Combination of supramolecular chemistry and nanomaterials: regulation of host guest interaction on cell phagocytosis of gold nanoparticles

Nanomaterials refer to materials with at least one dimension in the three-dimensional structure on the nanometer scale Because the electronic, magnetic and optical properties of materials can be controlled by changing the size, shape and composition of materials, nanomaterials have a wide range of potential applications in the fields of electricity, optics and information communication At the same time, nano materials, similar to many biomolecules and biological systems in size, can also have various functions after modification, so nano technology has great biomedical application value At present, nanomaterials have been used to carry diagnostic and therapeutic reagents, mediate the interaction between biomolecules and detect changes in the molecular level of organisms in a highly sensitive and high-throughput way Gold nanoparticles (AuNPs), also known as colloidal gold, are one of the most studied nanomaterials due to their direct and simple synthesis method, stable properties of the synthesized gold nanoparticles, as well as the photoelectric properties and good biocompatibility of all nanomaterials However, gold nanoparticles usually enter into cells through endocytosis, which has higher requirements on the size, shape and surface properties of nanoparticles In general, only nanoparticles with appropriate size and positive electric properties can enter cells with high efficiency, while neutral and negative nanoparticles are more difficult At the same time, compared with the single environment of solution, many substances in biological solution, such as protein, will affect the properties of nanoparticles Therefore, even if nanoparticles are electropositive in solution, they will become electronegative because of protein encapsulation In addition, the process of nanoparticles entering cells is usually spontaneous and difficult to control, so how to effectively regulate this process is the focus and difficulty of scholars Recently, Professor Luis M Liz marza ́ n of CIC biomagune research center in Spain and Jesu ́ s Mosquera of ikerbasque Foundation reported the method of controlling cell phagocytosis of gold nanoparticles by host guest combination (Figure 1) Although it has been found that cell phagocytosis of gold nanoparticles can be controlled by adjusting the solubility, aggregation and photophysical properties of gold nanoparticles, these methods are only limited to gold nanoparticles responsive to pH, and cannot be used as a general method The interaction of solvent green 7 (Pyr) and tetrahedral host compound (cage a) has successfully regulated the process of phagocytosis of gold nanoparticles, and it has been found that this highly selective host guest recognition behavior can ensure the efficient phagocytosis of cells even in the biological solution rich in protein This achievement was published in the Journal of the American Chemical Society (DOI: 10.1021 / JACS 7b1255) under the title of "cellular uptake of gold nanoparticles triggered by host − guestinteractions" Figure 1 The structure of host and guest molecules and their combined regulation of cell phagocytosis of gold nanoparticles (photo source: J am Chem SOC 2018, 140, 4469 − 4472) firstly, the gold nanoparticles (NP2) loaded with solvent green 7 were prepared by the improved brust Schiffrin method and the conventional NHS reaction The prepared gold nanoparticles and their combination with cage a were characterized by ζ - potential, TEM and UV / Vis The results show that the size of NP2 is about 2 nm, and the size of NP2 with cage a is about 2 nm as expected Before binding, the surface was electronegative (− 15 ± 1 MV) However, when combined with the main compound cage a (0.2eq), the surface potential of gold nanoparticles will rapidly change to + 15 ± 2 MV, while increasing the content of the main compound will further increase the surface potential of gold nanoparticles After confirming that the binding of cage a will change the surface potential of gold nanoparticles, the authors studied the effect of cage a on the process of phagocytosis of gold nanoparticles in cell environment, and found that HeLa cells did not actively phagocytize NP2 (one hour incubation result) However, in the presence of cage a, the phagocytosis of cells to nanoparticles is significantly enhanced Moreover, even in the DMEM solution rich in protein, cage a can effectively enhance the phagocytosis of HeLa cells to gold nanoparticles (Fig 2) Fig 2 The effect of cage a on the phagocytosis of NP2 by HeLa cells (photo source: J am Chem SOC 2018, 140, 4469 − 4472) in addition, because the host guest interaction is competitive, the authors speculate that the phagocytosis of gold nanoparticles can be regulated by regulating the proportion of host guest compounds In order to confirm this conjecture, the author observed the phagocytosis of gold nanoparticles by changing the ratio of host and guest compounds repeatedly The results showed that the phagocytosis of gold nanoparticles almost stopped when the solvent green 7 was excessive, and the phagocytosis of gold nanoparticles could be restored when a proper amount of cage a was added (Fig 3) Figure 3 Host guest regulated cell phagocytosis of gold nanoparticles (photo source: J am Chem SOC 2018, 140, 4469 − 4472) Full text author: Jes ú s mosquara, Malou Henriksen Lacey, Isabel Garc í a, Miguel mart í Nez Calvo, J é ssica Rodr í Guez, Jos L Mascare ñ as, and Luis M Liz marz á n