Privacy-preserving COVID-19 contact tracing solution based on blockchain.

The COVID-19 pandemic has severely affected daily life and caused a great loss to the global economy. Due to the very urgent need for identifying close contacts of confirmed patients in the current situation, the development of automated contact tracing app for smart devices has attracted more attention all over the world. Compared with expensive manual tracing approach, automated contact tracing apps can offer fast and precise tracing service, however, over-pursing high efficiency would lead to the privacy-leaking issue for app users. By combing with the benign properties (e.g., anonymity, decentralization, and traceability) of blockchain, we propose an efficient privacy-preserving solution in automated tracing scenario. Our main technique is a combination of non-interactive zero-knowledge proof and multi-signature with public key aggregation. By means of aggregating multiple signatures from different contacts at the mutual commitment phase, we only need fewer zero-knowledge proofs to complete the task of identifying contacts. It inherently leads to the benefits of saving storage and consuming less time for running verification algorithm on blockchain. Furthermore, we perform an experimental comparison by timing the execution of signature verification with and without aggregate signature, respectively. It shows that our solution can actually preserve the full-fledged privacy protection property with a lower computational cost.

Physicochemical and Preclinical Evaluation of Spermine-Derived Surfactant Liposomes for in Vitro and in Vivo siRNA-Delivery to Liver Macrophages.

Herein we report on a liposomal system for siRNA delivery consisting of cholesterol (Chol), distearoylphosphatidylcholine (DSPC), and surfactant TF (1-hydroxy-50-amino-3,4,7,10,13,16,19,22-octaoxa-37,41,45-triaza-pentacontane), a novel spermine derivative (HO-EG8-C12-spermine) which has shown improved siRNA delivery to cells in vitro and in vivo. Predominantly single-walled liposomes with reproducible sizes and moderately broad size distributions were generated with an automated extrusion device. The liposomes remained stable when prepared in the presence of siRNA at N/P ratios of 17-34. However, when mixed with human serum in equal volumes, larger aggregates in the size range of several hundred nanometers were observed by dynamic light scattering. These larger aggregates could potentially limit prolonged in vivo applications. Aggregate formation could be reduced by the addition of a cholesterol-hyperbranched polyglycerol surfactant (hbPG) that sterically shields the liposomal surface against serum induced aggregation. In vitro experiments with murine macrophages utilizing macrophage-specific anti-CD68 siRNA loaded liposomes showed potent and sequence specific reduction of CD68 transcript levels without cytotoxicity. Experiments in mice using intravenous application of CW800 NHS ester labeled liposomes, near-infrared in vivo imaging, and fluorescent assisted cell sorting of inflammatory cells demonstrated an almost quantitative accumulation of these liposomes, with and without hbPG, in the liver and a specific knockdown of CD68 mRNA of up to 70% in liver resident macrophages. It was found that aggregate formation of TF liposomes in serum does not significantly affect in vivo siRNA delivery to these central inflammatory cells of the liver.

Switchable surface and loading/release of target molecules in hierarchically porous PLA nonwovens based on shape memory effect.

In this work, hierarchically porous PLA (polylactic acid) shape memory nonwovens were prepared by electrospinning its blend solution with PEO (polyethylene oxide) and subsequent water etching. Based on shape memory effect resulting from tiny crystals and the amorphous matrix of PLA, the switch between compact and porous surfaces has been achieved via cyclical hot-pressing and recovery in a hot water bath. After hot-pressing, the disappearance of hierarchical pores contributes to compact surface, enabling embedding of the target molecule in PLA nonwoven (i.e., CLOSE state). Upon exposure to heat, PLA nonwoven recovers to its permanent shape and exhibits a porous surface, providing a penetrative diffusion pathway for small molecules (i.e., OPEN state). The hierarchically porous structure and shape memory effect endow PLA nonwoven with the capability of rapid release. Our results provide a good candidate for some potential applications, such as temperature-controlled quick-release of catalysts and drugs.

Hybrid assemblies based on a gadolinium-containing polyoxometalate and a cationic polymer with spermine side chains for enhanced MRI contrast agents.

Supramolecular assembly: Spherical and stable hybrid assemblies based on a cationic polymer with spermine side chains and an anionic Gd(3+)-containing polyoxometalate cluster (GdW) are prepared by electrostatic interaction. The T1-weighted MRI performance of GdW is enhanced about three times in the assemblies; meanwhile, the assemblies show good biocompatibility, which enables them to be promising candidates for MRI contrast agents.

Application value of plasma Neurofilament light combined with magnetic resonance imaging to comprehensively evaluate multiple sclerosis activity and status.

Objective: Compare the levels of plasma neurofilament light (NfL) in patients with multiple sclerosis (MS) at acute and remission stages and healthy individuals to explore the role of plasma NfL in monitoring the activity and severity of the disease and predicting disease prognosis. Methods: Information on healthy individuals and patients with MS who visited the outpatient and inpatient departments of Inner Mongolia Medical University Affiliated Hospital from October 2020 to August 2022 was collected. EDSS assessment and plain scan+enhanced magnetic resonance imaging (MRI). Plasma Nfl levels were measured using Simoa. Moreover, the relationship between the level of Nlf and the disease status of patients with MS was analyzed.. Results: Through the self-comparison of the plasma NfL levels of MS patients in the acute and remission stages, it was noted that the levels in the acute stage are higher than those in the remission stage (p < 0.001). Among the plasma NfL levels of healthy individuals and MS patients in the acute and remission stages, there were statistically significant differences (p < 0.001). Furthermore, the plasma NfL level did not correlate with age or course of disease (p = 0.614 and p = 0.058), whereas it correlated with EDSS score, the number of MRI T2 subtentorial and spinal cord lesions, and the number of MRI enhanced lesions (r = 0.789, p < 0.001; r = 0.846, p < 0.001; r = 0431, p = 0.005, respectively). Conclusion: Combining the level of plasma NfL with clinical and MRI estimations will be instrumental in monitoring condition changes and optimizing treatments. The level of plasma NfL is related to the activity and severity of MS, and it is expected to become a new biomarker for assessing the activity and disease status of MS.

Self-assembly and alterable relaxivity of an organic cation-encapsulated gadolinium-containing polyoxometalate.

A new amphiphilic molecule bearing poly(ethylene oxide) (PEO) and quaternary ammonium group, was designed and synthesized to encapsulate paramagnetic Gd(III)-containing polyoxometalate (Gd-POM) through electrostatic interaction for obtaining a water-soluble organic-inorganic hybrid building block based on POM. The yielding organic cation-encapsulated Gd-POM (OCEP-Gd) complex exhibited water-solubility and amphiphility, leading to the spontaneous self-assembly into a regular vesicular structure with PEO chains towards water phase and POM units locating at the middle. The vesicular aggregate which has a regular monolayer structure, was further studied by means of dynamic light scattering, transmission electron microscopy, and X-ray diffraction. Due to the synergy of different building units, the self-assembly of the complexes was demonstrated to be efficient to adjust the ability of Gd-POM to accelerate relaxation of water-proton, which results from the paramagnetic property of Gd-POM, to a large extent. The present work provides a new methodology to obtain water-soluble hybrid building blocks based on POM, which may generate more hybrid self-assembly structures in aqueous solution and further direct POM-based materials towards biomedical applications.