We developed a robust method to construct large-scale multi-layered assemblies with orthogonally oriented stripes on a capillary tube using a confined evaporative self-assembly (CESA) method. A mixture of conductive polymer poly(3-hexylthiophene) (P3HT) and biocompatible polylactic acid (PLA) was chosen as the model polymer and the molecular chain orientation of P3HT in an individual stripe could be assessed by laser confocal polarization Raman spectroscopy. These structures could provide contact cues to guide the growth of smooth muscle cells for potential tissue engineering applications.

•Highly alignment of anisotropic nanoparticles within hydrogel was developed.•TMVs displayed an ordered assembly structures in the gel state of alginate.•Concentrations of hydrogel and TMVs affected the orientation degree of final structures.•The hydrogels with defined structures have potential applications in variety of fields.Controlling the alignment of anisotropic nanoparticles within a three-dimensional (3D) environment over large-scale is still a challenge. In this paper, a facile method to align rod-like nanoparticles in hydrogel via shear flow to afford a long-range order is reported. The rod-like tobacco mosaic virus (TMV) was employed as a prototypical anisotropic particles in the study, and the shear force provided by the unidirectional flow of the precursor solution direct the alignment of TMVs, which could be quickly fixed through the fast sol-gel transition in situ. The degree of orientation and the distance between the TMV particles could be regulated by adjusting the concentration of hydrogels and TMVs. While the introduction of TMVs could reduce the degree of swelling of the hydrogel and help maintaining the mechanical strength of resultant hydrogels, both repulsion interaction and shear flow contributed synergistically to the assembly. This method does not require the usage of strong magnetic or electric fields, nor does it require the use of specialized lithography, thus offers a facile way to the fabrication of hydrogel materials with control of anisotropic structural features.Download high-res image (199KB)Download full-size image

3D tubular structures containing spatially distributed conductive stripe patterns of poly(3-hexylthiophene) (P3HT) and polylactic acid (PLA) were generated using a confined evaporative self-assembly (CESA) method on a flexible polyimide (PI) film. These tubular structures could provide contact cues to guide the growth and alignment of pre-osteoblasts and smooth muscle cells. In addition, the spatially electric signals from the conductive stripes could regulate the proliferation and osteogenic differentiation of pre-osteoblasts. This simple and effective strategy has the potential to mimic tubular tissues and has great promise in bone, cardiac and neural tissue engineering applications.

Stable and monodisperse phenylboronic acid-functionalized nanoparticles (PBA-NPs) were fabricated using the 3-((acrylamido)methyl)phenylboronic acid homopolymer (PBAH) via the solvent displacement technique. The effect of operating parameters, including stirring time, initial polymer concentration and the proportion of methanol, on the self-assembly process was systematically investigated. The diameters of PBA-NPs were increased by increasing the initial PBAH concentration and the proportion of methanol. Likewise, there was a linear dependence between the size of self-assembled nanoparticles and the polymer concentration. Moreover, the dissipative particle dynamics (DPD) simulation technique was used to investigate the mechanism of self-assembly behavior of the PBAH, which indicated that the interior of PBA-NPs was hydrophobic and compact, and boronic acid groups were displayed on both the exterior and interior of PBA-NPs. The resulting PBA-NPs could successfully encapsulate emodin through PBA–diol interaction and the encapsulation efficiency (EE%) and drug loading content (DLC%) of drug-loaded PBA-NPs were 78% and 2.1%, respectively. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from 7.4 to 5.0 could trigger the disassociation of the boronate ester bonds, which could accelerate the drug release from PBA–emodin-NPs. Besides, PBA–emodin-NPs showed a much higher cytotoxicity to HepG2 cells (cancer cells) than MC-3T3-E1 cells (normal cells). These results imply that PBA-NPs would be a promising scaffold for the delivery of polyphenolic drugs.

The generation of transplantable β-cells from pancreatic progenitor cells (PPCs) could serve as an ideal cell-based therapy for diabetes. Because the transplant efficiency depends on the size of islet-like clusters, it becomes one of the key research topics to produce PPCs with controlled cluster sizes in a scalable manner. In this study, we used inkjet printing to pattern biogenic nanoparticles, i.e., mutant tobacco mosaic virus (TMV), with different spot sizes to support the formation of multicellular clusters by PPCs. We successfully achieved TMV particle patterns with variable features and sizes by adjusting the surface wettability and printing speed. The spot sizes of cell-adhesive TMV mutant arrays were in the range of 50–150 μm diameter. Mouse PPCs were seeded on the TMV-RGD (arginine–glycine–aspartate)-patterned polystyrene (PS) substrate, which consists of areas that either favor (TMV-RGD) or prohibit (bare PS) cell adhesion. The PPCs stably attached, proliferated on top of the TMV-RGD support, thus resulting in the formation of uniform and confluent PPC clusters. Furthermore, the aggregated PPCs also maintained their multipotency and were positive for E-cadherin, indicating that the formation of cell–cell junctions is critical for enhanced cell–cell contact.Keywords: cell cluster; inkjet printing; pancreatic progenitor cell; surface pattern; tobacco mosaic virus;

We report here the construction of a bacteriophage M13-templated supramolecular nanosystem, i.e. M13-β-CD/Ada-FITC/Ada-RhB, which can be used as effective ratiometric fluorescent sensors for intracellular sensing.

We report a facile and robust route to fabrication of large area patterns of poly(3-hexylthiophene) (P3HT) by a controlled evaporative self-assembly (CESA) technique using mixed solvents. The alignment, self-assembly and patterning were achieved simultaneously in one step. Chain orientation via this method compares favorably with that attained by mechanical forces.

A facile and robust route to fabricate large area patterns of poly(3-hexylthiophene) (P3HT) was developed by controlled evaporative self-assembly (CESA) technique within a confined space (capillary tubes). Properties of P3HT, solvents effects and inner surface properties of the capillary tube were systematically investigated. The results showed that the patterns could be controlled to evolve from dot deposits and stripes with fingering instabilities, to highly regular, nearly perfect stripes. The orientation of P3HT within an individual stripe was characterized through confocal polarized Raman spectroscopy at molecular level, which revealed that the backbone chains of P3HT were parallel to the contact line. This simple method therefore provides a universal approach to control the morphology of patterns and chain orientation of functional polymers simultaneously.

Electroactive nanofibers were fabricated by in situ polymerization of aniline on the surface of tobacco mosaic virus (TMV) using sodium poly(styrenesulfonate) (PSS) as dopant. These electroactive TMV/PANi/PSS nanofibers were employed to support growth of neuronal cells, resulting in augmentation of the length of neurites. In addition, the percentage of cells with neurites was increased in comparison to cells cultured on TMV-derived nonconductive nanofibers. The TMV-based electroactive nanofibers could be aligned in capillaries that could guide the outgrowth direction of neurites, increase the percentage of cells with neurites, and lead to a bipolar cellular morphology. Our results demonstrate that the electroactivity and topographical cues provided by TMV/PANi/PSS nanofibers can synergistically stimulate neural cells differentiation and neurites outgrowth, which make it a promising scaffolding material for neural tissue engineering.

Simulation for the smooth muscle layer of blood vessel plays a key role in tubular tissue engineering. However, fabrication of biocompatible tube with defined inner nano/micro-structure remains a challenge. Here, we show that a biocompatible polymer tube from poly(l-lactide) (PLLA) and polydimethylsiloxane (PDMS) can be prepared by using electrospinning technique, with assistance of rotating collector and parallel auxiliary electrode. The tube has circumferentially aligned PLLA fibers in the inner surface for cell growth regulation and has a PDMS coating for better compressive property. MTT assay showed the composite PLLA/PDMS tube was suitable for various cells growth. In vitro smooth muscle cells (SMCs) cultured in the tube showed that the aligned PLLA fibers could induce SMCs’ orientation, and different expression of α-SMA and OPN genes were observed on the aligned and random PLLA fibers, respectively. The successful fabrication of composite PLLA/PDMS tubular scaffold for regulating smooth muscle cells outgrowth has important implications for tissue-engineered blood vessels.Keywords: alignment; cell culture; electrospinning; phenotype; smooth muscle cells; tubular scaffold;

A facile and robust method to align one-dimensional (1D) nanoparticles (NPs) in large scale has been developed. Using flow assembly, representative rod-like nanoparticles, including tobacco mosaic virus (TMV), gold nanorods, and bacteriophage M13, have been aligned inside glass tubes by controlling flow rate and substrate surface properties. The properties of 1D NPs, such as stiffness and aspect ratio, play a critical role in the alignment. Furthermore, these hierarchically organized structures can be used to support cell growth and control the cell orientation and morphology. When C2C12 myoblasts were cultured on surfaces coated with aligned TMV, we found that nanoscale topographic features were critical to guide the cell orientation and myogenic differentiation. This method can therefore be used in the fabrication of complex assemblies with 1D NPs and have wide applications in tissue engineering, sensing, electronics, and optical fields.Keywords: 1D nanoparticles; alignment; capillary; myogenic differentiation; self-assembly; tobacco mosaic virus

Stable and monodisperse phenylboronic acid-functionalized nanoparticles (PBA-NPs) were fabricated using the 3-((acrylamido)methyl)phenylboronic acid homopolymer (PBAH) via the solvent displacement technique. The effect of operating parameters, including stirring time, initial polymer concentration and the proportion of methanol, on the self-assembly process was systematically investigated. The diameters of PBA-NPs were increased by increasing the initial PBAH concentration and the proportion of methanol. Likewise, there was a linear dependence between the size of self-assembled nanoparticles and the polymer concentration. Moreover, the dissipative particle dynamics (DPD) simulation technique was used to investigate the mechanism of self-assembly behavior of the PBAH, which indicated that the interior of PBA-NPs was hydrophobic and compact, and boronic acid groups were displayed on both the exterior and interior of PBA-NPs. The resulting PBA-NPs could successfully encapsulate emodin through PBA–diol interaction and the encapsulation efficiency (EE%) and drug loading content (DLC%) of drug-loaded PBA-NPs were 78% and 2.1%, respectively. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from 7.4 to 5.0 could trigger the disassociation of the boronate ester bonds, which could accelerate the drug release from PBA–emodin-NPs. Besides, PBA–emodin-NPs showed a much higher cytotoxicity to HepG2 cells (cancer cells) than MC-3T3-E1 cells (normal cells). These results imply that PBA-NPs would be a promising scaffold for the delivery of polyphenolic drugs.

We report here the construction of a bacteriophage M13-templated supramolecular nanosystem, i.e. M13-β-CD/Ada-FITC/Ada-RhB, which can be used as effective ratiometric fluorescent sensors for intracellular sensing.