Self-assembling Systems Utilize DNA to Overcome Metastability Constraint

Professor Liang Haojun of the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) has proposed a new approach for catalytic assembly of escape from steady states in a far-from-equilibrium system of DNA-functionalized colloids. The study has been published in Proceedings of the National Academy of Sciences.

Self-assembly refers to the process in which assembled primitive elements (molecules, nanoparticles, etc.) spontaneously form ordered structures through non-covalent interactions. The system’s excellent ability to create new materials has attracted attention. In the perfect aggregation process, the system will reach a dynamically stable state with the least free energy and form a high-quality aggregation structure. However, for a collector system far from equilibrium, the system is prone to be stuck in susceptibility where the local free energy is extremely small, which precludes the formation of a high-quality collector structure.

How to circumvent metastasis in a system far from equilibrium is a difficult puzzle in the field of self-assembly. For DNA-activated nanoparticle assembly, which is a model system far from equilibrium, an entropy-controlled thermal annealing strategy constitutes a conventional and generally accepted method of evasability escape. However, the accumulation and dispersion of nanoparticles usually occurs over a narrow temperature range during annealing. When correcting for discontinuous non-covalent bonds, thermoenergy is not selective. Thermal annealing is not conducive to the aggregation of biologically active molecules or under physiological conditions.

Inspired by the concept of “catassembly” proposed by academician Tian Zhongqun of Xiamen University, Professor Liang and his team presented a new method for realizing catalytic assembly of DNA-driven colloidal nanoparticles in a system far from equilibrium. Basing their predictions on theoretical simulations and the results of previous research on a strategy of continuous enthalpy control for nanoparticle assembly, they used a removable molecule called a ‘pool’, which acts as a catalyst, to adjust imperfect bonds and help the system escape diffuse stability while maintaining the framework. The complex.

In this strategy, a short DNA strand acting as an accelerator has a direct competitive effect with the bonding end on the surface of nanoparticles within the assembly structure, and the non-covalent bonding of the missense splice can be corrected by the transient DNA strand replacement reaction, to help the system escape metastasis. During the process, the accelerator will not destroy the overall structure of the assembly structure, and it can be removed from the final assembly structure. Moreover, by changing the structural design of the accelerator, he could even reduce the dosage of the accelerator and improve its efficiency.

On the basis of the same principle, superlattice structures with different crystal symmetries can be obtained by changing the nucleation type of nanoparticles in a two-component system and adding the corresponding DNA accelerator directly after designing the DNA sequence. This strategy facilitates the implementation of nanoparticle aggregation as the chemical reaction takes place at a constant temperature.

Furthermore, this DNA accelerator regulation strategy is simple and efficient enough that the ‘solid-solid’ phase conversion between different colloidal crystals becomes easier to achieve, after breaking the constraints of temperature regulation and the initial free-energy phase state. It displays its application potential in structurally reconfigurable “solid–solid” inorganic biological compounds.

As a general method for regulating non-covalent interactions within assembly structures, the acceleration strategy proposed in this study is expected to be extended to control and innovation of assembly processes for other soft material systems (polypeptides, block copolymers, etc.) that are far from equilibrium.