| The gas-liquid interface is an asymmetric,inhomogeneous,multi-phase special structure ranging from the surface of oceans and lakes to atmospheric aerosols to human alveoli.The molecular properties and chemical processes at the gas-liquid interface play an important role in various scientific and technological fields.Nanobubbles(NBs),as spherical nanoscale gas-phase objects with special gas-liquid interfaces and existing in bulk water,also possess various unique properties of gasliquid interfaces,such as surface charge distribution,the orientation of water molecules,adsorption and repulsion of ions and solutes,and modification of the processes and rates of various chemical reactions.In addition,the gas-liquid interface of NBs is very different from the conventional flat-water interface due to the specificity of size generation.For example,greater potential resistance effect,more regular arrangement,huge interface-body comparison,and the ability to act without being confined to the surface of the water body.The main research of this paper is summarized as follows.Part Ⅰ: Dehydration condensation reactions are an important class of biochemical reactions;however,they are thermodynamically and kinetically unfavorable when carried out in the aqueous phase,i.e.,the reactions spontaneously tend to proceed in the reverse direction(aqueous decomposition).The solution to this problem in modern organisms is to use a large number of enzymes to accelerate the reaction by transferring molecules with excess water to a suitable water-deficient environment to remove water through a series of reactions.However,in the early days of life,there were necessarily no such sophisticated enzymes to perform the necessary reactions for dehydration condensation to produce macromolecules.The dehydration-condensation reactions of biomolecules at that time usually required demanding conditions such as solid-phase reactions,high concentrations of reactants,high temperatures,and high salt or mineral catalysis,but these conditions were difficult to meet at the site of origin of life.In recent years,the gas-liquid interface is able to solve the paradox due to its special properties such as water deficiency and electric field.However,the prevalent gas-liquid interface is far from the site of origin of life(deep sea)and it is difficult to solve the problem of dehydration and condensation of biomolecules.Fortunately,NBs can provide a large number of gas-liquid interfaces in the water phase,and the environment with low temperature,high pressure,and gas-rich in the deep ocean provides a basis for the existence of NBs.In summary,it is worth exploring whether NBs can solve the problem of dehydration and condensation of biomolecules in the aqueous phase.In this work,the effect of NBs on the structure of copper ions and the reaction of the two together to catalyze the condensation of glycine to form peptides were investigated.XAFS results showed that NBs decreased the number of coordination water molecules,increased the coordination distance,and decreased the valence state of copper ions.The IR and MS also demonstrated that NBs and copper ions can catalyze the formation of a series of oligopeptides in an aqueous solution over seven days.These results suggest that NBs may play an important role in prebiotic chemistry.The second part: Reactive Oxygen Species(ROS)accompany normal cellular metabolism in living organisms.At appropriate concentrations,they play an important role in cellular physiological processes,but above a threshold,they cause oxidative damage to a variety of important cellular components such as DNA.In normal physiological function,"oxidative stress" occurs when the balance between oxidants and antioxidants tilts toward oxidants.Various antioxidants have specific benefits,such as significantly reducing the risk of age-related macular degeneration and reducing the risk of atherosclerosis in patients with hyperlipidemia.However,many clinical trials have demonstrated that antioxidant supplementation is beneficial only for the treatment of acute diseases caused by oxidative stress,but not for chronic diseases caused by oxidative stress.Possible reasons for this have been attributed to the depleting conventional reducing agents,whose antioxidant capacity is not sustainable.Secondly,high doses of exogenous antioxidants and oxidation products place a huge burden on normal cells.Third,conventional antioxidants have difficulty reaching target organs and tissues.Finally,many antioxidants are susceptible to environmental influences and degradation during storage and transport.Studies have shown that the gas-liquid interface can enrich and modulate ROS.current studies have focused on accelerating oxidation through the gas-liquid interface,which we believe is also capable of antioxidants.It is envisioned that if the area of the gas-liquid interface is smaller than the substrate,it is more inclined to enrich ROS,but there is not enough space to accommodate a larger substrate and short-lived ROS will be enriched at the interface and self-extinguish.NBs can meet this requirement due to their nanoscale gas-liquid interface.The key to realizing the above idea is to generate sufficiently small NBs(<100 nm)comparable to the molecular scale.Therefore,it is worth exploring how to develop suitable NBs that use their gas-liquid interface for the regulation of free radicals and redox reactions to remove excess oxidation reactions.In this work,we prepared small particle size N2 and O2 NBs with particle size less than 10 nm in an ice-water mixture using the pressurization-decompression method and determined their ability to prevent the oxidation of TMB by hydroxyl radicals(OH·).The results showed that both small-size NBs showed a strong antioxidant effect on TMB with significant size dependence.The removal of NBs from the reaction system led to the restoration of TMB oxidation,suggesting that NBs did inhibit the oxidation reaction.This study provides a new solution for the removal of excess ROS from organisms in the absence of reducing agent supply. |
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