Biology subjects

Jooken, S.

Publications and source records attributed to Jooken, S..

4 recordsLinked to original sources

bioRxiv2024

Optically active, paper-based scaffolds for 3D cardiac tissue engineering

In this work, we report the design and fabrication of a light-addressable, paper-based, nanocomposite scaffold for optical modulation and read-out of in vitro grown cardiac tissue. The scaffold consists of paper cellulose microfibers functionalized with gold nanorods (GNRs) and semiconductor quantum dots (QDs), embedded into a cell-permissive collagen matrix. The GNRs enable cardiomyocyte activity modulation through local temperature gradients induced by near-infrared (NIR) laser illumination, with the local temperature changes reported by the temperature-dependent QD photoluminescence (PL). The micrometer size paper fibers promote the tubular organization of HL-1 cardiac muscle cells, while the NIR plasmonic stimulation modulates reversibly their activity. Given its high spatial resolution, NIR modulation offers an excellent alternative to electrode-based methods for cell activity modulation and is more compatible with 3D tissue constructs. As such, optical platforms based on nanocomposite scaffolds will have a significant impact on the progress of drug screening, toxicity studies, and heart disease modeling.

bioengineering↗

bioRxiv2023

Thermoplasmonic modulation of cardiomyocytes activity with local temperature read-out

Cardiomyocyte beating rate modulation is required in multiple in vitro assays and it is usually done by electrical or optogenetic methods. In this work, we develop and characterize a light-based strategy to modulate the cardiomyocyte beating rate by near-infrared (NIR) controlled plasmonic stimulation. For this purpose, gold nanorods (GNRs) acting as plasmonic heaters and silica-coated quantum dots (QDs) as nanothermometers are attached to surfaces used for cardiomyocyte cultures, while the cell electrophysiological activity is visualized by monitoring calcium transients via calcium imaging. This system is capable of modulating cardiac activity with near infrared-controllable plasmonic heating while measuring local temperature changes owing to the temperature-dependent fluorescence of silica-coated QDs. Table of Contents (TOC) O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/554091v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@4325fcorg.highwire.dtl.DTLVardef@72c48dorg.highwire.dtl.DTLVardef@c60849org.highwire.dtl.DTLVardef@14a1e27_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2021

Label-free imaging of membrane potentials by intramembrane field modulation, assessed by Second Harmonic Generation Microscopy

Optical interrogation of cellular electrical activity has proven itself essential for understanding cellular function and communication in complex networks. Voltage-sensitive dyes are important tools for assessing excitability but these highly lipophilic sensors may affect cellular function. Label-free techniques offer a major advantage as they eliminate the need for these external probes. In this work, we show that endogenous second harmonic generation (SHG) from live cells is highly sensitive to changes in membrane potential. Simultaneous electrophysiological control of a living (HEK293T) cell, through whole-cell voltage clamp reveals a linear relation between the SHG intensity and membrane voltage. Our results suggest that due to the high ionic strengths and fast optical response of biofluids, membrane hydration is not the main contributor to the observed field sensitivity. We further provide a conceptual framework that indicates that the SHG voltage sensitivity reflects the electric field within the biological asymmetric lipid bilayer owing to a nonzero [Formula] tensor. Changing the membrane potential without surface modifications such as electrolyte screening offers high optical sensitivity to membrane voltage (~40% per 100 mV), indicating the power of SHG for label-free read-out. These results hold promise for the design of a non-invasive label-free read-out tool for electrogenic cells.

biophysics↗

bioRxiv2020

Hybrid quantum dot - collagen extracellular matrices for in situ optical monitoring of cardiomyocyte activity by two photon fluorescence

The incorporation of functional nanoparticles in scaffolds for tissue constructs has led to the creation of artificial extracellular matrices that more accurately mimic the cues present in the native microenvironment of developing tissue. Additionally, light-sensitive inorganic nanoparticles can act as cell biosensors and report on the physiological parameters during tissue growth and organization. In this work, we functionalized collagen nanofibers with semiconductor quantum dots (QDs) and thereby created artificial extracellular matrices that can optically report on cardiomyocyte activity based on QD two-photon fluorescence. We have applied these optically-addressable nanofiber matrices to monitor activities of primary cardiomyocytes and compared the optical responses with patch-clamp data. Combining the long-term stability of QD fluorescence with the deeper light penetration depths achievable through multiphoton imaging, this approach can be used for continuous monitoring of cellular functions in cardiac tissue engineering. Abstract FigureConcept illustration: optical readout of cardiomyocyte activity with QD-functionalized collagen networks. Whole-cell current-clamp mode is used here to simultaneously monitor changes in the transmembrane voltage while the QD two-photon fluorescence is recorded. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/990846v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@55d3d1org.highwire.dtl.DTLVardef@c56892org.highwire.dtl.DTLVardef@5449a3org.highwire.dtl.DTLVardef@1ae7ce9_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗