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Self-assembly of synthetic lipid vesicles via lipid membrane fusion is a versatile tool for creating biomimetic nano- and micron-sized particles. These so-called liposomes are used in the development of biosensing platforms, design of drug delivery schemes, and for investigating protein-mediated fusion of biological membranes. This work demonstrates DNA-induced liposome fusion in a nanofluidic trap where the reaction occurs in a 15 femtoliter volume at homogeneous mixing. In contrast to current methods for fusion in bulk, we show that the fusion reaction follows second-order kinetics with a fusion rate of (170 ± 30)/(M−1s−1) times the square number of DNA molecules per liposome. The nanofluidic trapping gives a full characterization of the size and charge of the liposomes before and after fusion. The chip-based approach limits the amount of sample (down to 440 vesicles) and can be parallelized for systematic studies in synthetic biology, diagnostics, and drug delivery.

The central nervous system is lined by meninges, classically known as dura, arachnoid, and pia mater. We show the existence of a fourth meningeal layer that compartmentalizes the subarachnoid space in the mouse and human brain, designated the subarachnoid lymphatic-like membrane (SLYM). SLYM is morpho- and immunophenotypically similar to the mesothelial membrane lining of peripheral organs and body cavities, and it encases blood vessels and harbors immune cells. Functionally, the close apposition of SLYM with the endothelial lining of the meningeal venous sinus permits direct exchange of small solutes between cerebrospinal fluid and venous blood, thus representing the mouse equivalent of the arachnoid granulations. The functional characterization of SLYM provides fundamental insights into brain immune barriers and fluid transport

The properties of soft matter nanoparticles like exosomes are interesting for drug delivery and diagnostics applications. However, the simultaneous characterization of multiple properties, e.g.,size and zeta potential, can only be done serially and is highly sensitive to the purification prior to characterization. Here we show how a salt gradient established in a nanofluidic channel induces opposing transport of particles and liquid that trap the particles. Particles are thus accumulated in the trap. We show how optical microscopy images of the particle positions in the salinity gradient provide a measurement of the size and surface charge. We demonstrate the method on a sample of exosomes and on individual particles. Finally, we show how biomolecular reactions at the surface of the nanoparticle can be detected from the optical microscopy analysis of the particles’ trapping position.

Objective: The objective of this study was to evaluate the long-term predictive value of the Danish Whiplash Group Risk Assessment Score (DWGRAS) with 7 risk strata. Design: E-questionnaire-based follow-up study (n=927) combining 2 cohorts of whiplash-injured patients, 1 observational (n=187) and 1 interventional randomized controlled trial (n=740). Methods: Nine hundred twenty-seven previously healthy persons exposed to acute whiplash injury during motor vehicle collision were sent letter by postal service asking the addressee if they would respond to an E-questionnaire. Outcome measures were: whiplash-related disability, pain, use of medication/nonmedical treatment, work capacity. Results: The response rate was 37%. Fifty-five percent reported whiplash-related disability. Fourteen percent reported daily symptoms. A strong relationship was found between risk strata and impact of event and between risk strata and disabling symptoms. Conclusions: Internal and long-term validation of DWGRAS was performed, but a low response rate indicates that results should be interpreted with caution. Furthermore, external validation needs to be done in long-term studies. An receiver operating characteristics curve of 0.73 (95% confidence interval 0.67; 0.79) predicting daily or weekly whiplash-related disability after 12 to 14 years was found using the DWGRAS risk score.

As a consequence of its ordered pore architecture, mesoporous SBA-15 offers new possibilities for incorporating biological agents. Considering its applicability in oral vaccination, which shows more beneficial features when compared with parenteral vaccines, SBA-15 is also seen as a very promising adjuvant to carry, protect, and deliver entrapped antigens. Recent studies have shown several remarkable features in the immunization of hepatitis B, a viral disease transmitted mainly through blood or serum transfer. However, the surface antigen of the hepatitis B virus, HBsAg, is too large to fit inside the SBA-15 matrix with mean pore diameter around 10 nm, thus raising the question of how SBA-15 can protect the antigen. In this work, thermal analysis combined with neutron spectroscopy allowed us to shed light on the interactions between HBsAg and SBA-15 as well as on the role that these interactions play in the efficiency of this promising oral vaccination method. This information was obtained by verifying how the dynamic behaviour of the antigen is modified under confinement in SBA-15, thus also establishing an experimental method for verifying molecular dynamics simulations.