Search bioRxiv⌕ Search

Biology subjects

Naidu, A. S.

Publications and source records attributed to Naidu, A. S..

2 recordsLinked to original sources

A generalizable codesigned platform for solid-state nanopore sensing beyond the capacitive-noise constraints

Solid-state nanopores offer label-free, real-time single-molecule sensing, yet resolving rapidly translocating biomolecules requires high-bandwidth data acquisition, where increased high-frequency noise fundamentally limits reliable recovery of informative events. Here we establish a hardware-software co-designed nanopore sensing platform that overcomes this bandwidth-noise limitation by integrating scalable low-noise device engineering with deep learning-based signal reconstruction. A wafer-scale dielectric-engineering strategy using low-dielectric SU8 photoresist reduces total device capacitance to the picofarad regime and suppresses high-frequency noise by up to fivefold while maintaining facile, controllable and reproducible fabrication. This extends usable acquisition rate to 40 MHz and enables capture of fast molecular features. Combined with a reconstruction neural network trained on synthetic translocation signals embedded in experimentally measured noise, the platform recovers transient blockade sublevels while preserving temporal fidelity. Using engineered DNA molecules carrying dumbbell-like barcodes, we resolve nanometer-scale structural features on sub-microsecond timescales, and experimentally measure translocation velocity within the sub-5 nm regime. Dual-channel measurement on a single nanopore device further demonstrates transferability of the platform by showing robust cross-channel signal reconstruction across distinct baseline noise levels. This platform provides a general route for reliable recovery of previously inaccessible molecular information from high-bandwidth nanopore measurements.

biophysics↗

Non-contact direct sensing of material properties of biomolecular condensate using Scanning Ionic Conductance Microscopy

Biomolecular condensates are important regulators of cellular compartmentalization and biochemical processes. Understanding their material properties is critical to elucidate how they control molecular organization and dynamics within cells. However, quantitatively probing these properties remains challenging due to the wide range of length scales, concentrations, and timescales over which condensates operate, as well as the limited force ranges accessible to current nanoscale mechanical mapping methods. We explored the use of a non-contact 3D imaging tool Scanning Ion Conductance Microscopy (SICM) for stiffness measurements of liquid-liquid phase-separated biomolecular condensates. We focus on the Dhh1 protein, which is a regulator of cytoplasmic processing bodies (PBs) membrane-less cytoplasmic condensates that control the storage and degradation of untranslated mRNA. In our study, we investigate the properties of mCherry2- or His-mCherry2-tagged full-length Dhh1 and N- or C-terminus tail-deletion constructs, as well as the catalytically inactive mutant DQAD, under different pH and incubation times. We mapped both spatial and temporal changes in the material properties of the condensates, highlighting the capabilities of the instrument. We found that the removal of either of the two tails led to an increase in condensate stiffness upon shifting the pH from a stress-associated cellular environment (pH 6.5) to physiological conditions (pH 7.5). Additionally, the choice of protein tags led to vastly different results depending on the pH where mCherry2-Dhh1 exhibited a stiffening going from pH 6.0 to 6.5 while the double-tagged His-mCherry2 did not. Our measurements are verified and corroborated by established techniques such as optical tweezer-based fusion assays and fluorescence recovery after photobleaching (FRAP). Furthermore, we were able to track the same biomolecular condensate sample for up to 20 days getting insights on the ageing and evolution of the condensates. Overall, our study demonstrates the applicability of SICM for direct measurement of the material properties of biomolecular condensate.

biophysics↗