Application of Two-Photon Absorbing Fluorene-Containing Compounds in Bioimaging and Photodyanimc Therapy

Two-photon absorbing (2PA) materials has been widely studied for their highly localized excitation and nonlinear excitation efficiency. Application of 2PA materials includes fluorescence imaging, microfabrication, 3D data storage, photodynamic therapy, etc. Many materials have good 2PA photophysical properties, among which, the fluorenyl structure and its derivatives have attracted attention with their high 2PA cross-section and high fluorescence quantum yield. Herein, several compounds with 2PA properties are discussed. All of these compounds contain one or two fluorenyl core units as part of the conjugated system. The aim of this dissertation is to discuss the application of these compounds according to their photophysical properties. In chapters 2 to 4, compounds were investigated for cell imaging and tissue imaging. In chapter 5, compounds were evaluated for photodynamic therapy effects on cancer cells. Chapters 2 and 3 detail compounds with quinolizinium and pyran as core structures, respectively. Fluorene was introduced into structures as substituents. Quinolizinium structures exhibited a large increase in fluorescence when binding with Bovine Serum Albumin (BSA). Further experiments in cell imaging demonstrated a fluorescence turn-on effect in cell membranes, indicating the possibility for these novel compounds to be promising membrane probes. Pyran structures were conjugated with arginylglycylaspartic acid peptide (RGD) to recognize integrin and introduced in cells and an animal model with tumors. Both probes showed specific targeting of tumor vasculature. Imaging reached penetration as deep as 350 µm in solid tumors and exhibited good resolution. These results suggest the RGD-conjugated pyran structure should be a good candidate probe for live tissue imaging. Chapter 4 applied a fluorene core structure conjugated with RGD as well. Application of this fluorenyl probe compound is in wound healing animal models. Fluorescence was collected from vasculature and fibroblasts up to ≈ 1600 µm within wound tissue in lesions made on the skin of mice. The resolution of images is also high enough to recognize cell types by immunohistochemical staining. This technology can be applied for reliable quantification and illustration of key biological processes taking place during tissue regeneration in the skin. Chapter 5 describes three fluorenyl core structures with photoacid generation properties. One of the structures showed excellent photo-induced toxicity. Cancer cells underwent necrotic cell death due to pH decrease in lysosomes and endosomes, suggesting a new mechanism for photodynamic therapy

Deep Vascular Imaging in Wounds by Two-Photon Fluorescence Microscopy

Deep imaging within tissue (over 300 mu m) at micrometer resolution has become possible with the advent of two-photon fluorescence microscopy (2PFM). The advantages of 2PFM have been used to interrogate endogenous and exogenous fluorophores in the skin. Herein, we employed the integrin (cell-adhesion proteins expressed by invading angiogenic blood vessels) targeting characteristics of a two-photon absorbing fluorescent probe to image new vasculature and fibroblasts up to approximate to 1600 mu m within wound (neodermis)/granulation tissue in lesions made on the skin of mice. Reconstruction revealed three dimensional (3D) architecture of the vascular plexus forming at the regenerating wound tissue and the presence of a fibroblast bed surrounding the capillaries. Biologically crucial events, such as angiogenesis for wound healing, may be illustrated and analyzed in 3D on the whole organ level, providing novel tools for biomedical applications

Altered intestinal microbiota enhances adenoid hypertrophy by disrupting the immune balance

IntroductionAdenoid hypertrophy (AH) is a common upper respiratory disorder in children. Disturbances of gut microbiota have been implicated in AH. However, the interplay of alteration of gut microbiome and enlarged adenoids remains elusive.Methods119 AH children and 100 healthy controls were recruited, and microbiome profiling of fecal samples in participants was performed using 16S rRNA gene sequencing. Fecal microbiome transplantation (FMT) was conducted to verify the effects of gut microbiota on immune response in mice.ResultsIn AH individuals, only a slight decrease of diversity in bacterial community was found, while significant changes of microbial composition were observed between these two groups. Compared with HCs, decreased abundances of Akkermansia, Oscillospiraceae and Eubacterium coprostanoligenes genera and increased abundances of Bacteroides, Faecalibacterium, Ruminococcus gnavus genera were revealed in AH patients. The abundance of Bacteroides remained stable with age in AH children. Notably, a microbial marker panel of 8 OTUs were identified, which discriminated AH from HC individuals with an area under the curve (AUC) of 0.9851 in the discovery set, and verified in the geographically different validation set, achieving an AUC of 0.9782. Furthermore, transfer of mice with fecal microbiota from AH patients dramatically reduced the proportion of Treg subsets within peripheral blood and nasal-associated lymphoid tissue (NALT) and promoted the expansion of Th2 cells in NALT.ConclusionThese findings highlight the effect of the altered gut microbiota in the AH pathogenesis

Near-Ir Two-Photon Fluorescent Sensor For K\u3csup\u3e+\u3c/sup\u3e Imaging In Live Cells

A new two-photon excited fluorescent K+ sensor is reported. The sensor comprises three moieties, a highly selective K+ chelator as the K+ recognition unit, a boron-dipyrromethene (BODIPY) derivative modified with phenylethynyl groups as the fluorophore, and two polyethylene glycol chains to afford water solubility. The sensor displays very high selectivity (\u3e52-fold) in detecting K+ over other physiological metal cations. Upon binding K+, the sensor switches from nonfluorescent to highly fluorescent, emitting red to near-IR (NIR) fluorescence. The sensor exhibited a good two-photon absorption cross section, 500 GM at 940 nm. Moreover, it is not sensitive to pH in the physiological pH range. Time-dependent cell imaging studies via both one- and two-photon fluorescence microscopy demonstrate that the sensor is suitable for dynamic K+ sensing in living cells

Pag-Based Photodyanmic Therapy In Cancer Cells

We report custom-made photoacid generators (PAGs) that produced a pH drop within HCT 116 cells via one- or two-photon absorption, an alternative PDT modality to selectively induce cell death in oxygen-deprived tissue such as tumors. ©Optics in the Life Sciences Congress Technical Digest

Pag-Based Photodyanmic Therapy In Cancer Cells

We report custom-made photoacid generators (PAGs) that produced a pH drop within HCT 116 cells via one- or two-photon absorption, an alternative PDT modality to selectively induce cell death in oxygen-deprived tissue such as tumors. © 2013 The Optical Society (OSA)

Selective Cell Death By Photochemically Induced Ph Imbalance In Cancer Cells

Singlet oxygen sensitized photodynamic therapy (PDT) relies on the concentration of oxygen in the tissue to be treated. Most cancer lesions, however, have poor vasculature and, as a result, are hypoxic, significantly hindering PDT efficacies. An oxygen-independent PDT method may circumvent this limitation. To address this, we prepared sulfonium salts that produced a pH drop within HCT 116 cells via the generation of a photoacid within the cytosol. This process was driven by one- or two-photon absorption (1PA or 2PA) of the endocytosed photoacid generators (PAGs). One of these PAGs, which had a significantly lower dark cytotoxicity and was more efficient in generating a photoacid, effectively induced necrotic cell death in the HCT 116 cells. The data suggest that PAGs may be an attractive alternative PDT modality to selectively induce cell death in oxygen-deprived tissue such as tumors. © 2013 American Chemical Society

Pag-Based Photodyanmic Therapy In Cancer Cells

We report custom-made photoacid generators (PAGs) that produced a pH drop within HCT 116 cells via one- or two-photon absorption, an alternative PDT modality to selectively induce cell death in oxygen-deprived tissue such as tumors. Optics in the Life Sciences Congress Technical Digest © 2013 The Optical Society (OSA)

Near-Infrared Fluorescent 4,4-Difluoro-4-Bora-3A,4A-Diaza-S-Indacene Probes For One- And Two-Photon Fluorescence Bioimaging

Two new two-photon absorbing near-infrared (NIR) emitting 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives, DDC and SDC, were designed for one- and two-photon fluorescence microscopy imaging. Linear and nonlinear photophysical properties, including UV/Vis absorption, fluorescence, excitation anisotropy, photostability, and two-photon absorption cross sections, of the dyes were investigated to assess the potential of using the new probes as bioimaging agents. Cell viability and colocalization studies of DDC with Lysotracker Red, in COS 7 and HCT 116 cells demonstrated not only low toxicity but also selective targeting of lysosomes. SDC was encapsulated in silica-based nanoparticles for in vitro and ex vivo fluorescence bioimaging. The nanoparticles were modified with an RGD peptide to target αVβ3 integrin. The nanoprobe exhibited good biocompatibility and highly selective uptake in αVβ3 integrin-overexpressing cancers

Does Science Literacy Guarantee Resistance to Health Rumors? The Moderating Effect of Self-Efficacy of Science Literacy in the Relationship between Science Literacy and Rumor Belief

Health rumors not only incite unnecessary fears and skepticism, but may also cause individuals to refuse effective remedy and thus delay their treatment. Studies have found that health literacy may help the public identify the falsity of health rumors and avoid their negative impact. However, whether other types of literacy work in helping people disbelieve health rumors is still unknown. With a national survey in China (N = 1646), our study examined the effect of science literacy on rumor belief and further analyzed the moderating role of self-efficacy of science literacy in their relationship. Hierarchical regression analysis showed that science literacy significantly decreased the likelihood of people believing in health rumors, and moderator analysis showed that self-efficacy of science literacy plays a moderating role in this relationship; such that the relationship between science literacy and health rumor belief would be weakened if one′s self-efficacy of science literacy was low. This finding reveals that during campaigns to combat health rumors, improving and enhancing the self-efficacy of people′s science literacy is an effective way to prevent them from believing in health rumors. Our study highlights the benefits of science education in public health and the improvement of public science literacy