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Success of tumor photothermal immunotherapy requires a system that induces heat stress in cancer cells and enhances strong anti-tumor immune responses. Here, we designed a composite-type immunostimulatory DNA hydrogel consisting of a hexapod-like structured DNA (hexapodna) with CpG sequences and gold nanoparticles. Mixing of the properly designed hexapodna and oligodeoxynucleotide-modified gold nanoparticles resulted in the formation of composite-type gold nanoparticle-DNA hydrogels. Laser irradiation of the hydrogel resulted in the release of hexapodna, which efficiently stimulated immune cells to release proinflammatory cytokines. Then, EG7-OVA tumor-bearing mice received an intratumoral injection of a gold nanoparticle-DNA hydrogel, followed by laser irradiation at 780 nm. This treatment increased the local temperature and the mRNA expression of heat shock protein 70 in the tumor tissue, increased tumor-associated antigen-specific IgG levels in the serum, and induced tumor-associated antigen-specific interferon-γ production from splenocytes. Moreover, the treatment significantly retarded the tumor growth and extended the survival of the tumor-bearing mice.

We previously demonstrated that polypod-like structured DNA, or polypodna, constructed with three or more oligodeoxynucleotides (ODNs), is efficiently taken up by immune cells such as dendritic cells and macrophages, depending on its structural complexity. The ODNs comprising the polypodna should bend to form the polypod-like structure, and may do so by adopting either a bendtype conformation or a cross-type conformation. Here, we tried to elucidate the orientation and bending of ODNs in polypodnas using atomic force microscopy (AFM). We designed two types of pentapodnas (i.e., a polypodna with five pods) using 60- to 88-base ODNs, which were then immobilized on DNA origami frames. AFM imaging showed that the ODNs in the pentapodna adopted bend-type conformations. Tetrapodna and hexapodna also adopted bend-type conformations when they were immobilized on frames under unconstrained conditions. These findings provide useful information toward the coherent design of, and the structure–activity relationships for, a variety of DNA nanostructures.

We carried out synchrotron X-ray scattering experiments from four DNA supermolecules designed to form tetrapod shapes; these supermolecules had different sequences but identical numbers of total base pairs, and each contained an immunostimulatory CpG motif. We confirmed that the supermolecules did indeed form the expected tetrapod shape. The sample that had the largest radius of gyration (Rg) induced the most cytokine secretion from cultured immune cells. Structural analysis in combination with a rigid tetrapod model and an atomic scale DNA model revealed that the larger Rg can be ascribed to dissociation of the DNA double strands in the central connecting portion of the DNA tetrapod. This finding suggests that the biological activity is related to the ease with which single DNA strands can be formed.

1Department of Information Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan 2Department of Information and Media Studies, Nagoya Bunri University, 365 Maeda, Inazawa-cho, Inazawa, Aichi 492-8520, Japan 3Graduate School of Engineering Human and Artificial Intelligent Systems, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan 4Facility of Home Ergonomics, Kobe Women’s University, 2-1 Aoyama, Higashisuma, Suma-ku, Kobe 654-8585, Japan ∗E-mail address: miyao@nagoya-u.jp

A few studies have evaluated swaying motion of the body in the seated posture; however, these studies did not evaluate motion sickness caused by watching movies, traveling, etc. This study aimed to analyze stabilograms recorded while the individuals were seated. Stabilometry was performed on 7 healthy male subjects (age, 21–22 years) in the seated position 5 min before, and at 5-min intervals from 5 to 60 min after alcohol load. Alcohol caused a decrease in the cerebellar equilibrium function that controls the vestibulospinal reflex. We adjusted the degree of simulative effect on the human equilibrium function. The stabilograms of the test subjects were analyzed according to the area of sway, total locus length, and total locus length per unit area. We found that significant alcohol-induced changes in the sway values in the seated posture were similar to those in the upright posture.