ABSTRACT
Controlling the assembly of molybdenum disulfide (MoS2) layers into static and dynamic superstructures can impact on their use in optoelectronics, energy, and drug delivery. Toward this goal, we present a strategy to drive the assembly of MoS2 layers via the hybridization of complementary DNA linkers. By functionalizing the MoS2 surface with thiolated DNA, MoS2 nanosheets were assembled into mulitlayered superstructures, and the complementary DNA strands were used as linkers. A disassembly process was triggered by the formation of an intramolecular i-motif structure at a cystosine-rich sequence in the DNA linker at acidic pH values. We tested the versatility of our approach by driving the disassembly of the MoS2 superstructures through a different DNA-based mechanism, namely strand displacement. This study demonstrates how DNA can be employed to drive the static and dynamic assembly of MoS2 nanosheets in aqueous solution.
Subject(s)
Molybdenum , Nanostructures , DNA , Drug Delivery Systems , Nucleic Acid HybridizationABSTRACT
Herein a strategy is presented for the assembly of both static and stimuli-responsive single-molecule heterostructures, where the distance and electronic coupling between an individual functional nanomoiety and a carbon nanostructure are tuned via the use of DNA linkers. As proof of concept, the formation of 1:1 nanohybrids is controlled, where single quantum dots (QDs) are tethered to the ends of individual carbon nanotubes (CNTs) in solution with DNA interconnects of different lengths. Photoluminescence investigations-both in solution and at the single-hybrid level-demonstrate the electronic coupling between the two nanostructures; notably this is observed to progressively scale, with charge transfer becoming the dominant process as the linkers length is reduced. Additionally, stimuli-responsive CNT-QD nanohybrids are assembled, where the distance and hence the electronic coupling between an individual CNT and a single QD are dynamically modulated via the addition and removal of potassium (K+) cations; the system is further found to be sensitive to K+ concentrations from 1 pM to 25 × 10-3 m. The level of control demonstrated here in modulating the electronic coupling of reconfigurable single-molecule heterostructures, comprising an individual functional nanomoiety and a carbon nanoelectrode, is of importance for the development of tunable molecular optoelectronic systems and devices.
ABSTRACT
BACKGROUND: Adults with congenital heart disease are a relatively new population that progressively increases in size and complexity. In Italy, there are no accurate data concerning the distribution of congenital defects and the long-term outcome relating to both congenital heart disease per se and comorbidities, due to the aging process. METHODS: The Piedmont Adult Congenital Heart Disease Registry has been designed to investigate these aspects and to support a high quality healthcare development for grown-up congenital heart patients. Within 2 years, 459 consecutive patients routinely followed in 10 divisions of cardiology in Piedmont were included in the project. Electronic dedicated software has supported data collection. RESULTS: Mean age of patients is 35 ± 16 years. Septal defects are the most common type of congenital heart disease (35.3%). At baseline evaluation, 71.7% of patients reported a previous surgical and/or percutaneous treatment and 6.3% an electrophysiological procedure. Freedom from intervention is 44%, 81% and 56% at the age of 18, 30 and 45 years, respectively. Patients who had a treatment during infancy show a better intervention-free survival (p=0.038) compared with patients treated during adulthood. Despite the majority of the population had an almost preserved functional status, 27.5% had ≥1 long-term sequelae (arrhythmias 27.5%; pulmonary hypertension 5.2%; neurological problems 4.1%; cyanosis 4.8%; liver dysfunction 2.4%; enteropathy 2.4%; lung disease 2.2%). During 2 years of follow-up, the estimated mortality rate is 0.88%. CONCLUSIONS: Adults with congenital heart disease are a heterogeneous population of relatively young patients with relevant clinical and social problems. The late sequelae related to both the underlying heart disease and the advancing age require continuous monitoring and lifelong specialized care.
