Control of crosslinking of single chain nanoparticles by double wavelength light

Protein is a biopolymer with amino acid as its basic unit, which plays an extremely important role in almost all life activities Scholars have found that it can play such an important role in the study of protein structure and function, which is inseparable from its own advanced structure Therefore, it has become a research hotspot in chemistry, materials science, life science and other fields to accurately synthesize polymers to imitate protein folding and molecular transport functions Single chain nanoparticles (scnps) is a kind of material constructed by single chain nanotechnology, which has a wide range of uses, strong self-healing, high intelligent response, and can accurately control its own size and specific functions through various methods Scnps has become a great general in protein structure simulation materials Recently, Professor Christopher Barner kowollik of Queensland University of science and technology in Australia has developed a single chain orthogonal cross-linking technology (Figure 1a), which is not limited by the irradiation sequence The introduction of cross-linking reaction in the synthesis process is the most promising strategy to realize the four-stage structure simulation of protein based on single chain nanotechnology Compared with the reaction controlled by thermodynamics, photochemical reaction can control the spatial structure of protein more accurately Based on the cycloaddition of styrene pyrene and anthracene, the orthogonal cross-linking system was designed The scnps were successfully prepared from long wavelength to short wavelength and from short wavelength to long wavelength This achievement was published in German Applied Chemistry (DOI: 10.1002 / anie 201811541) under the title of "controlling chain coupling and single chain restriction by two colors of visible light" Fig 1 A) schematic diagram of scnp1 co peg prepared by different ways; B) The cycloaddition reaction of styrene pyrene; the cycloaddition reaction of C) 9-triazolyl anthracene (picture source: angel Chem Int ED) the structure of polymer matrix needs to meet two requirements: first, in order to obtain the secondary or tertiary structure, the polymer matrix should have the group which can carry out intramolecular crosslinking Second, in order to be able to carry out intermolecular cross-linking with other polymers, the other cross-linking groups on the polymer parent cannot react with the previous cross-linking groups In order to meet these two requirements, 9-triazolyl anthracene (Fig 1c) and styrene pyrene (Fig 1b) were introduced into the polymer skeleton to realize intramolecular and intermolecular crosslinking reactions, respectively Fig 2 A) molecular structure and reaction process of polymer matrix P1, scnp1 and scnp1 co peg; b) sec diagram of P1 after different long-term illumination; c) sec diagram before and after scnp1 illumination (picture source: angelw Chem Int ED) The study of polymer folding performance started from the sequence of short wave length to long wave length, because 330 nm The wavelength of light does not cause the dimerization of styryl pyrene, while anthracene will undergo [4 + 4] cycloaddition reaction Therefore, the author first illuminated the polymer matrix P1, and found that with the extension of light time, the molecular weight of the system decreased significantly, and reached stability in 10 minutes (Fig 2B) The results of NMR DOSY show that the hydrodynamic volume of P1 decreases by about 20%, which also confirms the author's conjecture After obtaining scnp1 with second or third order structure, the author considers how to selectively introduce another polymer chain to simulate the fourth order structure Since the cycloaddition product of anthracene does not decompose under 455 nm light, the author polymerized the styrypyrene on scnp1 with another styrypyrene containing PEG chain under 455 nm light, and obtained scnp1 co PEG (Fig 2a) The results of size exclusion chromatography (SEC) showed that the molecular weight of the polymer increased from 9800 g / mol to 14100 g / mol (Fig 2C) After that, the author tried to prepare the same polymer in the order of long wavelength to short wavelength The intermolecular crosslinking based on styrene pyrene was still carried out by 455 nm light, but 330 nm light caused the dimer of styrene pyrene to decompose (Figure 1b), so the author chose 410 nm Scnp1 co peg was also obtained by intramolecular crosslinking of short wavelength light Table 1 Physical properties of scnp1 co peg obtained by different ways (picture source: angelw Chem Int ED) Finally, the author compares some physical properties parameters of the polymers obtained by these two methods (Table 1) The results show that their molecular weight, volume and hydrodynamic diameter are very small, which shows that The preparation of the polymer is not affected by the light sequence Author: Hendrik Frisch, Fabian R bloesser and Christopher Barner kowollik.