Biomimetic Nanofibrillation in Two-Component Biopolymer Blends with Structural Analogs to Spider Silk.

Despite the enormous potential in bioinspired fabrication of high-strength structure by mimicking the spinning process of spider silk, currently accessible routes (e.g., microfluidic and electrospinning approaches) still have substantial function gaps in providing precision control over the nanofibrillar superstructure, crystalline morphology or molecular orientation. Here the concept of biomimetic nanofibrillation, by copying the spiders' spinning principles, was conceived to build silk-mimicking hierarchies in two-phase biodegradable blends, strategically involving the stepwise integration of elongational shear and high-pressure shear. Phase separation confined on nanoscale, together with deformation of discrete phases and pre-alignment of polymer chains, was triggered in the elongational shear, conferring the readiness for direct nanofibrillation in the latter shearing stage. The orderly aligned nanofibrils, featuring an ultralow diameter of around 100 nm and the "rigid-soft" system crosslinked by nanocrystal domains like silk protein dopes, were secreted by fine nanochannels. The incorporation of multiscale silk-mimicking structures afforded exceptional combination of strength, ductility and toughness for the nanofibrillar polymer composites. The proposed spider spinning-mimicking strategy, offering the biomimetic function integration unattainable with current approaches, may prompt materials scientists to pursue biopolymer mimics of silk with high performance yet light weight.

Shear-Induced Precursor Relaxation-Dependent Growth Dynamics and Lamellar Orientation of ß-Crystals in ß-Nucleated Isotactic Polypropylene.

Although a shear flow field and ß-nucleating agents (ß-NAs) can separately induce the formation of ß-crystals in isotactic polypropylene (iPP) in an efficient manner, we previously encountered difficulty in obtaining abundant ß-crystals when these two factors were applied due to the competitive growth of α- and ß-crystals. In the current study, to induce the formation of a high fraction of ß-crystals, a strategy that introduces a relaxation process after applying a shear flow field but before cooling to crystallize ß-nucleated iPP was proposed. Depending on the relaxation state of the shear-induced oriented precursors, abundant ß-crystals with a refined orientation morphology were indeed formed. The key to producing these crystals lay in the partially dissolved shear-induced oriented precursors as a result of the relaxation process's ability to generate ß-crystals by inducing the formation of needlelike ß-NAs. Therefore, the content of ß-crystals gradually increased with relaxation time, whereas the overall crystallization kinetics progressively decreased. Moreover, more time was required for the content of the ß-phase to increase to the (maximum) value observed in quiescent crystallization than for the effect of flow on crystallization kinetics to be completely eliminated. The c-axis of the oriented ß-lamellae was observed to be perpendicular, rather than parallel, to the fiber axis of the needlelike ß-NAs, as first evidenced by the unique small-angle X-ray scattering patterns obtained. The significance of the relaxation process was manifested in regulating the content and morphology of oriented ß-crystals in sheared, ß-nucleated iPP and thus in the structure and property manipulation of iPP.

Graphene Oxide Nanosheet Induced Intrachain Conformational Ordering in a Semicrystalline Polymer.

The physical origin of graphene oxide nanosheet (GONS)-driven polymer crystallization was studied from the perspective of intrachain conformational ordering. Time-resolved Fourier-transform infrared spectroscopy indicated that both conformational ordering and crystallization of isotactic polypropylene (iPP) were obviously accelerated by the presence of GONSs, indicating their efficient nucleation activity for iPP crystallization. Furthermore, the ordering of long helical segments occurred prior to the crystallization of iPP, as revealed by two-dimensional correlation infrared analysis. Compared to pure bulk system, the presence of GONSs was in favor of the formation of long ordering segments, especially at the early stage, accompanied by considerable enhancement of the crystallization kinetics. GONS-driven iPP crystallization was suggested to be attributed to this GONS-induced intrachain conformational ordering.

[Gene expression signature for lymphatic metastasis of human lung adenocarcinoma].

BACKGROUND AND OBJECTIVE: Distant metastasis is a major cause of mortality for patients with lung adenocarcinoma. So far, the mechanism of tumor metastasis is unknown. This study was to screen the gene expression signature in relation to lymphatic metastasis of human lung adenocarcinoma. METHODS: Primary lung adenocarcinoma tissues and regional lymph nodes were obtained from 22 patients underwent radical resection. The samples were classified into three groups: 11 cases of primary lung adenocarcinoma without lymphatic metastasis (TxN-), 11 cases of primary lung adenocarcinoma with lymphatic metastasis (TxN+), and 11 cases of the corresponding tumor cells from metastatic lymph nodes(N+). Total RNA was extracted from laser microdissected tumor samples. Adequate RNA starting materials from the primary tumors or metastatic nodes were labeled and then hybridized into the same microarray containing 6000 known human genes or expressed sequence tags (ESTs). After scanning, data analyses were performed using GeneSpring 6.2. RESULTS: Among 17 differentially expressed genes between the TxN+ and TxN-groups, 12 genes were significantly elevated and five genes were significantly downregulated in the TxN+ group compared with the TxN-group. There were 53 differentially regulated genes between the N+ and TxN+ groups, among which 25 genes were overexpressed and 28 genes were suppressed in the N+ group. CONCLUSION: The combination of early oncogenic alterations and later acquisition of a set of genetic alterations may determine the metastatic potential of lung adenocarcinoma.

Observation of circulating tumour cells in patients with non-small cell lung cancer by real-time fluorescent quantitative reverse transcriptase-polymerase chain reaction in peroperative period.

PURPOSE: To assess whether surgical manoeuvre or resection of lung cancer could lead to haematogenous dissemination of malignant cells. In the mean time, the relationship between the sequence of vessel ligation and the haematogenous dissemination of cancer cells during operation was determined. METHODS: Exploiting cytokeratin 19 (CK19)/carcinoembryonic antigen (CEA) mRNA as markers, 69 peripheral blood samples were collected from 23 consecutive patients with non-small cell lung cancer (NSCLC) who underwent surgical resection with curative intention in preoperative, intraoperative and postoperative period, respectively. Before the operation, all patients were randomly assigned to one of the two surgical procedure groups according to the order of vessel ligation, PV-first group and PA-first group. Additionally, the ten patients with benign lung disease served as control subjects undergoing surgical resection. The quantity and timing of the shedding of lung cancer cells into the circulation of patients were also monitored by fluorescent quantitative-reverse transcriptase-polymerase chain reaction before, during and after surgery. RESULTS: (1) The CK19 diagnostic test: the value of CK19 mRNA in operation was significantly higher than that of preoperation (5.246+/-0.196 vs. 4.472+/-0.164, P=0.000) and postoperation (5.246+/-0.196 vs. 4.694+/-0.177, P=0.013). The values between adenocarcinoma and squamous carcinoma were strikingly different (4.9110+/-1.0315 vs. 4.1891+/-0.4126, t=2.364, P=0.028). The values between PV-first group and PA-first group during perioperative period appear to be different (4.503 vs. 5.085, P=0.086). Before operation, of the 23 cases studied, 14 cases were positive (60.9%). Surprisingly, circulating epithelial cells were detected in two patients resected for benign lung disease. (2) The CEA diagnostic test: the level of CEA mRNA ascended continuously within this period. The postoperative values were significantly higher than those of preoperation (4.874 vs. 4.483, P=0.000) and those of operative day (4.874 vs. 4.537, P=0.000). The values between PV-first group and PA-first group appear to reach statistical significance (4.397 vs. 4.817, P=0.075). At the same time, there was a correlation between preoperative T-stage and perioperative CEA mRNA (4.267 vs. 4.760, P=0.025). Among the 23 cases, 10 cases were positive (43.5%). Both patients with benign lung disease served as control subjects undergoing surgical resection and the volunteers were negative. CONCLUSIONS: A considerable proportion of patients who appear to have resectable NSCLC might be regarded as having systemic disease, which is often undetectable by current tumour staging method. In terms of a marker used for the NSCLC patients who undergo operation, CEA is more suitable than CK19. The CK19-expressing epithelial cells are released intraoperatively into the circulation, meanwhile CEA-expressing tumour cells are disseminated mostly postoperatively. Surgical manipulation could promote the release of tumour cells into the bloodstream, but the ligation of pulmonary vein before the ligation of the pulmonary artery may partly prevent such release during surgery.

Detection of disseminated lung cancer cells in regional lymph nodes by assay of CK19 reverse transcriptase polymerase chain reaction and its clinical significance.

PURPOSE: To set up a molecular method (i.e. RT-PCR) that can be used to detect disseminated tumor cells (DTCs) in regional lymph nodes (LNs) in patients with lung cancer and to evaluate its clinical significance. METHODS: Cytokeratin 19 (CK(19)) was used as marker. Serial dilution study for LC-5 cells (a lung squamous cell line) was performed to detect sensitivity of the molecular protocol. Regional LNs (n = 261) and primary lung cancer tissue (n = 40) were obtained from 40 patients with lung cancer who underwent lobectomy or pneumonectomy. They were randomly categorized into two groups: group I (LN-based study, n = 20) and group II (patient-based study, n = 20). Each LN was halved. One half of a LN was subjected to histological examination (HE) and the other half was subjected to RT-PCR amplification of CK(19) mRNA. The effect on survival was analyzed. The cumulative survival was calculated by the Kaplan-Meier method and compared by the log rank test. The Cox model analyzed the prognostic factors. RESULTS: CK(19) mRNA expressed in all tumor tissues as well as LC-5, PAa cells (a lung adenocarcinoma cell line), but not in normal control LNs. Serial dilution study for LC-5 cells demonstrated that CK(19) mRNA was detectable at a concentration as low as 10 LC-5 cells in 1x10(7) LN cells. There was no significant difference between the detecting result of single LN and that of mixed LNs (P > 0.05). In 18 of 40 patients, the metastasis in regional LNs was found by both HE and RT-PCR. Of 22 patients without pathologically involved nodes, six (27%) were found to express CK(19) mRNA in regional LNs. According to the results of regional LNs in 40 patients by molecular assay, the presence of the CK(19) product in LNs was related to tumor size (chi(2) = 5.76, P < 0.025) as well as cell differentiation of the tumor (chi(2) = 7.08, P < 0.01). Following a median observation time of 26 months (range, 4 to 60 months), patients with DTCs in nodes showed significant shorter disease-free survival duration than node-negative patients (log-rank test, P = 0.001). The independence of this prognostic significance was demonstrated by a multivariate analysis (Cox regression model, P = 0.004). The results diagnosed by HE had no significant effect on prognoses (P = 0.455). CONCLUSIONS: Comparing with HE, RT-PCR can make more accurate assessment of metastatic status in LNs, which is helpful for screening the patients in whom the early subclinical metastasis exists and disclosing the intrinsic regulation of malignant metastasis. The presence of DTCs in LNs is an independent factor for prognosis. Molecular detection of DTCs in LNs is a supplement for current tumor staging in lung carcinoma.