Nicotinamide adenine dinucleotide(NAD^(+))reduction enabled by an atomically precise Au-Ag alloy nanocluster

The redox property of the ultrasmall coinage nanoclusters(with several to tens of Au/Ag atoms)has elucidated the electrontransfer capacity of nanoclusters,has been successfully utilized in a variety of redox conversions(such as from CO_(2)to CO).Nevertheless,their biological applications are mainly restricted by the scarcity of atomically precise,water-soluble metal nanoclusters,the limited application(mainly on the decomposition of H_(2)O_(2)in these days).Herein,mercaptosuccinic acid(MSA)protected ultrasmall alloy AuAg nanoclusters were prepared,the main product was determined[Au_(3)Ag_(5)(MSA)_(3)]−by electrospray ionization mass spectrometry(ESI-MS).The clusters can not only mediate the decomposition of H_(2)O_(2)to generate hydroxyl radicals,but is also able to mediate the reduction of nicotinamide adenine dinucleotide(NAD)to its reduced form of NADH.This is the first time that the atomically precise metal nanoclusters were used to mediate the coenzyme reduction.The preliminary mechanistic insights imply the reaction to be driven by the hydrogen bonding between the carboxylic groups(on the surface of MSA)and the amino N–H bonds(on NAD).In this context,the presence of the carboxylic groups,the sub-nanometer size regime(~1 nm),the synergistic effect of the Au-Ag clusters are pre-requisite to the NAD reduction.

Simple, fast, label-free, and nanoquencher-free system for operating multivalued DNA logic gates using polythymine templated CuNPs as signal reporters

Boolean logic devices play a key role in both traditional and nontraditional molecular logic circuits. This kind of binary logic, in which each bit is coded by （0, 1）, has only two output states--on or off （or high/low）. Because of the finite computing capacity and variation, it is facing challenges from multivalued logic gates while processing high-density or uncertain/imprecise information. However, a low-cost, simple, and universal system that can perform different multivalued logic computations has not yet been developed, and remains a concept for further study. Herein, taking the ternary OR and INHIBIT logic gates as model devices, we present the fabrication of a novel simple, fast, label-flee, and nanoquencher-free system for multivalued DNA logic gates using poly-thymine （T） templated copper nanoparticles （CuNPs） as signal reporters. The mixture of Cu2~ and ascorbic acid （AA） is taken as a universal platform for all ternary logic gates. Different kinds of poly-T strands and delicately designed complementary poly-adenine （A） strands are alternatively applied as ternary inputs to exhibit the ternary output states （low/0, medium/1, high/2）. Notably, there are no nanoquenchers in this platform as poly-A strands can function as not only inputs but also efficient inhibitors of poly-T templated CuNPs. Moreover, all DNA are unlabeled single-strand DNA that do not need sophisticated labeling procedures or sequence design. The above design greatly reduces the operating time, costs, and complexity. More importantly, the ternary logic computations can be completed within 20 min because of the fast formation of CuNPs, and all of them share the same threshold values.

Engineering DNA logic systems with non-canonical DNA-nanostructures:basic principles,recent developments and bio-applications

Engineering DNA logic systems is considered as one of the most promising strategies for next-generation molecular computers.Owing to the inherent features of DNA,such as low cost,easy synthesis,and controllable hybridization,various DNA logic devices with different functions have been developed in the recent decade.Besides,a variety of logic-programmed biological applications are also explored,which initiates a new chapter for DNA logic computing.Although this field has gained rapid developments,a systematical review that could not only elaborate the logic principles of diverse DNA logic devices but also outline recent representative works is urgently needed.In this review,we first elaborate the general classification and logical principle of diverse DNA logic devices,in which the operating strategy of these devices and representative examples are selectively presented.Then,we review state-of-the-art advancements in DNA computing based on different non-canonical DNA-nanostructures during the past decade,in which some classical works are summarized.After that,the innovative applications of DNA computing to logic-controlled bioanalysis,cell imaging,and drug load/delivery are selectively presented.Finally,we analyze current obstacles and suggest appropriate prospects for this area.