DNA nanotechnology-based nucleic acid delivery systems for bioimaging and disease treatment.

Nucleic acids, including DNA and RNA, have been considered as powerful and functional biomaterials owing to their programmable structure, good biocompatibility, and ease of synthesis. However, traditional nucleic acid-based probes have always suffered from inherent limitations, including restricted cell internalization efficiency and structural instability. In recent years, DNA nanotechnology has shown great promise for the applications of bioimaging and drug delivery. The attractive superiorities of DNA nanostructures, such as precise geometries, spatial addressability, and improved biostability, have enabled them to be a novel category of nucleic acid delivery systems for biomedical applications. In this review, we introduce the development of DNA nanotechnology, and highlight recent advances of DNA nanostructure-based delivery systems for cellular imaging and therapeutic applications. Finally, we propose the challenges as well as opportunities for the future development of DNA nanotechnology in biomedical research.

Modification of benzoindenothiophene-based organic dye with fused thiophenes for efficient dye-sensitized solar cells.

Recently low-energy-gap benzoindenothiophene (BIT)-based organic dyes have been experimentally sensitized to dye-sensitized solar cells (DSSCs) with impressive 10.9% power conversion efficiency. This paper presents a computational study of the modification of BIT-based dyes with fused thiophene moieties to build novel low band gap sensitizers. Density functional theory (DFT), tight-binding DFT, and time dependent DFT (TDDFT) approaches are used to demonstrate the electronic and optical properties of the BIT dyes and dye/(TiO2)46 complexes. Our calculations show that the structural modification by using fused thiophenes can effectively lower the band gap of the BIT dyes by 0.07-0.12 eV and affect the optical properties of BIT dyes. Enlarging the thiophene unit in BIT with thienothiophene and dithienothiophene improves the oscillator strength by 14%-25%, while the lowest-energy absorption peak basically remains at 559 nm. The incorporation of cyclopentadithiophene unit leads to a significant 47 nm red-shift of absorption peak and a 25% enhanced oscillator strength, compared to the original BIT dye. Those fused thiophenes modified BIT dyes also demonstrate ideal molecular orbital distribution patterns and ultra-fast injection time at the dye/(TiO2)46 interface. Our calculations provide useful guidance for the molecular design of novel naphthalene-based dyes for DSSC optimizations.