Authors:	Chen, Zhijun
Title:	Near-infrared-sensitive materials based on photoresponsive ruthenium(II) polypyridyl complexes-functionalized lanthanide-doped upconverting nanoparticles
Online publication date:	20-Apr-2017
Year of first publication:	2017
Language:	english
Abstract:	Photosensitive ruthenium(II) polypyridyl complexes (Ru complexes) show lots of applications in bio-medical area as they can be photocleaved to release a ligand by low-intensity visible/red light. However, visible/red light cannot penetrate deep tissue, which will hinder its further application in vivo. NIR light is preferred for bio-medical applications as it can penetrate through the deep tissue. Thus, construction of near-infrared (NIR)-sensitive Ru complexes for bio-meidcal use is necessary. For this purpose, lanthanide-doped upconverting nanoparticles (UCNPs) are introduced. UCNPs can convert NIR light to UV/visible light, which can be used by Ru complexes. As a result, NIR-sensitive Ru complexes assisted by UCNPs (UCNP-assisted Ru complexes) are developed through combination of UCNPs and Ru complexes. UCNP-assisted Ru complexes is systematically studied in this thesis and it shows lots of priorities for bio-medical applications in our study. Firstly, it can low the excitation intensity for traditional NIR-sensitive biomaterials assisted by UCNPs, which can reduce the overheating problem of high-intensity NIR irradiation (Chapter 2). Secondly, developing biomaterials based on UCNP-assisted Ru complexes can solve several challenges in bio-meidcal area including patterning biomaterials (Chapter 3), pH manipulation in biological systems (Chapter 4) and cellular enzyme photoinhibition (Chapter 5). Besides demonstrating application of UCNP-assisted Ru complexes in bio-medical area, a new type of NIR-triggered photocoupling technology for bio-medical use is also developed in this thesis (Chapter 6). In the chapter 2, we demonstrate UCNP-assisted Ru complexes can be triggered by low-intensity NIR light. We synthesized five photosensitive compounds including two Ru complexes with different absorption bands. A 974-nm laser was used to induce photoreactions of these photosensitive compounds in the presence of the UCNPs. The excitation thresholds of the photoreactions induced by 974-nm light were measured. Our results indicate that the threshold for UCNP-assisted Ru complexes can be reduced to 0.5 W/cm2, which is lower than the maximum permissible exposure of skin (0.726 W/cm2). Low excitation intensity in UCNP-assisted Ru complexes is important for biomedical applications because it minimizes the overheating problems of NIR light and causes less photodamage to biomaterials. In the chapter 3, we demonstrate that NIR light can be used for photolithography of biomaterials via UCNP-assisted Ru complexes. A blue-lightcleavable Ru complex (Ru1) and polyethylene glycol (PEG) were co-grafted onto the UCNP-decorated substrate. Proteins were adsorbed onto the surface via electrostatic interactions between the negatively charged proteins and the positively charged Ru complexes. For the patterning of proteins, a photomask was positioned between the NIR light and the proteins. In the exposed areas, UCNPs convert NIR light into blue light that induces cleavage of the Ru complexes and the local release of proteins. Protein patterns can be fabricated in this manner. In the chapter 4, pH manipulation is also developed based on UCNP-assisted Ru complexes. NIR light can be used to manipulate the pH of aqueous solutions by using upconverting nanoparticle-assisted photocleavage of a ruthenium complex photobase. Upconverting nanoparticles and the photobase were also introduced into a pH-responsive hydrogel, in which NIR irradiation induced swelling of the hydrogel. In the chapter 5, NIR photoinhibition of enzyme activities in living cells is developed using UCNP-assisted Ru complexes. To construct a platform for PUEI, a NaYF4:TmYb@NaYF4 UCNP and caged enzyme inhibitors (RuEI) are encapsulated in a hollow mesoporous silica nanoparticle (hmSiO2). UCNPs can convert NIR light to blue light, which can uncage enzyme inhibitor (EI) from RuEI upon NIR irradiation. After NIR photoactivation, the released EI can inhibit the activities of the cathepsin K enzyme in cells. In the chapter 6, a new type of NIR-triggered photocoupling technology assisted by UCNPs is developed. We report nitrile imine-mediated tetrazole-ene cycloadditions (NITEC) in the presence of UCNPs. The combination of NITEC and UCNPs technology was exploited for small molecule cycloadditions, polymer end-group modification and the formation of block copolymers from functional macromolecular precursors, constituting the first example of a NIR-induced cycloaddition. As the technique was attractive for potential in vivo applications, through-tissue experiments in the presence of a biologically relevant biotin coupling species were carried out. Quantitative cycloadditions and retention of biological activity of the biotin units were possible at 974 nm irradiation.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-3872
URN:	urn:nbn:de:hebis:77-diss-1000012577
Version:	Original work
Publication type:	Dissertation
License:	In Copyright
Information on rights of use:	https://rightsstatements.org/vocab/InC/1.0/
Extent:	VIII, 149 Seiten
Appears in collections:	JGU-Publikationen