Biology subjects

Demirel, M.

Publications and source records attributed to Demirel, M..

4 recordsLinked to original sources

bioRxiv2026

Endomicroscopic fluorescence lifetime imaging enables molecular detection and targeted sampling in the distal human lung

PurposeAccurate molecular characterisation of infection and inflammation within the distal human lung remains challenging, particularly in critically ill patients, due to limited access to the alveolar space and delayed diagnostic workflows. Molecular imaging approaches capable of real-time detection and targeted sampling could substantially improve diagnostic precision and the future translational development of molecular imaging probes and therapeutics. MethodsIn a preclinical setting, we evaluated a clinic-ready endomicroscopic fluorescence lifetime imaging microscopy (eFLIM) platform combined with molecularly targeted SmartProbes for in situ detection of bacteria and activated neutrophils in the distal human lung. A multifunctional 1.9-mm diameter imaging and sampling catheter (Eyes on Target; EoT) enabled real-time fluorescence intensity and lifetime imaging alongside directed alveolar microlavage via a 1.2-mm working channel. Fluorescence intensity and lifetime signatures of Gram-negative bacteria, Gram-positive bacteria, and activated neutrophils were characterised using three wash-free SmartProbes: NBD-PMX, Merocy-Van, and a neutrophil activation probe (NAP). Imaging and sampling performance were assessed in ventilated ex vivo human lungs. ResultsEoT reliably navigated to alveolar regions across all lung lobes in both phantom and ventilated human lung models. eFLIM distinguished alveolar microanatomy and enabled probe-specific molecular detection within the distal lung. Increased NBD-PMX signal was detected in Escherichia coli-instilled lobes, while Merocy-Van lifetime signatures selectively identified Staphylococcus aureus-instilled regions. Activated neutrophils were detected throughout lung tissue following NAP administration. Directed alveolar microlavage enabled recovery of cellular material and bacterial DNA from imaged regions for downstream analysis. ConclusioneFLIM using EoT combined with molecular SmartProbes enables real-time molecular imaging and targeted sampling within the distal human lung. This platform provides a translatable approach for evaluating infection and inflammation at the alveolar level and supports the clinical development of molecular imaging probes for pulmonary disease.

microbiology↗

bioRxiv2026

Anisotropic Thermal Conductivity in Topologically Networked Protein-MXene Composites

Governing thermal transport in engineered materials creates opportunities to redirect and recover the excess heat generated in electronic and energy-conversion devices. Materials that pair low cross-plane thermal conductivity with high in-plane thermal conductivity are particularly valuable because they confine heat and channel it away from sensitive regions, preventing localized device failure. Two-dimensional crystals are efficient building blocks for such anisotropic thermal conductors, but they are brittle, and the polymer composites used to toughen them usually forfeit much of the intrinsic anisotropy: in conventional percolation-based design, filler fraction is the only handle available, and it governs both in-plane and cross-plane conduction. Here we report a composite of Ti3C2Tx (MXene) nanosheets and squid ring teeth (SRT) inspired recombinant tandem-repeat (TR) proteins in which the protein serves as a molecular template and bridge, setting the spacing between nanosheets with angstrom-level precision through the number of tandem-repeat units and independently of the filler fraction. This structural handle provides a second, independent design parameter. At a fixed MXene loading, the number of repeats tunes the cross-plane conductivity (0.30 to 0.93 W/mK) and, with it, the thermal anisotropy ratio over a wide range (from about 70 down to 17), while the in-plane conductivity stays high (16 to 21 W/mK). We rationalize these trends with a Gaussian Network Model (GNM) of the protein embedded in a two-phase layered medium, which reproduces the measured directional conductivities from a single structural parameter and identifies the protein gallery as the cross-plane bottleneck. Extending the model to a mechanically loaded five-period stack, we find that the anisotropy is robust to reversible compression and twist, changing by only a few percent, so the number of tandem repeats, not the applied strain, is the dominant design handle. Because anisotropy is tuned structurally rather than volumetrically, these protein-MXene composites decouple thermal anisotropy from filler content, pointing toward flexible thermal materials that are not bound by the rules of mixture and percolation.

bioengineering↗

bioRxiv2020

Industrial Waste based Bio-manufacturing of Synthetic Tandem Repeat Protein Fibers

Protein-based fibers are lightweight, biodegradable, have excellent moisture and temperature regulation, and exceptional mechanical properties, but they are limited in production capacity. Biosynthetic protein-based fibers have the potential to overcome these concerns, but large-scale production with high yield (>1g/L) and purity (>%80), as well as low cost (<$50/kg), must be achieved. Here we developed an optimized expression and purification method for biosynthetic tandem repeat proteins, that are inspired from squid ring tooth (SRT) protein using three wetwaste feedstock, corn steep liquor, molasses, and soybean extract. SRT is composed of a highly stiff, naturally occurring bioplastic and these properties arise from the molecular architecture of the constituant proteins, which are segmented co-polymers with alternating semicrystalline and amorphous domains similar to silk. We have developed protocols to use liquid industrial and agricultural waste as feedstock for SRT production, which has the potential to divert waste streams into useful products. We also show that our biosynthetic protein powder, produced at 1 g/L yield and greater than 80% purity, can be manufactured into fibers using conventional split film or wet-spinning approaches.

synthetic biology↗

bioRxiv2016

ULTRAFAST LASER-PROBING SPECTROCOPY FOR STUDYING MOLECULAR STRUCTURE OF POLYMERIC PROTEINS

We report the development of a new technique to screen protein crystallinity quantitatively based on laser-probing spectroscopy with sub-picosecond resolution. First, we show theoretically that the temperature dependence of the refractive index of a polymeric protein is correlated to its crystallinity. Then, we performed time-domain thermo-transmission experiments on purified semi-crystalline proteins, both native and recombinant (i.e., silk and squid ring teeth), and also on intact E. coli cells bearing overexpressed recombinant protein. Our results demonstrate, for the first time, quantification of crystallinity in real time for polymeric proteins. Our approach can potentially be used for screening an ultra-large number of polymeric proteins in vivo.

biophysics↗