Elizabeth Adeogun | Searcharxiv

arXiv2026

Depletant-DNA Induces Chirality in the Condensed Domains of Lyotropic Liquid Crystals

We report on the phase behavior of solutions of a chromonic liquid crystal, disodium cromoglycate (DSCG) resulting from the presence of DNA that acts as a depletant. We show that DNA (both single and double stranded) can induce phase condensation of DSCG at volume fractions a thousand-fold lower than a commonly studied depletant of similar size, namely polyethylene glycol. Twist angle characterization via polarized optical microscopy reveals DNA introduces macroscopic chirality within the condensed phase, despite being present only in the continuous phase- as confirmed by imaging of fluorescently tagged DNA. UV-vis absorption spectroscopy reveals that the introduction of chirality reduces the absorption coefficient strongly, indicating that induced chirality leads to considerable increase in the average lengths of DSCG aggregates. We also show that DNA at concentrations (~nmol/L) typical for a post amplification event (such as PCR) can induce an isotropic-biphasic phase transition of DSCG enabling a fast optical method to report the presence of DNA. Overall, these findings establish DNA as exceptionally efficient depletants that regulate both phase condensation and chirality transfer in lyotropic liquid crystals and thereby providing a simple optical platform for detection of amplified DNA.

cond-mat.soft↗

arXiv2024

Rapid Sensing of Heat Stress using Machine Learning of Micrographs of Red Blood Cells Dispersed in Liquid Crystals

An imbalance between bodily heat production and heat dissipation leads to heat stress in organisms. In addition to diminished animal well-being, heat stress is detrimental to the poultry industry as poultry entails fast growth and high yield, resulting in greater metabolic activity and higher body heat production. When stressed, cells overexpress heat shock proteins (such as HSP70, a well-established intracellular stress indicator) and may undergo changes in their mechanical properties. Liquid crystals (LCs, fluids with orientational order) have been recently employed to rapidly characterize changes in mechanical properties of cells enabling a means of optically reporting the presence of disease in organisms. In this work, we explore the difference in the expression of HSP70 to a change in the LC response pattern via the use of convolutional neural networks (CNNs). The machine-learning (ML) models were trained on hundreds of such LC-response micrographs of chicken red blood cells with and without heat stress. Trained models exhibited remarkable accuracy of up to 99% on detecting the presence of heat stress in unseen microscope samples. We also show that crosslinking the chicken and human RBCs using glutaraldehyde in order to simulate a diseased cell was an efficient strategy for planning, building, training, and evaluating ML models. Overall, our efforts build towards the rapid detection of disease in organisms, which is accompanied by a distinct change in the mechanical properties of cells. We aim to eventuate CNN-enabled LC-sensors can rapidly report the presence of disease in scenarios where human judgment could be prohibitively difficult or slow.

physics.bio-ph↗