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Intercalation of drug molecules into synthetic DNA nanostructures formed through self-assembled origami has been postulated as a valuable future method for targeted drug delivery. This is due to the excellent biocompatibility of synthetic DNA nanostructures, and high potential for flexible programmability including facile drug release into or near to target cells. Such favourable properties may enable high initial loading and efficient release for a predictable number of drug molecules per nanostructure carrier, important for efficient delivery of safe and effective drug doses to minimise non-specific release away from target cells. However, basic questions remain as to how intercalation-mediated loading depends on the DNA carrier structure. Here we use the interaction of dyes YOYO-1 and acridine orange with a tightly-packed 2D DNA origami tile as a simple model system to investigate intercalation-mediated loading. We employed multiple biophysical techniques including single-molecule fluorescence microscopy, atomic force microscopy, gel electrophoresis and controllable damage using low temperature plasma on synthetic DNA origami samples. Our results indicate that not all potential DNA binding sites are accessible for dye intercalation, which has implications for future DNA nanostructures designed for targeted drug delivery.

With awareness growing that schools are disciplining and suspending minority students at alarming rates, the report provides powerful evidence that young people placed in the juvenile justice system-predominately minority males incarcerated for minor offenses-are receiving a substandard education. The report, "Just Learning: The Imperative to Transform Juvenile Justice Systems into Effective Educational Systems," argues that education for the 70,000 students in custody on any given day is setting them even further back in their ability to turn their lives around. Drawing upon the most recently available data from the nation's largest database on teaching and learning in juvenile justice systems, the report finds that the quality of the learning programs for incarcerated youth have had "little positive, enduring impact on the educational achievement of most children and youth in state custody." In 2009, for example, most "longer-term" students (those enrolled for 90 days or more) whose progress was documented failed to make any significant improvement in learning and academic achievement. Incarcerated youth in smaller facilities closer to their local communities actually made less progress than students enrolled in state systems. That was particularly true in the 15 Southern states, where the proportion of students enrolled in local facilities increased from 21 percent of all incarcerated students in 2007 to almost 60 percent in 2011. Part of the problem, the report says, is that the programs, which serve youth with serious learning and emotional problems, provide young people with limited supports. Taken as a whole, the report found that effects of juvenile justice programs are "profound and crippling," and set young people back when they should be turning lives around. However, it says that education in juvenile justice programs can be successful. It cites programs such as the Maya Angelou Academy in Washington, D.C., that use teaching and learning approaches that have proven to be effective for many high-risk students and in the general population. It also highlights research on an innovative educational program in Chicago demonstrating that cognitive behavior therapy resulted in a 44 percent reduction in violent crime arrests among participants during the program, as well as gains in schooling, measured by days in attendance, GPA, and school persistence. The report closes by describing a key strategy for creating positive turning points, potential economic gains from effective education, and by providing recommendations. The following are appended: (1) Youth in Residential Placement in Juvenile Justice Systems By Race, State, and Region: 2010; (2) A Void and Confusion of Data in Juvenile Justice Systems; (3) Calculations and Methodology; and (4) Measures of Academic Achievement-Neglected, Delinquent, and At-Risk Youth by State and Region: 2011. [Foreword by Kent McGuire. For the summary of this report, see ED555853.]

We present a modelling framework, and basic model parameterization, for the study of DNA origami folding at the level of DNA domains. Our approach is explicitly kinetic and does not assume a specific folding pathway. The binding of each staple is associated with a free-energy change that depends on staple sequence, the possibility of coaxial stacking with neighbouring domains, and the entropic cost of constraining the scaffold by inserting staple crossovers. A rigorous thermodynamic model is difficult to implement as a result of the complex, multiply connected geometry of the scaffold: we present a solution to this problem for planar origami. Coaxial stacking and entropic terms, particularly when loop closure exponents are taken to be larger than those for ideal chains, introduce interactions between staples. These cooperative interactions lead to the prediction of sharp assembly transitions with notable hysteresis that are consistent with experimental observations. We show that the model reproduces the experimentally observed consequences of reducing staple concentration, accelerated cooling and absent staples. We also present a simpler methodology that gives consistent results and can be used to study a wider range of systems including non-planar origami.

DNA nanostructures are made using synthetic DNA strands, the sequences of which are designed such that they will self-assemble into the desired form by hybridization of complementary domains. Various structures and devices have been presented, including DNA tweezers, nanorobots and a range of linear motors such as bipedal walkers. Inspiration for the latter is drawn from naturally occurring molecular motors like kinesin. This paper describes a concept for an autonomous rotary nanomotor made from DNA, which utilizes the well-known and widely-studied phenomenon of toehold-mediated DNA strand displacement. The motor is to be driven by a series of strand displacement reactions, the order of which is controlled by steric constraints arising from the secondary structure of the DNA strands comprising the motor mechanism. The capabilities of DNA motors would be extended significantly if autonomous rotary motion could be achieved. The device has a range of potential applications, including molecular computation and single-molecule manipulation., Comment: 14 pages, 8 figures