Search

DNA origami involves the folding of long single-stranded DNA into designed structures that may aid the development of useful nanomechanical DNA devices. In this study, DNA origami pliers and forceps are shown to undergo conformational changes on single-molecule binding.

Self-propelled molecular entities enable studying swarm behavior on a macroscopic scale but programmability of interactions has yet not been achieved. Here the authors show reversible regulation of DNA-functionalized microtubules by DNA signals and switching between solitary and swarm behaviour by employing photoresponsive DNA strands.

We developed a very quick and convenient preparative method for an injectable polymer (IP) formulation to overcome solubility problems of IPs. We investigated the effects of various additives on the dispersion time and gelation behavior for triblock polymers composed of poly(ɛ-caprolactone-co-glycolic acid) (PCGA) and PEG, and found that the addition of PEG with appropriate molecular weight was the best for quick preparation of IP suspension exhibiting temperature-responsive sol–gel transition. This method should be very convenient for usage at clinical scene.

A ‘box-shaped’ three-dimensional (3D) DNA origami of ~40-nm dimensions was selectively formed by closing a symmetric open motif with three orthogonal faces. This 3D DNA origami was used as an intelligent nano-container to encapsulate exactly one 10-nm gold nanoparticle (AuNP). AuNPs were functionalized with thiol-modified DNA strands and attached to one of the faces of the open motif, which was designed to be an interior surface of the box and decorated with three complementary strands. The open motif was then closed into the box shape as triggered by the addition of DNA strands joining the remaining edges. An examination of the suitable folding path of an M13 scaffold using fluorescently labeled staple strands revealed that the flexibility at the hinge was essential for the efficient closing of the DNA origami container. Atomic force microscope and transmission electron microscope imaging of agarose-gel-purified complexes clearly showed the successful encapsulation of one AuNP inside the shell.

DNA nanotechnology has enabled precise bottom-up integration of metal nanoparticles (NPs) on a nanometer scale. The DNA origami technique facilitated still more complicated control of the positioning not only in 2 dimensional (D) but also in 3D structures. We constructed an alternating streptavidin/gold NP heteroarray with 26 nm separation using a nanometer-sized cavity (a DNA well) embedded in a 2-nm-thick DNA origami sheet. The basic idea and other recent examples of such metal NP arrays on DNA nanostructures are reviewed.

The maintenance of stem cells multipotency and control of the differentiation direction are important for these applications in tissue engineering. We explored whether the multipotency of adipose derived stem cells (AdSCs) is maintained when they are removed from injectable polymer (IP) hydrogels with various degrees of cross-linking and induced to differentiate into osteoblasts and adipocytes. We confirmed that AdSCs cultured in IP hydrogels maintained an undifferentiated state. However, when cultured in an IP hydrogel, their multipotency was reduced.

On the gelation of thermogelling polymer solutions, polymer chain transfer between the micelles and subsequent aggregation of the micelles are important steps. In this study, we investigated polymer chain transfer by the fluorescence resonance energy transfer (FRET) method to reveal its role in the sol-to-gel transition. We synthesized amphiphilic triblock copolymer attaching naphthalene or dansyl groups at termini, tri-PCG-nap and tri-PCG-dan. The FRET behavior of the mixture of tri-PCG-nap/tri-PCG micelles and tri-PCG-dan/tri-PCG micelles was investigated.