While advances in microfluidics have enabled rapid and highly integrated detection of nucleic acid targets, the detection sensitivity is still unsatisfactory in the current POC (point-of-care) detection systems, especially for low abundance samples. In this study, a chip that integrates rapid nucleic acid extraction based on IFAST (immiscible phase filtration assisted by surface tension) and digital isothermal detection was developed to achieve highly sensitive POC detection within 60 min. Based on the interface theory, the factors influencing the interface stability of the IFAST process were studied, and the IFAST nucleic acid extraction conditions were optimized to increase the nucleic acid extraction recovery rate to 75%. Spiral mixing channel and flow-focusing droplet generation structure were designed to achieve the mixing and sample partitioning by applying negative pressure. A portable microdroplet fluorescence detection device was developed based on smartphone imaging. Validation tests were carried out for quantification of low-abundance cfDNA and detection of mutations.

No abstract

No abstract

Aim. This study investigated changes in small-world topology and brain functional connectivity in patients with optic neuritis (ON) by resting-state functional magnetic resonance imaging (rs-fMRI) and based on graph theory. Methods. A total of 21 patients with ON (8 males and 13 females) and 21 matched healthy control subjects (8 males and 13 females) were enrolled and underwent rs-fMRI. Data were preprocessed and the brain was divided into 116 regions of interest. Small-world network parameters and area under the integral curve (AUC) were calculated from pairwise brain interval correlation coefficients. Differences in brain network parameter AUCs between the 2 groups were evaluated with the independent sample t -test, and changes in brain connection strength between ON patients and control subjects were assessed by network-based statistical analysis. Results. In the sparsity range from 0.08 to 0.48, both groups exhibited small-world attributes. Compared to the control group, global network efficiency, normalized clustering coefficient, and small-world value were higher whereas the clustering coefficient value was lower in ON patients. There were no differences in characteristic path length, local network efficiency, and normalized characteristic path length between groups. In addition, ON patients had lower brain functional connectivity strength among the rolandic operculum, medial superior frontal gyrus, insula, median cingulate and paracingulate gyri, amygdala, superior parietal gyrus, inferior parietal gyrus, supramarginal gyrus, angular gyrus, lenticular nucleus, pallidum, superior temporal gyrus, and cerebellum compared to the control group ( P < 0.05 ). Conclusion. Patients with ON show typical “small world” topology that differed from that detected in HC brain networks. The brain network in ON has a small-world attribute but shows reduced and abnormal connectivity compared to normal subjects and likely causes symptoms of cognitive impairment.

A novel solid-phase microextraction (SPME) method based on molecularly imprinted polymer (MIP) monolith as the sorbent for the selective extraction of thiamphenicol (TAP) in milk and honey was developed. The newly developed MIP monolith was produced using TAP as the template molecule, 4-vinylpyridine (4-VP) as the functional monomer. The TAP-MIP monolith synthesized in a micropipette tip could be connected with syringes in different sizes simply to perform SPME process without any other treatment. The derivated MIP monolith showed high selectivity and enrichment ability for TAP. A simple, rapid and sensitive method for the determination of TAP in milk and honey using polymer monolith microextraction (PMME) based on the MIP monolith combined with high-performance liquid chromatography-photodiodes array detector was developed. Several parameters affecting MIP monolith microextraction were investigated, including the flow rate, volume, pH and salt concentration of sample, the type and volume of washing solution, the type and flow rate of eluent. The recovery of this method for TAP was investigated and high recoveries of 92.9-99.3% from milk and honey were obtained with relative standard deviations less than 4.9%.