Organic semiconducting donor–acceptor polymers are promising candidates for stretchable electronics owing to their mechanical compliance. However, the effect of the electron‐donating thiophene group on the thermomechanical properties of conjugated polymers has not been carefully studied. Here, thin‐film mechanical properties are investigated for diketopyrrolopyrrole (DPP)‐based conjugated polymers with varying numbers of isolated thiophene moieties and sizes of fused thiophene rings in the polymer backbone. Interestingly, it is found that these thiophene units act as an antiplasticizer, where more isolated thiophene rings or bigger fused rings result in an increased glass transition temperature (Tg) of the polymer backbone, and consequently elastic modulus of the respective DPP polymers. Detailed morphological studies suggests that all samples show similar semicrystalline morphology. This antiplasticization effect also exists in para‐azaquinodimethane‐based conjugated polymers, indicating that this can be a general trend for various conjugated polymer systems. Using the knowledge gained above, a new DPP‐based polymer with increased alkyl side chain density through attaching alky chains to the thiophene unit is engineered. The new DPP polymer demonstrates a record low Tg, and 50% lower elastic modulus than a reference polymer without side‐chain decorated on the thiophene unit. This work provides a general design rule for making low‐Tg conjugated polymers for stretchable electronics.

Zinc finger transcription factors are involved broadly in development and tumorigenesis. Here, we report that the little studied zinc finger transcription factor ZNF382 functions as a tumor suppressor in multiple carcinomas. Although broadly expressed in normal tissues, ZNF382 expression was attenuated in multiple carcinoma cell lines due to promoter CpG methylation. ZNF382 was also frequently methylated in multiple primary tumors (nasopharyngeal, esophageal, colon, gastric, and breast). Ectopic expression of ZNF382 in silenced tumor cells significantly inhibited their clonogenicity and proliferation and induced apoptosis. We further found that ZNF382 inhibited NF-κB and AP-1 signaling and downregulated the expression of multiple oncogenes including MYC, MITF, HMGA2, and CDK6, as well as the NF-κB upstream factors STAT3, STAT5B, ID1, and IKBKE, most likely through heterochromatin silencing. ZNF382 could suppress tumorigenesis through heterochromatin-mediated silencing, as ZNF382 was colocalized and interacted with heterochromatin protein HP1 and further changed the chromatin modifications of ZNF382 target oncogenes. Our data show that ZNF382 is a functional tumor suppressor frequently methylated in multiple carcinomas. Cancer Res; 70(16); 6516-26. ©2010 AACR.

Mechanical failure of π-conjugated polymer thin films is unavoidable under cyclic loading conditions, due to intrinsic defects and poor resistance to crack propagation. Here, the first tear-resistant and roomtemperature self-healable semiconducting composites is presented, consisting of conjugated polymers and butyl rubber elastomers. This new composite displays both record-low elastic modulus (< 1 MPa) and ultra-high deformability with fracture strain above 800%. More importantly, failure behavior is not sensitive to precut notches under deformation. Autonomous self-healing at room temperature, both mechanical and electronic, is demonstrated through physical contact of two separate films. The composite film also shows device stability in the ambient environment over five months due to muchimproved barrier property to both oxygen and water. Butyl rubber is broadly applicable to various Ptype and N-type semiconducting polymers for fabricating self-healable electronics to provide new resilient electronics that mimic the tear resistance and healable property of human skin.

The role of secreted frizzled-related protein (SFRP) genes in gastric cancer remains largely unknown. We determined the frequency and functional significance of SFRPs hypermethylation in human gastric cancer. The expression and methylation status of four SFRP members (SFRP1, 2, 4, and 5) in primary gastric cancer samples was screened. The biological effects of SFRP were analysed by flow cytometry, cell viability assay and in vivo tumour growth in nude mice. Among the four SFRPs, only SFRP2 was significantly downregulated in gastric cancer as compared to adjacent non-cancer samples (Po0.01). Promoter hypermethylation of SFRP2 was detected in 73.3% primary gastric cancer tissues, 37.5% of samples showing intestinal metaplasia and 20% adjacent normal gastric tissues. Bisulphite DNA sequencing confirmed the densely methylated SFRP2 promoter region. Demethylation treatment restored the expression of SFRP2 in gastric cancer cell lines. Forced expression of SFRP2 induced cell apoptosis, inhibited proliferation of gastric cancer cells and suppressed tumour growth in vivo. Moreover, methylated SFRP2 was detected in 66.7% of serum samples from cancer patients but not in normal controls. In conclusion, epigenetic inactivation of SFRP2 is a common and early event contributing to gastric carcinogenesis and may be a potential biomarker for gastric cancer.

A simple and efficient strategy to modulate the self-assembly and solid-state morphology of conjugated polymers has been developed by incorporating various amounts of amide-containing alkyl side chains to high charge carrier mobility conjugated polymers based on diketopyrrolopyrrole (DPP). Synthetically easily accessible and tunable, the incorporation of amide-containing side chains is a direct strategy to promote intermolecular hydrogen bonding between polymer chains and tune the solid-state morphology. Incorporation of 5–30 mol % of amides in the conjugated polymers was performed without a drastic decrease of solubility. The incorporation of hydrogen-bonding moieties allowed for an improvement of the charge carrier mobility in organic field-effect transistors (OFET) devices, which achieved a maximum value of 2.46 cm2/(V s) at 5 mol % of amides. Morphological investigation showed that the intermolecular hydrogen bonds formed between adjacent amide moieties directly affected the lamellar packing of the polymer and aggregation, without affecting the π-conjugation. Therefore, controlled self-assembly of conjugated polymers through hydrogen-bonding side chains is a promising strategy toward more efficient semiconducting polymers for thin film transistors and other organic electronics.

Human colorectal cancer stem cells (CSCs) are tumour initiating cells that can self-renew and are highly tumorigenic and chemoresistant. While genetic mutations associated with human colorectal cancer development are well-known, little is known about how and whether epigenetic factors specifically contribute to the functional properties of human colorectal CSCs. Here we report that the KDM3 family of histone demethylases plays an important role in tumorigenic potential and survival of human colorectal CSCs by epigenetically activating Wnt target gene transcription. The depletion of KDM3 inhibits tumorigenic growth and chemoresistance of human colorectal CSCs. Mechanistically, KDM3 not only directly erases repressive H3K9me2 marks, but also helps to recruit histone methyltransferase MLL1 to promote H3K4 methylation, thereby promoting Wnt target gene transcription. Our results suggest that KDM3 is a critical epigenetic factor in Wnt signalling that orchestrates chromatin changes and transcription in human colorectal CSCs, identifying potential therapeutic targets for effective elimination of CSCs.

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An efficient strategy to modify the mechanical properties of conjugated polymers has been developed through the incorporation of amide moieties.