A lobule-mimetic cell-patterning technique for on-chip reconstruction of centimetre-scale liver tissue of heterogeneous hepatic and endothelial cells via an enhanced field-induced dielectrophoresis (DEP) trap is demonstrated and reported. By mimicking the basic morphology of liver tissue, the classic hepatic lobule, the lobule-mimetic-stellate-electrodes array was designed for cell patterning. Through DEP manipulation, well-defined and enhanced spatial electric field gradients were created for in-parallel manipulation of massive individual cells. With this liver-cell patterning labchip design, the original randomly distributed hepatic and endothelial cells inside the microfluidic chamber can be manipulated separately and aligned into the desired pattern that mimicks the morphology of liver lobule tissue. Experimental results showed that both hepatic and endothelial cells were orderly guided, snared, and aligned along the field-induced orientation to form the lobule-mimetic pattern. About 95% cell viability of hepatic and endothelial cells was also observed after cell-patterning demonstration via a fluorescent assay technique. The liver function of CYP450-1A1 enzyme activity showed an 80% enhancement for our engineered liver tissue (HepG2+HUVECs) compared to the non-patterned pure HepG2 for two-day culturing.

A novel and disposable microchip (K-kit) with SiO(2) nano-membranes was developed and used as a specimen kit for in situ imaging of living organisms in an aqueous condition using transmission electron microscopy (TEM) without equipment modification. This K-kit enabled the successful TEM observation of living Escherichia coli cells and the tellurite reduction process in Klebsiella pneumoniae. The K. pneumoniae and Saccharomyces cerevisiae can stay alive in K-kit after continuous TEM imaging for up to 14 s and 42 s, respectively. Besides, different tellurite reduction profiles in cells grown in aerobic and anaerobic environments can be clearly revealed. These results demonstrate that the K-kit developed in this paper can be useful for observing living organisms and monitoring biological processes in situ.

Two soluble 1,4,5,8-naphthalenetetracarboxylic diimide (NTCDI) derivatives with phenylmethyl and (trifluoromethyl)benzyl groups (NTCDI-P and NTCDI-F, respectively) were synthesized and used as semiconductor layers in organic thin-film transistors (OTFTs) by a spin-coating process in air. These two synthesized materials were characterized by 1 H NMR and UV-vis spectra as well as mass analysis. The morphology and crystallinity of spin-coated NTCDI-P and NTCDI-F films have been inspected using atomic force microscopy (AFM) and X-ray diffraction (XRD), respectively. The channel mobilities of these two NTCDI derivatives were calculated to be about 1.2 × 10 -3 cm 2 V -1 s -1 in air, which degraded slightly while stabilized for NTCDI-F OTFTs after exposure in air for 1 month.

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In this study, the feasibility using atomic force microscopy (AFM) to study the interaction between bacteriophages (phages) and bacteria in situ was demonstrated here. Filamentous phage M13 specifically infects the male Escherichia coli, which expresses F-pili. After infection, E. coli become fragile and grows at a slower rate. AFM provides a powerful tool for investigating these changes in a near-physiological environment. Using high-resolution AFM in phosphate-buffered saline, the damage to the lipopolysaccharide (LPS) layer on the outer membrane of the M13 phage-infected E. coli was observed. The membrane became smoother and more featureless compared to those that were not infected. Besides, the force-distance (f-d) curves were measured to reveal the surface rigidity change in E. coli after M13 phage infection. The effective spring constant and Young's modulus of E. coli decreased after M13 phage infection. Furthermore, the AFM tip was pressed against E. coli to study the response of E. coli under load before and after M13 phage infection. The results showed that after infection E. coli became less rigid and the membrane was also damaged. However, the stiffness changes, including the spring constant and Young's modulus of E. coli, are negligible after M13 phage infection compared with those in previous reports, which may be one of the reasons that E. coli still can maintain its viability after filamentous phage infection.