Biology subjects

Sarker, S. R.

Publications and source records attributed to Sarker, S. R..

3 recordsLinked to original sources

bioRxiv2024

Harnessing Dye-induced Photothermal Confinement in Lipid Membranes: A Path to NIR-modulated Artificial Synaptic Vesicles

Optical heating coupled with near-infrared (NIR) light and photothermal materials enables thermal confinement within biospecimens, minimizing undesirable thermal damage. Here, we demonstrated that photothermally heating lipid bilayers embedded with a unique phthalocyanine dye (VPc) efficiently perturbs the bilayers, resulting in increased permeability. Notably, microscopic studies revealed that the mechanism causing changes in membrane permeability may not follow the conventional temperature-sensitive liposome model. Furthermore, the heat generated by NIR laser illumination rarely diffused into the surrounding environment, and the dye was located within the bilayers at the molecular level, where it effectively transferred heat to the lipid bilayer. We prepared VPc-embedded liposomes encapsulating acetylcholine (ACh) and demonstrated the NIR laser-triggered release of ACh, creating a concentration jump across a few cells or within a limited single cell region. This method induced Ca2+ flux through ACh receptor stimulation in thermally delicate biospecimens such as C2C12 myotubes and the Drosophila brain.

bioengineering↗

bioRxiv2023

qMaLioffG: A single green fluorescent protein FLIM indicator enabling quantitative imaging of endogenous ATP

The widespread use of fluorescence lifetime imaging microscopy (FLIM) for quantitative imaging is hindered by the limited availability of a FLIM-based genetically encoded indicator using a conventional 488 nm laser. Here, we present qMaLioffG, a single green fluorescent protein FLIM indicator showing a fluorescence lifetime change in ATP concentration within the physiological range. This allows quantitative imaging of endogenous ATP to investigate cellular energy status of different cell types.

biophysics↗

bioRxiv2021

Photothermal Dye-based Subcellular-sized Heat Spot Enabling the Modulation of Local Cellular Activities

Thermal engineering at microscale such as the control and measurement of temperature is a key technology in basic biological research and biomaterials development, which remains challenge yet. Here, we engineered the polymeric nanoparticle, in which a fluorescent temperature sensory dye and a photothermal dye were embedded in its polymer matrices, termed nanoHT. When a near infrared laser at 808 nm is illuminated to the particle, it enables to create the subcellular-sized heat spot in a live cell, where fluorescence thermometry allows the read out of the temperature increment concurrently at individual heat spots. Owing to the controlled local heating, we found that the cell death of HeLa cells was induced at the certain temperature at rate of a few seconds. It should be also noted that the cell death was triggered from the very local heat spot at subcellular level. Furthermore, nanoHT was applied for the induction of muscle contraction of the C2C12 myotube by heat. We successfully showed that the heat-induced contraction took place at the limited area of a single myotube according to the alteration of protein-protein interactions related to the contraction event. These studies demonstrated that even a single heat spot provided by a photothermal material could be very effective in altering cellular functions, paving the way for novel photothermal therapies.

bioengineering↗