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ACS Photonics

American Chemical Society (ACS)

Preprints posted in the last 30 days, ranked by how well they match ACS Photonics's content profile, based on 13 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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From Spectra to Digital Phenotypes: Wearable Multispectral Sensing for Precision Light and Green Space Exposure

Liu, R.; Han, Y.; Lu, H.; Zhou, Y.; Xue, T.

2026-05-18 bioengineering 10.64898/2026.05.14.724799 medRxiv
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Light is a modifiable determinant of health, yet real-world exposure assessment is often reduced to illuminance alone, lacks environmental context, or relies on privacy-sensitive sensing. We present SpectraVita, a low-cost, compact multispectral wearable that continuously samples 11 ultraviolet-to-near-infrared bands and, through a privacy-preserving pipeline without cameras or location tracking, produces interpretable digital phenotypes of lighting environment (natural vs. artificial and source type) and vegetation context alongside standard visual and non-visual light metrics. In extensive in-the-wild recordings spanning diverse scenes, times of day, weather conditions, and light sources, we observe distinctive spectral signatures that enable supervised models to achieve a macro-averaged F1 score of 0.988{+/-}0.004 for light-source classification and green-space detection in boundary-free environments. A sensor-derived normalized difference vegetation index (NDVI) emerges as an explainable, physically grounded marker linking natural light exposure and greenness. Robustness is supported by scenario-shift testing, image-segmentation validation, and mixed-environment experiments that demonstrate sensitivity to partial and transient exposures, as well as by longitudinal stationary monitoring and deployment in a cohort of thousands of participants capturing seasonal and behavioral variability. SpectraVita enables individualized, privacy-preserving, longitudinal monitoring of light and greenness exposure at scale, addressing a key measurement gap for precision and population health studies of daily photic environments.

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Triplet tumbling microscopy enables in situ quantification of protein complex assembly and dynamics

Lazzari-Dean, J. R.; Millett-Sikking, A.; Rao, P.; Jensvold, Z. D.; Baddock, H.; Ingaramo, M.; Nile, A. H.; York, A. G.; Preciado Lopez, M.

2026-05-11 biophysics 10.64898/2026.05.07.723557 medRxiv
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Protein-protein interactions (PPIs) mediate diverse cellular processes, but PPIs are typically characterized using reconstituted in vitro biochemical and biophysical approaches. Current approaches for PPI detection in living cells are limited in the scope of interactions they can capture and often require prior knowledge of the interacting partners. To close this gap, we developed triplet tumbling microscopy (TTM), which reveals the interactions of a tagged protein of interest in cells in real time. TTM reports protein complex size from rotational diffusion ("tumbling") by leveraging infrared-triggerable emission from triplet states to track tumbling over nanoseconds to hundreds of microseconds. These long-lived triplets overcome the size limitations of existing rotational diffusion-based approaches, enabling TTM to measure species from small protein complexes to organelle-scale beads. In living cells, we apply TTM to detect PPIs, quantify fraction bound, and distinguish protein complexes by size. We measure diverse types of interactions, including rapamycin-induced dimerization, p53 homo-oligomerization, and binding of the E3-ligase E6AP to the human papilloma virus 16 E6 protein. The required hardware is compatible with most fluorescent microscopes, making TTM a versatile way to extract molecular insights from the complex context of living cells. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/723557v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1e70768org.highwire.dtl.DTLVardef@974813org.highwire.dtl.DTLVardef@1fd122borg.highwire.dtl.DTLVardef@1b3da96_HPS_FORMAT_FIGEXP M_FIG C_FIG

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3D-PAULM: Integrated Photoacoustic Tomography and Ultrasound Localization Microscopy for Multiparametric Brain and Tumor Imaging

Xu, Y.; Yao, R.; Sheng, H.; Wang, N.; Yu, X.; Cai, X.; Cai, J.; Luo, J.; Li, J.; Yang, W.; Song, P.; Verkhusha, V.; Yao, J.

2026-05-05 bioengineering 10.64898/2026.04.30.722008 medRxiv
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Understanding processes such as blood-brain barrier (BBB) disruption and tumor progression can greatly benefit from simultaneous molecular, functional, and hemodynamic imaging in deep tissue, yet few existing imaging modalities can provide all three in a single system. Here, we present an integrated imaging platform that combines 3D photoacoustic tomography with ultrasound localization microscopy (3D-PAULM) to enable intrinsically co-registered, multiparametric imaging. 3D-PAULM unifies multispectral photoacoustic molecular imaging, ultrasound B-mode imaging, microbubble-enhanced power Doppler, and ultrasound localization microscopy, and concurrently measures blood oxygenation, blood perfusion, microvascular flow dynamics, and molecular probes from near-infrared dyes and photoswitchable phytochromes. We apply 3D-PAULM to quantify BBB leakage in focal ischemia and systemic inflammation, and to perform high-sensitivity molecular imaging of solid tumors alongside functional mapping of tumor hypoxia and super-resolved vascular remodeling. Together, these results establish 3D-PAULM as a versatile platform for integrated functional and molecular imaging in deep tissue.

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Counting fluorescent emitters with a single photon avalanche diode array

Seitz, C.; Evans-Molina, C.; Liu, J.

2026-05-05 biophysics 10.64898/2026.05.01.722215 medRxiv
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For decades, the photon counting histogram (PCH) was used as the sole method to quantify fluorophore numbers in a diffraction-limited focal volume. This technique combines spatial excitation profiles, and the distribution of photon counts to register the photon emission statistics of individual fluorophores. However, this approach has not yet been transferred to widefield fluorescent imaging due to the lack of fast and single photon sensitive camera sensors which can capture the photon emission statistics of a single fluorophore. Here, we explore avenues towards quantitative analysis of the active fluorophore number by leveraging recent advancements in single photon avalanche diode (SPAD) array technology. Binary exposures of a SPAD array can be synchronized with picosecond laser pulses to measure the PCH in a widefield setting. Then, by modeling the statistical relationship between the active fluorophore number and the PCH in a region of interest following a laser pulse, we can perform Bayesian inference of this number. The model is demonstrated experimentally by counting quantum dots and various numbers of fluorescent dye molecules bound to DNA origamis. We find that this method has several important applications in widefield microscopy, including enhanced localization microscopy and constrained fitting of multiple unresolvable fluorescent emitters.

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Facility-Scale Workflows for Data Acquisition, Standardization, Machine Learning Analysis, and Reproducible Science

Madugula, S. S.; Brown, S. R.; Bible, A. N.; Solsona, R. M.; Checa, M.; Massenburg, L.; Williams, A. N.; Collins, L.; Harris, S. B.; Morrell-Falvey, J.; Retterer, S. T.; Vasudevan, R. K.

2026-05-11 microbiology 10.64898/2026.05.06.723241 medRxiv
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Scientific user facilities routinely generate large-scale microscopy datasets across diverse instruments and vendors, differing substantially in file formats, dimensionality, and resolution. Beyond these inconsistencies, datasets are frequently fragmented living across isolated instruments and constrained by security policies and uneven metadata practices. Consequently, tracking, standardizing, processing, and visualizing these datasets in a manner compatible with modern machine learning and autonomous experimentation workflows remains a major challenge. While existing initiatives address data archiving, standardization, or analysis individually, few provide integrated solutions that bridge instrument-level acquisition and scalable ML workflows within heterogeneous, security-constrained user facilities. Here, we establish a deployable, facility-scale infrastructure that bridges instrument-level data generation with cloud-based ML analytics while remaining compliant with institutional network constraints. Our framework integrates on-premises cloud computing, the in-house Pycroscopy ecosystem, and an open-source metadata management platform to transform heterogeneous microscopy datasets into standardized, ML-ready representations. We demonstrate this approach across distinct microscopy modalities through end-to-end workflows encompassing metadata capture, format harmonization, automated database ingestion, segmentation-based ML inference, and interactive visualization. By structurally separating acquisition from cloud-based analysis services, the framework enables scalable model deployment and iterative refinement without direct connectivity to instrument computers. Together, this work provides a reproducible blueprint for facility-scale data and AI infrastructure, enabling ML-ready analytics, metadata traceability, and future autonomous experimentation workflows in microscopy-driven research.

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Three-Dimensional Photoacoustic Tomography with Ultrasound Localization Priors

Huo, H.; Xu, Y.; Yao, R.; Lowerison, M.; Song, P.; Yao, J.

2026-05-07 bioengineering 10.64898/2026.05.04.722751 medRxiv
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Three-dimensional photoacoustic tomography (3D-PAT) enables noninvasive structural and functional imaging with optical absorption contrast and ultrasonic detection depth. However, its spatial resolution is limited by acoustic diffraction, and incomplete detection geometry can substantially degrade image fidelity and quantitative accuracy. Here, we present a ULM-guided model-based reconstruction framework, termed 3D-PAULMprior that incorporates sub-diffraction vascular priors from concurrent ultrasound localization microscopy (ULM) into 3D photoacoustic reconstruction. The method uses weighted regional Laplacian regularization to integrate high-resolution vascular information into the inverse problem, thereby enhancing vascular sharpness, suppressing limited-view artifacts, and improving blood oxygen saturation estimation. We validated 3D-PAULMprior using numerical simulations, tissue-mimicking phantoms, and in vivo mouse brain imaging. Compared with conventional reconstruction, 3D- PAULMprior improved spatial resolution by over 50%, increased contrast-to-noise ratio by 261.2%, and enhanced structural similarity index by 24.6%. In vivo, 3D-PAULMprior recovered vascular structures that were poorly resolved or missing in conventional reconstructions and produced more spatially confined sO2 maps. These results establish 3D-PAULMprior as a robust multimodal reconstruction strategy for high-resolution structural and functional photoacoustic imaging.

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Dynamic visualization of physiological CaMKII activity using sensitive FRET biosensors

Mehta, S.; Thaker, N. A.; Adachi, K.; Ko, C. Y.; Liu, B.; Divkaruni, S. S.; Koc, O. C.; Lyons, A. C.; Sanchez, S. A.; Löffler, P.; Nakahata, Y.; Martin, J. L.; Johnson, J. L.; Yaron-Barir, T. M.; Cantley, L. C.; Lohse, M. J.; Bock, A.; Bers, D. M.; Yasuda, R.; Fissore, R.; Huganir, R. L.; Stratton, M. M.; Zhang, J.

2026-05-22 bioengineering 10.64898/2026.05.20.726522 medRxiv
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Calcium-calmodulin (CaM)-dependent protein kinase II (CaMKII) is a key mediator of complex physiological processes throughout the body, from the brain to the reproductive system, where CaMKII translates spatiotemporally dynamic calcium elevations into specific biological functions. Directly visualizing CaMKII activity dynamics in living cells using genetically encoded fluorescent biosensors can thus provide crucial insights into the molecular regulation of health and disease. Yet the ability to sensitively and specifically monitor endogenous CaMKII activity in physiologically relevant contexts is limited by the lack of sensors that can achieve robust, quantitative visualization of CaMKII responses. Here, we leveraged a recent serine/threonine kinome-wide substrate atlas to rationally engineer a powerful suite of Forster resonance energy transfer (FRET)-based CaMKII kinase activity reporters with high specificity, sensitivity, and signal-to-noise ratio. Using these biosensors, we were able to sensitively and robustly visualize endogenous CaMKII activity dynamics in both cultured cell lines and primary cells, including cardiomyocytes, oocytes, and neurons. We further utilized 2pFLIM imaging of organotypic hippocampal slices to quantitatively track LTP-induced CaMKII activity within single dendritic spines, highlighting a major advance in the study of physiological CaMKII signaling.

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Two-dye-imager DNA-PAINT enables volumetric nanoscopy of expanded cells

Sauer, M.; Weingart, J.; Eilts, J.; Kiesel, C.; Perozhy, H.; Kollmannsberger, P.; Helmerich, D. A.; Doose, S.

2026-05-20 biophysics 10.64898/2026.05.18.725916 medRxiv
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Refined single-molecule localization microscopy methods demonstrated superior localization precisions on isolated sample but remain limited by labeling density and imaging speed in cells. Here we combine expansion microscopy (ExM) with two-dye-imager (TDI)-DNA-PAINT to resolve fine molecular details of protein assemblies in [~]8-fold expanded cells with nanometer resolution. Using lattice light-sheet (LLS) microscopy, Ex-TDI-DNA-PAINT provides a robust platform for three-dimensional (3D) volumetric nanoscopy of the molecular organization of cells.

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Super-Resolution Macrophage Imaging via Ultrasound Localization Microscopy and Blinking Nanodroplets

Gotshal Zahavi, S.; Bismuth, M.; Bercovici, T.; Ilovitsh, T.

2026-05-11 bioengineering 10.64898/2026.05.07.723418 medRxiv
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Tracking immune cells deep within living tissue remains a fundamental challenge due to the diffraction-limited resolution of ultrasound imaging and the inability to resolve dense cellular populations. Here, we introduce an intracellular super-resolution ultrasound imaging framework based on stochastic phase-changing nanodroplets (NDs) and ultrasound localization microscopy (ULM). We engineer [~]170 nm perfluorocarbon NDs that undergo reversible, stochastic liquid-gas transitions under acoustic excitation, generating temporally sparse "blinking" signals. Leveraging the intrinsic endocytic activity of macrophages, these NDs are internalized, enabling intracellular contrast generation independent of vascular flow. We validate this approach across imaging scales, from controlled phantoms and in vitro systems to in vivo tumor models, demonstrating robust intracellular blinking, high cell viability, and consistent super-resolution reconstruction in dense cellular environments. The stochastic blinking of internalized NDs provides the temporal separation required to localize individual sources, overcoming a central limitation of conventional ULM. Following systemic administration, ND-labeled macrophages are tracked in vivo after homing to the liver, where super-resolution ULM resolves cellular distributions with a spatial resolution of 26.3 {+/-} 3.2 {micro}m, corresponding to a 6.1-fold improvement over diffraction-limited imaging. This work establishes a previously unexplored paradigm for ultrasound-based intracellular super-resolution imaging, enabling non-invasive visualization of immune cell organization in deep tissue. By introducing spatiotemporally programmable intracellular contrast, this approach expands ultrasound beyond vascular imaging toward functional cellular imaging, with broad implications for immunology, diagnostics, and cell-based therapies.

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Millisecond nonlinear state changes during droplet coalescence identify therapeutic-antibody developability liabilities

St John, A. N.; Holland, J.; Lam, E. S.-H.; Lee, S.; Caramazza, P.; Thomas, A. N.; Shrivastava, S.

2026-05-08 biophysics 10.64898/2026.05.06.723251 medRxiv
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Apohas Liquid State Intelligence Platform (LSIP) records ellipsometric waveforms from injections depositing sub-microgram quantities of antibody drop-by-drop onto a liquid reservoir. We previously showed that a behavioural feature extracted from the waveforms, VIBE1, identified antibodies carrying multiple biophysical liabilities in an industrial dataset of 71 monoclonal antibodies, and enriched for clinical failure across a larger dataset of 235 therapeutic antibodies [1]. Here, we use an auxiliary coalescence-sensor channel to decode VIBE1 by separating the coalescence event from its propagation through the substrate. The pertitration drop-to-drop standard deviation of pinch-off time,{sigma}{tau} , explains most of VIBE1s variance across the dataset (R2 = 0.92, n = 1182). High-speed imaging at 10,000 frames per second reveals that all imaged drops initially thin at the same Newtonian capillary-inertial rate while the neck remains wide. In drops from certain antibodies, the thinning bridge then decelerates as internal strain builds in the narrowing neck. This elasto-capillary stiffening response has a timescale{lambda} that decreases as pinch-off time{tau} i increases across the imaged set.{sigma}{tau} is therefore a readout of the antibodys propensity to undergo a transient gel-like stiffening response during coalescence, and that variability is what VIBE1 captures. The signal is concentration dependent, and absent in bovine serum albumin (BSA) tested at up to an order of magnitude higher molarity than the antibodies, despite BSA being a strongly surface-active globular protein. The instrument is configured so that complex behaviours of this kind appear in its recorded waveforms; the gel-like coalescence response we identify here is one such phenomenon.

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In vivo elastography of the human retina using light-evoked intrinsic actuation

Liu, T.; Li, H.; Pandiyan, V. P.; Chen, K.; Bharadwaj, P.; Wendel, B. J.; Mustafi, D.; Chao, J. R.; Ling, T.; Sabesan, R.

2026-05-04 biophysics 10.64898/2026.05.01.722017 medRxiv
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The biomechanical properties of the retina govern its function, structural integrity, and susceptibility to disease, yet remain difficult to measure in vivo due to the lack of safe, spatially localized mechanical actuation. Here, we introduce a framework for probing retinal biomechanics in the living human eye by leveraging intrinsic optical actuation driven by phototransduction. Using phase-resolved optical coherence tomography with a local phase-referencing approach, we resolved signed, nanometer-scale displacements of the major outer retinal interfaces evoked by light. The resulting deformation field, originating in the photoreceptor outer segment, was distributed across retinal compartments in an eccentricity-dependent manner, with efficient axial transfer in the fovea and attenuated propagation in the parafovea. A hybrid analytical and finite-element framework was developed that retrieved the biomechanical properties of the retinal compartments based on their coordinated deformation and the anatomical variation in retinal structure versus eccentricity. In retinitis pigmentosa, the paradigm enabled the detection of light-evoked deformation in the transition zone despite the loss of native lamination, enabling a functional readout of the vulnerable photoreceptors at the leading edge of degeneration. Together, these results establish intrinsic optical stimulation as a basis for in vivo retinal elastography and enable the non-invasive, quantitative imaging of retinal biomechanics and function in the living human retina.

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Mapping the diffusional landscape of short NEAT1 in living cells

Zappone, S.; Perego, E.; Slenders, E.; Diaspro, A.; Oneto, M.; Sunbul, M.; Vicidomini, G.

2026-05-16 biophysics 10.64898/2026.05.13.724860 medRxiv
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The long non-coding RNA NEAT1 is a fundamental architect of nuclear condensates, specifically paraspeckles. While the scaffold-essential isoform NEAT1-2 has been extensively characterized, the function and dynamics of its shorter isoform, NEAT1-1, remain poorly understood. Investigating NEAT1-1 in live cells has been historically hindered by its genomic overlap with NEAT1-2. Traditional visualization study designs require either the genetic ablation of NEAT1-2, which disrupts paraspeckle integrity, or the use of bulky tandem tagging arrays, which can sterically hinder RNA folding and partitioning. Here, we implemented a non-invasive imaging strategy and performed diffusivity analysis of NEAT1-1 using the fluorescence light-up aptamer biRhoBAST. This small, high-affinity RNA tag enables high-contrast visualization of NEAT1-1 while preserving the structural integrity of both isoforms and their associated nuclear bodies. By combining imaging and fluorescence fluctuation spectroscopy, we provide characterization of NEAT1-1 within intact micro-and para-speckles. Our results reveal that NEAT1-1 is not purely sequestered within visible condensates; rather, a fraction exists in a distinct diffusive state within the nucleoplasm, likely as nanoscale complexes. These findings suggest that NEAT1-1 possesses a previously unrecognized regulatory role independent of the primary paraspeckle scaffold, offering new insights into the functional diversity of the lncRNA isoforms.

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High-throughput CRISPR live-cell imaging of low-frequency chromosomal events quantifies the latent efficiency of chromosome engineering

Hu, X.; Iwamoto, Y.; Yamazaki, K.; Kishima, N.; Otaki, N.; Miyamoto, H.; Miyaoka, Y.; Kazuki, Y.; Ota, S.

2026-05-13 bioengineering 10.64898/2026.05.10.724155 medRxiv
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Abstract/SummaryQuantifying low-frequency chromosomal alterations in living cell populations at early stages is essential in many fields including cancer studies and chromosome engineering, yet selection-based readouts impose delays and can lose fragile positives before readout, biasing frequency estimates; CRISPR imaging rarely reports detection limits at 10^-4. Here, we developed High-throughput CRISPR Imaging (Hi-CRI), integrating engineered dCas9-sgRNA ribonucleoprotein (RNP) labeling, suppression of nonspecific aggregates via metabolic modulation and protease treatment, high-speed volumetric imaging by oblique plane microscopy, GPU-accelerated image analysis, and an explicit error-controlled detection-limit framework. Using per-cell signal-to-noise ratio calling, Hi-CRI achieves a 0.01% detection limit for target-positive cell fractions. In microcell-mediated chromosome transfer of a mouse artificial chromosome (MAC) into HT1080 recipients, Hi-CRI measured 0.03% MAC-positive cells among 184,235 recipients at day 1 post-fusion, versus 0.0007% by antibiotic-selection-based clonogenic assay at day 8 post-fusion, consistent with substantial loss before readout (pre-readout attrition). Hi-CRI enables viability-preserving, selection-independent quantification of low-frequency chromosomal states. TeaserRare chromosome events can be counted in living cells by high-throughput CRISPR imaging before selection hides them.

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Multi-Stage Singular Value Decomposition for Ultrafast Ultrasound Imaging of Microbubbles

Zhang, G.; Leroy, H.; Rideau, B.; Reygrobellet, A.; Pernot, M.; Deffieux, T.; Ialy-Radio, N.; Pezet, S.; Tanter, M.

2026-05-07 bioengineering 10.64898/2026.05.04.722634 medRxiv
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Microbubble contrast-enhanced ultrasound (CEUS) relies on discriminating nonlinear bubble signals from linear tissue backscattering. While Singular Value Decomposition (SVD) filtering improves this discrimination, existing techniques often fail to retain the slowly-moving microbubble signals from static clutter. Here, we present a novel multi-stage singular value decomposition (MS-SVD) framework for ultrafast CEUS imaging. Our method employs plane-wave transmissions at multiple angles and acoustic pressure levels (implemented via duty-cycle modulation) and alternating transmit polarity. The beamformed data are then processed by three sequential SVD filters: (1) spatial-angular SVD to extract coherent signals across all transmit angles, (2) spatial-pressure SVD to separate linear fundamental and nonlinear harmonic components, and (3) spatiotemporal SVD to isolate moving microbubble echoes from tissue clutter. In in vitro flow phantoms and in vivo rat brain through a cranial window, MS-SVD dramatically improves microbubble detection compared to conventional SVD filtering, MS-SVD yields much stronger vascular contrast and suppresses tissue clutter to a greater extent. The resulting power-Doppler and super-resolution maps are notably cleaner and more complete: MS-SVD detects substantially more microbubble events in ULM, revealing finer vessel details and more accurate flow speeds. By capturing the full acoustic signature of microbubbles (both fundamental and harmonic), MS-SVD achieves higher contrast-to-noise and sensitivity in CEUS. These gains make it a powerful front-end for super-resolution ultrasound localization microscopy and other high-sensitivity microvascular imaging applications.

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Dimensionally traceable 3D microstructures for multimodal microscope calibration

Jiang, J.; Jones, C.; Reid, B.; Tsikritsis, D.; Mingard, K.; Ghai, P.; Kurttila, M.; Shaw, M. J.

2026-05-11 bioengineering 10.64898/2026.05.07.722194 medRxiv
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High-resolution microscopy techniques are used across research and industry to analyse biological systems, from biomolecules to subcellular organelles, multicellular models and tissues. As multimodal imaging workflows and quantitative analysis of bioimaging data become increasingly widespread, there is a growing need for materials and methods to calibrate imaging systems and evaluate the fidelity of generated image data. Here, we present three-dimensional microscopy phantoms fabricated using two-photon photolithography from transparent resins that exhibit both broadband visible autofluorescence and Raman scattering across the fingerprint and C-H stretching regions. Suitable for analysis using optical profilometry, the phantoms were dimensionally calibrated with SI traceability using a metrological confocal microscope. Immersible in air and common aqueous imaging media, the phantoms are compatible with a wide variety of optical microscopy techniques, including one and two-photon excited fluorescence and coherent Raman scattering microscopy. We employed a forked wedge design to validate image deconvolution results and a stacked lattice phantom to recover image distortion matrices under realistic biological imaging conditions. We demonstrate the impact of correcting chromatic offsets and axial scaling errors for a representative application: analysis of a cell seeded scaffold using confocal laser scanning fluorescence microscopy. These phantoms provide a versatile platform for calibration, quality control and validation of multimodal imaging pipelines and improved quantitative optical microscopy.

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Altair-dvOPM: an open-access platform for large-field three-dimensional tissue imaging

Ngo, T.; Faiyazuddin, M.; Nguyen, T. D.; Haug, J.; Shen, Q.; Gałecki, S.; Borges, H. M.; Chen, B.; Wang, X.; Zhu, H.; Pappas, S. S.; Voigt, F. F.; FIolka, R.; Dean, K. M.

2026-05-12 biophysics 10.64898/2026.05.08.723912 medRxiv
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Altair-dvOPM is an open-access direct-view oblique plane microscope designed for large-field, three-dimensional imaging of cleared and expanded tissue sections. By combining photographic-lens-based detection, externally launched oblique illumination and precision-registered modular baseplates, the system achieves micrometer-scale lateral resolution over a ~5.4 mm field of view without custom objectives or highly specialized alignment procedures. We demonstrate imaging across scales, from subcellular structures in expanded cells to centimeter-scale expanded tissue sections, and provide documentation, CAD files, Zemax models and open-source control software to support replication and extension.

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A CandiChrome toolkit for multicolor labeling of Candida cells

Ke, C.-L.; Xu, J.; Frazer, C.; Bennett, R. J.

2026-05-12 microbiology 10.64898/2026.05.11.723596 medRxiv
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Here, we develop CandiChrome, a multiplex labeling toolkit for Candida albicans, through combined in vitro and in vivo characterization of fluorescent proteins in a standard strain background. To this end, we screened 13 candidate fluorophores across the visible spectrum and assessed their practical performance based on brightness, stability, and usability. This analysis identified a seven-fluorophore set that achieved the most effective balance of signal strength, robustness, and compatibility. We used this optimized panel to build a modular multicolor platform that enables strain labeling, mixed-population imaging, and competition assays in C. albicans. This platform could resolve up to 21 distinct populations by flow cytometry and microscopy. Importantly, CandiChrome supported the resolution of differentially labeled populations both in vitro and in the murine host, supporting the simultaneous tracking of multiple strains in complex settings. Together, these results establish CandiChrome as a flexible platform for multiplex fungal imaging in a pathogenic species where multicolor tools remain underdeveloped.

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Quantifying the spatio-temporal image degradation under motion blur in fluorescence microscopy

Korovin, S.; Ugurlu, K.; Kalisvaart, D.; Kok, M.; Heintzmann, R.; Prakash, K.; Smith, C.

2026-05-08 biophysics 10.64898/2026.05.06.723301 medRxiv
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The spatial resolution of optical imaging systems is fundamentally restricted by the diffraction limit. However, in widefield live-cell microscopy, the achievable resolution is further constrained by the specimen motion, which indicates the existence of a fundamental spatio-temporal resolution trade-off between signal accumulation during the full frame integration and the resulting motion blur. To improve the fidelity with which moving objects can be imaged, a quantitative understanding of this spatio-temporal trade-off is necessary. Here, we present a systematic analysis of motion-induced resolution dynamics measured with spectral signal-to-noise ratio (SSNR). We developed a simulation framework which models the image formation of objects undergoing arbitrary motion, to evaluate the degradation of the spatial resolution under translational and rotational dynamics. Our results demonstrate that for translating objects, the spatial resolution is anisotropically reduced as a function of the orientation of the object relative to the motion vector, leading to the spectral signal-to-noise ratio degrading by up to 50% and the resolution by up to 40% for a 90{degrees} change in the motion direction. Furthermore, we show that for rotational motion, conventional radially averaged metrics such as the Fourier Ring Correlation are not able to quantify the effects of angular blur. On the other hand, the SSNR is able to accurately quantify this degradation. These findings underscore the necessity of an object-oriented imaging approach, in which acquisition parameters such as exposure time are tuned to specific biological spatio-temporal characteristics to optimize the trade-off between motion blur and spatial fidelity.

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Novel COX-2 Targeted Nanobodies for Molecular Endoscopic Imaging of Colorectal Adenomas

Uddin, M. J.; Xu, S.; Goodman, M. C.; Aleem, A. M.; Niitsu, H.; Rose, K. L.; Crews, B. C.; Banerjee, S.; DeJulius, C. R.; Hoogenboezem, E. N.; Kingsley, P. J.; Reyzer, M. L.; Klendworth, J.; Milad, M.; Lin, S.; Wadzinski, B.; Spiller, B. W.; Duvall, C. L.; Coffey, R. J.; Marnett, L. J.

2026-05-19 bioengineering 10.64898/2026.05.16.724741 medRxiv
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Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality in men and women. Timely detection and diagnosis are key to management of CRC, which is under-diagnosed because colorectal aberrant crypt foci, hyperplastic polyps, and microadenomas are often missed with conventional colonoscopy. The enzyme cyclooxygenase-2 (COX-2) is overexpressed in early stages of colorectal carcinogenesis and plays an important regulatory role in the process, suggesting that it could be a valuable target for enhanced imaging of nascent disease. Thus, we have generated an alpaca-derived library of 73 COX-2-specific nanobody clones. Here, we describe one such nanobody, F9-K45Q-K77Q-ROX, in which two native lysine residues have been mutated followed by conjugation to a fluorophore at the N-terminus with retention of COX-2-selective binding. The site of fluorophore conjugation and COX-2 binding affinity of F9-K45Q-K77Q-ROX were determined by proteomic and microscale thermophoretic analyses, respectively. In cell culture studies using 1483 human head and neck squamous cell carcinoma cells, F9-K45Q-K77Q-ROX accumulated inside cells and bound to intracellular COX-2, as visualized by fluorescence microscopy. In vivo pharmacokinetic, and toxicological analyses revealed that F9-K45Q-K77Q-ROX is detectable in circulation with a plasma half-life of 17.9 min and there is no short-term toxicity associated with single injections of 10 mg/kg, 20 mg/kg, or 40 mg/kg doses at 24 h post-administration. Noninvasive in vivo fluorescence endoscopic imaging validated tumor-specific accumulation of F9-K45Q-K77Q-ROX in azoxymethane/dextran sodium sulfate-induced colorectal adenomas in mice. This work demonstrates the first COX-2-targeted nanobodies including a fluorescent derivative that offers significant promise for targeted endoscopic imaging of COX-2-expressing neoplasms. Significance StatementCurrent colorectal cancer screening procedures, such as white-light colonoscopy, chromoendoscopy, and narrow-band imaging aim to detect solid colon tumors and precursor lesions. However, these methods tend to detect only raised solid tumors and mature cancers, whereas precursor lesions, such as aberrant crypt foci, hyperplastic polyps, and small adenomas are frequently missed. To address the need for better visualization of early lesions, we developed a library of alpaca-derived nanobodies targeted to cyclooxygenase-2 (COX-2), an enzyme that is overexpressed in colorectal adenomas. COX-2-targeted nanobodies bearing a fluorescent tag accumulate and are retained in colonic adenomas, facilitating their endoscopic visualization. This novel COX-2-targeted nanobody platform may also be valuable for early detection of other neoplastic diseases in which COX-2 overexpression occurs. (Word counts 119, limit 120)

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In Vivo 4D Oxy-Wavelet MRI as a Non-Invasive Biomarker of Brain Mitochondrial Function across the Lifespan

Cortes, D. R. E.; Hartwick, S.; Becker-Szurszewski, T.; Schwab, K. E.; Ruck, C.; Manzoor, S.; Coulson, N. W.; West, D.; Stapleton, M. C.; Wyman, S.; Lo, C. W.-Y.; Bharathi, S.; Goetzman, E. S.; Chirstodoulou, A. G.; Wu, Y. L.

2026-05-23 bioengineering 10.64898/2026.05.21.726892 medRxiv
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Mitochondria are essential for cellular energy production and are particularly critical for brain development and function. Neurons rely predominantly on oxidative phosphorylation for energy production, rendering the brain highly vulnerable to mitochondrial dysfunction. Consequently, impaired mitochondrial function contributes to a broad spectrum of neurological and systemic disorders, making mitochondria attractive therapeutic targets. Despite this importance, there is currently no non-invasive, spatially resolved method to assess mitochondrial function in the intact living brain. Here, we establish a non-invasive functional MRI approach--4D Oxy-wavelet MRI--to probe in vivo mitochondrial electron transport chain (ETC) function in a spatially specific manner across the lifespan, from fetal to adult brains. This method employs a low-rank k-t sub-Nyquist acquisition strategy to achieve simultaneous structural and functional imaging with high spatial (78 m) and temporal ([~]14 ms) resolution, enabling motion-robust imaging in multi-fetal mouse pregnancies. Mitochondrial ETC function is interrogated by measuring oxygen homeostasis responses to brief hypoxic challenges, analyzed using computational time-frequency wavelet profiling. We validate this approach in mouse models of mitochondrial respiratory chain disease and late-onset Alzheimers disease, from in utero fetuses to adults, and demonstrate reproducibility and specificity using pharmacological hyperemia and ETC complex I inhibition. We further show parallel wavelet responses in placenta and fetal brain, enabling multi-organ interrogation of the placenta-brain axis. Finally, we present first-in-human feasibility data, supporting translational potential for non-invasive assessment of mitochondrial function in living brains across the lifespan.