BACKGROUND: Circulating tumor DNA (ctDNA) has emerged as a noninvasive biomarker for dynamically monitoring tumors. However, published data on perioperative ctDNA in patients with operable non-small cell lung cancer (NSCLC) are currently limited. METHODS: This prospective study recruited 123 patients with resectable stage I to IIIA NSCLC. Preoperative and postoperative plasma samples and tumor tissue samples were subjected to next-generation sequencing with a panel of 425 cancer-related genes. Peripheral blood samples were collected before surgery, postoperatively within 1 month, and every 3 to 6 months for up to 3 years. RESULTS: After 4 exclusions, 119 eligible patients were enrolled from June 2016 to February 2019. Presurgical ctDNA was detectable in 29 of 117 patients (24.8%) and was associated with inferior recurrence-free survival (RFS; hazard ratio [HR], 2.42; 95% CI, 1.11-5.27; P = .022) and inferior overall survival (OS; HR, 5.54; 95% CI, 1.01-30.35; P = .026). Similarly, ctDNA was detected in 12 of 116 first postsurgical samples (10.3%) and was associated with shorter RFS (HR, 3.04; 95% CI, 1.22-7.58; P = .012). During surveillance after surgery, longitudinal ctDNA-positive patients (37 of 119; 31.1%) had significantly shorter RFS (HR, 3.46; 95% CI, 1.59-7.55; P < .001) and significantly shorter OS (HR, 9.99; 95% CI, 1.17-85.78; P = .010) in comparison with longitudinal ctDNA-negative patients. Serial ctDNA detection preceded radiologic disease recurrence by a median lead time of 8.71 months. CONCLUSIONS: These results suggest that perioperative ctDNA analyses can predict recurrence and survival, and serial ctDNA analyses can identify disease recurrence/metastasis earlier than routine radiologic imaging in patients with resectable NSCLC.

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Compared with commercial polyolefin separators, the poor mechanical performance of electrospun polymeric membranes limits their usage as battery separators. Herein, poly(methyl methacrylate) (PMMA) and SiO2 nanoparticles were introduced into electrospun poly(vinylidene fluoride) (PVdF) membranes to form a PVdF/PMMA/SiO2 nonwoven membrane. A hot‐pressing method controlled the thickness of the electrospun membranes and improved their mechanical performance further. SEM tests show that PMMA partly melts in the composite membrane, which bonds neighboring electrospun fibers to reinforce the mechanical strength of the membrane. Uniformly distributed SiO2 nanoparticles on the electrospun fibers could supply higher resistance to mechanical impact. As a result, the composite membrane shows a high tensile strength (32.69 MPa) and high elongation at breakage (137.50 %). Differential scanning calorimetry and hot oven tests indicate that the composite membrane has excellent thermal stability. Furthermore, the addition of PMMA and SiO2 can decrease the crystallinity of PVdF and further improve the absorption of liquid electrolyte. According to the results of electrochemical tests, the composite membrane exhibits higher ionic conductivity (4.0×10−3 S cm−1) and lower interfacial resistance than those of the Celgard separator. The lithium‐ion cell assembled from the composite membrane exhibits more stable cycle performance, higher discharge capacity (158 mA h g−1), and excellent capacity retention.

The magnetic chitosan nanoparticles were prepared by reversed-phase suspension method using Span-80 as an emulsifier, glutaraldehyde as cross-linking reagent. And the nanoparticles were characterized by TEM, FT-IR and hysteresis loop. The results show that the nanoparticles are spherical and almost superparamagnetic. The laccase was immobilized on nanoparticles by adsorption and subsequently by cross-linking with glutaraldehyde. The immobilization conditions and characterizations of the immobilized laccase were investigated. The optimal immobilization conditions were as follows: 10 mL of phosphate buffer (0.1 M, pH 7.0) containing 50 mg of magnetic chitosan nanoparticles, 1.0 mg·mL -1 of laccase and 1% (v/v) glutaraldehyde, immobilization temperature of 4 ℃ and immobilization time of 4 h. The immobilized laccase exhibited an appreciable catalytic capability (480 units·g -1 support) and had good storage stability and operation stability. The K m of immobilized and free laccase for ABTS were 140.6 and 31.1 μM in phosphate buffer (0.1 M, pH 3.0) at 37 ℃, respectively. The immobilized laccase is a good candidate for the research and development of biosensors based on laccase catalysis.

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