future studies should evaluate whether these features contribute to wound severity assessment, prognosis, and risk stratification.

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Barriers and facilitators to Medical Emergency Team activation among healthcare professionals: protocol for a multicentre cross-sectional survey in four Swiss hospitals

Goetz, N. S.; Wolfensberger, A.; Ludwig, R.; Schefold, J. C.; Fontana, F.; Kopp Lugli, A.; Berger, D.; Tuchscherer, D.; Suter, R.; Cioccari, L.

2026-09-04 intensive care and critical care medicine 10.64898/2026.09.01.26359689 medRxiv
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Background: Medical Emergency Teams (METs) are intended to provide early expert assessment and treatment for deteriorating hospitalised patients. However, MET activation may occur only after prolonged physiological deterioration. Potential explanations include uncertainty about activation criteria, professional hierarchy, departmental culture, perceived pressure to manage deterioration without help, fear of criticism, and concerns that activation may reflect poorly on professional competence. This study aims to identify modifiable barriers and facilitators to timely MET activation among healthcare professionals caring for hospitalised adults. Methods: This multicentre cross-sectional web survey will be conducted sequentially at four Swiss hospitals: two cantonal hospitals and two tertiary university hospitals. Eligible participants are physicians, nurses, nurses in training, physiotherapists, occupational therapists, and speech and language therapists involved in the care of hospitalised adult patients in areas where MET activation may occur. Staff working primarily in paediatrics, emergency medicine, anaesthesia, intensive care, operating theatres, recovery areas, or outpatient care, and MET members themselves, are excluded. The German-language questionnaire was developed from relevant items identified in published MET and rapid response system surveys and was informed by the revised 14-domain Theoretical Domains Framework (TDF). The TDF was used to assess the theoretical breadth of the candidate item pool and to ensure coverage of all domains judged relevant to timely MET activation. Two physician investigators independently mapped candidate items to the single TDF domain judged most appropriate; disagreements were resolved by consensus. All 14 TDF(v2) domains were judged potentially relevant to the target behaviour, and additional items were developed when relevant domains were not adequately represented. The questionnaire was pilot tested by physicians and nurses. The four prespecified primary outcomes comprise one proximal self-reported behavioural indicator - non-activation despite fulfilment of MET criteria - and three potential determinants of timely activation: perceived pressure to avoid activation, concern that activation may reflect poorly on professional competence, and absence of a departmental culture supporting immediate activation. These outcomes were specified in the protocol and statistical analysis plan before inspection of the pooled multicentre results. The primary professional comparison is physicians versus nurses. Ordinal logistic regression will adjust for hospital, years of professional experience, clinical area, and previous personal MET activation. Secondary outcomes will be analysed descriptively and exploratorily. No comparison by MET maturity will be undertaken. Ethics and dissemination: The project was classified as research outside the scope of the Swiss Human Research Act. Site-specific ethics determinations and institutional endorsements will be reported. Participation is voluntary. Responses are confidential rather than fully anonymous because optional contact details may be entered in the same survey record. Results will be disseminated through a peer-reviewed publication, presentations, and aggregated feedback to participating hospitals. Registration: Because data collection has already been completed at one hospital, the registration will be described as a prospective registration of the pooled analysis rather than a fully prospective preregistration.

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Near-infrared optoacoustic modulation of the blood-brain barrier permeability using size-tuned hyperbranched gold nanoconstructs

Wu, Y.; Ge, Y.; Li, X.; Sun, H.; Zhang, Y.; Li, C.; Chen, G.; Jiang, J.

2026-09-01 bioengineering 10.64898/2026.08.30.748173 medRxiv
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The blood-brain barrier (BBB) constitutes a major bottleneck for the systemic delivery of most therapeutic agents to the central nervous system. Here, we report near-infrared reversible optoacoustic modulation of the BBB permeability (NIR-ROAMBBB), leveraging endothelial tight junction targeting hyperbranched gold nanoconstructs (HBGNCs) to amplify localized optoacoustic transduction under femtosecond laser excitation. We first synthesized HBGNCs with tunable particle sizes (62-150 nm) and consistent branch morphologies via a seed-mediated growth approach, and uncovered a non-monotonic relationship between particle dimension and optoacoustic output, where the 62 nm HBGNCs generated nearly twofold stronger optoacoustic signal than gold nanorods and gold nanostars under matched excitations. Conjugation with BV11 antibodies against junctional adhesion molecule A increased HBGNC endothelial association and cerebral accumulation, enabling focal and fluence-dependent transient BBB opening (3-6 h) under 800 nm femtosecond pulsed laser excitation, as validated by in vitro trans-endothelial electrical resistance measurements, ex vivo Evans blue extravasation staining, and in vivo NIR imaging. Featuring deep tissue penetration of NIR light, robust optoacoustic conversion of HBGNCs, and negligible femtosecond laser-induced photothermal damage, this non-invasive strategy enables precise focal modulation of BBB permeability and potential drug delivery.

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Serial neoGFAP outperforms total GFAP for monitoring and 6-month outcome discrimination after moderate to severe traumatic brain injury: an exploratory single-site cohort study

Wang, K. K.; Cai, G.; Boukholda, K.; Kobeissy, F.; Elbayoumi, E.; Jackson, D.; Tehas, K.; Radeker, K.; DeLizza, A.; Popper, C.; Tsetsou, S.; Robertson, C.; Haskins, W. E.

2026-09-03 intensive care and critical care medicine 10.64898/2026.09.01.26361862 medRxiv
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Background: Serial glial fibrillary acidic protein (GFAP) trajectories have become an important framework for contextualizing evolving secondary-injury pathophysiology after moderate-to-severe traumatic brain injury (msTBI). However, total GFAP pools release and clearance signals that may be less useful for longitudinal bedside decisions than a proteoform-resolved assay. We compared total GFAP with neoGFAP, defined here as calpain-generated GFAP proteoforms intended to index active astroglial proteolysis during the subacute phase. Methods: We analyzed 651 serial serum samples from 95 msTBI patients from a previously described single-site cohort. Total GFAP and neoGFAP were measured on the same MSD platform from 6 to 240 hours after injury. Early (6 to 72 h) and late (96 to 240 h) windows, data-derived tertiles, and serial trajectory summaries were calculated directly from serial samples. Models were benchmarked against age plus admission post-resuscitation Glasgow Coma Scale (GCS) and the admission IMPACT extended risk score using five-fold stratified cross-validation. Outcomes were unfavorable outcome (GOSE 1 to 4), less-than-good recovery (GOSE 1 to 6), Disability Rating Scale (DRS) [&ge;]15, mortality, and neuroimaging worsening at 6 months. Results: The cohort contributed 95 serial biomarker profiles, with 90 participants evaluable for 6-month GOSE and 89 for DRS. Unfavorable outcome occurred in 57/90 (63.3%), and less-than-good recovery in 79/90 (87.8%). For unfavorable outcome, IMPACT plus early neoGFAP reached AUROC 0.85 versus 0.84 for IMPACT plus early total GFAP and 0.81 for IMPACT alone. For less-than-good recovery, IMPACT plus late neoGFAP achieved AUROC 0.90 versus 0.84 for late total GFAP and 0.82 for IMPACT alone. Secondary analyses for DRS, mortality, and neuroimaging worsening showed smaller differences. Conclusions: In this retrospective analysis, neoGFAP provided clearer incremental value than total GFAP for recovery-oriented monitoring, especially when late-window reassessment of patients who remained at risk for less-than-good recovery was required. Results support prospective testing of neoGFAP as a pathophysiology-informed adjunct to serial bedside decision making, repeat-assessment thresholds, and recovery stratification.

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Senotherapeutic role of pemafibrate through autophagy/mitophagy regulation in chronic obstructive pulmonary disease

Matsubayashi, S.; Ito, S.; Hosaka, Y.; Yoshida, M.; Kadota, T.; Hashimoto, M.; Hatano, S.; Maruyama, T.; Fujimoto, S.; Nishioka, S.; Inukai, S.; Fujita, Y.; Minagawa, S.; Hara, H.; Nakada, T.; Nakayama, K.; Ohtuska, T.; Kuwano, K.; Araya, J.

2026-09-02 respiratory medicine 10.64898/2026.08.31.26361865 medRxiv
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Inadequate autophagy promotes smoking-induced cellular senescence involved in chronic obstructive pulmonary disease (COPD) pathogenesis. Transcription factor EB (TFEB) is a master regulator of the autophagy-lysosome axis. For the first time, we investigated the therapeutic potential of pemafibrate, a putative TFEB inducer. COPD lung epithelial cells showed reduced TFEB expression. Pemafibrate enhanced autophagy/mitophagy flux and restored lysosomal acidification observed during cigarette smoke (CS) extract exposure in human bronchial epithelial cells, resulting in reduced cellular senescence. TFEB knockdown demonstrated involvement of pemafibrate-induced TFEB in these effects. Pemafibrate induced TFEB expression, mitigated alveolar enlargement and airflow obstruction, and attenuated the CS-induced increase in static lung compliance in a long-term CS-exposed mouse model. It reduced the CS exposure-induced cellular senescence, possibly through autophagy/mitophagy, as suggested by bulk RNA sequencing of mouse lungs. A retrospective cohort study showed that patients given pemafibrate displayed attenuated FEV1.0 decline compared with those given bezafibrate or fenofibrate. In conclusion, pemafibrate is a promising therapeutic agent for COPD, potentially exerting its effects through the regulation of the TFEB-autophagy/mitophagy-lysosome axis.

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Optimizing Aqueous Humor Liquid Biopsy: Safety and Performance of a Short, Low-Dead-Space Ophthalmic Needle for Anterior Chamber Paracentesis

Singh, A. M.; Yeh, T.-C.; DeBoer, C.; Al-Moujahed, A.; Lin, J. B.; Smith, S. J.; Sanislo, S.; Janjua, K. A.; Lin, T.-C.; Almeida, D. R. P.; Mruthyunjaya, P.; Mahajan, V. B.

2026-09-02 ophthalmology 10.64898/2026.08.26.26361364 medRxiv
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Purpose: To evaluate the safety, procedural performance, sample recovery, and surgeon preference of an ophthalmic needle designed specifically for anterior chamber (AC) paracentesis. Methods: In this multicenter study, AC paracentesis was performed in clinic and operating-room settings using a 32-gauge x 4-mm needle with low dead space. The procedure was evaluated using a standardized physician survey. Prespecified outcomes included procedure-related adverse events (primary outcome), needle entry and handling, aspiration and sample recovery, comparative performance versus a 30-gauge needle, and physician preference for future use. Results: A total of 110 needle uses by eight surgeons were included. No ocular complications occurred, including lens or iris injury, hyphema, AC collapse, wound leak, hypotony, infection, or retinal complication, and no procedure required needle exchange or conversion to another device. Two technical events without ocular sequelae were noted, in which needle entry was partial thickness and did not reach the AC (1.8%; exact 95% CI, 0.2%-6.4%). Physicians rated needle entry, handling and sample recovery as good or excellent. Compared with a 30-gauge needle, the study needle was rated as at least comparable across all assessed domains. All surgeons rated it better or much better for intra-procedural safety and preferred it for future AC taps. Conclusions and Relevance: This short, 32-gauge low-dead-space ophthalmic needle demonstrated a favorable safety profile and was preferred over a 30-gauge needle by all surgeons. As aqueous humor liquid biopsy expands in clinical diagnostics and trials, an ophthalmic-specific needle design may help improve the consistency and safety of aqueous humor collection for molecular analysis and broader clinical use. Keywords: Anterior chamber paracentesis; Aqueous humor; Liquid biopsy; Low dead space; Ophthalmic needle

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Measuring Positive Stress Appraisal Among Nursing Students: Development and Psychometric Evaluation of the Nursing Student Positive Stress Scale (NSPSS)

Yan, H.; O'Brien, A. J.; Yoon, S. H.; Shaw, V.; vakavosaki, k.

2026-09-02 nursing 10.64898/2026.08.30.26361779 medRxiv
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Background: Stress research in nursing education has largely focused on distress, stressors, and negative outcomes, although challenging experiences may also support motivation, confidence, learning, and growth when appraised positively. Objective: To develop and evaluate the psychometric properties of the Nursing Student Positive Stress Scale (NSPSS). Design: A methodological instrument development and psychometric evaluation study. Methods: The NSPSS was developed using a deductive, theory-driven approach informed by the transactional theory of stress and coping and positive psychology perspectives. Content validity was assessed by an international nursing expert panel. Psychometric evaluation used national survey data from nursing students in New Zealand. Of 539 responses, 507 were analysed. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were conducted using separate subsamples. Internal consistency was assessed using Cronbach's alpha and McDonald's omega, and convergent validity through correlation with Perceived Stress Scale-10 scores. Results: Content validity was strong (I-CVI = .88-1.00; S-CVI/Ave = .975; S-CVI/UA = .800). EFA identified a dominant factor explaining 41.38% of variance (loadings = .528-.735). CFA supported a two-context Academic and Clinical Positive Stress model with correlated residuals between five parallel item pairs, chi-square(29) = 60.49, CFI = .970, TLI = .954, RMSEA = .063, SRMR = .065. Internal consistency was good (alpha = .839; omega = .843). NSPSS scores correlated negatively with PSS-10 scores (r = -.298, p < .001). Conclusion: The NSPSS demonstrated strong content validity, preliminary evidence of structural and convergent validity, and good internal consistency reliability for assessing positive stress appraisal among nursing students. Further validation in independent samples is warranted.

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Cross-System Meta-Analysis of Machine Learning Predictors Identifies Value-Specific Risk Drivers and Interactions Underlying Acute Kidney Injury

Chan, H. Y.; Li, D.; Yu, A. S. L.; Kellum, J. A.; Fuhrman, D. Y.; Xu, Q.; Chrischilles, E. A.; Cowell, L. G.; Chandaka, S.; Anzalone, A. J.; Kean, J.; McTigue, K. M.; Mosa, A. S. M.; Taylor, B.; Syed, M.; Waitman, L. R.; Hu, Y.; Liu, M.

2026-09-02 nephrology 10.64898/2026.08.31.26361849 medRxiv
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Background: Current understanding of acute kidney injury (AKI) risk factors remains largely descriptive, offering limited precision into how specific biomarker values or physiologic thresholds influence susceptibility. We aimed to synthesize knowledge from machine learning models trained across multiple health systems to identify generalizable, value-specific risk drivers and biomarker interactions contributing to AKI risk. Methods: We analyzed electronic health records (EHRs) from 785,497 adult inpatients between 2010 and 2019 across nine U.S. academic medical centers within PCORnet. Interpretable gradient boosting machine models were independently developed at each health system to quantify predictor-outcome associations. Meta-regression was applied to integrate these site-level results, characterize nonlinear value-risk relationships, and identify bivariate interactions between predictors. Results: Meta-analysis revealed consistent, value-specific risk drivers across health systems. An increase in glucose from 100 mg/dL to 140 mg/dL was associated with a 1.46-fold higher risk of AKI. Chloride and anion gap also demonstrated elevated AKI risk with risk increases overlapping portions of their reference ranges, with anion gap showing a 1.14-fold increase across 4-12 mmol/L and chloride a 1.28-fold increase across 96-100 mEq/L. Electrolytes including potassium, calcium, and sodium showed quadratic associations with AKI risk. Bivariate meta-regression identified interactions between key predictors, highlighting pathways that jointly modulate AKI risk. Conclusion: This cross-system meta-analysis synthesizes machine learning-derived evidence into clinically interpretable knowledge, revealing how specific biomarker ranges and interactions modulate AKI risk. By moving beyond surface-level associations to quantitative, generalizable physiologic thresholds, these findings provide actionable insights to enhance risk stratification and personalized prevention in hospital care.