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Hexadecyltrimethylammonium bromide (CTAB), which is necessary for the preparation of gold nanorods (NRs), was extracted from a NR solution into a chloroform phase containing phosphatidylcholine (PC). After three extractions, the zeta potential of the NRs remained positive, but its magnitude decreased from +67 +/- 1 to +15 +/- 1 mV. Transmission electron microscopy and energy-dispersive X-ray analysis indicated that the NRs were passivated with PC. The PC layer on the NR surface contributed to the prevention of NR aggregation. The PC-passivated NRs showed low cytotoxicity in comparison with twice-centrifuged NRs. It was shown that a negligible amount of CTAB was dispersed in the NR solution after the extraction. The extraction using a chloroform phase containing PC was found to be a convenient way of replacing the CTAB with alternative capping agents such as PC. This is a key technique for preparing functional NRs that can have practical applications.

Novel thermoresponsive polymer brush surfaces for harvesting cell sheet were fabricated by the surface-initiated RAFT polymerization of N-isopropylacrylamide (IPAAm) on azoinitiator-immobilized glass substrates in the presence of dithiobenzoate compound as a chain transfer agent (CTA). The chain length of the grafted PIPAAm on the surface was controlled by changing CTA concentration. Additionally, PIPAAm graft density on the surface was successfully regulated by grafting from azoinitiator-immobilized surfaces with various densities. By adjusting both the chain length and the density of grafted PIPAAm, a series of thermoresponsive polymer brush surfaces were prepared to regulate cell adhesion/detachment behavior by solely temperature change across the PIPAAm's lower critical solution temperature of 32 degrees C. PIPAAm brush surfaces were successfully optimized to recover the cell sheets of bovine carotid artery endothelial cells. Additionally, the immunostaining study revealed that the cell sheets can be recovered with their intact extracellular matrix (ECM) from PIPAAm surfaces, indicating that the cell sheets can be effectively transplanted to damaged tissues and organs.

Pulsed near-infrared laser irradiation induced release of plasmid DNA immobilized on gold nanorods without structural degradation, by selective excitation of longitudinal plasmon oscillation.

Newly developed fabrication technique of thermoresponsive surface using RAFT-mediated block copolymerization and photolithography achieved stripe-like micropatterning of poly(N-isopropylacrylamide) (PIPAAm) brush domains and poly(N-isopropylacrylamide)-b-poly(N-acryloylmorpholine) domains. Normal human dermal fibroblasts were aligned on the physicochemically patterned surfaces simply by one-pot cell seeding. Fluorescence images showed the well-controlled orientation of actin fibers and fibronectin in the confluent cell layers with associated extracellular matrix (ECM) on the surfaces. Furthermore, the aligned cells were harvested as a tissue-like cellular monolayer, called "cell sheet" only by reducing temperature below PIPAAm's lower critical solution temperature (LCST) to 20 °C. The cell sheet harvested from the micropatterned surface possessed a different shrinking rate between vertical and parallel sides of the cell alignment (approximately 3:1 of aspect ratio). This indicates that the cell sheet maintains the alignment of cells and related ECM proteins, promising to show the mechanical and biological aspects of cell sheets harvested from the functionalized thermoresponsive surfaces.

In some parts of native tissues, the orientation of cells and/or extracellular matrixes is well organized. We know that because anisotropy produces important tissue functions, an appropriate anisotropy needs to be designed to biomimetically construct complex tissue. Here, we show the unique features of anisotropic myoblast sheets for organizing the three-dimensional (3D) orientation of myoblasts and myotubes. Utilizing a micropatterned thermoresponsive surface, human skeletal muscle myoblasts were aligned on the surface, and manipulated as a single anisotropic cell sheet by reducing the culture temperature. Consequently, layering of anisotropic myoblast sheets using gelatin gel allowed 3D myotube constructs to be built up with the desired anisotropy. We also discovered a surprising myoblast behavior. An anisotropic cell sheet placed on top of other cell sheets in fabricating thick tissue was able to change the cell orientation in several layered cell sheets underneath. This self-organization is believed to provide the uniqueness required in designing 3D cell orientation architecture for reconstructed muscle tissue.

High-fidelity surface functional group (e.g., N-hydroxysuccinimide (NHS) reactive ester) patterning is readily and reliably achieved on commercial poly(ethylene glycol) (PEG)-based polymer films already known to exhibit high performance non-fouling properties in full serum and in cell culture conditions. NHS coupling chemistry co-patterned with methoxy-capped PEG using photolithographic methods is directly spatially imaged using imaging time-of-flight secondary ion mass spectrometry (ToF-SIMS) and principal components statistical analysis. Patterned NHS surface reactive zones are clearly resolved at high sensitivity despite the complexity of the polymer matrix chemistry. ToF-SIMS imaging also reveals the presence of photo-resist residue remaining from typical photolithography processing methods. High cross-correlation between various ion-derived ToF-SIMS images is observed, providing sensitive chemical corroboration of pattern chemistry and biological reactivity in complex milieu. Surface-specific protein coupling is observed first by site-selective reaction of streptavidin with NHS patterns, followed by identical patterns of biotinylated Alexa-labeled albumin coupling. This suggests that streptavidin immobilized on the patterns remains bioactive. Fluorescently labeled full serum is shown to react selectively with NHS-reactive regions, with minimal signal from methoxy-capped regions. Insufficient serum is adsorbed under any conditions to these surfaces to support cell attachment in serum-containing media. This reflects the high intrinsic non-adsorptive nature of this chemistry. Fibroblasts attach and proliferate in serum culture only when a cell adhesion peptide (RGD) is first grafted to NHS regions on the PEG-based surfaces. Longer-term serum-based cell culture retains high cell-pattern fidelity that correlates with chemical imaging of both the NHS and RGD patterns and also lack of cell adhesion to methoxy-capped regions. Cell staining shows orientation of adherent cells within the narrow patterned areas. Cell patterns are consistently retained beyond 15 days in serum media.

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