Biology subjects

Uji-i, H.

Publications and source records attributed to Uji-i, H..

5 recordsLinked to original sources

bioRxiv2026

When lysosomes persist: resolving the proton-sponge paradox in nanoparticle-based intracellular delivery

Proton-sponge-active polymers are widely used in nanomedicine to enhance intracellular delivery, yet the mechanism by which they promote cytosolic release of therapeutic cargo remains under debate. Whether these materials drive complete endolysosomal escape or instead alter lysosomal integrity without full nanoparticle release remains unclear. Here we show that polyethylene imine (PEI), a prototypical proton sponge active polymer, induces lysosomal membrane destabilization rather than full nanoparticle escape. Using PEI-coated mesoporous silica nanoparticles as a model delivery system, we show that PEI promotes cytosolic release of small-molecule cargo while nanoparticles remain confined within membrane-enclosed LAMP1-positive compartments. This behaviour arises from the combination of partial lysosomal membrane permeabilization and lysosomal deacidification, which together enable cargo leakage while impairing detection of lysosomes by pH-dependent probes. Our results resolve a long-standing ambiguity in the nanomedicine field and provide a revised mechanistic framework for interpreting endolysosomal escape in intracellular delivery. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/721565v2_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@74b98org.highwire.dtl.DTLVardef@f405eborg.highwire.dtl.DTLVardef@b0a276org.highwire.dtl.DTLVardef@79f154_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

Cellular Responses to Photothermal Therapy: Heat-Induced ERK Signaling and Intercellular Communication in Solid Tumors

Nanoparticle-mediated photothermal therapy (PTT) shows promise as a standalone cancer treatment but faces clinical challenges due to inconsistent efficacy. Its translation is further hindered by a limited understanding of plasmon-induced heat effects, such as stress responses and intercellular signaling. Here, we investigate how plasmon-induced local heating affects cellular behavior and fate within tumor spheroids by focusing on the activity of the extracellular signal-regulated kinase (ERK). Spheroids were prepared from HeLa cells that express a FRET-based ERK sensor, and ERK activity changes under photothermal stimuli were tracked using a deep-learning program, 3DeeCellTracker. Gold nanostars were used as highly efficient photothermal transducers. Our results revealed significant alterations in ERK signaling patterns upon photothermal stimulation compared to spontaneous ERK activity in untreated spheroids, including changes in the activation frequency, timing, and duration. Notably, photothermal-induced ERK activity propagated across neighboring cells within the spheroid, suggesting intercellular communication. Furthermore, analysis of cell death and division further demonstrated that laser power modulates cellular fate during photothermal therapy. This study provides insights for predicting the therapeutic effects of PPT and guides the rational design of next-generation photothermal strategies. Additionally, our approach demonstrates the potential of FRET-based biosensors and deep-learning tools as powerful methods to study the effects of various therapeutic stimuli on solid tumors at the single-cell level.

cancer biology↗

bioRxiv2024

Nanoparticle Accumulation and Penetration in 3D Tumor Models: the Effect of Size, Shape, and Surface Charge

Preclinical studies have demonstrated that nanoparticles (NPs) hold significant potential for advancing cancer therapy by enhancing therapeutic efficacy while reducing side effects. Their effectiveness in solid tumors is, however, often constrained by insufficient accumulation and penetration. Understanding how the physicochemical properties of NPs - such as size, shape, and surface charge - influence their interaction with cells within the tumor is critical for optimizing NP design. In this study, we addressed the challenge of inconsistent NP behavior by systematically evaluating NP uptake in both 2D and 3D tumor models, and NP penetration in spheroids. Our results showed that larger NPs exhibited higher internalization rates in 2D models but limited penetration in 3D spheroids. Furthermore, negatively charged NPs consistently achieved superior accumulation and deeper penetration than neutral and positively charged NPs. Spherical NPs outperformed rod-shaped NPs in tumor accumulation and penetration. These findings underscore the importance of carefully tailoring NP properties to the complex tumor microenvironment for improved therapeutic outcomes in real tumors.

cancer biology↗

bioRxiv2024

Biocompatible Neodymium-Doped Nanocrystals as Probes for Diffraction-limited, in vitro Temperature Sensing

Localized hyperthermia is a promising approach to cancer therapy. However, its clinical potential is limited by heterogeneous heat distribution within tumors, and advanced methods to measure temperature at the sub-micron level are therefore required. To address this challenge, luminescent nanothermometers, such as lanthanide-doped nanocrystals (Ln-NC) operating in the near-infrared (NIR), have been investigated for accurate spatiotemporal thermal monitoring. In this study, the synthesis of neodymium-doped, sodium yttrium fluoride nanocrystals (Nd-NCs) was optimized to achieve high photoluminescence (PL) intensity by adjusting the dopant concentration and by shelling with inert layers. Standard curves for luminescence-based temperature readout were developed using ratiometric analysis of the temperature-dependent PL spectra in the 850-920 nm biological window, showing excellent linearity and high thermal sensitivity. A silica shell was added to the particles and shown to confer excellent aqueous stability and biocompatibility in A549 lung cancer cells. Finally, luminescent thermal readout was demonstrated in vitro in A549 cells by spectrally resolving the diffraction-limited luminescence spots at a single-particle scale over a clinically relevant temperature range from 20-50 {degrees}C. The application of the developed nanothermometer as preclinical tools for NP-HT characterization could provide crucial information on the therapeutic temperature achieved in and around the tumor area. This could be key to optimizing NP properties and therapeutic parameters, for the development of viable hyperthermal cancer treatments. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=84 SRC="FIGDIR/small/579538v2_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@1b06abdorg.highwire.dtl.DTLVardef@12fa23corg.highwire.dtl.DTLVardef@4439c1org.highwire.dtl.DTLVardef@12bcedd_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2021

Versatile and Robust Method for Antibody Conjugation to Nanoparticles with High Targeting Efficiency

The application of antibodies in nanomedicine is now standard practice in research since it represents an innovative approach to deliver chemotherapy agents selectively to tumours. The variety of targets or markers that are overexpressed in different types of cancers results in a high demand for antibody conjugated nanoparticles which are versatile and easily customizable. Considering upscaling, the synthesis of antibody conjugated nanoparticles should be simple and highly reproducible. Here, we developed a facile coating strategy to produce antibody conjugated nanoparticles using click chemistry and further evaluated their selectivity towards cancer cells expressing different markers. Our approach was consistently repeated for the conjugation of antibodies against CD44 and EGFR, which are prominent cancer cell markers. The functionalized particles presented excellent cell specificity towards CD44 and EGFR overexpressing cells, respectively. Our results indicated that the developed coating method is reproducible, versatile, non-toxic, and can be used for particle functionalization with different antibodies. This grafting strategy can be applied to a wide range of nanoparticles and will contribute to the development of future targeted drug delivery systems.

biochemistry↗