In combining DNA nanotechnology and high-bandwidth single-molecule detection in nanopipettes, we demonstrate an all-electric, label-free hybridisation sensor for short DNA sequences (< 100 nt).Such short fragments are known to occur as circulating cell-free DNA in various bodily fluids, such as blood plasma and saliva, and have been identified as disease markers for cancer and infectious diseases. To this end, we use as a model system a 88-mer target from the RV1910c gene in Mycobacterium tuberculosis that is associated with antibiotic (isoniazid) resistance in TB. Upon binding to short probes attached to long carrier DNA, we show that resistive pulse sensing in nanopipettes is capable of identifying rather subtle structural differences, such as the hybridisation state of the probes, in a statistically robust manner. With significant potential towards multiplexing and highthroughput analysis, our study points towards a new, single-molecule DNA assay technology that is fast, easy to use and compatible with point of care environments. Nanopore devices are a new class of stochastic single-molecule sensors. As nanoscale analogues of the well-known Coulter counter, which is routinely used for cell counting in hospital environments, they have been developed towards fast and label-free DNA sequencing. 1 This feat has now largely been achieved with (modified) biological pores, such as -hemolysin. 2 However, resistive pulse sensing with solid-state nanopores and nanopipettes offers a range of other potential applications.These nanodevices are relatively easy to fabricate (especially nanopipettes 3,4 ) and there is usually considerable flexibility in their design, with regards to the pore dimensions (diameter, channel length,

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are just two of the neurodegenerative diseases characterised by the presence of pathological aggregates. 40% of familiar cases in ALS and FTD have been correlated to expansion of the hexanucleotide repeat (GGGGCC)n, which has been previously shown to assemble into G-quadruplexes (G4s) structures. In this study we investigated the role of nucleic acids and secondary structure formation in the generation of ALS/FTD aggregates, something that has often been relegated as a peripheral effect in the protein-led aggregation. We showed a correlation between the emergence of multimolecular G4s (mG4s) formed by the DNA (GGGGCC)n repeats and the formation of protein free insoluble aggregates. We revealed that the aggregation is dependent on K+ concentration and repeat-length, suggesting that G4-formation plays a role in the the formation of aggregates. G4-structures were detected in the aggregates by staining with the G4-specific fluorescent dye NMM. G4-unfolding promoted by NMM-mediated guanine photo-oxidation led to prompt disassembly of the insoluble aggregates, further confirming a G4-based mechanism. To reinforce the physiological relevance of our observations, we characterised the aggregation of RNA (GGGGCC)n, which is thought to contribute to pathological aggregation in ALS/FTD. We observed that RNA repeats can aggregate at significant lower concentrations compared to DNA, suggesting that under physiological conditions RNA repeats can aggregate in the absence of any protein. Our findings constitute the first evidence supporting the formation of mG4-structures to drive protein-free aggregation, highlighting the potential of mG4s as therapeutic target to for the treatment of ALS and FTD.

Synthetic cells, like their biological counterparts, require internal compartments with distinct chemical and physical properties where different functionalities can be localised. Inspired by membrane-less compartmentalisation in biological cells, here we demonstrate how micro-phase separation can be used to engineer heterogeneous cell-like architectures with programmable morphology and compartment-targeted activity. The synthetic cells self-assemble from amphiphilic DNA nanostructures, producing core-shell condensates due to size-induced de-mixing. Lipid deposition and phase-selective etching are then used to generate a porous pseudo-membrane, a cytoplasm analogue, and membrane-less organelles. The synthetic cells can sustain RNA synthesis via in vitro transcription, leading to cytoplasm and pseudo-membrane expansion caused by an accumulation of the transcript. Our approach exemplifies how architectural and functional complexity can emerge from a limited number of distinct building blocks, if molecular-scale programmability, emergent biophysical phenomena, and biochemical activity are coupled to mimic those observed in live cells.

The wet-web strength of paper immediately after the press section of a paper machine is a critical factor in determining machine runnability. However, it is difficult to determine at commercial scale, because the web has to be broken and production interrupted in order to obtain a sample for measurement. The use of microfibrillated cellulose (MFC) is believed to increase wet-web strength, as it has allowed filler level increases of 10% or more on many commercial paper machines. In this paper, we describe a laboratory method for estimating the effect of MFC on wet sheet strength after pressing, as well as actual measurements of wet-web strength from a pilot paper machine trial. These experiments have demonstrated the positive effect of MFC. At solids contents in the range typically observed after pressing, sheets with MFC at fixed filler content are significantly stronger, but also wetter, than those without it. When the use of MFC is combined with a typical increase in filler content, the wet web remains slightly stronger, but also becomes drier than the reference condition. These results are compatible with the theory put forward by van de Ven that wet-web strength is mainly a result of friction between entangled fibers, and they also suggest that the presence of MFC increases this friction.